A. Lawrence Gould

Prostate volume predicts outcome of treatment of benign prostatic hyperplasia with finasteride: Meta-analysis of randomized clinical trials

OBJECTIVES Six randomized clinical trials have compared at least 1 year of 5 mg finasteride to placebo in the treatment of clinical benign prostatic hyperplasia (BPH). The findings for the 2601 men in these trials provide an opportunity to investigate the heterogeneity of the effects seen in the individual studies and to identify pretreatment predictors of outcomes as expressed by symptoms or peak urinary flow rates. METHODS A formal meta-analysis using an Empirical Bayes approach employed data from all finasteride studies which included the Phase III trials in North America and Internationally, the Prospect, Early Intervention, and SCARP trials, and the Veterans Administration Cooperative Study which compared terazosin, finasteride, and the combination of these two drugs. A pooled analysis was also undertaken on the combined dataset. RESULTS The effect of finasteride treatment on improvements in total symptom severity, frequency score, and peak urinary flow rate was consistent across all six trials and similar among men with similar prostate volumes at baseline. Symptom severity improved by 1.8 points (95% confidence interval [CI], 0.7 to 2.9) in men with prostate volumes less than 20 cc (n = 72), while the improvement was 2.8 points (95% CI, 2.1 to 3.5) for men with volumes greater than 60 cc (n = 272) on the Quasi-IPSS Scale (range 0 to 30). Similarly, improvements in peak urinary flow rate ranged from 0.89 mL/s (95% CI, -0.05 to 1.83) for men with prostate volumes less than 20 cc to 1.84 mL/s (95% CI, 1.37 to 2.30) in men with volumes greater than 60 cc. The difference in the magnitude of improvement between finasteride and placebo becomes significant (that is, no overlap in 95% CI) for men with a baseline prostate volume assessed by either transrectal ultrasonography or magnetic resonance imaging of greater than 40 cc, which encompasses approximately 50% of the entire population. Baseline prostate volume is a key predictor of treatment outcomes: approximately 80% of the variation in the treatment effects noted between studies could be attributed to differences in mean prostate volumes at baseline. Variation in entry criteria results in large differences in baseline symptom severity status, prostate volume, and consequently apparent inconsistencies in the overall outcomes of these trials. CONCLUSIONS This meta-analysis suggests that finasteride is most effective in men with large prostates. Men with small prostates may not be suitable candidates for finasteride therapy for BPH. The need for a careful reevaluation of the definitions and terminology used when discussing urination problems is apparent.

Serum prostate-specific antigen as a predictor of prostate volume in men with benign prostatic hyperplasia

OBJECTIVES To assess the utility of prostate-specific antigen (PSA) as a predictor of prostate volume by characterizing the relationship between prostate volume and serum PSA in men with symptomatic benign prostatic hyperplasia (BPH) and no evidence of prostate cancer, stratified by decade of life. METHODS Placebo-controlled multicenter trials in patients with BPH and a safety study in normal young men provided baseline measurements of serum PSA and prostate volume. The analyses included patients with a baseline prostate volume measured by either transrectal ultrasound (TRUS) or magnetic resonance imaging and baseline serum PSA. A common central laboratory was used for all but one of the individual studies; both laboratories used the Hybritech method. Patients 80 years of age or older were excluded. Patients with a baseline serum PSA greater than 10 ng/mL were excluded to reduce the likelihood of including occult prostate cancer cases. The patients in the BPH trials were screened at baseline by digital rectal examination (DRE) and serum PSA. Those with suspicious findings underwent TRUS-guided biopsy; only patients with negative biopsies are included in these analyses. RESULTS The analyses included 4627 patients, 4448 from the BPH trials and 179 from the safety study. The men in the BPH trials were older (mean age+SE, 63.7+0.10 years) than the men in the safety study (mean age + SE, 30.8+/-0.43), had larger prostates (mean volume+/-SE, 43.7+/-0.38 mL versus 26.3+/-0.49 mL in the safety study), and had higher serum PSA values (mean+/-SE, 2.6+/-0.03 ng/mL versus 0.7+/-0.39 ng/mL in the safety study). The relationship between prostate volume and serum PSA was evaluated using only the BPH trial data. Prostate volume and serum PSA have an age-dependent log-linear relationship (ie, their logarithms are linearly related, and the parameters of the relationship depend on age). Older men tend to have a steeper rate of increase in prostate volume with increasing serum PSA (P < 0.00 for differences between slopes), and there was a slight tendency for PSA density to increase with age. Receiver operating characteristic (ROC) curves were constructed to evaluate the ability of serum PSA to predict threshold prostate sizes in men with BPH. The ROC curve analyses revealed that PSA had good predictive value for assessing prostate volume, with areas under the curve ranging from 0.76 to 0.78 for various prostate volume cutoff points (30, 40, and 50 mL). Conclusions. Prostate volume is strongly related to serum PSA in men with BPH and no evidence of prostate cancer, and the relationship depends on age. Since treatment outcome or risk of long-term complications depend on baseline prostate volume, serum PSA can estimate the degree of prostate enlargement sufficiently accurately to be useful for therapeutic decision making. To achieve a specificity of 70% while maintaining a sensitivity between 65% and 70%, approximate age-specific criteria for detecting men with prostate glands exceeding 40 mL are PSA > 1.6 ng/mL, >2.0 ng/mL, and >2.3 ng/mL for men with BPH in their 50s, 60s, and 70s, respectively.

Sample size re-estimation without unblinding for normally distributed outcomes with unknown variance

Monitoring clinical trials in nonfatal diseases where ethical considerations do not dictate early termination upon demonstration of efficacy often requires examining the interim findings to assure that the protocol-specified sample size will provide sufficient power against the null hypothesis when the alternative hypothesis is true. The sample size may be increased, if necessary to assure adequate power. This paper presents a new method for carrying out such interim power evaluations for observations from normal distributions without unblinding the treatment assignments or discernably affecting the Type 1 error rate. Simulation studies confirm the expected performance of the method.

Perspectives on the Use of Data Mining in Pharmacovigilance

In the last 5 years, regulatory agencies and drug monitoring centres have been developing computerised data-mining methods to better identify reporting relationships in spontaneous reporting databases that could signal possible adverse drug reactions. At present, there are no guidelines or standards for the use of these methods in routine pharmacovigilance. In 2003, a group of statisticians, pharmacoepidemiologists and pharmacovigilance professionals from the pharmaceutical industry and the US FDA formed the Pharmaceutical Research and Manufacturers of America-FDA Collaborative Working Group on Safety Evaluation Tools to review best practices for the use of these methods.In this paper, we provide an overview of: (i) the statistical and operational attributes of several currently used methods and their strengths and limitations; (ii) information about the characteristics of various postmarketing safety databases with which these tools can be deployed; (iii) analytical considerations for using safety data-mining methods and interpreting the results; and (iv) points to consider in integration of safety data mining with traditional pharmacovigilance methods. Perspectives from both the FDA and the industry are provided.Data mining is a potentially useful adjunct to traditional pharmacovigilance methods. The results of data mining should be viewed as hypothesis generating and should be evaluated in the context of other relevant data. The availability of a publicly accessible global safety database, which is updated on a frequent basis, would further enhance detection and communication about safety issues.

Practical pharmacovigilance analysis strategies

To compare two recently proposed Bayesian methods for quantitative pharmacovigilance with respect to assumptions and results, and to describe some practical strategies for their use.

Cholesterol reduction yields clinical benefits: meta-analysis including recent trials

BACKGROUND Previous meta-analyses reported by Gould et al found significant decreases of 15% in the risk for coronary heart disease (CHD)-related mortality and 11 % in risk for all-cause mortality per decrease of 10% in total cholesterol (TC) level. OBJECTIVE To evaluate the effects of reducing cholesterol on clinical events after including data from recent clinical trials. METHODS Using a literature search (MeSH key terms, including: bezafibrate, coronary disease, efficacy, gemfibrozil, hydroxymethylglutaryl-CoA reductase inhibitors, hypercholesterolemia, niacin [nicotinic acids], randomized controlled trials, and treatment outcome; years: 1999-2005), we identified trials published in English that assessed the effects of lipid-modifying therapies on CHD end points, including CHD-related death, myocardial infarction, and angina pectoris. We also included all studies from the previously published meta-analysis. Using the same analytic approach as previously, we determined the effects of net absolute reductions (1 mmol/L [38.7 mg/dL]) in TC and low-density lipoprotein cholesterol (LDL-C) on the relative risks (RRs) for all-cause mortality, CHD-related mortality, any CHD event (mortality or nonfatal myocardial infarction), and non-CHD-related mortality. RESULTS We included 62 studies involving 216,616 patients, including 126,474 from 24 randomized controlled trials the findings of which were published since the previous meta-analysis (1998). Among all patients, for every 1-mmol/L decrease in TC, there was a 17.5 reduction in RR for all-cause mortality; 24.5 %, for CHD-related mortality; and 29.5% for any CHD event. Corresponding reductions for every 1-mmol/L decrease in LDL-C were 15.6%, 28.0%, and 26.6%, respectively. Similar relationships were observed in patients without CHD. No significant relationship was found between lipid reduction and non-CHD-related mortality risk. CONCLUSIONS The results from the present analysis support conclusions from previous meta-analyses that cholesterol lowering is clinically beneficial in patients with CHD or at elevated CHD risk. These results also support the previous finding that non-CHD-related mortality is unrelated to lipid reductions.

Expanded clinical evaluation of lovastatin (EXCEL) study results: IV. Additional perspectives on the tolerability of lovastatin

This randomized, double-blind, multicenter, diet-and-placebo-controlled study was designed to clarify the dose-response relationship of lovastatin therapy to lipid-modifying efficacy and drug-related adverse events. Exclusion criteria were minimized so that study patients were representative of the majority of patients with moderate hypercholesterolemia seen in medical practice. After 6 weeks on the American Heart Association Step 1 Diet, a total of 8,245 patients were randomly assigned to 48 weeks of treatment with diet and placebo or lovastatin at dosages of 20 or 40 mg once a day or 20 or 40 mg twice a day. All adverse events were monitored, with particular attention to evaluation of liver and muscle. Liver transaminase elevations suggestive of possible hepatotoxicity, defined as successive elevations in either aspartate transaminase or alanine aminotransferase greater than 3 times the upper limit of normal, occurred in equal numbers of placebo and lovastatin 20 mg/day treated patients (0.1%). The frequencies were higher in lovastatin 40 mg/day and 80 mg/day patient groups (0.9 and 1.5%, respectively). No patient was diagnosed as having clinically symptomatic hepatic dysfunction. Creatinine kinase (CK) elevations above the upper limit of normal occurred frequently in placebo- (29%), as well as lovastatin-treated patients (29-35%), and muscle symptoms were reported with similar frequency in all groups (7-9%). The combination of muscle symptoms with marked CK elevations (greater than 10 times the upper limit of normal) was seen in only five patients: one in a 40 mg/day dose group and four in the 80 mg/day dose group. No patient developed rhabdomyolysis. The incidence of clinical and laboratory adverse events requiring discontinuation was 6% for the placebo group and from 7% (20 mg/day) to 9% (80 mg/day) for lovastatin treatment groups. No new types of adverse experiences related to lovastatin treatment were reported. Lovastatin, as an adjunct to diet for the reduction of elevated LDL cholesterol, was generally very well tolerated.

COMPARISON OF ALTERNATIVE STRATEGIES FOR ANALYSIS OF LONGITUDINAL TRIALS WITH DROPOUTS

Problem: Patients may withdraw from longitudinal clinical trials for many reasons. Methods for handling the problem presented by missing data of patients who withdraw before reaching the time point of the primary measurement include carrying the last observation forward (LOCF), data as observed analysis (DAO), mixed model approaches, and pattern mixture models. Method: We evaluate a multiple imputation (MI) approach that has the flexibility to adjust inferences about the treatment effect for the withdrawn patients relative to currently used alternatives. Sensitivity analyses are performed under a collection of scenarios that include many circumstances that may arise in practice, including different assumptions about treatment effects post-withdrawal and about the missing data mechanism. Simulations are used to compare the results of analyses based on the MI approach with those based on the LOCF, DAO, and the mixed model approaches. Results: The LOCF and DAO approaches cannot be recommended as strategies for handling missing responses, at least for these scenarios, because they provide biased estimates of treatment effects and biased tests of the null hypothesis of no treatment effect. Application of the various approaches to the analysis of clinical data from a longitudinal trial confirms the underestimation of the variability when the LOCF approach is used. *Dr. Paul Gallo served as Acting Editor for this manuscript.

Design of the DEFINE trial: Determining the EFficacy and Tolerability of CETP INhibition with AnacEtrapib

BACKGROUND Residual cardiovascular (CV) risk often remains high despite statin therapy to lower low-density lipoprotein cholesterol (LDL-C). New therapies to raise high-density lipoprotein cholesterol (HDL-C) are currently being investigated. Anacetrapib is a cholesteryl ester transfer protein (CETP) inhibitor that raises HDL-C and reduces LDL-C when administered alone or with a statin. Adverse effects on blood pressure, electrolytes, and aldosterone levels, seen with another drug in this class, have not been noted in studies of anacetrapib to date. METHODS Determining the EFficacy and Tolerability of CETP INhibition with AnacEtrapib (DEFINE) is a randomized, double-blind, placebo-controlled trial to assess the efficacy and safety profile of anacetrapib in patients with coronary heart disease (CHD) or CHD risk equivalents (clinical trials.gov NCT00685776). Eligible patients at National Cholesterol Education Program-Adult Treatment Panel III LDL-C treatment goal on a statin, with or without other lipid-modifying medications, are treated with anacetrapib, 100 mg, or placebo for 18 months, followed by a 3-month, poststudy follow-up. The primary end points are percent change from baseline in LDL-C and the safety and tolerability of anacetrapib. Comprehensive preplanned interim safety analyses will be performed at the 6- and 12-month time points to examine treatment effects on key safety end points, including blood pressure and electrolytes. A preplanned Bayesian analysis will be performed to interpret the CV event distribution, given the limited number of events expected in this study. RESULTS A total of 2,757 patients were screened at 153 centers in 20 countries, and 1,623 patients were randomized into the trial. Lipid results, clinical CV events, and safety outcomes from this trial are anticipated in 2010.

Expanded clinical evaluation of lovastatin (EXCEL) study results II. Assessment of the human lens after 48 weeks of treatment with lovastatin

The crystalline lenses of hypercholesterolemic patients were assessed before and after 48 weeks of treatment with lovastatin or placebo to determine the effect of lovastatin on the human lens. Patients were given a biomicroscopic (slit-lamp) examination of the lens, and a previously validated, standardized classification system was used to describe the findings. A total of 8,245 patients were randomly assigned in equal numbers to treatment with placebo or lovastatin 20 or 40 mg once or twice daily in this double-blind, parallel-group study. Statistical analyses of the distribution of cortical, nuclear and subcapsular opacities at 48 weeks, adjusted for age and presence of an opacity at baseline, showed no significant differences (p less than 0.01) between the placebo and lovastatin-treated groups. Visual acuity assessments at week 48 were also not found to have significantly different distributions among treatment groups. Moreover, no significant differences were found among the groups in the frequencies of greater than or equal to 2-line worsening in visual acuity with concurrent progression in lenticular opacity, cataract extraction, or any spontaneously reported adverse ophthalmologic experience. No evidence was found for an effect of lovastatin on the human lens after 48 weeks of treatment.