What underlies the perception that a medical intervention is effective? An exploratory study among smokers

The perceived ineffectiveness of medical interventions is a key predictor of their underuse. This study explores the nature of this perception with regards to a range of medical interventions. Adult smokers (n = 18) completed interviews and questionnaires using the repertory grid technique to elicit personal constructs underlying perceptions of effectiveness of a range of medical interventions (three to stop smoking, three to prevent heart disease, one to reduce pain, one to lose weight, and one to treat depression). Principle components analysis was applied to identify the key underlying dimensions within the constructs. Numerical estimates of the effectiveness of the interventions were also collected from participants to compare them with the published evidence. Constructs clustered around three dimensions: "therapeutic impact," "behavior-dependent impact," and "impact facilitates general health." Smokers perceived impacts that are dependent on the individuals' behavior to offer small therapeutic impacts, while facilitating individuals' general health. These three characteristics were attributed to nonbiomedical interventions (e.g., talk-based interventions), while the opposite characteristics were attributed to biomedical interventions (i.e., medication and surgery). Numerical estimates showed that the effectiveness of stop-smoking interventions was underestimated relative to interventions to prevent heart disease. The elicited dimensions provide a basis for communicating evidence concerning the effectiveness of medical interventions, with a view to increasing their use.