Primary non-compliance with prescribed medication in primary care.

OBJECTIVE: To determine the rate of patients not redeeming their prescriptions (primary noncompliance) and assess the factors influencing this. DESIGN: Observational study comparing copies of prescriptions written by general practitioners with those dispensed by pharmacists and subsequent case record review. SETTING: A large rural general practice in Tayside. SUBJECTS: All 4854 patients who received prescriptions (20,921) written between January 1989 and March 1989. MAIN OUTCOME MEASURES: The rate of non-redemption of prescriptions. RESULTS: Seven hundred and two patients (14.5%) did not redeem 1072 (5.2%) prescriptions during the study period, amounting to 11.5% of men and 16.3% of women. Non-redemption was highest in women aged 16-29 (27.6% of women) and men aged 40-49 (18.3% of men). Of prescriptions issued to women for oral contraceptives 24.8% were not redeemed during the study period. In those who redeemed prescriptions 17% were not exempt from prescription charges compared with 33% of patients who failed to redeem them. The non-redemption rate was highest for prescriptions issued at the weekends, although this was a small proportion of all prescribing. Prescriptions issued by trainee general practitioners were also less likely to be redeemed. CONCLUSIONS: Non-redemption varies with age, sex, general practitioner, exemption status, and with day of the week the prescription was written. Observational studies of drug exposure can be more accurately estimated from dispensing rather than prescribing data.