Formal systematic review of data on patients in all relevant trials is required

EDITOR—The increased death rate with selegiline in the Parkinson's Disease Research Group's trial highlights the problem of interpreting the results of a small trial in isolation. Ben-Shlomo et al emphasised the internal consistency of this finding,1 which is not surprising because much of the original data were reanalysed. The hazard ratio was lower than in the original report (1.32 v 1.57), which suggests that the trial might have stopped on a random high.

There is no formal systematic review of all unconfounded randomised trials comparing long term selegiline with control treatment in patients with early Parkinson's disease. One attempt by the manufacturers of selegiline did not say which trials were included.2 I found three such trials in the Cochrane controlled trials register, with follow up ranging from 2.5 to 8.2 years—that is, after the increase in deaths with selegiline started in the Parkinson's Disease Research Group's …