Interventions to change health behaviours: evidence-based or evidence-inspired?

This critical review assesses whether evaluation studies can answer three key questions about behaviour change interventions: ‘Do they work? How well do they work? How do they work?’ Reviews of intervention evaluations are examined, particularly those addressing decreasing unprotected sexual intercourse and smoking. Selection of outcome measures and calculation of effect sizes are discussed. The article also considers the extent to which evaluation reports specify (i) discrete intervention techniques and (ii) psychological mechanisms that account for observed behavioural change. It is concluded that intervention descriptions are often not specific about the techniques employed and that there is no clear correspondence between theoretical inspiration and adoption of particular change techniques. The review calls for experimental testing of specific theory-based techniques, separately and in combination.