Data sources

Studies were identified by searching Medline, CINAHL, PsycLIT, SOCIOFILE, IPA, EMBASE/Excerpta Medica, and the Cochrane Library (all from 1967 to August 2001). Bibliographies of relevant articles were reviewed, and authors of included studies were asked to suggest other published or unpublished trials that had been missed.

Study selection

Studies were selected if they were unconfounded randomised controlled trials (RCTs) of an intervention to improve adherence with self administered prescribed medications for a medical or psychiatric disorder, measured both medication adherence and treatment outcome, had ≥80% follow up of each group studied, and duration of follow up for studies with positive initial findings was ≥6 months.

Data extraction

Data were extracted on sample size, details of intervention strategies for adherence, details of treatment for the underlying medical or mental disorder, study quality, and outcomes (adherence rates and patient outcomes).

Main results

33 RCTs met the selection criteria. These trials evaluated 39 unconfounded interventions. Adherence interventions were tested alone and in combination, with common themes such as more instruction for patients (oral and written material and programmed learning); increased communication and counselling (eg, compliance therapy and family intervention); increased convenience of care (eg, provision at the worksite and simplified dosing); involving patients more in their care through self monitoring of their blood pressure, seizures, or respiratory function; reminders (eg, special reminder pill packaging); and reinforcement or rewards for both improved adherence and treatment response (eg, reduced frequency of visits and partial payment for blood pressure monitoring equipment). Conditions studied included hypertension (8 RCTs); schizophrenia or acute psychosis (8 RCTs); asthma, chronic obstructive pulmonary disease, or both (5 RCTs); depression (2 RCTs); human immunodeficiency virus (2 RCTs); diabetes (2 RCTs); rheumatoid arthritis (1 RCT); epilepsy (1 RCT); and hyperlipidaemia and cardiovascular disease (1 RCT). 3 RCTs examined treatment compliance in short term conditions.

49% (19/39) of interventions tested were associated with statistically significant increases in medication adherence, and 44% (17/39) reported statistically significant improvement in treatment outcome. Adherence interventions that were effective were mainly complex, including combinations of more convenient care, information, counselling, reminders, self monitoring, reinforcement, family therapy, and other forms of additional supervision or attention. Simple interventions that received some support included simplified dosing regimens for patients taking antihypertensive and lipid lowering medications and counselling about the importance of full adherence to antibiotic regimens reinforced by written instructions. Effective interventions were not distinguished from ineffective interventions in terms of number or type of components (behavioural, cognitive, or social).

Conclusion

In patients with medical or mental disorders (but not addictions), evidence for the effectiveness of interventions designed to assist patients’ adherence to prescribed medications shows that some interventions may be effective, but no consistent characteristics of effective interventions were identified.