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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↗
PubMed2005

Assessing the relationship between antigenicity and immunogenicity of human rabies vaccines. Results of a meta-analysis.

A meta-analysis was done to study the relationship between antigenecity and immunogenecity of human rabies vaccines. The data of ten cell culture human rabies vaccine studies conducted at a single centre during 1993-2004 were used in the study. The vaccines studied included Purified Chick Embryo Cell Vaccine (Kaketsuken, Japan and Rabipur, India), Purified Vero cell Rabies Vaccine (Verorab, France), Human Diploid Cell Vaccine (MIRV, France and Rabivax, Adsorbed and Lyophilized, India) and Rhesus Diploid Rabies Vaccine (adsorbed, USA). Interestingly, it was revealed that an higher antigenecity of rabies vaccines viz. potency of > or = 5 IU per single intramuscular dose did not result in significantly higher immunogenecity, as measured by rabies virus neutralizing antibody (RVNA) titers in the vaccinees, both on day 14 (t = 0.42, p > 0.66, GMR = 1.06, 95% CI of GMR = 0.82, 1.37) and day 90 (t = 0.80, p > 0.43, GMR = 1.15, 95% CI of GMR = 0.74, 1.14). However, as there are no reports of meta-analysis of cell culture human rabies vaccine trials, to confirm this observation the authors recommend further studies in this regard.

Adolescent↗
PubMed2001

Update on intravenous tissue plasminogen activator for acute stroke: from clinical trials to clinical practice.

Tissue plasminogen activator (tPA) injected intravenously within 3 hours of symptom onset has emerged as a treatment option for acute ischemic stroke. Although controversial and not universally accepted, its use in carefully selected patients is supported by evidence from randomized controlled trials and by mounting community experience. In this paper we review the literature published in the past 5 years regarding the safety, clinical trial efficacy and real-world effectiveness of intravenous tPA for stroke. First we review data from the phase III clinical trials on which approval for tPA is based. Then we summarize a growing literature of postmarketing phase IV studies and discuss the limitations and challenges that lie ahead. Our aim is to provide clinicians with an overview of this evolving therapy.

Acute Disease↗
PubMed2005

Clinical data gap between phase III clinical trials (pre-marketing) and phase IV (post-marketing) studies: evaluation of etanercept in rheumatoid arthritis.

BACKGROUND: There are fundamental differences in design between phase III clinical trials and phase IV post-marketing studies that involve patient characteristics, the clinical setting (environment) and the manner of drug use. As well, many phase IV studies are extensions of randomized clinical trials (RCTs) and suffer from selection bias. OBJECTIVE: To determine if the data obtained from RCTs of etanercept (Enbrel) in the treatment of rheumatoid arthritis would be representative of the effects attainable in community practice. METHOD: An analysis was conducted comparing data from published RCTs of etanercept use in rheumatoid arthritis patients with data collected in a community based cohort study that was not an extension of an RCT. RESULTS: Baseline clinical data, such as tender or painful joint count, patient's global assessment, the heath assessment questionnaire, physical and mental component summary of the SF-36, and rheumatoid arthritis drug profile were significantly different between the patients receiving etanercept in the phase IV community cohort study and the patients enrolled in the RCTs. Differences in the baseline data for the control patients were also noted amongst the RCT studies. The treatment outcome, American College of Rheumatology (ACR) response rate of 20%, 50% and 70% at 6 month, was the same between the cohort study and the RCTs, but at 12 months the clinical response was less for the community based patients than for the RCT patients. At 6 months there were fewer withdrawals involving community-based patients than RCT patients due to less frequent withdrawals associated with lack of efficacy. At 12 months the withdrawal rate due to either a lack of efficacy or from adverse events was similar between data sets. CONCLUSION: The data from the etanercept phase III RCTs may not reflect the characteristics of patients using etanercept in community practice, nor the clinical outcomes observed by RA patients at 12 months. These discrepancies may be derived from methodological differences in study design and patient selection. On the other hand, outcomes such as withdrawal rates at 12 months appear comparable between the two types of populations.

Antirheumatic Agents↗
PubMed2006

Description of controlled trials published in Methods and Findings, 1979-2002.

It is thought that the controlled trial (CT) is the most adequate research method to assess a therapeutic intervention in terms of efficacy, and it also constitutes the basis for the development of systematic reviews on health interventions. To identify and obtain the majority of published CTs is not an easy task, mainly because of limitations concerning the currently available electronic sources. The aim of the present work was to identify, describe, and assess the quality of CTs published in the journal Methods and Findings in Experimental and Clinical Pharmacology (M&F). Additionally, to assess the retrievability of both methods, a search was performed in Medline (PubMed access) through the use of an optimal search strategy for CTs. A total of 189 original studies out of a total of 2796 reviewed articles met the CT criteria according to the Jadad scale score, we could hold that only 58% of the CTs were of good quality. The present work confirms, once again, the limitations of a CT search performed exclusively through Medline (sensitivity 64% and specificity 98%). In conclusion, we suggest that the journal M&F explicitly joins the International CONSORT Statement.

Clinical Trials, Phase III as Topic↗
PubMed1993

Differences in adverse drug reactions in phase III and phase IV of the drug evaluation process.

The study of medications in routine use is called "Phase IV" of the drug evaluation process. Information gathered about drugs in Phases I through III does not provide a sufficient basis for final conclusions about the clinical value of medications after marketing. Changes in preferred indications, patient characteristics (e.g., multimorbidity), treatment mode, or treatment setting in routine as compared to controlled scientific studies lead to changes in causes, incidence, prevalence, predictability, meaning, consequences, and cost-benefit ratios of adverse drug reactions (ADRs). Rare but serious ADRs are only one aspect of postmarketing surveillance; other questions are at least as important. In contrast to Phase III, which has a single study design--the controlled, randomized, double-blind study--Phase IV requires different designs for each of the many different questions. Established methodologies include spontaneous reports, stimulated spontaneous reports, comprehensive observation studies, Phase IV intervention studies, case control studies, prescription event record linkage, and data bank comparisons.

Clinical Trials, Phase III as Topic↗
PubMed2000

Ropinirole for levodopa-induced complications in Parkinson's disease.

BACKGROUND: Long-term levodopa therapy for Parkinson's disease is complicated by the development of motor fluctuations and abnormal involuntary movements. One approach is to add a dopamine agonist at this stage of the disease to reduce the time the patient spends immobile or off and to reduce the dose of levodopa in the hope of reducing such problems in the future. OBJECTIVES: To compare the efficacy and safety of adjuvant ropinirole therapy versus placebo in patients with Parkinson's disease already established on levodopa therapy and suffering from motor complications. SEARCH STRATEGY: Electronic searches of MEDLINE, EMBASE and the Cochrane Controlled Trials Register. Handsearching of the neurology literature as part of the Cochrane Movement Disorders Group's strategy. Examination of the reference lists of identified studies and other reviews. Contact with SmithKline Beecham. SELECTION CRITERIA: Randomised controlled trials of ropinirole versus placebo in patients with a clinical diagnosis of idiopathic Parkinson's disease and long-term complications of levodopa therapy. DATA COLLECTION AND ANALYSIS: Data was abstracted independently by the authors and differences settled by discussion. The outcome measures used included Parkinson's disease rating scales, levodopa dosage, 'off' time measurements and the frequency of withdrawals and adverse events. MAIN RESULTS: Three double-blind, parallel group, randomised, controlled trials have been conducted on 263 patients. The two phase II studies were relatively small, were conducted over the short term (12 weeks), and used relatively low doses of ropinirole. The other phase III study was medium term (26 weeks) and used ropinirole doses in line with the current UK licensed maximum. Additional data from the manufacturer showed that the difference in the reduction in off time was non-significantly greater with ropinirole than placebo (weighted mean difference [WMD] 0.19 hours; -0.63, 1.00 95% CI). As an adverse event, dyskinesia was significantly increased in those who received ropinirole (odds ratio [OR] 2.59; 1.35, 4.96 95% CI; p < 0.004). Measurements of motor impairments and disability were poor in these studies with incomplete information available. Levodopa dose could be reduced in two studies with a significantly larger reduction on ropinirole than on placebo (WMD 136.5mg/d; 74.5, 198.6 95% CI; p =0.00002). No significant differences in the frequency of adverse event reports were noted between ropinirole and placebo apart from the increase in dyskinesia with ropinirole. There was a trend towards fewer withdrawals from ropinirole but this did not reach statistical significance. REVIEWER'S CONCLUSIONS: Ropinirole therapy can reduce levodopa dose but at the expense of increased dyskinetic adverse events. No significant effect on off time reduction was found but this may have been due to under-powered trials and the low doses of ropinirole used in the phase II studies. Inadequate data on motor impairments and disability was collected to assess these outcomes. These conclusions apply to short and medium term treatment, up to 26 weeks. Further longer term trials are required, with measurements of effectiveness, and also studies to compare the newer with the older dopamine agonists.

Antiparkinson Agents↗
PubMed2006

[New substances in the therapy of head and neck cancer].

During the last 3 years the FDA approved numerous innovative drugs for cancer therapy. Drugs relevant to the otolaryngologist are presented and discussed. These new therapeutic tools may play a future part also in the therapy of head and neck cancer.

Administration, Oral↗
PubMed2003

[Adjuvant and additive therapy for cancer of the pancreas].

Recent advances have been made in the treatment of pancreas cancer. Specialized pancreas centres have reported an increasing rate of resections with reduced postoperative mortality. On account of the highly aggressive nature of pancreas cancer, there is a great challenge in identifying effective therapy concepts for advanced stages of the cancer as well as for the development of resection-associated measures. As large-scale, randomised, controlled studies are lacking, the additive therapy concepts after resection do not have a sufficiently scientific basis. The ESPAC-1 study, which included 600 patients, surpassed all previous studies on adjuvant therapy for pancreas cancer. This study has shown,for example, that the most promising adjuvant chemotherapy with 5-fluorouracil and folic acid leads to an equal if not better result than the multimodal regimen. This regimen can be superseded with the use of Gemcitabine, which will be evaluated in the ESPAC-3 study that includes 990 patients from various European countries including Germany, as well as from Canada and Australia. Participation in the large, phase-3 study therefore plays a key role in the continued development of the management of pancreas cancer.

Antimetabolites, Antineoplastic↗