Objectives. This article summarizes the results of 153 studies published between 1977 and 1994 that evaluated the effectiveness of interventions to improve patient compliance with medical regimens.
Methods. The compliance interventions were classified by theoretical focus into educational, behavioral, and affective categories within which specific intervention strategies were further distinguished. The compliance indicators broadly represent five classes of compliance-related assessments: (1) health outcomes (eg, blood pressure and hospitalization), (2) direct indicators (eg, urine and blood tracers and weight change), (3) indirect indicators (eg, pill count and refill records), (4) subjective report (eg, patients' or others' reports), and (5) utilization (appointment making and keeping and use of preventive services).
An effect size (ES) r, defined as Fisher's Z transformation of the Pearson correlation coefficient, representing the association between each intervention (intervention versus control) and compliance measure was calculated. Both an unweighted and weighted r were calculated because of large sample size variation, and a combined probability across studies was calculated.
Results. The interventions produced significant effects for all the compliance indicators (combined Z values more than 5 and less than 32), with the magnitude of effects ranging from small to large. The largest effects (unweighted) were evident for refill records and pill counts and in blood/urine and weight change studies. Although smaller in magnitude, compliance effects were evident for improved health outcomes and utilization. Chronic disease patients, including those with diabetes and hypertension, as well as cancer patients and those with mental health problems especially benefited from interventions.
Conclusions. No single strategy or programmatic focus showed any clear advantage compared with another. Comprehensive interventions combining cognitive, behavioral, and affective components were more effective than single-focus interventions.