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PubMed1996

Safety of the calcium antagonist lacidipine evaluated from a phase III-IV trial database.

OBJECTIVE: We reviewed the clinical safety profile of lacidipine with the help of the rather comprehensive datafile of the manufacturer. Although a number of prospective, randomly allocated trials under way at present are investigating the effects of treatment with calcium antagonists on cardiovascular morbidity and mortality, these results are not yet available. Therefore, the present approach may be useful. A fuller account of this work has been published in Blood Pressure. DESIGN: Since 1985,50 phase III-IV trials have been performed to investigate antihypertensive efficacy in patients with hypertension; 32 were controlled trials with comparison treatment and 18 were open studies of lacidipine treatment. Only data from trials completed before 1 January 1995 are presented here. SUBJECTS: In all, 16590 patients were treated with lacidipine; 13419 in open studies and 3171 in double-blind comparative trials. A total of 1810 patients were given active comparative treatment and 451 were given placebo. Altogether, 5124 person-years of data were obtained. MAIN OUTCOME MEASURES: Numbers of both fatal and non-fatal cardiovascular events were estimated. Efficacy (change in blood pressure and heart rate), adverse event rates and drop-out rates were compared for the different treatment regimens. RESULTS: In all trials, 2-6 mg lacidipine was effective in lowering blood pressure. In the controlled trials, systolic/diastolic blood pressure fell from 166/102 to 144/85 mmHg and the heart rate fell from 75.6 to 74.1 beats/min. The estimated event rate for a possible myocardial infarction in all studies was 5.46/1000 person-years; the fatal (all-cause) event rate was 5.27/1000 person-years and the estimated fatal cardiovascular event rate was 2.93/1000 person-years. There were 21 malignant events during treatment with lacidipine, for all studies yielding a crude incidence of 4.10/1000 person-years. In patients treated with lacidipine, the age-standardized (according to the world population) incidences were 1.49 (men) and 0.79/1000 person-years (women) compared with 2.74 (men) and 2.09/1000 person-years (women) in the European Community in 1990. The overall incidence in the comparative studies of one or more adverse events included 30.3% for lacidipine, 43.8% for other calcium antagonists, 18.7% for diuretics, 48.7% for beta-receptor blockers, 10.4% for angiotensin converting enzyme inhibitors and 15.7% for placebo. The adverse effects of lacidipine were, as expected, headaches, flushing, pedal oedema and palpitations. CONCLUSIONS: Lacidipine proved to be an effective and well tolerated drug in almost 19000 hypertensive patients. It displayed a reasonable adverse profile that was typical of a calcium antagonist of the dihydropyridine group. This analysis has two obvious limitations: (1) it is a retrospective analysis; and (2) the data were obtained from a large cohort of patients, but most were treated with lacidipine for a relatively short period of time. Although we found a lower fatal event rate than that reported by Collins et al., their meta-analysis included 10 times more person-years than our analysis, and therefore our event rate may be less accurate. Further prospective studies are under way at present to determine whether these drugs can produce reductions in atherosclerosis or in the incidence of cardiovascular disease.

Adolescent↗
PubMed2007

A 25-year review of sequential methodology in clinical studies.

This paper explores the theoretical developments and subsequent uptake of sequential methodology in clinical studies in the 25 years since Statistics in Medicine was launched. The review examines the contributions which have been made to all four phases into which clinical trials are traditionally classified and highlights major statistical advancements, together with assessing application of the techniques. The vast majority of work has been in the setting of phase III clinical trials and so emphasis will be placed here. Finally, comments are given indicating how the subject area may develop in the future.

Clinical Trials as Topic↗
PubMed2005

[Clinical trials. An overview].

Since the mid-1950s, the basis for evaluating medical therapies has shifted from transferred knowledge, subjective impression and personal experience towards clinical trials, first, in reaction to side effect tragedies, in drug licensing, then to a growing extent in other parts of medicine such as the assessment of medical devices or surgical procedures. Clinical trials are prospective studies of the efficacy and safety of therapies by repeated application. For this purpose, therapies are usually compared to controls, based on statistical reasoning. Initial comparability of study groups is best guaranteed by randomisation while equality of observation and of concomitant treatment is best guaranteed by blinding. Clinical trials do not result in clear-cut yes/no answers, but reduce the range of reasonable interpretations regarding efficacy and safety of a therapy. Thus, they allow decisions to be made on solid objective grounds. In this way, clinical trials have contributed substantially to medical progress over the last 50 years and are indispensable for today's medical research.

Clinical Trials as Topic↗
PubMed2004

Activity of telithromycin against key pathogens associated with community-acquired respiratory tract infections.

OBJECTIVES: To investigate the correlation between in vitro susceptibility of isolates and clinical outcomes with telithromycin in respiratory tract infections. METHODS: The activity of telithromycin was determined by in vitro susceptibility testing of key respiratory tract pathogens isolated from patients with community-acquired pneumonia, acute exacerbations of chronic bronchitis or acute maxillary sinusitis enrolled in 14 Phase III/IV clinical trials evaluating the clinical efficacy of telithromycin. RESULTS: In this pooled analysis, telithromycin mode minimum inhibitory concentration (MIC) and MIC90, respectively, were: 0.016 and 0.03 mg/l against Streptococcus pneumoniae (n=626); 0.03 and 0.5 mg/l for penicillin-resistant S. pneumoniae (n=56); 0.03 and 1 mg/l for erythromycin-resistant S. pneumoniae (n=81); 2 and 4 mg/l against Haemophilus influenzae (including beta-lactamase producers; n=627); both 0.12 mg/l for Moraxella catarrhalis (n=159) and both 0.25 mg/l for Staphylococcus aureus (n=124). Telithromycin (5 or 7-10 days) resulted in overall clinical and bacteriologic success rates of 88.1% (1593/1808) and 89% (1593/1789), respectively. CONCLUSIONS: High levels of in vitro susceptibility to telithromycin are paralleled by high rates of clinical cure and bacteriologic eradication.

Acute Disease↗
PubMed1995

Design of field trials for the evaluation of antibacterial products for therapy of bovine clinical mastitis.

In this paper, the design and statistical analysis of field trials for the evaluation of the efficacy of clinical mastitis therapeutics is covered. First, general issues underlying the design of clinical trials are reviewed. These include bias and confounding; randomization and blocking; and study objectives and choice of the corresponding hypothesis. Specific issues in the design of clinical mastitis trials are also discussed. Selection of subjects is discussed with regard to choice of experimental units, identification of reference population and study population, inclusion and exclusion criteria, and sample size calculation. Next, a section on treatment administration and evaluation of cure reviews treatment, blinding, choice of response measure, as well as compliance, withdrawal, and early termination. The statistical analysis section addresses possible statistical models, treatment of confounding, and fixed vs. random effects. In conclusion, well-conducted clinical mastitis trials represent an invaluable, albeit difficult and expensive, effort to evaluate efficacy and tolerance under usual circumstances of use.

Animals↗
PubMed1998

Sample size justification in phase III/IV clinical trials.

A sample size justification is often a key component in securing funding to conduct a clinical trial. Sample size computations typically require supplying values of parameters that are unknown and subject to misspecification. As an alternative, we advocate a power analysis approach based on a range of reasonable values for such parameters. We illustrate this approach in the context of a secondary stroke prevention trial.

Clinical Trials, Phase III as Topic↗
PubMed2001

Cardiovascular thrombotic events in controlled, clinical trials of rofecoxib.

BACKGROUND: In comparing aspirin, nonselective nonsteroidal antiinflammatory agents (NSAIDs), and cyclooxygenase (COX)-2 inhibitors, variation in platelet inhibitory effects exists that may be associated with differential risks of cardiovascular (CV) thrombotic events. Among the randomized, controlled trials with the COX-2 inhibitor rofecoxib, one study demonstrated a significant difference between rofecoxib and its NSAID comparator (naproxen) in the risk of CV thrombotic events. A combined analysis of individual patient data was undertaken to determine whether there was an excess of CV thrombotic events in patients treated with rofecoxib compared with those treated with placebo or nonselective NSAIDs. METHODS AND RESULTS: CV thrombotic events were assessed across 23 phase IIb to V rofecoxib studies. Comparisons were made between patients taking rofecoxib and those taking either placebo, naproxen (an NSAID with near-complete inhibition of platelet function throughout its dosing interval), or another nonselective NSAIDs used in the development program (diclofenac, ibuprofen, and nabumetone). The major outcome measure was the combined end point used by the Antiplatelet Trialists' Collaboration, which includes CV, hemorrhagic, and unknown deaths; nonfatal myocardial infarctions; and nonfatal strokes. More than 28 000 patients, representing >14 000 patient-years at risk, were analyzed. The relative risk for an end point was 0.84 (95% CI: 0.51, 1.38) when comparing rofecoxib with placebo; 0.79 (95% CI: 0.40, 1.55) when comparing rofecoxib with non-naproxen NSAIDs; and 1.69 (95% CI: 1.07, 2.69) when comparing rofecoxib with naproxen. CONCLUSIONS: This analysis provides no evidence for an excess of CV events for rofecoxib relative to either placebo or the non-naproxen NSAIDs that were studied. Differences observed between rofecoxib and naproxen are likely the result of the antiplatelet effects of the latter agent.

Aged↗
PubMed2006

Predictive factors and a corresponding treatment algorithm for controlled ovarian stimulation in patients treated with recombinant human follicle stimulating hormone (follitropin alfa) during assisted reproduction technology (ART) procedures. An analysis of 1378 patients.

BACKGROUND: Identifying parameters that can accurately predict the response to controlled ovarian stimulation (COS) would be of great benefit in assisted reproductive technology (ART) procedures. An analysis was undertaken with the objective of determining whether specific factors could optimally predict a response to stimulation in ART, and to then develop a corresponding treatment algorithm that could be used to calculate the optimal starting dose of recombinant human follicle stimulating hormone (r-hFSH; follitropin alfa) for selected patients. METHODS: The overall population consisted of 2280 normo-ovulatory ART patients from 11 randomised clinical trials. However, for the final analysis population, only patients less than 35 years of age who received r-hFSH monotherapy (N = 1378) were included. RESULTS: Backwards stepwise regression modelling indicated that predictive factors for ovarian response included basal FSH, BMI, age and number of follicles < 11 mm at baseline screening. The concordance probability index was 59.5% for this model. CONCLUSIONS: In the largest data series so far analysed to determine predictive factors of ovarian response, basal FSH, BMI, age and number of follicles < 11 mm at screening were the most important variables in ART patients less than 35 years of age who were treated with r-hFSH monotherapy. Using these four predictive factors, a follitropin alfa starting dose calculator was developed that can be used to select the FSH starting dose required for an optimal response. The relevance of this dose calculator will be evaluated in a prospective clinical trial.

Adolescent↗
PubMed2003

Clinical trials.

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Clinical Protocols↗