A systematic review of lay views about infant size and growth was undertaken as part of a series of interlinked reviews examining the evidence for associations between early growth and a number of later outcomes. The systematic review of views included both qualitative and quantitative studies.
Study methods and findings are reported in greater detail elsewhere [10
]. Standard systematic review methods were employed, following guidance from the Centre for Reviews and Dissemination [14
] and from an advisory group with backgrounds in public health, paediatrics, infant nutrition, qualitative and quantitative methods, systematic reviewing, and including representatives from user groups. Twelve databases were searched using terms for growth, height, weight and infancy as well as appropriate methodological terms. 2,694 abstracts were retrieved, from which 19 studies met the inclusion criteria for the review.
Two researchers independently extracted findings by interrogating each study using the following questions developed from the aims of the review:
1. What is healthy growth/size?
2. How important is growth/size to participants?
3. What concepts are used to define healthy growth/size?
4. How do participants assess growth/size?
5. Where does growth lie among priorities for child health?
6. What information influences views/behaviour?
7. Who influences views/behaviour?
Directly reported participant data (e.g. verbatim quotations or scores on attitudinal scales) and author interpretations were recorded separately, to retain the richness or 'thickness' of the contributing data. 'Thickness' in this context refers to the kinds of relatively detailed descriptions and contextual material which help the reader to make judgements about the trustworthiness of the data, particularly when applying it to different contexts [15
]. Study characteristics and quality assessment were summarised (for examples see Table ). There is vigorous debate on whether qualitative research can be assessed using standard quality criteria, or whether this process is contrary to the nature of qualitative enquiry [17
]. While the controversy on the use of critical appraisal in systematic reviews including qualitative data lies beyond the scope of this article, with views ranging from those who believe that critical appraisal is core to qualitative synthesis [18
] to those who, like Barbour [19
] consider that critical appraisal of qualitative research can be reductionist, it is notable that there is general agreement that a checklist approach to critical appraisal can bring its own problems, particularly in relation to transparency in assessing interpretative work. We took the view that applying quality criteria rigidly would be likely to exclude relevant studies that had failed to comply with a particular reporting regime. Thus, all studies meeting our inclusion criteria listed were included and quality appraisal was used at the data synthesis stage contributing to strength of evidence.
Two methods were proposed for synthesis of findings, textual narrative and thematic, both of which the advisory group agreed were appropriate to our needs. The first, the textual narrative approach, involves a commentary reporting on study characteristics, context, quality, and findings, using the scope, differences and similarities among studies were used to draw conclusions across the studies, whilst the second, the thematic approach, groups data into the themes. Given the relatively small number of studies located, it was feasible to test both methods. Findings from the review are provided briefly for illustration, but the focus of this paper is on the process of synthesis and a comparison of methods used. The two reviews ran in tandem, as the thematic review needed time for response and comparison between reviewers.