Prevalence and Outcomes of Pharmaceutical Industry-sponsored Clinical Trials Involving Clozapine, Risperidone, or Olanzapine

Objective: The literature continues to highlight the debate on the ethics and merits of trials sponsored by the pharmaceutical industry. This study attempts to determine the prevalence and outcomes of industry-sponsored trials involving clozapine, risperidone, or olanzapine.

Methods: We searched the literature from January 1, 1990, to December 31, 2001, to capture all eligible clinical trials involving clozapine, risperidone, or olanzapine. The primary outcome measured was the clinical outcome of industry-sponsored studies. Secondary outcome measures included the following parameters: disclosure of any sponsorship and financial support, author(s) employed by the industry, use of comparator drug(s) within the trial, sample size, blinding, and use of placebo.

Results: The database comprised 372 articles. Of these trials, 124 (33.3%) were sponsored by the pharmaceutical industry. In general, trials sponsored by Eli Lilly or Janssen had better research design than trials not funded by the pharmaceutical industry. With regard to authorship, more trials funded by Eli Lilly (74.6%) were coauthored by an employee of the company, compared with trials funded by either Janssen (23.3%) or Novartis/Sandoz (5.6%). Further, more trials sponsored by Eli Lilly reported positive outcomes (92.1%), compared with Janssen-sponsored trials (88.4%) and Sandoz/Novartis-sponsored trials (72.2%). No negative results were reported in any of the industry-funded trials.

Conclusions: One-third of the published clinical trials involving clozapine, risperidone, or olanzapine were funded by their respective manufacturer. The reported outcomes of the sponsored trials highly favour the manufacturer's product.