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Noninvasive Glucose Monitoring
CLINICAL QUESTION: How accurate is noninvasive glucose monitoring?
BACKGROUND: Tight glycemic control has been shown to improve diabetic outcomes, but current methods for monitoring blood glucose levels are painful and invasive. This trial compares traditional finger-stick glucose monitoring with the non- invasive technique of transdermal iontophoresis.
POPULATION STUDIED: A total of 92 adults with either type 1 or type 2 diabetes were enrolled from 2 diabetes centers and 3 contract research organizations. The mean age was 42 years, and 60% were women. The study population seems similar to that of a typical family practice with respect to the accuracy of noninvasive glucose monitoring.
STUDY DESIGN AND VALIDITY: The noninvasive Glucowatch biographer was compared with finger-stick capillary glucose measurements. After calibration by a single finger-stick measurement, participants wore up to 2 biographers for 12 to 15 hours while getting 2 finger-sticks per hour. Diet and insulin regimens were altered to provide a wide range of glucose levels (40-400 mg/dL).
OUTCOMES MEASURED: The major outcomes assessed were the correlation between biographer and finger-stick measures and the clinical significance of errors. Adverse effects of the biographer were also noted. Other patient-oriented outcomes, such as cost, patient satisfaction, reduction of symptoms, complications of hypoglycemia and hyperglycemia, and ease of use were not addressed.
RESULTS: Biographer readings lagged behind blood glucose measurements by a mean of 18 minutes. There was close tracking of blood glucose levels over a range of 40 to 400 mg/dL for up to 12 hours after a single calibration, and 97% of the biographer readings were associated with a finger-stick reading that was therapeutically equivalent. The average difference between measurements was 15.6%. The highest frequency of clinically significant errors was seen at blood glucose levels below 70 mg/dL; nearly one half of finger-stick measures below 70 mg/dL were read by the biographer as higher. Mild skin irritation occurred at the iontophoresis site.
Noninvasive glucose monitoring using transdermal iontophoresis can be used to track capillary glucose levels. Clinicians should understand, however, that this report is still very preliminary, and important patient-oriented outcomes have not been assessed. At a clinical level, the need for calibration, the relatively poor performance with low blood sugars, and skin irritation after 12 to 15 hours of use need further exploration. More important, this research was done by the manufacturing company on a single set of patients over a 1-day period in a laboratory environment with a suboptimal gold standard.
Although the allure of noninvasive monitoring is great, it is important to think carefully about the clinical settings in which it would be used. For patients with type 2 diabetes, the major concern has been long-term control, which may be better measured using hemoglobin A 1C every 3 months. In terms of improving clinical outcomes, there is increasing evidence that smoking cessation, low- density lipoprotein reduction, blood pressure control, and aspirin use may be much more important than blood glucose control.
CLINICAL QUESTION: How accurate is noninvasive glucose monitoring?
BACKGROUND: Tight glycemic control has been shown to improve diabetic outcomes, but current methods for monitoring blood glucose levels are painful and invasive. This trial compares traditional finger-stick glucose monitoring with the non- invasive technique of transdermal iontophoresis.
POPULATION STUDIED: A total of 92 adults with either type 1 or type 2 diabetes were enrolled from 2 diabetes centers and 3 contract research organizations. The mean age was 42 years, and 60% were women. The study population seems similar to that of a typical family practice with respect to the accuracy of noninvasive glucose monitoring.
STUDY DESIGN AND VALIDITY: The noninvasive Glucowatch biographer was compared with finger-stick capillary glucose measurements. After calibration by a single finger-stick measurement, participants wore up to 2 biographers for 12 to 15 hours while getting 2 finger-sticks per hour. Diet and insulin regimens were altered to provide a wide range of glucose levels (40-400 mg/dL).
OUTCOMES MEASURED: The major outcomes assessed were the correlation between biographer and finger-stick measures and the clinical significance of errors. Adverse effects of the biographer were also noted. Other patient-oriented outcomes, such as cost, patient satisfaction, reduction of symptoms, complications of hypoglycemia and hyperglycemia, and ease of use were not addressed.
RESULTS: Biographer readings lagged behind blood glucose measurements by a mean of 18 minutes. There was close tracking of blood glucose levels over a range of 40 to 400 mg/dL for up to 12 hours after a single calibration, and 97% of the biographer readings were associated with a finger-stick reading that was therapeutically equivalent. The average difference between measurements was 15.6%. The highest frequency of clinically significant errors was seen at blood glucose levels below 70 mg/dL; nearly one half of finger-stick measures below 70 mg/dL were read by the biographer as higher. Mild skin irritation occurred at the iontophoresis site.
Noninvasive glucose monitoring using transdermal iontophoresis can be used to track capillary glucose levels. Clinicians should understand, however, that this report is still very preliminary, and important patient-oriented outcomes have not been assessed. At a clinical level, the need for calibration, the relatively poor performance with low blood sugars, and skin irritation after 12 to 15 hours of use need further exploration. More important, this research was done by the manufacturing company on a single set of patients over a 1-day period in a laboratory environment with a suboptimal gold standard.
Although the allure of noninvasive monitoring is great, it is important to think carefully about the clinical settings in which it would be used. For patients with type 2 diabetes, the major concern has been long-term control, which may be better measured using hemoglobin A 1C every 3 months. In terms of improving clinical outcomes, there is increasing evidence that smoking cessation, low- density lipoprotein reduction, blood pressure control, and aspirin use may be much more important than blood glucose control.
CLINICAL QUESTION: How accurate is noninvasive glucose monitoring?
BACKGROUND: Tight glycemic control has been shown to improve diabetic outcomes, but current methods for monitoring blood glucose levels are painful and invasive. This trial compares traditional finger-stick glucose monitoring with the non- invasive technique of transdermal iontophoresis.
POPULATION STUDIED: A total of 92 adults with either type 1 or type 2 diabetes were enrolled from 2 diabetes centers and 3 contract research organizations. The mean age was 42 years, and 60% were women. The study population seems similar to that of a typical family practice with respect to the accuracy of noninvasive glucose monitoring.
STUDY DESIGN AND VALIDITY: The noninvasive Glucowatch biographer was compared with finger-stick capillary glucose measurements. After calibration by a single finger-stick measurement, participants wore up to 2 biographers for 12 to 15 hours while getting 2 finger-sticks per hour. Diet and insulin regimens were altered to provide a wide range of glucose levels (40-400 mg/dL).
OUTCOMES MEASURED: The major outcomes assessed were the correlation between biographer and finger-stick measures and the clinical significance of errors. Adverse effects of the biographer were also noted. Other patient-oriented outcomes, such as cost, patient satisfaction, reduction of symptoms, complications of hypoglycemia and hyperglycemia, and ease of use were not addressed.
RESULTS: Biographer readings lagged behind blood glucose measurements by a mean of 18 minutes. There was close tracking of blood glucose levels over a range of 40 to 400 mg/dL for up to 12 hours after a single calibration, and 97% of the biographer readings were associated with a finger-stick reading that was therapeutically equivalent. The average difference between measurements was 15.6%. The highest frequency of clinically significant errors was seen at blood glucose levels below 70 mg/dL; nearly one half of finger-stick measures below 70 mg/dL were read by the biographer as higher. Mild skin irritation occurred at the iontophoresis site.
Noninvasive glucose monitoring using transdermal iontophoresis can be used to track capillary glucose levels. Clinicians should understand, however, that this report is still very preliminary, and important patient-oriented outcomes have not been assessed. At a clinical level, the need for calibration, the relatively poor performance with low blood sugars, and skin irritation after 12 to 15 hours of use need further exploration. More important, this research was done by the manufacturing company on a single set of patients over a 1-day period in a laboratory environment with a suboptimal gold standard.
Although the allure of noninvasive monitoring is great, it is important to think carefully about the clinical settings in which it would be used. For patients with type 2 diabetes, the major concern has been long-term control, which may be better measured using hemoglobin A 1C every 3 months. In terms of improving clinical outcomes, there is increasing evidence that smoking cessation, low- density lipoprotein reduction, blood pressure control, and aspirin use may be much more important than blood glucose control.
Preventing Stroke in Patients with Atrial Fibrillation
CLINICAL QUESTION: Should we use warfarin or aspirin to prevent stroke in patients with nonvalvular atrial fibrillation?
BACKGROUND: Patients with atrial fibrillation have a substantial risk of stroke, but the best medication for anticoagulation remains unclear. This meta-analysis compared the safety and effectiveness of warfarin and aspirin in preventing stroke in patients with nonvalvular atrial fibrillation.
POPULATION STUDIED: This paper combined the results of 16 randomized-controlled trials from Europe and North America of 9874 patients with nonvalvular atrial fibrillation. The mean age of subjects was 69 to 71 years, 29% to 38% were women, 45% had hypertension, and 20% to 40% had a previous stroke or transient ischemic attack (TIA). International normalized ratio targets in most studies were 2 to 3 or 2 to 3.5; aspirin dosages ranged from 50 mg per day to 1300 mg per day.
STUDY DESIGN AND VALIDITY: The authors of this meta-analysis reviewed published randomized trials found through OVID and MEDLINE (1966-1999) and by inquiries to the Cochrane Collaboration Stroke Review Group and the Antithrombotic Trialists Collaboration. Studies of valvular atrial fibrillation were excluded. Primary (those that included patients without previous stroke) and secondary (those that included patients with previous stroke or TIA) prevention trials were included. Trials reporting results for subgroups of patients with atrial fibrillation were included, as were nonblinded trials. Two reviewers extracted information on exposure and outcomes by intention-to-treat analysis; homogeneity was tested for each comparison. This was a well-done meta-analysis. Its strengths included the limitation to randomized-controlled trials and the use of independent reviewers; weaknesses included the lack of assessment of study quality, inconsistent reporting of tests for homogeneity, and the lack of analysis of confounders such as risks for hemorrhage, other risks for strokes, or amount of medication. Important outcomes not addressed include cost, patient acceptability, functional status, and quality of life.
OUTCOME MEASURED: The primary outcome reported was the occurrence of all strokes (hemorrhagic and ischemic) presented as relative risk reduction (RRD), absolute risk reduction (ARR) and number needed to treat (NNT) for primary and secondary prevention. Other outcomes included were occurrence of ischemic stroke, intracranial hemorrhage, all-cause mortality, and major extracranial bleeding.
RESULTS: The mean follow-up of patients was 1.7 years. Treatment with adjusted-dose warfarin was superior to placebo for all trials, yielding a 62% RRD (95% confidence interval [CI], 48% - 72%). In patients without a history of stroke or TIA, warfarin produced an ARR of 2.7% (NNT = 37). For secondary prevention, 12 patients needed to be treated to prevent another significant event from occurring (ARR = 2.7%). Of those patients, 60 had to be treated to prevent one death of any cause (ARR = 2.7%).
This meta-analysis provides good evidence that adjusted-dose warfarin is superior to aspirin for stroke prevention in patients with nonvalvular atrial fibrillation. The magnitude of this benefit varies with the risk for stroke. Patients who are at high risk (those with previous stroke or TIA or secondary prevention) have the most to gain from treatment with warfarin compared with aspirin. For patients with a lower risk of stroke (primary prevention), the risks of therapy with warfarin begin to outweigh the benefits.1
CLINICAL QUESTION: Should we use warfarin or aspirin to prevent stroke in patients with nonvalvular atrial fibrillation?
BACKGROUND: Patients with atrial fibrillation have a substantial risk of stroke, but the best medication for anticoagulation remains unclear. This meta-analysis compared the safety and effectiveness of warfarin and aspirin in preventing stroke in patients with nonvalvular atrial fibrillation.
POPULATION STUDIED: This paper combined the results of 16 randomized-controlled trials from Europe and North America of 9874 patients with nonvalvular atrial fibrillation. The mean age of subjects was 69 to 71 years, 29% to 38% were women, 45% had hypertension, and 20% to 40% had a previous stroke or transient ischemic attack (TIA). International normalized ratio targets in most studies were 2 to 3 or 2 to 3.5; aspirin dosages ranged from 50 mg per day to 1300 mg per day.
STUDY DESIGN AND VALIDITY: The authors of this meta-analysis reviewed published randomized trials found through OVID and MEDLINE (1966-1999) and by inquiries to the Cochrane Collaboration Stroke Review Group and the Antithrombotic Trialists Collaboration. Studies of valvular atrial fibrillation were excluded. Primary (those that included patients without previous stroke) and secondary (those that included patients with previous stroke or TIA) prevention trials were included. Trials reporting results for subgroups of patients with atrial fibrillation were included, as were nonblinded trials. Two reviewers extracted information on exposure and outcomes by intention-to-treat analysis; homogeneity was tested for each comparison. This was a well-done meta-analysis. Its strengths included the limitation to randomized-controlled trials and the use of independent reviewers; weaknesses included the lack of assessment of study quality, inconsistent reporting of tests for homogeneity, and the lack of analysis of confounders such as risks for hemorrhage, other risks for strokes, or amount of medication. Important outcomes not addressed include cost, patient acceptability, functional status, and quality of life.
OUTCOME MEASURED: The primary outcome reported was the occurrence of all strokes (hemorrhagic and ischemic) presented as relative risk reduction (RRD), absolute risk reduction (ARR) and number needed to treat (NNT) for primary and secondary prevention. Other outcomes included were occurrence of ischemic stroke, intracranial hemorrhage, all-cause mortality, and major extracranial bleeding.
RESULTS: The mean follow-up of patients was 1.7 years. Treatment with adjusted-dose warfarin was superior to placebo for all trials, yielding a 62% RRD (95% confidence interval [CI], 48% - 72%). In patients without a history of stroke or TIA, warfarin produced an ARR of 2.7% (NNT = 37). For secondary prevention, 12 patients needed to be treated to prevent another significant event from occurring (ARR = 2.7%). Of those patients, 60 had to be treated to prevent one death of any cause (ARR = 2.7%).
This meta-analysis provides good evidence that adjusted-dose warfarin is superior to aspirin for stroke prevention in patients with nonvalvular atrial fibrillation. The magnitude of this benefit varies with the risk for stroke. Patients who are at high risk (those with previous stroke or TIA or secondary prevention) have the most to gain from treatment with warfarin compared with aspirin. For patients with a lower risk of stroke (primary prevention), the risks of therapy with warfarin begin to outweigh the benefits.1
CLINICAL QUESTION: Should we use warfarin or aspirin to prevent stroke in patients with nonvalvular atrial fibrillation?
BACKGROUND: Patients with atrial fibrillation have a substantial risk of stroke, but the best medication for anticoagulation remains unclear. This meta-analysis compared the safety and effectiveness of warfarin and aspirin in preventing stroke in patients with nonvalvular atrial fibrillation.
POPULATION STUDIED: This paper combined the results of 16 randomized-controlled trials from Europe and North America of 9874 patients with nonvalvular atrial fibrillation. The mean age of subjects was 69 to 71 years, 29% to 38% were women, 45% had hypertension, and 20% to 40% had a previous stroke or transient ischemic attack (TIA). International normalized ratio targets in most studies were 2 to 3 or 2 to 3.5; aspirin dosages ranged from 50 mg per day to 1300 mg per day.
STUDY DESIGN AND VALIDITY: The authors of this meta-analysis reviewed published randomized trials found through OVID and MEDLINE (1966-1999) and by inquiries to the Cochrane Collaboration Stroke Review Group and the Antithrombotic Trialists Collaboration. Studies of valvular atrial fibrillation were excluded. Primary (those that included patients without previous stroke) and secondary (those that included patients with previous stroke or TIA) prevention trials were included. Trials reporting results for subgroups of patients with atrial fibrillation were included, as were nonblinded trials. Two reviewers extracted information on exposure and outcomes by intention-to-treat analysis; homogeneity was tested for each comparison. This was a well-done meta-analysis. Its strengths included the limitation to randomized-controlled trials and the use of independent reviewers; weaknesses included the lack of assessment of study quality, inconsistent reporting of tests for homogeneity, and the lack of analysis of confounders such as risks for hemorrhage, other risks for strokes, or amount of medication. Important outcomes not addressed include cost, patient acceptability, functional status, and quality of life.
OUTCOME MEASURED: The primary outcome reported was the occurrence of all strokes (hemorrhagic and ischemic) presented as relative risk reduction (RRD), absolute risk reduction (ARR) and number needed to treat (NNT) for primary and secondary prevention. Other outcomes included were occurrence of ischemic stroke, intracranial hemorrhage, all-cause mortality, and major extracranial bleeding.
RESULTS: The mean follow-up of patients was 1.7 years. Treatment with adjusted-dose warfarin was superior to placebo for all trials, yielding a 62% RRD (95% confidence interval [CI], 48% - 72%). In patients without a history of stroke or TIA, warfarin produced an ARR of 2.7% (NNT = 37). For secondary prevention, 12 patients needed to be treated to prevent another significant event from occurring (ARR = 2.7%). Of those patients, 60 had to be treated to prevent one death of any cause (ARR = 2.7%).
This meta-analysis provides good evidence that adjusted-dose warfarin is superior to aspirin for stroke prevention in patients with nonvalvular atrial fibrillation. The magnitude of this benefit varies with the risk for stroke. Patients who are at high risk (those with previous stroke or TIA or secondary prevention) have the most to gain from treatment with warfarin compared with aspirin. For patients with a lower risk of stroke (primary prevention), the risks of therapy with warfarin begin to outweigh the benefits.1
Concerns of Women Regarding Hormone Replacement Therapy
CLINICAL QUESTION: What are the concerns of women considering hormone replacement therapy (HRT)?
BACKGROUND: Counseling women about HRT is common in family practice, but available research has focused on risks and benefits from the perspective of providers. This qualitative study explores the perspective of patients.
POPULATION STUDIED: Twenty-six women who received new HRT prescriptions at a staff-model health maintenance organization were interviewed. Originally, 176 were identified as potential participants; reasons for exclusion included premenopausal state, previous use of estrogens, and use of topical estrogens. Thirty-four women refused to participate, 20 were never contacted, and 34 consented but were never interviewed because study data were sufficient. The median age was 53, 85% were white, and median annual income was $46,000. Fifty-four percent stated they had initiated discussion of HRT with their provider, and 81% had filled the HRT prescription at the time of interview.
STUDY DESIGN AND VALIDITY: This was a qualitative study. Each woman was interviewed for 1 hour, and the audiotape was transcribed and analyzed. Three judges used a consensus process to identify the variety of domains (specific concerns) the women mentioned. Another investigator assigned patient comments to specific domains. Interviewing new subjects stopped when no new information was being added.
OUTCOMES MEASURED: This qualitative study identified womens’ concerns about HRT. By design, a qualitative study can neither quantify the prevalence or strength of particular concerns nor address clinical outcomes.
RESULTS: Influences on the decision to begin HRT were broad and included provider opinion (96% of interviewees reported), media reports (81%), experiences and opinions of friends (77%), and experiences and opinions of family (65%). Specific clinical concerns cited included risk for breast cancer, having to take medication, prevention of osteoporosis, hot flashes, prevention of heart disease, insomnia, living with medical uncertainty, menstrual-type bleeding, and genitourinary symptoms.
This study provides good evidence that women who have received a prescription for HRT use many sources of information—in addition to the opinion of their physicians—to make their decision about whether to begin the therapy. These women have concerns about HRT that are substantially broader than those identified in the medical literature. Physicians should take into account the impact of their recommendations and the influence of the patients’ family, friends, and the media and should seek to identify the specific concerns of individual patients.
CLINICAL QUESTION: What are the concerns of women considering hormone replacement therapy (HRT)?
BACKGROUND: Counseling women about HRT is common in family practice, but available research has focused on risks and benefits from the perspective of providers. This qualitative study explores the perspective of patients.
POPULATION STUDIED: Twenty-six women who received new HRT prescriptions at a staff-model health maintenance organization were interviewed. Originally, 176 were identified as potential participants; reasons for exclusion included premenopausal state, previous use of estrogens, and use of topical estrogens. Thirty-four women refused to participate, 20 were never contacted, and 34 consented but were never interviewed because study data were sufficient. The median age was 53, 85% were white, and median annual income was $46,000. Fifty-four percent stated they had initiated discussion of HRT with their provider, and 81% had filled the HRT prescription at the time of interview.
STUDY DESIGN AND VALIDITY: This was a qualitative study. Each woman was interviewed for 1 hour, and the audiotape was transcribed and analyzed. Three judges used a consensus process to identify the variety of domains (specific concerns) the women mentioned. Another investigator assigned patient comments to specific domains. Interviewing new subjects stopped when no new information was being added.
OUTCOMES MEASURED: This qualitative study identified womens’ concerns about HRT. By design, a qualitative study can neither quantify the prevalence or strength of particular concerns nor address clinical outcomes.
RESULTS: Influences on the decision to begin HRT were broad and included provider opinion (96% of interviewees reported), media reports (81%), experiences and opinions of friends (77%), and experiences and opinions of family (65%). Specific clinical concerns cited included risk for breast cancer, having to take medication, prevention of osteoporosis, hot flashes, prevention of heart disease, insomnia, living with medical uncertainty, menstrual-type bleeding, and genitourinary symptoms.
This study provides good evidence that women who have received a prescription for HRT use many sources of information—in addition to the opinion of their physicians—to make their decision about whether to begin the therapy. These women have concerns about HRT that are substantially broader than those identified in the medical literature. Physicians should take into account the impact of their recommendations and the influence of the patients’ family, friends, and the media and should seek to identify the specific concerns of individual patients.
CLINICAL QUESTION: What are the concerns of women considering hormone replacement therapy (HRT)?
BACKGROUND: Counseling women about HRT is common in family practice, but available research has focused on risks and benefits from the perspective of providers. This qualitative study explores the perspective of patients.
POPULATION STUDIED: Twenty-six women who received new HRT prescriptions at a staff-model health maintenance organization were interviewed. Originally, 176 were identified as potential participants; reasons for exclusion included premenopausal state, previous use of estrogens, and use of topical estrogens. Thirty-four women refused to participate, 20 were never contacted, and 34 consented but were never interviewed because study data were sufficient. The median age was 53, 85% were white, and median annual income was $46,000. Fifty-four percent stated they had initiated discussion of HRT with their provider, and 81% had filled the HRT prescription at the time of interview.
STUDY DESIGN AND VALIDITY: This was a qualitative study. Each woman was interviewed for 1 hour, and the audiotape was transcribed and analyzed. Three judges used a consensus process to identify the variety of domains (specific concerns) the women mentioned. Another investigator assigned patient comments to specific domains. Interviewing new subjects stopped when no new information was being added.
OUTCOMES MEASURED: This qualitative study identified womens’ concerns about HRT. By design, a qualitative study can neither quantify the prevalence or strength of particular concerns nor address clinical outcomes.
RESULTS: Influences on the decision to begin HRT were broad and included provider opinion (96% of interviewees reported), media reports (81%), experiences and opinions of friends (77%), and experiences and opinions of family (65%). Specific clinical concerns cited included risk for breast cancer, having to take medication, prevention of osteoporosis, hot flashes, prevention of heart disease, insomnia, living with medical uncertainty, menstrual-type bleeding, and genitourinary symptoms.
This study provides good evidence that women who have received a prescription for HRT use many sources of information—in addition to the opinion of their physicians—to make their decision about whether to begin the therapy. These women have concerns about HRT that are substantially broader than those identified in the medical literature. Physicians should take into account the impact of their recommendations and the influence of the patients’ family, friends, and the media and should seek to identify the specific concerns of individual patients.