Monitoring randomised controlled trials

BMJ 1998; 316 doi: https://doi.org/10.1136/bmj.316.7139.1183 (Published 18 April 1998) Cite this as: BMJ 1998;316:1183

Parkinson's disease trial illustrates the dangers of stopping early

  1. Keith R Abrams, Senior lecturer in medical statistics
  1. Department of Epidemiology and Public Health, University of Leicester, Leicster LE1 6TP

    Papersp 1191

    The trial of the Parkinson's Disease Research Group reported by Ben-Shlomo et al in this issue (p 1191), which updates the results of a previously curtailed randomised controlled trial,1 raises several methodological issues. The current results relate to an initial three arm trial in which 782 patients with early stage Parkinson's disease were randomised to treatment with either levodopa alone (arm 1), levodopa and selegiline in combination (arm 2), or bromocriptine (arm 3). The first trial report, based on follow up to December 1991, showed no significant differences at the 5% level between arms 1 and 2 in disability levels, but both arms showed significant improvements over baseline.2 At this stage there were too few deaths to assess differences in mortality. The second report was based on follow up to December 1993, resulting in an average 5.6 years follow up.3 As with the earlier report, there continued to be no significant differences between arms 1 and 2 in terms of disability levels. However, based on 44 deaths in 249 patients in arm 1 and 76 in 271 patients in arm 2, a significant difference in all cause mortality was …

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