Assessing equity, applicability and scaling up issues in Cochrane reviews: a worked example from a review of lay health worker interventions in primary and community health care

Article type
Authors
Munabi-Babigumira S, Lewin S, Bosch-Capblanch X, van Wyk B, Glenton C, Scheel I, Aja G, Zwarenstein M, Daniels K, David Oxman A
Abstract
Background: There is growing interest within the Cochrane Collaboration on how review authors can consider the effects of interventions on health inequalities. Also important to the users of reviews are, firstly, the extent to which interventions can be applied in other settings and whether similar effects might be expected (applicability) and, secondly, factors likely to influence the widespread implementation of the intervention (scaling up). However, these issues are often not discussed by review authors.
Objectives: To assess the evidence on health inequalities and on the applicability and scaling up of interventions available from RCTs included in a review of the effects of lay health worker (LHW) programmes.
Methods: For each RCT included in the review, data were extracted on the groups targeted by the intervention, including their geographic location, demographic details, socio-economic status and 'ethnic' background. We also assessed whether the LHWs were intended to extend a health service to 'hard-to-reach' groups (e.g. geographically remote or groups that do not usually access health services). These data were used, when interpreting findings, to consider issues of equity, applicability and scaling up of the interventions examined. Questions such as 'Could these interventions work in other settings?' and 'Will these interventions work in other settings?' were used to guide this process.
Results: Overall, the included studies provided little data regarding differential effects of the interventions across different populations making the equity effects difficult to assess. Some differences in the effectiveness of LHW interventions in promoting breastfeeding were found between high and low income settings, possibly due to differences in baseline levels of breastfeeding in these settings. Also, some interventions relied on technologies (e.g. telephone-based support) that may not be widely available to low income households. The range of study settings included in some review subgroups, and the consistent pattern of findings across these studies, suggested that the measured effects may be transferable across settings for these health issues. However, for other subgroups where most studies were conducted in a single setting, such as the USA, it is not clear whether the effects could be transferred to other settings with different systems of health care delivery. Consideration of factors affecting the scaling up of the interventions was limited by poor reporting of the LHW interventions and how these were linked to other health systems components.