Biomedical subjects

Pendar Farahani

Publications and source records attributed to Pendar Farahani.

4 recordsLinked to original sources

PubMed2006

Exploring design-related bias in clinical studies on receptor genetic polymorphism of hypertension.

BACKGROUND AND OBJECTIVES: Although several candidate genes of Renin-Angiotensin-Aldosterone System (RAAS) have been investigated, the gene-drug relationship remains unclear. The objective was to appraise the elements of research methodology and explore potential biases, which may be contributing to discordant results in the gene-drug interaction assessment for RAAS. METHODS: Systematic review of studies involving candidate polymorphisms, searching PubMed, and EMBASE. RESULTS: Sixteen studies were identified. Nine studies had a genomic evaluation as the primary question. Six studies investigated more than one gene. A gene-drug interaction was evaluated in two studies and only one of the studies had a placebo arm for accurately exploring the interaction. Almost, 90% of the studies had sample sizes of less than 500 patients. Four studies combined the allele frequencies of the heterozygotes group with one of the homozygotes groups. Almost one quarter of the studies combined different therapeutics in one group. Five studies included patients in one group from previous studies in which selection criteria were not quite similar. CONCLUSION: Most studies contain several methodological limitations. Also biases driven from patient selection, combining different alleles, combining different therapeutics, and combining end points may have occurred in these studies. These limitations and biases may contribute to inconsistency of the results of these studies.

Angiotensin II Type 1 Receptor Blockers↗

PubMed2006

Community-based evaluation of etanercept in patients with rheumatoid arthritis.

OBJECTIVES: Etanercept is one of a new subgroup of biological disease modifying antirheumatic drugs (DMARD) to treat patients with rheumatoid arthritis (RA) who are non-responsive or intolerant to conventional DMARD. We evaluated the effects of etanercept (Enbrel) therapy in patients with RA in community-based clinical practice in Canada. METHODS: Using a cohort design, patients requesting etanercept therapy were stratified into treatment and control arms based upon their individual accessibility to obtain the drug. Patients were interviewed serially during a 12-month period of monitoring. The study measured painful or tender joint count, morning stiffness, pain severity, quality of life measures, medication utilization, health services utilization, and presence of adverse events. RESULTS: The baseline demographic and clinical variables for the treatment group (n = 223) and the control group (n = 208) were similar, except for education, income, and drug plan coverage. In followup, there was greater improvement in most clinical variables in the treatment arm compared to the control arm during the first 6 months, but the magnitude of difference between the 2 groups for some clinical variables decreased or became non-significant during the second 6 months. During the 12 month followup period there were 40 (18%) patient dropouts in the treatment group. CONCLUSION: In a community based setting for the treatment of RA, etanercept can effectively improve the disease state, functional class, work disability, and quality of life during the first 6 months of use. To determine the longterm sustainability of these effects studies with more than 12 months' duration will be required.

Antirheumatic Agents↗

PubMed2006

A comparison between integrating clinical practice setting and randomized controlled trial setting into economic evaluation models of therapeutics.

BACKGROUND: Cost-effectiveness analyses generated from randomized controlled trials (RCTs) represent results obtained under ideal experimental conditions (efficacy) and the applicability of these data to real-world settings (effectiveness) may be questionable. OBJECTIVE: To compare cost-effectiveness results obtained from a RCT setting with the results derived from community-based clinical practice. METHODS: Using data from a community-based cohort study and from a RCT, two cost-effectiveness analyses were performed and the incremental cost-effectiveness ratios (ICERs) were calculated for the use of etanercept in the treatment of patients with rheumatoid arthritis. RESULTS: Using an effectiveness-based analysis, the mean quality-adjusted life years (QALYs) gained during the 12-month monitoring period were 0.45 and 0.35 for the treatment and control groups respectively. The ICER for etanercept treatment was 174,200 dollars (CDN) per QALY (95% confidence limits between 119,500 dollars and 285,000 dollars). Incorporating efficacy data obtained from the RCT into the analysis, the mean QALYs gained were 0.56 and 0.35 for the treatment and control groups respectively. This resulted in a substantially lower ICER for etanercept treatment of 82,952 dollars per QALY (95% confidence limits between 66,500 dollars and 103,430 dollars). CONCLUSION: Depending on the type of clinical setting used for the analysis, the resulting ICER for etanercept treatment was very different. These results help to explain the difference in cost-effectiveness reported in previous modeling studies, some based on RCT assumptions and some based on effectiveness setting.

Anti-Inflammatory Agents, Non-Steroidal↗

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↗