Intended for healthcare professionals

Endgames Statistical Question

The Hawthorne effect

BMJ 2012; 344 doi: (Published 04 January 2012) Cite this as: BMJ 2012;344:d8262
  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 evaluated the effectiveness of a newly developed integrated care programme in facilitating the return to work for patients with chronic low back pain. The newly developed programme was a combined patient and workplace directed intervention delivered in the outpatient setting. A randomised controlled trial study design was used. The control arm received usual care. The study lasted one year.1

Trial participants were recruited from primary and secondary care if they were aged 18-65 years, had been having low back pain for more than 12 weeks, were in paid work for at least eight hours a week, and were absent or partially absent from work. The primary outcome was length of time absent from work until a fully sustained return to work. …

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