Glucose and cholesterol elevations during thiazide therapy: intention-to-treat versus actual on-therapy experience

The Principle of Intention to Treat Analysis in Clinical Studies: Its Use and Controversies

The principle of intention-to-treat (ITT) has become the standard policy for comparing treatment and control groups in clinical studies. Yet, ITT is not without its critics, controversies, and misunderstandings. To properly judge results reported from clinical studies, it is imperative that pharmacists be able to assess the underlying assumptions and the methodological issues associated with ITT. This article will provide an exposition of the history, assumptions, definitions, methodology, and controversies of ITT.

The effect of antihypertensive drugs on chronic kidney disease: a comprehensive review

Data from randomized clinical trials and epidemiological evidence identify systemic hypertension as the second most common modifiable risk factor for chronic kidney disease (CKD) progression after diabetes mellitus. CKD may progress silently over the years and early diagnosis and control of hypertension is of major importance in delaying renal function decline. Recent guidelines for the treatment of hypertension suggest the use of a variety of antihypertensive drugs in order to achieve the desired blood pressure levels. Renin-angiotensin system inhibitors have been undoubtedly studied the most and are suggested by guidelines and experts as first choice in patients with hypertension and renal injury, particularly in those with diabetes, as they have repeatedly shown to significantly reduce proteinuria. Other classes of antihypertensive drugs have been studied to a lesser extent and they have their own unique properties and effects. However, it is now common knowledge that adequate blood pressure control is the most important factor for the preservation of renal function, so every drug that effectively lowers hypertension is believed to be renoprotective. The present article will review the latest data on the role and properties of each class of antihypertensive drugs on CKD.

Determinants of new-onset diabetes among 19,257 hypertensive patients randomized in the Anglo-Scandinavian Cardiac Outcomes Trial--Blood Pressure Lowering Arm and the relative influence of antihypertensive medication

OBJECTIVE

The purpose of this study was to determine the baseline predictors of new-onset diabetes (NOD) in hypertensive patients and to develop a risk score to identify those at high risk of NOD.

RESEARCH DESIGN AND METHODS

Among 19,257 hypertensive patients in the Anglo-Scandinavian Cardiac Outcomes Trial-Blood Pressure Lowering Arm (ASCOT-BPLA) who were randomly assigned to receive one of two antihypertensive regimens (atenolol +/- thiazide or amlodipine +/- perindopril), 14,120 were at risk of developing diabetes at baseline. Of these, 1,366 (9.7%) subsequently developed NOD during median follow-up of 5.5 years. A multivariate Cox model was developed to identify the independent predictors of NOD and individual risk scores.

RESULTS

NOD was significantly associated with an increase in baseline fasting plasma glucose (FPG), BMI, serum triglycerides, and systolic blood pressure. In contrast, amlodipine +/- perindopril in comparison with atenolol +/- thiazide treatment (hazard ratio 0.66 [95% CI 0.59-0.74]), high HDL cholesterol, alcohol use, and age >55 years were found to be significantly protective factors. FPG was the most powerful predictor with risk increasing by 5.8 times (95% CI 5.23-6.43) for each millimole per liter rise >5 mmol/l. The risk of NOD increased steadily with increasing quartile of risk score, with a 19-fold increase (95% CI 14.3-25.4) among those in the highest compared with those in the lowest quartile. The model showed excellent internal validity and discriminative ability.

CONCLUSIONS

Baseline FPG >5 mmol/l, BMI, and use of an atenolol +/- diuretic regimen were among the major determinants of NOD in hypertensive patients. The model developed from these data allows accurate prediction of NOD among hypertensive subjects.

Renin-angiotensin-system blockade in the prevention of diabetes

Type 2 diabetes often occurs in association with hypertension and cardiovascular disease, and markedly increases cardiovascular risk. Strategies to reduce the incidence of diabetes in patients with cardiovascular disease or at high risk for such disease are therefore important. Certain classes of antihypertensive agents, namely the thiazide diuretics and beta-blockers, have an adverse impact on the metabolic profile and increase the risk for new-onset diabetes in hypertensive subjects. In contrast, angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), which are blockers of the renin-angiotensin system (RAS), have been shown to increase insulin sensitivity. They may also reduce the risk of diabetes in patients with hypertension or cardiovascular disorders. Some of the evidence in favour of ACE inhibitors and ARBs has come from studies with active comparators that have potential adverse metabolic effects. However, the Candesartan in Heart failure-Assessment of Reduction in Mortality and morbidity (CHARM) programme demonstrated that the ARB candesartan reduced the incidence of diabetes in heart failure patients in comparison to placebo. The mechanisms responsible for the beneficial effects of RAS blockade remain to be established. Nevertheless, a treatment that can control hypertension and reduce the risk of onset of type 2 diabetes at the same time is certainly desirable.

Medical evaluation and treatment of urolithiasis

Nephrolithiasis is responsible for 1 in 1000 to 1 in 7600 pediatric hospital admissions annually throughout the United States. Seventy-five percent of children with nephrolithiasis have an identifiable predisposition to stone formation. This article reviews the different causes and disease states associated with nephrolithiasis in the pediatric population. The initial evaluation and the metabolic evaluation of children with nephrolithiasis are reviewed. Treatment modalities for the different stone types are also described.

Differential effects of antihypertensive drugs on new-onset diabetes?

Since the late 1950s, new-onset diabetes has been a recognized adverse effect of some antihypertensive drugs. Although diagnostic criteria for diabetes mellitus have changed greatly since then, epidemiologic and physiologic studies suggest that there are differences in glucose tolerance and incident diabetes across antihypertensive drug classes. Data about incident diabetes are now available from 16 long-term, randomized, clinical trials of antihypertensive drugs. From traditional meta-analyses, the rank-ordering of the drug classes is: beta-blocker approximately thiazide diuretic > placebo approximately calcium antagonist > angiotensin-converting enzyme (ACE) inhibitor approximately angiotensin receptor blocker (ARB). Earlier studies indicated that most individuals who developed incident diabetes were "pre-diabetic" before beginning antihypertensive therapy, and ipso facto had increased cardiovascular risk compared with individuals with normal glucose tolerance. An earlier diagnosis of diabetes mellitus generally has little impact (over 5 years) on cardiovascular risk. The clinical importance of differential effects of antihypertensive drugs on incident diabetes is, therefore, much less clear.

Antimicrobials as potential adjunctive agents in the treatment of biofilm infection with Staphylococcus epidermidis

BACKGROUND

This study was performed to evaluate the interaction of erythromycin or rifampin with vancomycin against Staphylococcus epidermidis biofilms.

METHODS

Biofilm-forming S. epidermidis strains (ATCC 35983, 35984) and polyurethane (PU) sheets were incubated for the formation of bacterial biofilms. Biofilms on PU sheets were treated with various antibiotic regimens. The number of viable bacteria on the sheets was counted.

RESULTS

While erythromycin or vancomycin alone did not significantly reduce the biofilm bacterial concentration, the combination of vancomycin and erythromycin resulted in a clear reduction in bacterial concentration compared with the single agents. Rifampin was the most active single agent against biofilm-forming S. epidermidis, while the combination of rifampin and vancomycin showed further reduction in bacterial concentration.

CONCLUSIONS

These data suggest that the combination of erythromycin or rifampin and vancomycin is more effective than vancomycin alone in the treatment of biofilm infections caused by biofilm-forming S. epidermidis.

Effect of low-dose thiazide diuretics on plasma lipids: results from a double-blind, randomized clinical trial in older men and women

OBJECTIVES

To determine the effects of low doses of hydrochlorothiazide (HCTZ) on plasma lipids in healthy older men and women.

DESIGN

Randomized, double-blind, placebo-controlled clinical trial for 3 years followed by a 1 year extension without medication.

SETTING

Research clinic of a nonprofit health maintenance organization.

PARTICIPANTS

Two hundred five women and 115 men aged 60 to 79 with normal blood pressure, bone density within two standard deviations of mean for age, and low-density lipoprotein cholesterol (LDL-C) levels less than 190 mg/dL.

INTERVENTION

Placebo or HCTZ 12.5 or 25 mg/d.

MEASUREMENTS

Plasma cholesterol, LDL-C, high-density lipoprotein cholesterol, triglycerides.

RESULTS

There were no significant differences in the change in the plasma lipids between placebo and either group. The mean changes +/- standard deviation in LDL-C after 3 years in men were -5.2 +/- 3.9 mg/dL (placebo), -4.6 +/- 3.7 (12.5 mg), and 1.1 +/- 3.8 (25 mg) and in women were 1.3 +/- 2.8 (placebo), -1.1 +/- 2.8 (12.5 mg), and -6.8 +/- 2.8 (25 mg). No significant differences were seen when analysis was done only for subjects who adhered to study medication.

CONCLUSION

This study provides evidence that low doses of thiazide diuretics have minimal effects on cholesterol metabolism in healthy older adults. Therefore, effects on lipid levels need not limit use of thiazides for prevention of osteoporotic fractures.

Treatment of hypertension in type 2 diabetes

Hypertension is one of the most common medical conditions in the United States, affecting 50 million American adults and accounting for one of four physician office visits. It is often undetected and undertreated, creating significant public health consequences. In diabetes, hypertension is an even greater problem, as diabetes has become the most common single cause of end-stage renal disease (ESRD) in the world, and diabetes is increasing in prevalence. The most important factor in slowing the decline of renal function in diabetes is aggressive treatment of hypertension. Recent guidelines have emphasized that the target blood pressure levels for patients with diabetes should be lower than in other hypertensive groups. The best specific approach for the treatment of hypertension in diabetic patients is the subject of much debate. It may be in the end that the specific drug choice has less overall importance than the actual attainment of adequate blood pressure control. In addition, more credence must be placed on the value of treating systolic hypertension than has traditionally been given. Coexisting diabetes and hypertension are a common clinical scenario that can set off a vicious cycle of increasing renal damage, rising blood pressure, and increased cardiovascular morbidity and mortality. Treatment often requires multiple drugs to effectively preserve renal function and prevent complications.

The relationship between urinary calcium, sodium, and potassium excretion and the role of potassium in treating idiopathic hypercalciuria

OBJECTIVES

1) To evaluate the relationships between urinary sodium (UNa), potassium (UK), and calcium (UCa) excretion in the pediatric population; and 2) to determine the effect of increasing potassium intake in patients with idiopathic hypercalciuria and investigate whether this intervention can be offered as another mode of therapy in this patient population.

DESIGN

Prospectively, we determined UNa, UK, UCa, and creatinine (Cr) concentrations in randomly collected urine samples from children on initial evaluation for urinary frequency, dysuria, hematuria, enuresis, or kidney stones to identify children with hypercalciuria.

SETTING

The outpatient renal clinic of an academic hospital.

PARTICIPANTS

Twenty-three black children (13 girls and 10 boys) and 77 white children (44 girls and 33 boys) 3.92 to 16.67 years of age.

INTERVENTIONS

Eleven children with hypercalciuria were given potassium supplementation or placed on a high-potassium diet for at least 2 weeks.

OUTCOME MEASURES

UNa to UK, UNa to Cr, UK to Cr, and UCa to Cr ratios were calculated from measured levels of urinary minerals. These were repeated in 11 hypercalciuric patients after 2 weeks of increased potassium intake.

RESULTS

A total of 100 urine samples were analyzed. The UCa/Cr ratio in blacks 0.04 +/- 0.06 (mean +/- standard deviation) was significantly lower than in whites 0.16 +/- 0.12. There were 21 hypercalciuric white children versus only 1 black child. Linear regression analysis revealed a positive direct correlation between UNa/Cr and UCa/Cr in all 100 subjects and in whites alone but not in blacks. An inverse relationship existed between UK/Cr and UCa/Cr in all subjects and in whites and showed a strong trend in blacks. A marked direct relationship was found between UNa/K and UCa/Cr in all subjects (r = .43) as well as in whites (r = .59) and blacks (r = .49). One black child and 10 white hypercalciuric children were treated with "extra" K for at least 2 weeks. The UNa/K decreased from 4.73 +/- 2.28 to 1.98 +/- 1.09, and the UCa/Cr decreased from 0. 31 +/- 0.10 to 0.14 +/- 0.07, with resolution or improvement of the patients' symptoms.

CONCLUSIONS

In our patient population with urinary symptoms, the UCa/Cr ratio in black children is lower and hypercalciuria less common than in white children. In both white and black populations, the UNa/K ratio had the strongest association with the UCa/Cr ratio, indicating an opposing role of UNa and UK on the UCa/Cr ratio. Increased potassium intake was found to be beneficial for hypercalciuric children by decreasing the UNa/K ratio and, consequently, the UCa/Cr ratio.

Intention-to-treat analysis in randomized trials: who gets counted?

This article discusses the rationale and implications associated with the selection and use of analysis strategies for randomized clinical trials as they relate to protocol deviations. The topics addressed specifically are the conceptual and methodologic approaches and biases of clinical efficacy and effectiveness assessment. Examples are provided that highlight the consequences of different analytic strategies, particularly regarding intention-to-treat analysis. Favored by statisticians intention-to-treat analysis seeks to answer the question, "Is it better to adopt a policy of treatment A if possible, with deviations if necessary, or a policy of treatment B if possible, with deviations if necessary?" This is a relevant question, sometimes more relevant than "Is treatment A better than treatment B?" The authors suggest that different analytic strategies may be more or less appropriate depending on the intended audience.

The impact of thiazide diuretics on the initiation of lipid-reducing agents in older people: a population-based analysis

OBJECTIVE

The objective of this study was to examine how often treatment for hyperlipidemia followed the use of thiazides, compared with the use of other antihypertensive drugs, in older patients.

DESIGN

Retrospective follow-up of all health claims filed over a 12-month period.

SETTING

New Jersey Medicaid and Medicare programs.

PARTICIPANTS

A total of 9274 enrollees, aged 65 to 99, who were newly initiated on antihypertensive medications from 1981-1989.

MEASUREMENTS

We measured rates of lipid-reducing agent (LRA) initiation among patients in the 2 years following antihypertensive initiation (thiazide, non-thiazide drug, or combinations of the two) compared with rates among patients not currently taking antihypertensive agents. We used Cox regression analyses to estimate relative risks (RR), accounting for switching in antihypertensive therapy and for time when drug therapy was not currently available according to pharmacy refill records.

RESULTS

There were 226 patients (2.4%) in the cohort who were started on LRA during the follow-up period. After adjusting for potential confounders, we found no significant relationship between LRA initiation and overall thiazide use (RR 1.47, 95% CI 0.89-2.40), or other antihypertensive use, relative to no current exposure. However, use of high-dose thiazides (> or = 50 mg) was associated significantly with LRA initiation (RR 1.97, 95% CI 1.12-3.45). Factors associated with decreased incidence of LRA use included age > or = 85 (RR 0.59, 95% CI 0.36-0.96), black race (RR 0.58, 95% CI 0.37-0.91), and nursing home residency (RR 0.20, 95% CI 0.11-0.35).

CONCLUSION

Use of low-cost and effective thiazide diuretics in older hypertensives was not associated with more common initiation of lipid-reducing agents, except with high-dose use of thiazides currently seen as inappropriate in most cases. Age and race were important determinants of LRA use.

Tolerability, safety, and quality of life and hypertensive therapy: the case for low-dose diuretics

The safety and tolerability of antihypertensive therapies are an important clinical concern, because the demonstrated benefits of successful blood pressure-lowering depend on long-term compliance with pharmacologic treatments. Thiazide diuretics and beta blockers have been specifically recommended as preferred initial drug therapy by the Fifth Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC-V), unless their use is contraindicated by concomitant disease, there is intolerance to these agents, or there is a specific indication for another drug class. These recommendations are a result of the lengthy clinical experience with these drugs and the results of long-term clinical trials that have demonstrated significant reductions in cardiovascular morbidity and mortality. However, data from these same clinical studies have also shown that diuretics (and beta blockers) can cause abnormalities in carbohydrate, electrolyte, and lipid metabolism and also may influence quality of life. The safety of diuretics was evaluated with regard to effects on carbohydrate, electrolyte, and lipid metabolism by seeking references from a MEDLINE search of documents published from 1966 to 1994 based on the search terms "hypertension," "human," and "hydrochlorothiazide" (HCTZ) dosed in a range of 12.5-25 mg daily. Two long-term clinical trials using low-dose (12.5-15 mg/day) chlorthalidone-the Systolic Hypertension in the Elderly Program (SHEP) and the Treatment of Mild Hypertension Study (TOMHS)-were also included. During the course of treatment with HCTZ in these studies, serum potassium was reduced and uric acid was increased in a dose-dependent manner. Although low doses of HCTZ elevated serum glucose, cholesterol, and triglycerides, the magnitude of effect was small in most cases and was probably of no clinical significance. Other laboratory parameters were not adversely affected, and subjective reporting of clinical adverse events was generally lower with low-dose HCTZ than with placebo or standard HCTZ dosing. The literature on the effects of low-dose diuretic therapy on quality of life is not large, although the results from the SHEP and TOMHS studies support the concept that diuretics either do not interfere with, or may actually improve, quality of life in hypertensive patients. Low-dose thiazide treatment is a well-tolerated, excellent first-line choice for hypertensive patients, especially older patients. However, diuretics should probably be avoided, whenever possible, in patients with preexisting diabetes, gout, and in men with erectile dysfunction.

The impact of ethnicity on response to antihypertensive therapy

The aim of this review is to assess the prevalence of complications and responses to various antihypertensive drug therapies in ethnic minority groups in the United States. In some instances, these comments are extended to responses of citizens in their countries of origin. The incidence of hypertension, mortality from hypertensive heart disease, stroke, and hypertensive renal disease are higher in African Americans. Although some Hispanic Americans have a lesser risk for hypertension, they have a greater risk for other risk factors such as diabetes and dyslipidemia. There is a similar association between income and mortality for both African Americans and Hispanic Americans. When compared to European Americans and other ethnic minorities, African Americans respond less favorably to beta blockers and angiotensin-converting enzyme (ACE) inhibitors. Nevertheless, the observed response in African Americans to ACE inhibitors and beta blockers is clinically significant. The available literature indicates that Asian American responses to calcium antagonists seem to be more favorable than responses to ACE inhibitors and equivalent to their responses to diuretic and beta blocker therapy. Although there are few published studies of drug efficacy in Hispanic Americans, there appears to be no hierarchy in response to the various antihypertensive drug classes. Ethnicity is not an accurate criterion for predicting poor response to any class of antihypertensive therapy. Thus, there is little justification to use racial profiling as a criterion for the avoidance of selected drug classes because of presumed lack of efficacy. Observed differences in the incidence of hypertension and its poor outcomes have led some investigators to postulate that the etiology of hypertension in ethnic minority groups is intrinsically different from whites. Awareness of racial differences in hypertension outcomes evolved in the United States within a historical context that does not fully appreciate that race is often a surrogate for many social and economic factors that influence health status and healthcare delivery. Poor outcomes in ethnic minority groups occur in many diseases, not only hypertension. The goal of ethnicity-related research should be to describe the diversity of disease expression in humans and to target at-risk groups for prevention and early intervention. The use of racial descriptors to explain genetic differences in ethnic groups should take a lesser priority.

Diabetes mellitus and raised serum triglyceride concentration in treated hypertension--are they of prognostic importance? Observational study

OBJECTIVE

To analyse whether metabolic changes during long term treatment with antihypertensive drugs are associated with an increased risk of coronary heart disease.

DESIGN

Observational study.

SETTING

Gothenburg, Sweden.

SUBJECTS

686 middle aged hypertensive men, recruited after screening of a random population sample, and followed for 15 years during treatment with predominantly beta adrenoceptor blockers or thiazide diuretics, or both. Coronary heart disease and diabetes mellitus were registered at yearly patient examinations. Entry characteristics, as well as within study serum concentrations of cholesterol and triglycerides and the development of diabetes mellitus, were related to the incidence of coronary heart disease in a time dependent Cox's regression analysis.

MAIN OUTCOME VARIABLE

Coronary heart disease morbidity.

RESULTS

Diabetes mellitus, raised serum cholesterol and triglyceride concentrations present at the beginning of the study were all significantly predictive of coronary heart disease in univariate analysis. The relative risk of diabetes mellitus and of a 1 mmol/l increase in the cholesterol and triglyceride concentrations was 2.12 (95% confidence interval 1.11 to 4.07), 1.21 (1.05 to 1.39), and 1.21 (1.03 to 1.43) respectively. However, when the within study metabolic variables were analysed, only the serum cholesterol concentration was significantly and independently associated with coronary heart disease (relative risk 1.07 (1.02 to 1.13)). Although the triglyceride concentrations increased slightly during the follow up, the within study serum triglyceride concentrations were not associated with the incidence of coronary heart disease (1.04 (0.96 to 1.10)). New diabetes mellitus-that is, onset during follow up-was not significantly associated with an increased risk for coronary heart disease (1.48 (0.37 to 6.00)).

CONCLUSIONS

Metabolic disturbances such as diabetes mellitus and hyperlipidaemia presenting before the start of antihypertensive treatment have a prognostic impact in middle aged, treated hypertensive men. Moreover, while within study cholesterol concentration was an independent predictor of coronary heart disease, drug related diabetes mellitus and raised serum triglyceride concentrations that are associated with treatment do not seem to have any major impact on the coronary heart disease prognosis in this category of patients.