How skeptical should we be about industry-sponsored studies?

Abstract

In this issue of Neurology , Blum et al.1 report a randomized controlled study (RCT) that examines cognitive function following the addition of 500 mg/day of lamotrigine or 300 mg/day of topiramate to existing treatment with either carbamazepine or phenytoin. They show that topiramate has greater potential to harm cognitive function than does lamotrigine at the fixed doses used, something that might be expected from previous placebo-controlled regulatory studies of the two drugs, from some limited comparative studies of volunteers and patients, and from clinical experience gained post-marketing.2–5 Surely, then, we should simply applaud the fact that such careful methodology has been applied to a subject as important as the cognitive effects of antiepileptic drugs (AEDs). But perhaps we should pause for thought and consider some of the issues that lie behind the study design and its reporting, because it highlights a number of issues about RCTs sponsored by industry. Industry of course has two main reasons for sponsoring RCTs: in order to license a drug for specific indications, usually by placebo-controlled add-on studies in epilepsy, and to support a drug’s marketing. The Blum et al. study can be considered a marketing study. RCTs are accepted as the least biased means of detecting small but …