Limitations of randomized controlled clinical trials to depict accurately long-term outcomes in rheumatoid arthritis

Journal/Book: Z Rheumatol 1998; 57: 046 - 049. 1998;

Abstract: T. Pincus; Professor of Medicine Division for Rheumatology and Immunology Vanderbilt University School of Medicine Nashville The randomized controlled clinical trial is the "gold standard" to evaluate therapeutic interventions (1) since first reported about 50 years ago (2). This method conforms to the biomedical model of a "scientific experiment" (3) in isolating a single variable - a test drug - versus a control drug or placebo. The value and importance of a randomized trial to determine the efficacy of a therapy is indisputable. However clinical trials are most effective in acute diseases and may limitations are seen in application to chronic diseases noted in a number of thoughtful reports by several observers (3 - 18) as well as in some of our own commentaries (19 - 23). A brief summary of limitations of clinical trials is presented to help explain why clinical trial data are poor descriptors of long-term outcomes in RA: 1. Exclusion criteria in clinical trials often restrict eligibility to a small minority of patients who will receive the intervention In theory all individuals with RA should be eligible to participate in clinical trials of therapies in this disease. In practice however designers of clinical trails recognize that many variables other than assignment to an intervention or a placebo may affect outcomes including age education level disease severity other diseases previous and concomitant interventions and others. Therefore exclusion criteria are commonly incorporated into trial design the extent of which is determined in part by whether the designers are oriented to a more "fastidious" or "practical" approach as described by Feinstein (3). In my experience in more than 20 clinical trials in RA fewer than 20 % of consecutive patients were eligible for participation in all but one (23). ... le

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