ASN Kidney Week 2011

PHILADELPHIA – Poor glycemic control is associated with decreased survival in diabetes patients on maintenance hemodialysis, according to a study presented at Kidney Week 2011.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh of the Harbor-UCLA Medical Center in Torrance, Calif.

Although some guidelines, such as those from the National Kidney Foundation Kidney Disease Outcomes Quality Initiative, recommend that diabetic dialysis patients follow the American Diabetes Association targets for glycemic control (hemoglobin A_1c less than 7%), "there is no consistent evidence to support these targets in dialysis patients," Dr. Kalantar-Zadeh said, noting that recent studies with different methodologies have reached opposing conclusions.

To determine the predictive value of glycemic control on mortality, Dr. Kalantar-Zadeh and his colleagues evaluated the association between HbA_1c and random serum glucose and survival in a large, contemporary cohort of diabetes patients treated at DaVita dialysis clinics from July 2001 to June 2006 with follow-up through June 2007.

Of 164,789 hemodialysis patients, the investigators identified 54,757 with diabetes for whom HbA_1c data were available, and analyzed death hazard ratios according to HbA_1c values and serum glucose levels, Dr. Kalantar-Zadeh explained. The adjusted all-cause death hazard ratio for baseline HbA_1c increments of 8.0%-8.9%, 9.0%-9.9%, and 10% or greater, respectively, were 1.06, 1.05, and 1.19, compared with a reference HbA_1c value of 7.0%-7.9%; the respective all-cause death hazard ratios for time-averaged HbA_1c were 1.11, 1.36, and 1.59, he said, noting that "a similarly consistent increase in cardiovascular mortality" was also observed.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh.

In fully adjusted models, decreased survival was also directly associated with time-averaged HbA_1c levels in the low range, with all-cause-death hazard ratios of 1.05, 1.08, and 1.35, respectively, for baseline HbA_1c values of 6.0-6.9%, 5.0-5.9%, and less than 5%, compared with 7.0-7.9%, Dr. Kalantar-Zadeh said. Further, the adjusted all-cause-death hazard ratios for time-averaged blood glucose levels of 175-199 mg/dL, 200-249 mg/dL, 250-299 mg/dL, and 300 mg/dL or higher were 1.03, 1.14, 1.30, and 1.66, respectively, compared with the reference range of 150-175 mg/dL.

The results are limited by the fact that HbA_1c levels are known to significantly underestimate glycemic control in hemodialysis patients, Dr. Kalantar-Zadeh acknowledged at the meeting, sponsored by the American Society of Nephrology. Also, "the information on comorbidity in our study was limited to that obtained from Medical Evidence Form 2728, in which comorbid conditions are significantly underestimated," he said. Lastly, "the study data did not include information on diabetes medication used at home or treatment adherence."

Limitations notwithstanding, the findings indicate that poor glycemic control (defined as HbA_1c of 8% or greater or a serum glucose level of 200mg/dL) is associated with death in diabetes patients on maintenance hemodialysis, and, unlike most diabetic patients, "those with kidney failure do not benefit from HbA_1c levels lower than 7%," Dr. Kalantar-Zadeh said. It appears that the most beneficial percentage is somewhere inside 6-8% in this patient population, "although controlled clinical trials to target HbA_1c at 6-8% are needed to determine the optimal range," he concluded.

Dr. Kalantar-Zadeh disclosed financial relationships with Abbott, Amgen, DaVita, Fresenius, Otsuka, Shire, Vifor, the National Institutes of Health, and the National Kidney Foundation. The study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.

PHILADELPHIA – Poor glycemic control is associated with decreased survival in diabetes patients on maintenance hemodialysis, according to a study presented at Kidney Week 2011.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh of the Harbor-UCLA Medical Center in Torrance, Calif.

Although some guidelines, such as those from the National Kidney Foundation Kidney Disease Outcomes Quality Initiative, recommend that diabetic dialysis patients follow the American Diabetes Association targets for glycemic control (hemoglobin A_1c less than 7%), "there is no consistent evidence to support these targets in dialysis patients," Dr. Kalantar-Zadeh said, noting that recent studies with different methodologies have reached opposing conclusions.

To determine the predictive value of glycemic control on mortality, Dr. Kalantar-Zadeh and his colleagues evaluated the association between HbA_1c and random serum glucose and survival in a large, contemporary cohort of diabetes patients treated at DaVita dialysis clinics from July 2001 to June 2006 with follow-up through June 2007.

Of 164,789 hemodialysis patients, the investigators identified 54,757 with diabetes for whom HbA_1c data were available, and analyzed death hazard ratios according to HbA_1c values and serum glucose levels, Dr. Kalantar-Zadeh explained. The adjusted all-cause death hazard ratio for baseline HbA_1c increments of 8.0%-8.9%, 9.0%-9.9%, and 10% or greater, respectively, were 1.06, 1.05, and 1.19, compared with a reference HbA_1c value of 7.0%-7.9%; the respective all-cause death hazard ratios for time-averaged HbA_1c were 1.11, 1.36, and 1.59, he said, noting that "a similarly consistent increase in cardiovascular mortality" was also observed.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh.

In fully adjusted models, decreased survival was also directly associated with time-averaged HbA_1c levels in the low range, with all-cause-death hazard ratios of 1.05, 1.08, and 1.35, respectively, for baseline HbA_1c values of 6.0-6.9%, 5.0-5.9%, and less than 5%, compared with 7.0-7.9%, Dr. Kalantar-Zadeh said. Further, the adjusted all-cause-death hazard ratios for time-averaged blood glucose levels of 175-199 mg/dL, 200-249 mg/dL, 250-299 mg/dL, and 300 mg/dL or higher were 1.03, 1.14, 1.30, and 1.66, respectively, compared with the reference range of 150-175 mg/dL.

The results are limited by the fact that HbA_1c levels are known to significantly underestimate glycemic control in hemodialysis patients, Dr. Kalantar-Zadeh acknowledged at the meeting, sponsored by the American Society of Nephrology. Also, "the information on comorbidity in our study was limited to that obtained from Medical Evidence Form 2728, in which comorbid conditions are significantly underestimated," he said. Lastly, "the study data did not include information on diabetes medication used at home or treatment adherence."

Limitations notwithstanding, the findings indicate that poor glycemic control (defined as HbA_1c of 8% or greater or a serum glucose level of 200mg/dL) is associated with death in diabetes patients on maintenance hemodialysis, and, unlike most diabetic patients, "those with kidney failure do not benefit from HbA_1c levels lower than 7%," Dr. Kalantar-Zadeh said. It appears that the most beneficial percentage is somewhere inside 6-8% in this patient population, "although controlled clinical trials to target HbA_1c at 6-8% are needed to determine the optimal range," he concluded.

Dr. Kalantar-Zadeh disclosed financial relationships with Abbott, Amgen, DaVita, Fresenius, Otsuka, Shire, Vifor, the National Institutes of Health, and the National Kidney Foundation. The study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.

PHILADELPHIA – Poor glycemic control is associated with decreased survival in diabetes patients on maintenance hemodialysis, according to a study presented at Kidney Week 2011.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh of the Harbor-UCLA Medical Center in Torrance, Calif.

Although some guidelines, such as those from the National Kidney Foundation Kidney Disease Outcomes Quality Initiative, recommend that diabetic dialysis patients follow the American Diabetes Association targets for glycemic control (hemoglobin A_1c less than 7%), "there is no consistent evidence to support these targets in dialysis patients," Dr. Kalantar-Zadeh said, noting that recent studies with different methodologies have reached opposing conclusions.

To determine the predictive value of glycemic control on mortality, Dr. Kalantar-Zadeh and his colleagues evaluated the association between HbA_1c and random serum glucose and survival in a large, contemporary cohort of diabetes patients treated at DaVita dialysis clinics from July 2001 to June 2006 with follow-up through June 2007.

Of 164,789 hemodialysis patients, the investigators identified 54,757 with diabetes for whom HbA_1c data were available, and analyzed death hazard ratios according to HbA_1c values and serum glucose levels, Dr. Kalantar-Zadeh explained. The adjusted all-cause death hazard ratio for baseline HbA_1c increments of 8.0%-8.9%, 9.0%-9.9%, and 10% or greater, respectively, were 1.06, 1.05, and 1.19, compared with a reference HbA_1c value of 7.0%-7.9%; the respective all-cause death hazard ratios for time-averaged HbA_1c were 1.11, 1.36, and 1.59, he said, noting that "a similarly consistent increase in cardiovascular mortality" was also observed.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh.

In fully adjusted models, decreased survival was also directly associated with time-averaged HbA_1c levels in the low range, with all-cause-death hazard ratios of 1.05, 1.08, and 1.35, respectively, for baseline HbA_1c values of 6.0-6.9%, 5.0-5.9%, and less than 5%, compared with 7.0-7.9%, Dr. Kalantar-Zadeh said. Further, the adjusted all-cause-death hazard ratios for time-averaged blood glucose levels of 175-199 mg/dL, 200-249 mg/dL, 250-299 mg/dL, and 300 mg/dL or higher were 1.03, 1.14, 1.30, and 1.66, respectively, compared with the reference range of 150-175 mg/dL.

The results are limited by the fact that HbA_1c levels are known to significantly underestimate glycemic control in hemodialysis patients, Dr. Kalantar-Zadeh acknowledged at the meeting, sponsored by the American Society of Nephrology. Also, "the information on comorbidity in our study was limited to that obtained from Medical Evidence Form 2728, in which comorbid conditions are significantly underestimated," he said. Lastly, "the study data did not include information on diabetes medication used at home or treatment adherence."

Limitations notwithstanding, the findings indicate that poor glycemic control (defined as HbA_1c of 8% or greater or a serum glucose level of 200mg/dL) is associated with death in diabetes patients on maintenance hemodialysis, and, unlike most diabetic patients, "those with kidney failure do not benefit from HbA_1c levels lower than 7%," Dr. Kalantar-Zadeh said. It appears that the most beneficial percentage is somewhere inside 6-8% in this patient population, "although controlled clinical trials to target HbA_1c at 6-8% are needed to determine the optimal range," he concluded.

Dr. Kalantar-Zadeh disclosed financial relationships with Abbott, Amgen, DaVita, Fresenius, Otsuka, Shire, Vifor, the National Institutes of Health, and the National Kidney Foundation. The study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.

PHILADELPHIA – The detection of urinary podocytes in mid-pregnancy is a highly sensitive and specific marker for preeclampsia and may be the first reliable tool for predicting which women will develop the potentially life-threatening hypertensive complication, according to Dr. Iasmina M. Craici.

Previously, investigators determined that the urinary excretion of viable podocytes (glomerular epithelial cells) was significantly higher in patients with preeclampsia, compared with normotensive patients, and that it had a greater positive predictive value for diagnosing preeclampsia than certain specific angiogenic factors of the condition (Am. J. Obstet. Gynecol. 2007;196:320.e1-7).

"There are currently no tests that will reliably predict who will develop preeclampsia, so the possibility of being able to identify, in mid-gestation, those women who will later go on to develop preeclampsia is especially important," Dr. Craici stated. "It will give us the opportunity to implement early treatment of severe high blood pressure and by doing so will improve maternal and fetal outcomes," she said.

The current study was designed to ascertain whether podocyturia is present in the urine before the onset of preeclampsia and whether it can be used to differentiate between preeclampsia, gestational hypertension, and normal pregnancy, said Dr. Craici of the Mayo Clinic in Rochester, Minn.

From a prospective cohort of 315 patients, 267 successful deliveries were included in the final analysis. Of these, 204 women had normal pregnancies and 30 had hypertensive pregnancies, including 15 cases each of preeclampsia and gestational hypertension, Dr. Craici reported at Kidney Week 2011, sponsored by the American Society of Nephrology. The remaining 33 pregnancies were complicated by other problems, including gestational diabetes, intrauterine growth retardation, and preterm delivery, she said.

All patients had their blood pressure and protein/creatinine ratios checked at mid-gestation (weeks 25-28), prior to the onset of preeclampsia or gestational hypertension. Urine sediments collected in mid-pregnancy, prior to 210 days gestation, were cultured for 24 hours to select for viable cells, "and we identified podocytes using podocin staining," Dr. Craici explained. For purposes of the comparative analysis, 45 patients were selected from the normal pregnancy group as controls, she said, noting that there was no age difference between the groups.

At mid-pregnancy, "none of the 45 normotensive or the 15 gestational hypertensive women had podocyturia present in their urine specimens, but it was present in the urine of all of the preeclamptic women," said Dr. Craici. At this time point, she said, none of the women who would later develop preeclampsia had signs of the condition. "They did not have hypertension, nor did they yet have protein in the urine."

At delivery, podocyturia was again absent in all of the normotensive pregnancies and present in all of the preeclamptic pregnancies, Dr. Craici said, noting that it was present in only one of the women with gestational hypertension.

Dr. Craici disclosed that the technology used in this research has been licensed to a commercial entity and that senior investigator Dr. Vesna D. Garovic and the Mayo Clinic have contractual rights to receive royalties from the licensing of the technology.

PHILADELPHIA – The detection of urinary podocytes in mid-pregnancy is a highly sensitive and specific marker for preeclampsia and may be the first reliable tool for predicting which women will develop the potentially life-threatening hypertensive complication, according to Dr. Iasmina M. Craici.

Previously, investigators determined that the urinary excretion of viable podocytes (glomerular epithelial cells) was significantly higher in patients with preeclampsia, compared with normotensive patients, and that it had a greater positive predictive value for diagnosing preeclampsia than certain specific angiogenic factors of the condition (Am. J. Obstet. Gynecol. 2007;196:320.e1-7).

"There are currently no tests that will reliably predict who will develop preeclampsia, so the possibility of being able to identify, in mid-gestation, those women who will later go on to develop preeclampsia is especially important," Dr. Craici stated. "It will give us the opportunity to implement early treatment of severe high blood pressure and by doing so will improve maternal and fetal outcomes," she said.

The current study was designed to ascertain whether podocyturia is present in the urine before the onset of preeclampsia and whether it can be used to differentiate between preeclampsia, gestational hypertension, and normal pregnancy, said Dr. Craici of the Mayo Clinic in Rochester, Minn.

From a prospective cohort of 315 patients, 267 successful deliveries were included in the final analysis. Of these, 204 women had normal pregnancies and 30 had hypertensive pregnancies, including 15 cases each of preeclampsia and gestational hypertension, Dr. Craici reported at Kidney Week 2011, sponsored by the American Society of Nephrology. The remaining 33 pregnancies were complicated by other problems, including gestational diabetes, intrauterine growth retardation, and preterm delivery, she said.

All patients had their blood pressure and protein/creatinine ratios checked at mid-gestation (weeks 25-28), prior to the onset of preeclampsia or gestational hypertension. Urine sediments collected in mid-pregnancy, prior to 210 days gestation, were cultured for 24 hours to select for viable cells, "and we identified podocytes using podocin staining," Dr. Craici explained. For purposes of the comparative analysis, 45 patients were selected from the normal pregnancy group as controls, she said, noting that there was no age difference between the groups.

At mid-pregnancy, "none of the 45 normotensive or the 15 gestational hypertensive women had podocyturia present in their urine specimens, but it was present in the urine of all of the preeclamptic women," said Dr. Craici. At this time point, she said, none of the women who would later develop preeclampsia had signs of the condition. "They did not have hypertension, nor did they yet have protein in the urine."

At delivery, podocyturia was again absent in all of the normotensive pregnancies and present in all of the preeclamptic pregnancies, Dr. Craici said, noting that it was present in only one of the women with gestational hypertension.

Dr. Craici disclosed that the technology used in this research has been licensed to a commercial entity and that senior investigator Dr. Vesna D. Garovic and the Mayo Clinic have contractual rights to receive royalties from the licensing of the technology.

PHILADELPHIA – The detection of urinary podocytes in mid-pregnancy is a highly sensitive and specific marker for preeclampsia and may be the first reliable tool for predicting which women will develop the potentially life-threatening hypertensive complication, according to Dr. Iasmina M. Craici.

Previously, investigators determined that the urinary excretion of viable podocytes (glomerular epithelial cells) was significantly higher in patients with preeclampsia, compared with normotensive patients, and that it had a greater positive predictive value for diagnosing preeclampsia than certain specific angiogenic factors of the condition (Am. J. Obstet. Gynecol. 2007;196:320.e1-7).

"There are currently no tests that will reliably predict who will develop preeclampsia, so the possibility of being able to identify, in mid-gestation, those women who will later go on to develop preeclampsia is especially important," Dr. Craici stated. "It will give us the opportunity to implement early treatment of severe high blood pressure and by doing so will improve maternal and fetal outcomes," she said.

The current study was designed to ascertain whether podocyturia is present in the urine before the onset of preeclampsia and whether it can be used to differentiate between preeclampsia, gestational hypertension, and normal pregnancy, said Dr. Craici of the Mayo Clinic in Rochester, Minn.

From a prospective cohort of 315 patients, 267 successful deliveries were included in the final analysis. Of these, 204 women had normal pregnancies and 30 had hypertensive pregnancies, including 15 cases each of preeclampsia and gestational hypertension, Dr. Craici reported at Kidney Week 2011, sponsored by the American Society of Nephrology. The remaining 33 pregnancies were complicated by other problems, including gestational diabetes, intrauterine growth retardation, and preterm delivery, she said.

All patients had their blood pressure and protein/creatinine ratios checked at mid-gestation (weeks 25-28), prior to the onset of preeclampsia or gestational hypertension. Urine sediments collected in mid-pregnancy, prior to 210 days gestation, were cultured for 24 hours to select for viable cells, "and we identified podocytes using podocin staining," Dr. Craici explained. For purposes of the comparative analysis, 45 patients were selected from the normal pregnancy group as controls, she said, noting that there was no age difference between the groups.

At mid-pregnancy, "none of the 45 normotensive or the 15 gestational hypertensive women had podocyturia present in their urine specimens, but it was present in the urine of all of the preeclamptic women," said Dr. Craici. At this time point, she said, none of the women who would later develop preeclampsia had signs of the condition. "They did not have hypertension, nor did they yet have protein in the urine."

At delivery, podocyturia was again absent in all of the normotensive pregnancies and present in all of the preeclamptic pregnancies, Dr. Craici said, noting that it was present in only one of the women with gestational hypertension.

Dr. Craici disclosed that the technology used in this research has been licensed to a commercial entity and that senior investigator Dr. Vesna D. Garovic and the Mayo Clinic have contractual rights to receive royalties from the licensing of the technology.

PHILADELPHIA – Early, intensive treatment for type 1 diabetes with conventional therapy halves the long-term risk of developing an impaired glomerular filtration rate, the common pathway leading to end-stage kidney disease, Dr. Ian H. de Boer said in a late-breaking presentation at Kidney Week 2011.

He reported new data from the Diabetes Control and Complications Trial (DCCT) and the follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study demonstrating a nearly 50% reduction in the risk of glomerular filtration rate (GRF) impairment – defined as an incident estimated GFR less than 60 mL/minute per 1.73 m² of body surface area at two consecutive study visits – among individuals randomly assigned to intensive diabetes treatment versus those assigned to conventional treatment over a 22-year median follow-up.

In the multicenter DCCT, 1,441 individuals with type 1 diabetes were randomized to 6.5 years of conventional therapy (730 patients) consisting of one or two insulin injections daily designed to prevent hyperglycemic symptoms or to intensive diabetes treatment (711 patients) consisting of three or more insulin injections daily or the use of an insulin pump in an attempt to achieve a glycated hemoglobin level of less than 6.05%, "as close to the nondiabetic range as possible," Dr. de Boer reported at the meeting sponsored by the American Society of Nephrology.

The study population included patients in a primary intervention cohort who had diabetes for 1-5 years with an albumin excretion rate of less than 40 mg per 24 hours and no retinopathy and those in a secondary intervention cohort with a 1- to 15-year history of diabetes, an albumin excretion rate of 200 mg or less per 24 hours, and no more than moderate nonproliferative retinopathy, he noted.

Of the DCCT participants, 1,375 agreed to participate in the observational extension EDIC study, including a statistically similar number of patients from the intensive and conventional therapy groups, Dr. de Boer reported. As per the protocol of both studies, serum creatinine levels were measured annually.

The mean hemoglobin A_1c level during the DCCT was 7.3% in the intensive treatment group and 9.1% in the conventional therapy group. "In the EDIC years 1-16, the mean hemoglobin A_1c was nearly 8% in each group, with no clinically or statistically significant difference," said Dr. de Boer of the University of Washington in Seattle.

During the combined 22 years of follow-up for both studies, "70 patients developed impaired [GFR], including 24 who had been assigned to intensive therapy and 46 who received conventional treatment," Dr. de Boer stated, noting that most of the cases occurred during the EDIC study period. The time of the events is important, he said. "Only 4 of the 70 occurred during DCCT, and 66 occurred during EDIC study follow-up. Almost all of the events occurred more than 10 years after randomization."

The intensive therapy reduced the risk of impaired GFR by 50%, according to statistical analyses, Dr. de Boer said. Twenty years after randomization, "the cumulative incidence of an impaired GFR was 2.0% among those assigned to intensive therapy and 5.5% in those assigned to conventional therapy," representing an absolute risk reduction of 3.5%, he explained. Through the follow-up period, 8 patients in the intensive treatment group and 16 in the conventional treatment group developed end-stage kidney disease.

The reduction in the mean estimated GFR was greater in the intensive vs. conventional treatment groups during the DCCT, at a rate of 1.7 mL/min per 1.73 m², but during the EDIC study, "intensive therapy was associated with a slower rate of GFR reduction and an increase in the mean estimated GFR of 2.5 mL/min per 1.73 m²," Dr. de Boer said. After adjustment for glycated hemoglobin levels or albumin excretion rates, "the beneficial effect [of intensive therapy on the risk of GFR impairment] was fully attenuated," he noted.

The findings demonstrate the enduring kidney benefits of intensive diabetes treatment early in the disease course, according to Dr. de Boer. "After combining these data with previous reports that DCCT intensive therapy reduces the risk of retinopathy, neuropathy, albuminuria, and cardiovascular disease, these results support current recommendations to target hemoglobin A_1c in the care of patients with type 1 diabetes," he stated. The results cannot be extrapolated to the treatment of individuals with type 2 diabetes, he said.

The study results were reported concurrently with the online publication of the data (N. Engl. J. Med. 2011 Nov. 12 [doi:10.1056/NEJMoa1111732]).

The study was funded by U.S. government grants and through a Genentech Cooperative Research and Development Agreement with the National Institute of Diabetes and Digestive and Kidney Diseases. Abbott, Animas, Aventis, Bayer, Becton Dickinson, Can Am, Eli Lilly, LifeScan, Medtronic, MiniMed, Omron, OmniPod, Roche, and Sanofi-Aventis provided research supplies or equipment and the University of Washington received support from Abbott Laboratories.

PHILADELPHIA – Early, intensive treatment for type 1 diabetes with conventional therapy halves the long-term risk of developing an impaired glomerular filtration rate, the common pathway leading to end-stage kidney disease, Dr. Ian H. de Boer said in a late-breaking presentation at Kidney Week 2011.

He reported new data from the Diabetes Control and Complications Trial (DCCT) and the follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study demonstrating a nearly 50% reduction in the risk of glomerular filtration rate (GRF) impairment – defined as an incident estimated GFR less than 60 mL/minute per 1.73 m² of body surface area at two consecutive study visits – among individuals randomly assigned to intensive diabetes treatment versus those assigned to conventional treatment over a 22-year median follow-up.

In the multicenter DCCT, 1,441 individuals with type 1 diabetes were randomized to 6.5 years of conventional therapy (730 patients) consisting of one or two insulin injections daily designed to prevent hyperglycemic symptoms or to intensive diabetes treatment (711 patients) consisting of three or more insulin injections daily or the use of an insulin pump in an attempt to achieve a glycated hemoglobin level of less than 6.05%, "as close to the nondiabetic range as possible," Dr. de Boer reported at the meeting sponsored by the American Society of Nephrology.

The study population included patients in a primary intervention cohort who had diabetes for 1-5 years with an albumin excretion rate of less than 40 mg per 24 hours and no retinopathy and those in a secondary intervention cohort with a 1- to 15-year history of diabetes, an albumin excretion rate of 200 mg or less per 24 hours, and no more than moderate nonproliferative retinopathy, he noted.

Of the DCCT participants, 1,375 agreed to participate in the observational extension EDIC study, including a statistically similar number of patients from the intensive and conventional therapy groups, Dr. de Boer reported. As per the protocol of both studies, serum creatinine levels were measured annually.

The mean hemoglobin A_1c level during the DCCT was 7.3% in the intensive treatment group and 9.1% in the conventional therapy group. "In the EDIC years 1-16, the mean hemoglobin A_1c was nearly 8% in each group, with no clinically or statistically significant difference," said Dr. de Boer of the University of Washington in Seattle.

During the combined 22 years of follow-up for both studies, "70 patients developed impaired [GFR], including 24 who had been assigned to intensive therapy and 46 who received conventional treatment," Dr. de Boer stated, noting that most of the cases occurred during the EDIC study period. The time of the events is important, he said. "Only 4 of the 70 occurred during DCCT, and 66 occurred during EDIC study follow-up. Almost all of the events occurred more than 10 years after randomization."

The intensive therapy reduced the risk of impaired GFR by 50%, according to statistical analyses, Dr. de Boer said. Twenty years after randomization, "the cumulative incidence of an impaired GFR was 2.0% among those assigned to intensive therapy and 5.5% in those assigned to conventional therapy," representing an absolute risk reduction of 3.5%, he explained. Through the follow-up period, 8 patients in the intensive treatment group and 16 in the conventional treatment group developed end-stage kidney disease.

The reduction in the mean estimated GFR was greater in the intensive vs. conventional treatment groups during the DCCT, at a rate of 1.7 mL/min per 1.73 m², but during the EDIC study, "intensive therapy was associated with a slower rate of GFR reduction and an increase in the mean estimated GFR of 2.5 mL/min per 1.73 m²," Dr. de Boer said. After adjustment for glycated hemoglobin levels or albumin excretion rates, "the beneficial effect [of intensive therapy on the risk of GFR impairment] was fully attenuated," he noted.

The findings demonstrate the enduring kidney benefits of intensive diabetes treatment early in the disease course, according to Dr. de Boer. "After combining these data with previous reports that DCCT intensive therapy reduces the risk of retinopathy, neuropathy, albuminuria, and cardiovascular disease, these results support current recommendations to target hemoglobin A_1c in the care of patients with type 1 diabetes," he stated. The results cannot be extrapolated to the treatment of individuals with type 2 diabetes, he said.

The study results were reported concurrently with the online publication of the data (N. Engl. J. Med. 2011 Nov. 12 [doi:10.1056/NEJMoa1111732]).

The study was funded by U.S. government grants and through a Genentech Cooperative Research and Development Agreement with the National Institute of Diabetes and Digestive and Kidney Diseases. Abbott, Animas, Aventis, Bayer, Becton Dickinson, Can Am, Eli Lilly, LifeScan, Medtronic, MiniMed, Omron, OmniPod, Roche, and Sanofi-Aventis provided research supplies or equipment and the University of Washington received support from Abbott Laboratories.

PHILADELPHIA – Early, intensive treatment for type 1 diabetes with conventional therapy halves the long-term risk of developing an impaired glomerular filtration rate, the common pathway leading to end-stage kidney disease, Dr. Ian H. de Boer said in a late-breaking presentation at Kidney Week 2011.

He reported new data from the Diabetes Control and Complications Trial (DCCT) and the follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study demonstrating a nearly 50% reduction in the risk of glomerular filtration rate (GRF) impairment – defined as an incident estimated GFR less than 60 mL/minute per 1.73 m² of body surface area at two consecutive study visits – among individuals randomly assigned to intensive diabetes treatment versus those assigned to conventional treatment over a 22-year median follow-up.

In the multicenter DCCT, 1,441 individuals with type 1 diabetes were randomized to 6.5 years of conventional therapy (730 patients) consisting of one or two insulin injections daily designed to prevent hyperglycemic symptoms or to intensive diabetes treatment (711 patients) consisting of three or more insulin injections daily or the use of an insulin pump in an attempt to achieve a glycated hemoglobin level of less than 6.05%, "as close to the nondiabetic range as possible," Dr. de Boer reported at the meeting sponsored by the American Society of Nephrology.

The study population included patients in a primary intervention cohort who had diabetes for 1-5 years with an albumin excretion rate of less than 40 mg per 24 hours and no retinopathy and those in a secondary intervention cohort with a 1- to 15-year history of diabetes, an albumin excretion rate of 200 mg or less per 24 hours, and no more than moderate nonproliferative retinopathy, he noted.

Of the DCCT participants, 1,375 agreed to participate in the observational extension EDIC study, including a statistically similar number of patients from the intensive and conventional therapy groups, Dr. de Boer reported. As per the protocol of both studies, serum creatinine levels were measured annually.

The mean hemoglobin A_1c level during the DCCT was 7.3% in the intensive treatment group and 9.1% in the conventional therapy group. "In the EDIC years 1-16, the mean hemoglobin A_1c was nearly 8% in each group, with no clinically or statistically significant difference," said Dr. de Boer of the University of Washington in Seattle.

During the combined 22 years of follow-up for both studies, "70 patients developed impaired [GFR], including 24 who had been assigned to intensive therapy and 46 who received conventional treatment," Dr. de Boer stated, noting that most of the cases occurred during the EDIC study period. The time of the events is important, he said. "Only 4 of the 70 occurred during DCCT, and 66 occurred during EDIC study follow-up. Almost all of the events occurred more than 10 years after randomization."

The intensive therapy reduced the risk of impaired GFR by 50%, according to statistical analyses, Dr. de Boer said. Twenty years after randomization, "the cumulative incidence of an impaired GFR was 2.0% among those assigned to intensive therapy and 5.5% in those assigned to conventional therapy," representing an absolute risk reduction of 3.5%, he explained. Through the follow-up period, 8 patients in the intensive treatment group and 16 in the conventional treatment group developed end-stage kidney disease.

The reduction in the mean estimated GFR was greater in the intensive vs. conventional treatment groups during the DCCT, at a rate of 1.7 mL/min per 1.73 m², but during the EDIC study, "intensive therapy was associated with a slower rate of GFR reduction and an increase in the mean estimated GFR of 2.5 mL/min per 1.73 m²," Dr. de Boer said. After adjustment for glycated hemoglobin levels or albumin excretion rates, "the beneficial effect [of intensive therapy on the risk of GFR impairment] was fully attenuated," he noted.

The findings demonstrate the enduring kidney benefits of intensive diabetes treatment early in the disease course, according to Dr. de Boer. "After combining these data with previous reports that DCCT intensive therapy reduces the risk of retinopathy, neuropathy, albuminuria, and cardiovascular disease, these results support current recommendations to target hemoglobin A_1c in the care of patients with type 1 diabetes," he stated. The results cannot be extrapolated to the treatment of individuals with type 2 diabetes, he said.

The study results were reported concurrently with the online publication of the data (N. Engl. J. Med. 2011 Nov. 12 [doi:10.1056/NEJMoa1111732]).

The study was funded by U.S. government grants and through a Genentech Cooperative Research and Development Agreement with the National Institute of Diabetes and Digestive and Kidney Diseases. Abbott, Animas, Aventis, Bayer, Becton Dickinson, Can Am, Eli Lilly, LifeScan, Medtronic, MiniMed, Omron, OmniPod, Roche, and Sanofi-Aventis provided research supplies or equipment and the University of Washington received support from Abbott Laboratories.

PHILADELPHIA – Race, socioeconomic status, and insurance status all impact survival for children with end-stage renal disease, with poor, uninsured black children at greater risk of death than all others.

Dr. Sandra G. Amaral of Children’s Hospital of Philadelphia and her colleagues used information from the United States Renal Data System to identify racial and socioeconomic disparities associated with mortality risk in pediatric end-stage renal disease (ESRD).

"We know that, among children with [ESRD], death risk is much lower for those who receive a kidney transplant, compared with those who stay on dialysis, but we don’t know much about which children die before reaching transplant," Dr. Amaral said. "We wanted to determine whether there are racial or ethnic differences in the risk of dying when children remain on dialysis."

They identified 8,146 patients younger than 21 years who had been diagnosed with ESRD from Jan. 2000 through Sept. 2008 and followed through September 2009, looking at patients who were on dialysis but had not been transplanted and whose race/ethnicity was white, Hispanic, or black. Of the 8,146 children, 896 died before reaching transplant, she said at the meeting, sponsored by the American Society of Nephrology.

"We wanted to determine whether there are racial or ethnic differences in the risk of dying when children remain on dialysis."

Of the patients who died, 357 were white, 161 were Hispanic, and 378 were black, Dr. Amaral said. By health insurance status, 179 were privately insured, 527 were publicly insured, 87 children were uninsured, and 103 were classified as "other," she said.

The number of children who died, independent of race/ethnicity, was related to neighborhood poverty. Specifically, 304 of the children who died had lived in the poorest neighborhoods – those where at least 20% of residents were at or below the federal poverty line – compared with 80 children from the wealthiest neighborhoods in which 0 to 4.9% of the residents had incomes at or below poverty level, she said.

"We saw significant differences by race, health insurance, and poverty among patients who were alive vs. those who died, and proportionally, among all of the black patients, more died than in any other subgroup," Dr. Amaral said, adding that "more patients among those who died had public insurance and were from poorer neighborhoods."

Survival curves showed that Hispanic children had the highest rate of survival, followed by white children. "Black children had the lowest rate of survival," Dr. Amaral stated. In an analysis adjusted for age, gender, and diagnosis, "the poorest children, regardless of race, had higher mortality."

However, the risk of death among those of different ethnic backgrounds varied by type of health insurance and not by poverty. "Uninsured black children, for example, had a 78% increased risk, compared with uninsured white children," she said, while black children with private insurance had only a 19% increased risk, compared with privately insured white children.

The current findings are limited by the fact that the data set included only patients who had been diagnosed with ESRD, Dr. Amaral said.

"We don’t know what happened to them before that," she said. "There may be issues in patient access to care. It’s possible that the reason patients are not even getting wait-listed at diagnosis is that they’re too sick," she said.

Dr. Amaral disclosed having no financial conflicts of interest related to her presentation.

PHILADELPHIA – Race, socioeconomic status, and insurance status all impact survival for children with end-stage renal disease, with poor, uninsured black children at greater risk of death than all others.

Dr. Sandra G. Amaral of Children’s Hospital of Philadelphia and her colleagues used information from the United States Renal Data System to identify racial and socioeconomic disparities associated with mortality risk in pediatric end-stage renal disease (ESRD).

"We know that, among children with [ESRD], death risk is much lower for those who receive a kidney transplant, compared with those who stay on dialysis, but we don’t know much about which children die before reaching transplant," Dr. Amaral said. "We wanted to determine whether there are racial or ethnic differences in the risk of dying when children remain on dialysis."

They identified 8,146 patients younger than 21 years who had been diagnosed with ESRD from Jan. 2000 through Sept. 2008 and followed through September 2009, looking at patients who were on dialysis but had not been transplanted and whose race/ethnicity was white, Hispanic, or black. Of the 8,146 children, 896 died before reaching transplant, she said at the meeting, sponsored by the American Society of Nephrology.

"We wanted to determine whether there are racial or ethnic differences in the risk of dying when children remain on dialysis."

Of the patients who died, 357 were white, 161 were Hispanic, and 378 were black, Dr. Amaral said. By health insurance status, 179 were privately insured, 527 were publicly insured, 87 children were uninsured, and 103 were classified as "other," she said.

The number of children who died, independent of race/ethnicity, was related to neighborhood poverty. Specifically, 304 of the children who died had lived in the poorest neighborhoods – those where at least 20% of residents were at or below the federal poverty line – compared with 80 children from the wealthiest neighborhoods in which 0 to 4.9% of the residents had incomes at or below poverty level, she said.

"We saw significant differences by race, health insurance, and poverty among patients who were alive vs. those who died, and proportionally, among all of the black patients, more died than in any other subgroup," Dr. Amaral said, adding that "more patients among those who died had public insurance and were from poorer neighborhoods."

Survival curves showed that Hispanic children had the highest rate of survival, followed by white children. "Black children had the lowest rate of survival," Dr. Amaral stated. In an analysis adjusted for age, gender, and diagnosis, "the poorest children, regardless of race, had higher mortality."

However, the risk of death among those of different ethnic backgrounds varied by type of health insurance and not by poverty. "Uninsured black children, for example, had a 78% increased risk, compared with uninsured white children," she said, while black children with private insurance had only a 19% increased risk, compared with privately insured white children.

The current findings are limited by the fact that the data set included only patients who had been diagnosed with ESRD, Dr. Amaral said.

"We don’t know what happened to them before that," she said. "There may be issues in patient access to care. It’s possible that the reason patients are not even getting wait-listed at diagnosis is that they’re too sick," she said.

Dr. Amaral disclosed having no financial conflicts of interest related to her presentation.

PHILADELPHIA – Race, socioeconomic status, and insurance status all impact survival for children with end-stage renal disease, with poor, uninsured black children at greater risk of death than all others.

Dr. Sandra G. Amaral of Children’s Hospital of Philadelphia and her colleagues used information from the United States Renal Data System to identify racial and socioeconomic disparities associated with mortality risk in pediatric end-stage renal disease (ESRD).

"We know that, among children with [ESRD], death risk is much lower for those who receive a kidney transplant, compared with those who stay on dialysis, but we don’t know much about which children die before reaching transplant," Dr. Amaral said. "We wanted to determine whether there are racial or ethnic differences in the risk of dying when children remain on dialysis."

They identified 8,146 patients younger than 21 years who had been diagnosed with ESRD from Jan. 2000 through Sept. 2008 and followed through September 2009, looking at patients who were on dialysis but had not been transplanted and whose race/ethnicity was white, Hispanic, or black. Of the 8,146 children, 896 died before reaching transplant, she said at the meeting, sponsored by the American Society of Nephrology.

"We wanted to determine whether there are racial or ethnic differences in the risk of dying when children remain on dialysis."

Of the patients who died, 357 were white, 161 were Hispanic, and 378 were black, Dr. Amaral said. By health insurance status, 179 were privately insured, 527 were publicly insured, 87 children were uninsured, and 103 were classified as "other," she said.

The number of children who died, independent of race/ethnicity, was related to neighborhood poverty. Specifically, 304 of the children who died had lived in the poorest neighborhoods – those where at least 20% of residents were at or below the federal poverty line – compared with 80 children from the wealthiest neighborhoods in which 0 to 4.9% of the residents had incomes at or below poverty level, she said.

"We saw significant differences by race, health insurance, and poverty among patients who were alive vs. those who died, and proportionally, among all of the black patients, more died than in any other subgroup," Dr. Amaral said, adding that "more patients among those who died had public insurance and were from poorer neighborhoods."

Survival curves showed that Hispanic children had the highest rate of survival, followed by white children. "Black children had the lowest rate of survival," Dr. Amaral stated. In an analysis adjusted for age, gender, and diagnosis, "the poorest children, regardless of race, had higher mortality."

However, the risk of death among those of different ethnic backgrounds varied by type of health insurance and not by poverty. "Uninsured black children, for example, had a 78% increased risk, compared with uninsured white children," she said, while black children with private insurance had only a 19% increased risk, compared with privately insured white children.

The current findings are limited by the fact that the data set included only patients who had been diagnosed with ESRD, Dr. Amaral said.

"We don’t know what happened to them before that," she said. "There may be issues in patient access to care. It’s possible that the reason patients are not even getting wait-listed at diagnosis is that they’re too sick," she said.

Dr. Amaral disclosed having no financial conflicts of interest related to her presentation.

PHILADELPHIA – The use of potentially nephrotoxic dietary supplements is common in the general U.S. population and among individuals with chronic kidney disease, a study has shown.

The findings suggest that chronic kidney disease patients and their physicians may be unaware of the dangers associated with supplementation, and also that physicians may be unaware that their patients are taking dietary supplements, Dr. Vanessa Grubbs reported Nov. 10 at the annual meeting of the American Society of Nephrology.

©Zlatko Ivancok/Fotolia.com

"Nearly 1 in 10 adult Americans takes a dietary supplement that is potentially harmful to the kidneys, regardless of kidney disease status," said Dr. Grubbs of the University of California, San Francisco. The irony, she noted, "is that these individuals believe they are improving their health by taking supplements, when they may be causing harm."

The National Kidney Foundation (NKF) has identified 39 herbs that may be harmful, particularly in the setting of chronic kidney disease, but physician oversight of patient intake is difficult, Dr. Grubbs said, "because the dietary supplements containing these herbs are regulated like foods, not like drugs."

Among the more common kidney-unfriendly herbs identified by the NKF are those that serve as diuretics, including bucha leaves and juniper berries, and those that interact with prescription drugs, such as St. John’s wort, echinacea, ginkgo, garlic, ginger, and blue cohosh.

To determine the prevalence of the use of supplements containing these herbs in the general U.S. population and by chronic kidney disease status, Dr. Grubbs and her colleagues used data from the 1999-2008 National Health and Nutrition Examination Survey (NHANES) to ascertain the reported use of dietary supplements in the past 30 days among 21,169 nonpregnant adults over age 20. For purposes of the analysis, chronic kidney disease was defined by a urinary albumin-to-creatinine ratio of at least 30 mg/g with an estimated glomerular filtration rate (eGFR) of 60 mL/min/1.73 m² or greater (stage I/II), or an eGFR of 15-59 mL/min/1.73 m² (stage III/IV), she said. To estimate the prevalence and odds of taking a potentially harmful supplement by chronic kidney disease status, "we used multivariate logistic regression weighted to the U.S. population," she said at the meeting sponsored by the American Society of Nephrology.

More than half (52.4%) of survey participants reported taking any dietary supplement, among which 15.3% reported taking a supplement containing at least one of the potentially harmful herbs, Dr. Grubbs reported. Although the crude estimated prevalence of individuals taking any dietary supplement increased with greater chronic kidney disease severity – with reported use by 51.4% of individuals with no kidney disease, 49.1% of those with stage I/II disease, and 65.8% of those with stage III/IV disease – it decreased among those taking a potentially harmful supplement – with reported use by 16.1%, 13.0%, and 10.0%, respectively, she said.

"Nearly 1 in 10 adult Americans takes a dietary supplement that is potentially harmful to the kidneys."

After adjusting for demographics, comorbid disease, and health care visits, however, "chronic kidney disease status was not a significant determinant of taking any supplement or of taking a potentially harmful supplement," Dr. Grubbs said.

The fact that so many individuals are taking supplements with ingredients that can be harmful to the kidneys is especially problematic, she stressed, "because many people with advanced kidney disease – up to 10% – are not aware that they have kidney disease." Further, she noted, the list of potentially harmful supplements may not be exhaustive, and because the supplements are not regulated as drugs, the amounts of the ingredients in question are unknown and thus may be more harmful than anticipated.

Until policy makers can be convinced to update the regulatory standards for dietary supplements, the onus for protecting patients is on physicians and on the patients themselves. "We have to educate ourselves about dietary supplements and ask patients about everything they are taking, and we have to educate our patients [about kidney disease] and the possibility of [supplements] doing more harm than good," Dr. Grubbs said.

Dr. Grubbs reported having no financial conflicts of interest.

PHILADELPHIA – The use of potentially nephrotoxic dietary supplements is common in the general U.S. population and among individuals with chronic kidney disease, a study has shown.

The findings suggest that chronic kidney disease patients and their physicians may be unaware of the dangers associated with supplementation, and also that physicians may be unaware that their patients are taking dietary supplements, Dr. Vanessa Grubbs reported Nov. 10 at the annual meeting of the American Society of Nephrology.

©Zlatko Ivancok/Fotolia.com

"Nearly 1 in 10 adult Americans takes a dietary supplement that is potentially harmful to the kidneys, regardless of kidney disease status," said Dr. Grubbs of the University of California, San Francisco. The irony, she noted, "is that these individuals believe they are improving their health by taking supplements, when they may be causing harm."

The National Kidney Foundation (NKF) has identified 39 herbs that may be harmful, particularly in the setting of chronic kidney disease, but physician oversight of patient intake is difficult, Dr. Grubbs said, "because the dietary supplements containing these herbs are regulated like foods, not like drugs."

Among the more common kidney-unfriendly herbs identified by the NKF are those that serve as diuretics, including bucha leaves and juniper berries, and those that interact with prescription drugs, such as St. John’s wort, echinacea, ginkgo, garlic, ginger, and blue cohosh.

To determine the prevalence of the use of supplements containing these herbs in the general U.S. population and by chronic kidney disease status, Dr. Grubbs and her colleagues used data from the 1999-2008 National Health and Nutrition Examination Survey (NHANES) to ascertain the reported use of dietary supplements in the past 30 days among 21,169 nonpregnant adults over age 20. For purposes of the analysis, chronic kidney disease was defined by a urinary albumin-to-creatinine ratio of at least 30 mg/g with an estimated glomerular filtration rate (eGFR) of 60 mL/min/1.73 m² or greater (stage I/II), or an eGFR of 15-59 mL/min/1.73 m² (stage III/IV), she said. To estimate the prevalence and odds of taking a potentially harmful supplement by chronic kidney disease status, "we used multivariate logistic regression weighted to the U.S. population," she said at the meeting sponsored by the American Society of Nephrology.

More than half (52.4%) of survey participants reported taking any dietary supplement, among which 15.3% reported taking a supplement containing at least one of the potentially harmful herbs, Dr. Grubbs reported. Although the crude estimated prevalence of individuals taking any dietary supplement increased with greater chronic kidney disease severity – with reported use by 51.4% of individuals with no kidney disease, 49.1% of those with stage I/II disease, and 65.8% of those with stage III/IV disease – it decreased among those taking a potentially harmful supplement – with reported use by 16.1%, 13.0%, and 10.0%, respectively, she said.

"Nearly 1 in 10 adult Americans takes a dietary supplement that is potentially harmful to the kidneys."

After adjusting for demographics, comorbid disease, and health care visits, however, "chronic kidney disease status was not a significant determinant of taking any supplement or of taking a potentially harmful supplement," Dr. Grubbs said.

The fact that so many individuals are taking supplements with ingredients that can be harmful to the kidneys is especially problematic, she stressed, "because many people with advanced kidney disease – up to 10% – are not aware that they have kidney disease." Further, she noted, the list of potentially harmful supplements may not be exhaustive, and because the supplements are not regulated as drugs, the amounts of the ingredients in question are unknown and thus may be more harmful than anticipated.

Until policy makers can be convinced to update the regulatory standards for dietary supplements, the onus for protecting patients is on physicians and on the patients themselves. "We have to educate ourselves about dietary supplements and ask patients about everything they are taking, and we have to educate our patients [about kidney disease] and the possibility of [supplements] doing more harm than good," Dr. Grubbs said.

Dr. Grubbs reported having no financial conflicts of interest.

PHILADELPHIA – The use of potentially nephrotoxic dietary supplements is common in the general U.S. population and among individuals with chronic kidney disease, a study has shown.

The findings suggest that chronic kidney disease patients and their physicians may be unaware of the dangers associated with supplementation, and also that physicians may be unaware that their patients are taking dietary supplements, Dr. Vanessa Grubbs reported Nov. 10 at the annual meeting of the American Society of Nephrology.

©Zlatko Ivancok/Fotolia.com

"Nearly 1 in 10 adult Americans takes a dietary supplement that is potentially harmful to the kidneys, regardless of kidney disease status," said Dr. Grubbs of the University of California, San Francisco. The irony, she noted, "is that these individuals believe they are improving their health by taking supplements, when they may be causing harm."

The National Kidney Foundation (NKF) has identified 39 herbs that may be harmful, particularly in the setting of chronic kidney disease, but physician oversight of patient intake is difficult, Dr. Grubbs said, "because the dietary supplements containing these herbs are regulated like foods, not like drugs."

Among the more common kidney-unfriendly herbs identified by the NKF are those that serve as diuretics, including bucha leaves and juniper berries, and those that interact with prescription drugs, such as St. John’s wort, echinacea, ginkgo, garlic, ginger, and blue cohosh.

To determine the prevalence of the use of supplements containing these herbs in the general U.S. population and by chronic kidney disease status, Dr. Grubbs and her colleagues used data from the 1999-2008 National Health and Nutrition Examination Survey (NHANES) to ascertain the reported use of dietary supplements in the past 30 days among 21,169 nonpregnant adults over age 20. For purposes of the analysis, chronic kidney disease was defined by a urinary albumin-to-creatinine ratio of at least 30 mg/g with an estimated glomerular filtration rate (eGFR) of 60 mL/min/1.73 m² or greater (stage I/II), or an eGFR of 15-59 mL/min/1.73 m² (stage III/IV), she said. To estimate the prevalence and odds of taking a potentially harmful supplement by chronic kidney disease status, "we used multivariate logistic regression weighted to the U.S. population," she said at the meeting sponsored by the American Society of Nephrology.

More than half (52.4%) of survey participants reported taking any dietary supplement, among which 15.3% reported taking a supplement containing at least one of the potentially harmful herbs, Dr. Grubbs reported. Although the crude estimated prevalence of individuals taking any dietary supplement increased with greater chronic kidney disease severity – with reported use by 51.4% of individuals with no kidney disease, 49.1% of those with stage I/II disease, and 65.8% of those with stage III/IV disease – it decreased among those taking a potentially harmful supplement – with reported use by 16.1%, 13.0%, and 10.0%, respectively, she said.

"Nearly 1 in 10 adult Americans takes a dietary supplement that is potentially harmful to the kidneys."

After adjusting for demographics, comorbid disease, and health care visits, however, "chronic kidney disease status was not a significant determinant of taking any supplement or of taking a potentially harmful supplement," Dr. Grubbs said.

The fact that so many individuals are taking supplements with ingredients that can be harmful to the kidneys is especially problematic, she stressed, "because many people with advanced kidney disease – up to 10% – are not aware that they have kidney disease." Further, she noted, the list of potentially harmful supplements may not be exhaustive, and because the supplements are not regulated as drugs, the amounts of the ingredients in question are unknown and thus may be more harmful than anticipated.

Until policy makers can be convinced to update the regulatory standards for dietary supplements, the onus for protecting patients is on physicians and on the patients themselves. "We have to educate ourselves about dietary supplements and ask patients about everything they are taking, and we have to educate our patients [about kidney disease] and the possibility of [supplements] doing more harm than good," Dr. Grubbs said.

Dr. Grubbs reported having no financial conflicts of interest.