Anti-depressants in primary care: Analysis of treatment discontinuations

It is well known that adherence to anti-depressant therapy is often poor, b ut the literature describes little in the way of systematic analyses to det ermine co-relation between treatment discontinuation and possible contribut ing factors. We used a community dispensing database to review anti-depress ant prescribing patterns and continuity of therapy over a period of 10 mont hs among a population of community-based general practice patients. Some 10 9,228 anti-depressant prescriptions were dispensed to 24,073 patients, of w hom 37.5% collected a single prescription only. Tricyclic anti-depressant p rescribing declined significantly during the observation period (from 70% o f prescriptions in month 1 to 66% in month 10) while that of selective sero tonin reuptake inhibitors (SSRIs) increased (23% in month 1, 28% in month 1 0) (p < 0.0001). Some 27% of those on tricyclics were prescribed < 50% of t he defined daily dose (DDD) compared with 2% of those on SSRIs. Among patie nts new to therapy who collected >1 prescription, adherence was poor and de clined over time. The factors that influenced the extent to which patients failed to adhere to therapy included dosage level (% DDD) and age (p < 0.00 01 for both), but not drug class or sex. The findings suggest that low dosa ge is a contributory factor in treatment discontinuation, and that contrary to common perception, SSRIs are not necessarily associated with better adh erence to therapy than tricyclics. Copyright (C) 2000 John Wiley & Sons, Lt d.