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Use of qualitative methods alongside randomised controlled trials of complex healthcare interventions: methodological study

BMJ 2009; 339 doi: (Published 10 September 2009) Cite this as: BMJ 2009;339:b3496
  1. Simon Lewin, senior lecturer12,
  2. Claire Glenton, senior researcher3,
  3. Andrew D Oxman, senior researcher3
  1. 1Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, London WC1E 7HT
  2. 2Health Systems Research Unit, Medical Research Council of South Africa
  3. 3Norwegian Knowledge Centre for the Health Services, Oslo, Norway
  1. Correspondence: S Lewin simon.lewin{at}
  • Accepted 28 January 2009


Objective To examine the use of qualitative approaches alongside randomised trials of complex healthcare interventions.

Design Review of randomised controlled trials of interventions to change professional practice or the organisation of care.

Data sources Systematic sample of 100 trials published in English from the register of the Cochrane Effective Practice and Organisation of Care Review Group.

Methods Published and unpublished qualitative studies linked to the randomised controlled trials were identified through database searches and contact with authors. Data were extracted from each study by two reviewers using a standard form. We extracted data describing the randomised controlled trials and qualitative studies, the quality of these studies, and how, if at all, the qualitative and quantitative findings were combined. A narrative synthesis of the findings was done.

Results 30 of the 100 trials had associated qualitative work and 19 of these were published studies. 14 qualitative studies were done before the trial, nine during the trial, and four after the trial. 13 studies reported an explicit theoretical basis and 11 specified their methodological approach. Approaches to sampling and data analysis were poorly described. For most cases (n=20) we found no indication of integration of qualitative and quantitative findings at the level of either analysis or interpretation. The quality of the qualitative studies was highly variable.

Conclusions Qualitative studies alongside randomised controlled trials remain uncommon, even where relatively complex interventions are being evaluated. Most of the qualitative studies were carried out before or during the trials with few studies used to explain trial results. The findings of the qualitative studies seemed to be poorly integrated with those of the trials and often had major methodological shortcomings.


  • We thank Xavier Bosch-Capblanch, Anna Gaze, Marit Johansen, Matthew Oxman, and Marcus Prescott for their assistance with various aspects of the study.

  • Contributors: SL and ADO conceived the idea for the paper. SL and CG retrieved the articles, extracted the data, and did the analysis. SL, CG, and ADO drafted the paper. SL is the guarantor.

  • Funding: This work was supported by a UK Medical Research Council health services research training fellowship to SL. The Norwegian Knowledge Centre for the Health Services provided support to CG and ADO. The funding sources played no part in the conception of the study, data collection, analysis, or writing the article.

  • Competing interests: ADO was an investigator for two of the included trials and CG worked in the unit in which these trials were coordinated.

  • Ethical approval: Not required.

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