Social Return on Investment (SROI) methodology to account for value for money of public health interventions: a systematic review

Background: Increased scarcity of public resources has led to a concomitant drive to account for value-for-money of interventions. Traditionally, cost-effectiveness, cost-utility and cost-benefit analyses have been used to assess value-for-money of public health interventions. The social return on investment (SROI) methodology has capacity to measure broader socio-economic outcomes, analysing and computing views of multiple stakeholders in a singular monetary ratio. This review provides an overview of SROI application in public health, explores lessons learnt from previous studies and makes recommendations for future SROI application in public health. Methods: A systematic review of peer-reviewed and grey literature to identify SROI studies published between January 1996 and December 2014 was conducted. All articles describing conduct of public health SROI studies and which reported a SROI ratio were included. An existing 12-point framework was used to assess study quality. Data were extracted using pre-developed codes: SROI type, type of commissioning organisation, study country, public health area in which SROI was conducted, stakeholders included in study, discount rate used, SROI ratio obtained, time horizon of analysis and reported lessons learnt. Results: 40 SROI studies, of varying quality, including 33 from high-income countries and 7 from low middle-income countries, met the inclusion criteria. SROI application increased since its first use in 2005 until 2011, declining afterwards. SROI has been applied across different public health areas including health promotion (12 studies), mental health (11), sexual and reproductive health (6), child health (4), nutrition (3), healthcare management (2), health education and environmental health (1 each). Qualitative and quantitative methods have been used to gather information for public health SROI studies. However, there remains a lack of consensus on who to include as beneficiaries, how to account for counterfactual and appropriate study-time horizon. Reported SROI ratios vary widely (1.1:1 to 65:1). Conclusions: SROI can be applied across healthcare settings. Best practices such as analysis involving only beneficiaries (not all stakeholders), providing justification for discount rates used in models, using purchasing power parity equivalents for monetary valuations and incorporating objective designs such as case-control or before-and-after designs for accounting for outcomes will improve robustness of public health SROI studies.