Intended for healthcare professionals

Endgames Statistical Question

Placebo run in periods

BMJ 2012; 344 doi: (Published 07 June 2012) Cite this as: BMJ 2012;344:e3827
  1. Philip Sedgwick, senior lecturer in medical statistics
  1. 1Centre for Medical and Healthcare Education, St George’s, University of London, Tooting, London, UK
  1. p.sedgwick{at}

Researchers investigated the efficacy of hypericum extract (St John’s wort) compared with paroxetine in patients with moderate to severe major depression. A randomised double blind, double dummy, multicentre non-inferiority trial study design of six weeks’ duration was used. Treatment consisted of 300 mg hypericum extract WS 5570 three times a day or 20 mg paroxetine once a day for six weeks. The primary outcome was change in score on the Hamilton depression scale from baseline at six weeks.1

In total, 301 patients were recruited from psychiatric primary centres in Germany. After a screening examination patients underwent a single (patient) blind, double dummy, placebo run in period of three to seven days before the trial started. Subsequently, 251 patients aged 18-70 years were recruited to the trial, and 125 were randomised to the hypericum treatment group and 126 to paroxetine. The researchers reported that in the treatment of moderate to severe major depression, hypericum extract WS 5570 …

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