Using Implementation Theory to Explain Variation in Delivery of a Complex Social Intervention: Process Evaluation of the Strengthening Families Programme (10-14UK) in Wales UK

Studies of the Strengthening Families Program (SFP10-14) universal substance-misuse prevention intervention in the United States have produced evidence of effectiveness but say little about implementation processes.  This paper presents findings from the mixed-methods process evaluation of a trial of SFP in Wales (Project SFP10-14UK) during 2010-2012, investigating fidelity and how it was influenced by local contexts.

Structured observation; reports from SFP facilitators; and routine monitoring data assessed the extent to which SFP10-14UK was implemented as intended.  Semi-structured interviews with implementers elicited their perceptions of SFP and implementation processes. Qualitative data were coded using a thematic framework.  Quantitative and qualitative data were used together to examine reasons for variation in fidelity across research sites.  Results were interpreted using the four constructs of the General Theory of Implementation.

Fifty-six programmes were delivered across 7 research sites to 218 families with children aged 10-14 (60% of 361 in the intervention group).  National training and positive attitudes of local staff achieved high coverage rates; targets for staffing; and provision of free travel, refreshments and child care. Staffing standards were easier to attain when staff were employed by the same organisation.  Targets for group size and composition were met less frequently due to challenges in participant recruitment.  Reduced capacity in public-sector organisations during an economic recession (2010-2012) aggravated difficulties in recruiting staff and participant families. 

While coverage rates and staffing reached high standards of fidelity, requirements for group size and composition were less often met.  Mixed methods provided insights into staff and participant recruitment; and the utility of General Implementation Theory in a pragmatic study of a complex intervention was demonstrated.