Joan Stephenson

NEW YORK (Reuters Health) - Rates of kidney stones have increased substantially over the past 20 years, particularly among children, adolescents, females, and blacks, according to a population-based study in South Carolina.

Historically, the highest rates of kidney stone disease have been in middle-aged white men, but the new findings underscore emerging changes in this pattern. Prior studies have found that prevalent kidney stone disease has nearly doubled in the United States over the past two decades. The extent to which specific groups of patients have been affected has been less clear, although there have been reports of increasing frequency of kidney stones among youth.

"My colleagues and I wondered if kidney stones were increasing preferentially among adolescents more than in other age groups," lead researcher Dr. Gregory Tasian, of the University of Pennsylvania Perelman School of Medicine in Philadelphia, told Reuters Health by email.

To estimate the annual kidney stone incidence in South Carolina in their repeated cross-sectional study, the researchers used U.S. Census data and data from the South Carolina Medical Encounter Data and Financial Reports, which includes information on all surgeries, emergency department visits, and inpatient hospitalizations in the state from 1997 to 2012. Using linear mixed models, they also sought to identify the patient groups in whom the rate of stones has increased the most.

Nearly 153,000 adult and pediatric patients among a state population of about 4.6 million received care for kidney stones from 1997 to 2012, the researchers reported online January 14 in the Clinical Journal of the American Society of Nephrology.

The annual incidence increased 16% during that time, with the largest increases occurring in teens, blacks, and women.  Teens 15 to 19 years comprised the age group with the largest increase in incidence of kidney stones from 1997 (an age-specific rate of nearly 80 per 100,000) to 2012 (about 155 per 100,000).

Overall, teens 15 to 19 experienced a 26% increase per five years (incidence rate ratio, 1.26), after adjusting for sex and race. The increase was substantially greater among teen girls,

with an annual incidence 52% higher than for teen boys.

Increases in cumulative risk of kidney stones during childhood were similar for girls (87%) and boys (90%), although the risks in 2012 were "modest," at 0.9% (for girls) and 0.6% (for boys), the researchers say. They note that the "emergence of nephrolithiasis as a disease that begins in childhood is worrisome because there is limited evidence about how to best treat children" with the condition.

After adjusting for age and race, incidence of kidney stones  increased an estimated 15% per five years (IRR, 1.15) among females of all ages during the study period, but was stable among males (IRR, 0.99). The estimated lifetime risk for women increased from 10.5% in 1997 to 15.2% in 2012, but remained unchanged for men at about 23%. Incidence of kidney stones among blacks rose an estimated 15% per five years (IRR, 1.15) during the study period, compared with an estimated 3% among whites (IRR, 1.03).

"We were not surprised by the high occurrence of kidney  stones among adolescents and females (5% and 3% per year), which is consistent with other studies reported to date," Dr. Tasian

said. "We were, however, surprised by how much kidney stones were increasing in African-Americans, as previous studies have not really studied differences in kidney stone occurrence among different racial groups."

Although the study focused on kidney stone disease in South Carolina, it's likely that similar patterns exist across the nation, he said.

"Kidney stones have increased 70% over the last 30 years in adults in the U.S., and we are also seeing higher rates of kidney stones in children across the U.S.," Dr. Tasian said.

However, even though kidney stones are also increasing in many areas in the world, for many reasons, the results should not be generalized beyond the United States, he noted.

"This study is an important step forward in understanding the changing epidemiology of kidney stone disease," Dr. Charles D. Scales, of Duke University Medical Center in Durham, North Carolina, told Reuters Health by email. The underlying causes of the increase are unclear. "In adults, it may be related to the tidal wave of obesity and diabetes in the United States," said Dr. Scales, an expert in kidney stones who was not involved with the study.

These epidemiologic trends provide more support for the concept that "chronic and poorly understood metabolic derangements are likely causing all of these new stones in previously low-risk individuals," he said.

Increased consumption of high-sodium processed food and dehydration also may be contributing factors, he added. "Emerging evidence suggests that a kidney stone may foreshadow future medical problems, such as heart disease, bone density loss, and chronic kidney disease," Dr. Scales said. "So from the public-health perspective, the worst may be yet to come as these teenagers with stones become adults."

The study had no commercial funding and the authors reported no disclosures.

NEW YORK (Reuters Health) - Rates of kidney stones have increased substantially over the past 20 years, particularly among children, adolescents, females, and blacks, according to a population-based study in South Carolina.

Historically, the highest rates of kidney stone disease have been in middle-aged white men, but the new findings underscore emerging changes in this pattern. Prior studies have found that prevalent kidney stone disease has nearly doubled in the United States over the past two decades. The extent to which specific groups of patients have been affected has been less clear, although there have been reports of increasing frequency of kidney stones among youth.

"My colleagues and I wondered if kidney stones were increasing preferentially among adolescents more than in other age groups," lead researcher Dr. Gregory Tasian, of the University of Pennsylvania Perelman School of Medicine in Philadelphia, told Reuters Health by email.

To estimate the annual kidney stone incidence in South Carolina in their repeated cross-sectional study, the researchers used U.S. Census data and data from the South Carolina Medical Encounter Data and Financial Reports, which includes information on all surgeries, emergency department visits, and inpatient hospitalizations in the state from 1997 to 2012. Using linear mixed models, they also sought to identify the patient groups in whom the rate of stones has increased the most.

Nearly 153,000 adult and pediatric patients among a state population of about 4.6 million received care for kidney stones from 1997 to 2012, the researchers reported online January 14 in the Clinical Journal of the American Society of Nephrology.

The annual incidence increased 16% during that time, with the largest increases occurring in teens, blacks, and women.  Teens 15 to 19 years comprised the age group with the largest increase in incidence of kidney stones from 1997 (an age-specific rate of nearly 80 per 100,000) to 2012 (about 155 per 100,000).

Overall, teens 15 to 19 experienced a 26% increase per five years (incidence rate ratio, 1.26), after adjusting for sex and race. The increase was substantially greater among teen girls,

with an annual incidence 52% higher than for teen boys.

Increases in cumulative risk of kidney stones during childhood were similar for girls (87%) and boys (90%), although the risks in 2012 were "modest," at 0.9% (for girls) and 0.6% (for boys), the researchers say. They note that the "emergence of nephrolithiasis as a disease that begins in childhood is worrisome because there is limited evidence about how to best treat children" with the condition.

After adjusting for age and race, incidence of kidney stones  increased an estimated 15% per five years (IRR, 1.15) among females of all ages during the study period, but was stable among males (IRR, 0.99). The estimated lifetime risk for women increased from 10.5% in 1997 to 15.2% in 2012, but remained unchanged for men at about 23%. Incidence of kidney stones among blacks rose an estimated 15% per five years (IRR, 1.15) during the study period, compared with an estimated 3% among whites (IRR, 1.03).

"We were not surprised by the high occurrence of kidney  stones among adolescents and females (5% and 3% per year), which is consistent with other studies reported to date," Dr. Tasian

said. "We were, however, surprised by how much kidney stones were increasing in African-Americans, as previous studies have not really studied differences in kidney stone occurrence among different racial groups."

Although the study focused on kidney stone disease in South Carolina, it's likely that similar patterns exist across the nation, he said.

"Kidney stones have increased 70% over the last 30 years in adults in the U.S., and we are also seeing higher rates of kidney stones in children across the U.S.," Dr. Tasian said.

However, even though kidney stones are also increasing in many areas in the world, for many reasons, the results should not be generalized beyond the United States, he noted.

"This study is an important step forward in understanding the changing epidemiology of kidney stone disease," Dr. Charles D. Scales, of Duke University Medical Center in Durham, North Carolina, told Reuters Health by email. The underlying causes of the increase are unclear. "In adults, it may be related to the tidal wave of obesity and diabetes in the United States," said Dr. Scales, an expert in kidney stones who was not involved with the study.

These epidemiologic trends provide more support for the concept that "chronic and poorly understood metabolic derangements are likely causing all of these new stones in previously low-risk individuals," he said.

Increased consumption of high-sodium processed food and dehydration also may be contributing factors, he added. "Emerging evidence suggests that a kidney stone may foreshadow future medical problems, such as heart disease, bone density loss, and chronic kidney disease," Dr. Scales said. "So from the public-health perspective, the worst may be yet to come as these teenagers with stones become adults."

The study had no commercial funding and the authors reported no disclosures.

NEW YORK (Reuters Health) - Rates of kidney stones have increased substantially over the past 20 years, particularly among children, adolescents, females, and blacks, according to a population-based study in South Carolina.

Historically, the highest rates of kidney stone disease have been in middle-aged white men, but the new findings underscore emerging changes in this pattern. Prior studies have found that prevalent kidney stone disease has nearly doubled in the United States over the past two decades. The extent to which specific groups of patients have been affected has been less clear, although there have been reports of increasing frequency of kidney stones among youth.

"My colleagues and I wondered if kidney stones were increasing preferentially among adolescents more than in other age groups," lead researcher Dr. Gregory Tasian, of the University of Pennsylvania Perelman School of Medicine in Philadelphia, told Reuters Health by email.

To estimate the annual kidney stone incidence in South Carolina in their repeated cross-sectional study, the researchers used U.S. Census data and data from the South Carolina Medical Encounter Data and Financial Reports, which includes information on all surgeries, emergency department visits, and inpatient hospitalizations in the state from 1997 to 2012. Using linear mixed models, they also sought to identify the patient groups in whom the rate of stones has increased the most.

Nearly 153,000 adult and pediatric patients among a state population of about 4.6 million received care for kidney stones from 1997 to 2012, the researchers reported online January 14 in the Clinical Journal of the American Society of Nephrology.

The annual incidence increased 16% during that time, with the largest increases occurring in teens, blacks, and women.  Teens 15 to 19 years comprised the age group with the largest increase in incidence of kidney stones from 1997 (an age-specific rate of nearly 80 per 100,000) to 2012 (about 155 per 100,000).

Overall, teens 15 to 19 experienced a 26% increase per five years (incidence rate ratio, 1.26), after adjusting for sex and race. The increase was substantially greater among teen girls,

with an annual incidence 52% higher than for teen boys.

Increases in cumulative risk of kidney stones during childhood were similar for girls (87%) and boys (90%), although the risks in 2012 were "modest," at 0.9% (for girls) and 0.6% (for boys), the researchers say. They note that the "emergence of nephrolithiasis as a disease that begins in childhood is worrisome because there is limited evidence about how to best treat children" with the condition.

After adjusting for age and race, incidence of kidney stones  increased an estimated 15% per five years (IRR, 1.15) among females of all ages during the study period, but was stable among males (IRR, 0.99). The estimated lifetime risk for women increased from 10.5% in 1997 to 15.2% in 2012, but remained unchanged for men at about 23%. Incidence of kidney stones among blacks rose an estimated 15% per five years (IRR, 1.15) during the study period, compared with an estimated 3% among whites (IRR, 1.03).

"We were not surprised by the high occurrence of kidney  stones among adolescents and females (5% and 3% per year), which is consistent with other studies reported to date," Dr. Tasian

said. "We were, however, surprised by how much kidney stones were increasing in African-Americans, as previous studies have not really studied differences in kidney stone occurrence among different racial groups."

Although the study focused on kidney stone disease in South Carolina, it's likely that similar patterns exist across the nation, he said.

"Kidney stones have increased 70% over the last 30 years in adults in the U.S., and we are also seeing higher rates of kidney stones in children across the U.S.," Dr. Tasian said.

However, even though kidney stones are also increasing in many areas in the world, for many reasons, the results should not be generalized beyond the United States, he noted.

"This study is an important step forward in understanding the changing epidemiology of kidney stone disease," Dr. Charles D. Scales, of Duke University Medical Center in Durham, North Carolina, told Reuters Health by email. The underlying causes of the increase are unclear. "In adults, it may be related to the tidal wave of obesity and diabetes in the United States," said Dr. Scales, an expert in kidney stones who was not involved with the study.

These epidemiologic trends provide more support for the concept that "chronic and poorly understood metabolic derangements are likely causing all of these new stones in previously low-risk individuals," he said.

Increased consumption of high-sodium processed food and dehydration also may be contributing factors, he added. "Emerging evidence suggests that a kidney stone may foreshadow future medical problems, such as heart disease, bone density loss, and chronic kidney disease," Dr. Scales said. "So from the public-health perspective, the worst may be yet to come as these teenagers with stones become adults."

The study had no commercial funding and the authors reported no disclosures.

NEW YORK - Restenosis rates are similar one year after implantation of an everolimus-eluting bioresorbable vascular scaffold or an everolimus-eluting metallic stent, but the scaffold has a higher risk of device thrombosis within 30 days, a new meta-analysis shows.

The meta-analysis suggests that the two interventions have a "similar requirement of repeat revascularization out to 1-year follow-up, despite inferior angiographic performance," first author Dr. Salvatore Cassese said by email.

This higher risk of stent thrombosis, twice as high with the bioresorbable device compared with the metallic stent after one year, "is somewhat surprising," said Dr. Cassese, of the Technical University of Munich's German Heart Center Munich. "The higher risk of scaffold thrombosis in relatively simple clinical (lesion) settings represents the new important finding showed by this meta-analysis."

A number of recently completed randomized trials showed comparable mid-term outcomes with the two devices, but data from routine clinical practice suggests a "somewhat higher rate of adverse events" with the bioresorbable scaffold, he said.

Most randomized trials comparing the two types of devices were small and not adequately powered to assess clinical endpoints, the authors noted. For their meta-analysis, they identified six trials involving 3,738 patients (mainly men, median age 62.3 years) that met their inclusion criteria (randomized design, an analysis by intention to treat, and a follow-up of at least six months).

The meta-analysis included 2,337 patients who received a bioresorbable scaffold and 1,401 who received a metallic stent. Median follow-up was 12 months.

Both groups had a 3% rate of target lesion revascularization, the primary efficacy outcome, the researchers noted in a report online November 16 in The Lancet.

The risk of the primary safety outcome, definite or probable stent/scaffold thrombosis, was significantly higher for those treated with a bioresorbable scaffold compared with those who received a metallic stent (1.3% versus 0.5%; odds ratio, 1.99), with the highest risk within 30 days after implantation.

In-device late lumen loss was also significantly greater in lesions treated with the bioresorbable device compared with the metallic stent.

Risk of myocardial infarction appeared to be higher in patients with the bioresorbable scaffolds than in those with metallic stents, but the difference was not statistically significant (5.2% versus 3.5%, p=0.06). The groups had similar rates of target lesion failure and risk of death.

The authors noted that their finding of at least similar efficacy of the bioresorbable scaffold versus the existing best-in-class drug-eluting stent at 12 months was achieved in a highly selected population that included mainly stable patients with single de-novo non-complex target lesions and excluded patients who had a higher risk for device failure.

Two large-scale randomized trials are under way that are expected to shed more light on the devices' relative efficacy in higher-risk populations.

Although the study's findings "should heighten concerns about the current generation of bioresorbable vascular scaffold technology, they should by no means be interpreted to mean that bioresorbable scaffolds are not worth pursuing," noted an editorial that accompanied the new meta-analysis. "Just as with first-generation drug-eluting stents, a complete understanding of the limitations of such technology is necessary before further advancements can be made."

"Little information appears available regarding the incidence of symptoms of angina in the comparison groups," Dr. Richard Chazal, who was not involved in the study, said in an email.

"This is important, as the principal utility of stents in stable patients is the relief of such symptoms," noted Dr. Chazal, president-elect of the American College of Cardiology and medical director of the Lee Memorial Health Systems' Heart and Vascular Institute in Fort Myers, Fla.

"Disappearing" bioresorbable scaffolds are viewed as a possible solution to potential problems of leaving metallic stents permanently inside a coronary vessel. These problems include impairing the function of the wall of the artery and limiting future options for treating the artery, especially with a bypass operation, explained Dr. Chazal.

Emergence of their anticipated benefit over metallic stents is expected several years after implantation, when elution of the anti-restenotic drug has stopped and the scaffold has dissolved.

"Longer-term follow-up will be needed to clarify whether these newer devices provide hoped-for advantages over metallic stents, or whether the early issues with thrombosis/clotting and vessel narrowing eventually results in more clinical problems," Dr. Chazal said.

The study had no funding source. Two of the 10 coauthors reported receiving fees from stent manufacturers or holding patents related to drug-eluting stent technologies, "outside the submitted work." A third coauthor is a member of the advisory board of Abbott, which includes a division that makes an everolimus-eluting bioresorbable vascular scaffold.

NEW YORK - Restenosis rates are similar one year after implantation of an everolimus-eluting bioresorbable vascular scaffold or an everolimus-eluting metallic stent, but the scaffold has a higher risk of device thrombosis within 30 days, a new meta-analysis shows.

The meta-analysis suggests that the two interventions have a "similar requirement of repeat revascularization out to 1-year follow-up, despite inferior angiographic performance," first author Dr. Salvatore Cassese said by email.

This higher risk of stent thrombosis, twice as high with the bioresorbable device compared with the metallic stent after one year, "is somewhat surprising," said Dr. Cassese, of the Technical University of Munich's German Heart Center Munich. "The higher risk of scaffold thrombosis in relatively simple clinical (lesion) settings represents the new important finding showed by this meta-analysis."

A number of recently completed randomized trials showed comparable mid-term outcomes with the two devices, but data from routine clinical practice suggests a "somewhat higher rate of adverse events" with the bioresorbable scaffold, he said.

Most randomized trials comparing the two types of devices were small and not adequately powered to assess clinical endpoints, the authors noted. For their meta-analysis, they identified six trials involving 3,738 patients (mainly men, median age 62.3 years) that met their inclusion criteria (randomized design, an analysis by intention to treat, and a follow-up of at least six months).

The meta-analysis included 2,337 patients who received a bioresorbable scaffold and 1,401 who received a metallic stent. Median follow-up was 12 months.

Both groups had a 3% rate of target lesion revascularization, the primary efficacy outcome, the researchers noted in a report online November 16 in The Lancet.

The risk of the primary safety outcome, definite or probable stent/scaffold thrombosis, was significantly higher for those treated with a bioresorbable scaffold compared with those who received a metallic stent (1.3% versus 0.5%; odds ratio, 1.99), with the highest risk within 30 days after implantation.

In-device late lumen loss was also significantly greater in lesions treated with the bioresorbable device compared with the metallic stent.

Risk of myocardial infarction appeared to be higher in patients with the bioresorbable scaffolds than in those with metallic stents, but the difference was not statistically significant (5.2% versus 3.5%, p=0.06). The groups had similar rates of target lesion failure and risk of death.

The authors noted that their finding of at least similar efficacy of the bioresorbable scaffold versus the existing best-in-class drug-eluting stent at 12 months was achieved in a highly selected population that included mainly stable patients with single de-novo non-complex target lesions and excluded patients who had a higher risk for device failure.

Two large-scale randomized trials are under way that are expected to shed more light on the devices' relative efficacy in higher-risk populations.

Although the study's findings "should heighten concerns about the current generation of bioresorbable vascular scaffold technology, they should by no means be interpreted to mean that bioresorbable scaffolds are not worth pursuing," noted an editorial that accompanied the new meta-analysis. "Just as with first-generation drug-eluting stents, a complete understanding of the limitations of such technology is necessary before further advancements can be made."

"Little information appears available regarding the incidence of symptoms of angina in the comparison groups," Dr. Richard Chazal, who was not involved in the study, said in an email.

"This is important, as the principal utility of stents in stable patients is the relief of such symptoms," noted Dr. Chazal, president-elect of the American College of Cardiology and medical director of the Lee Memorial Health Systems' Heart and Vascular Institute in Fort Myers, Fla.

"Disappearing" bioresorbable scaffolds are viewed as a possible solution to potential problems of leaving metallic stents permanently inside a coronary vessel. These problems include impairing the function of the wall of the artery and limiting future options for treating the artery, especially with a bypass operation, explained Dr. Chazal.

Emergence of their anticipated benefit over metallic stents is expected several years after implantation, when elution of the anti-restenotic drug has stopped and the scaffold has dissolved.

"Longer-term follow-up will be needed to clarify whether these newer devices provide hoped-for advantages over metallic stents, or whether the early issues with thrombosis/clotting and vessel narrowing eventually results in more clinical problems," Dr. Chazal said.

The study had no funding source. Two of the 10 coauthors reported receiving fees from stent manufacturers or holding patents related to drug-eluting stent technologies, "outside the submitted work." A third coauthor is a member of the advisory board of Abbott, which includes a division that makes an everolimus-eluting bioresorbable vascular scaffold.

NEW YORK - Restenosis rates are similar one year after implantation of an everolimus-eluting bioresorbable vascular scaffold or an everolimus-eluting metallic stent, but the scaffold has a higher risk of device thrombosis within 30 days, a new meta-analysis shows.

The meta-analysis suggests that the two interventions have a "similar requirement of repeat revascularization out to 1-year follow-up, despite inferior angiographic performance," first author Dr. Salvatore Cassese said by email.

This higher risk of stent thrombosis, twice as high with the bioresorbable device compared with the metallic stent after one year, "is somewhat surprising," said Dr. Cassese, of the Technical University of Munich's German Heart Center Munich. "The higher risk of scaffold thrombosis in relatively simple clinical (lesion) settings represents the new important finding showed by this meta-analysis."

A number of recently completed randomized trials showed comparable mid-term outcomes with the two devices, but data from routine clinical practice suggests a "somewhat higher rate of adverse events" with the bioresorbable scaffold, he said.

Most randomized trials comparing the two types of devices were small and not adequately powered to assess clinical endpoints, the authors noted. For their meta-analysis, they identified six trials involving 3,738 patients (mainly men, median age 62.3 years) that met their inclusion criteria (randomized design, an analysis by intention to treat, and a follow-up of at least six months).

The meta-analysis included 2,337 patients who received a bioresorbable scaffold and 1,401 who received a metallic stent. Median follow-up was 12 months.

Both groups had a 3% rate of target lesion revascularization, the primary efficacy outcome, the researchers noted in a report online November 16 in The Lancet.

The risk of the primary safety outcome, definite or probable stent/scaffold thrombosis, was significantly higher for those treated with a bioresorbable scaffold compared with those who received a metallic stent (1.3% versus 0.5%; odds ratio, 1.99), with the highest risk within 30 days after implantation.

In-device late lumen loss was also significantly greater in lesions treated with the bioresorbable device compared with the metallic stent.

Risk of myocardial infarction appeared to be higher in patients with the bioresorbable scaffolds than in those with metallic stents, but the difference was not statistically significant (5.2% versus 3.5%, p=0.06). The groups had similar rates of target lesion failure and risk of death.

The authors noted that their finding of at least similar efficacy of the bioresorbable scaffold versus the existing best-in-class drug-eluting stent at 12 months was achieved in a highly selected population that included mainly stable patients with single de-novo non-complex target lesions and excluded patients who had a higher risk for device failure.

Two large-scale randomized trials are under way that are expected to shed more light on the devices' relative efficacy in higher-risk populations.

Although the study's findings "should heighten concerns about the current generation of bioresorbable vascular scaffold technology, they should by no means be interpreted to mean that bioresorbable scaffolds are not worth pursuing," noted an editorial that accompanied the new meta-analysis. "Just as with first-generation drug-eluting stents, a complete understanding of the limitations of such technology is necessary before further advancements can be made."

"Little information appears available regarding the incidence of symptoms of angina in the comparison groups," Dr. Richard Chazal, who was not involved in the study, said in an email.

"This is important, as the principal utility of stents in stable patients is the relief of such symptoms," noted Dr. Chazal, president-elect of the American College of Cardiology and medical director of the Lee Memorial Health Systems' Heart and Vascular Institute in Fort Myers, Fla.

"Disappearing" bioresorbable scaffolds are viewed as a possible solution to potential problems of leaving metallic stents permanently inside a coronary vessel. These problems include impairing the function of the wall of the artery and limiting future options for treating the artery, especially with a bypass operation, explained Dr. Chazal.

Emergence of their anticipated benefit over metallic stents is expected several years after implantation, when elution of the anti-restenotic drug has stopped and the scaffold has dissolved.

"Longer-term follow-up will be needed to clarify whether these newer devices provide hoped-for advantages over metallic stents, or whether the early issues with thrombosis/clotting and vessel narrowing eventually results in more clinical problems," Dr. Chazal said.

The study had no funding source. Two of the 10 coauthors reported receiving fees from stent manufacturers or holding patents related to drug-eluting stent technologies, "outside the submitted work." A third coauthor is a member of the advisory board of Abbott, which includes a division that makes an everolimus-eluting bioresorbable vascular scaffold.