Intended for healthcare professionals

Education And Debate

Integrating qualitative research with trials in systematic reviews

BMJ 2004; 328 doi: (Published 22 April 2004) Cite this as: BMJ 2004;328:1010
  1. James Thomas, research officer (,
  2. Angela Harden, research officer1,
  3. Ann Oakley, professor of sociology and social policy1,
  4. Sandy Oliver, reader in public policy1,
  5. Katy Sutcliffe, research officer1,
  6. Rebecca Rees, research officer1,
  7. Ginny Brunton, research officer1,
  8. Josephine Kavanagh, research officer1
  1. 1Evidence for Policy and Practice Information and Coordinating (EPPI) Centre, Social Science Research Unit, Institute of Education, London WC1H 0NR
  1. Correspondence to: J Thomas
  • Accepted 10 February 2002

An example review from public health shows how integration is possible and some potential benefits

The value of including data from different types of studies in systematic reviews of health interventions is increasingly recognised. A recent editorial accepted that qualitative research should be included in systematic reviews, but pointed to a “daunting array of theoretical and practical problems.”1 This article presents an approach to combining qualitative and quantitative research in a systematic review. We describe how we used this approach in a systematic review of interventions to promote healthy eating among children, full details of which are available.2

The review framework

The review question was: “What is known about the barriers to, and facilitators of, healthy eating among children aged 4-10 years?” The specific focus of the review was fruit and vegetable intake. We searched for two types of research: controlled trials (randomised or non-randomised) that examined interventions to promote healthy eating and studies that examined children's perspectives and understandings (views studies), often by using qualitative research methods—for example, in-depth interviews and focus groups.

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But will she eat her greens?


We used conventional systematic review methods: sensitive searching, systematic screening, and independent quality assessment. These methods found 33 trials and eight qualitative studies that met our prespecified inclusion criteria.

We assessed studies for quality and reliability according to standards for their specific study types; they were then synthesised individually by using methods appropriate to the study. We conducted a meta-analysis with the data extracted from trials, used qualitative methods to synthesise the textual data extracted from the qualitative studies, and then integrated the findings from the qualitative synthesis with those from the meta-analysis. This gave us one review with three syntheses (fig 1).

Fig 1

Stages of the review

Quality assessment

We maintained the key principles of avoiding bias and maximising …

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