Adherence to treatment regimen in depressed patients treated with amitriptyline or fluoxetine

Objective: Non-compliance presents a constant challenge to effective therap y, Many studies only investigate early treatment discontinuation and not ot her measures like adherence to treatment regimen. We compared adherence in depressed patients using either a selective serotonin reuptake inhibitor (f luoxetine) or a tricyclic antidepressant (amitriptyline), and examined its clinical relevance through adverse events, drop-out rates, and outcome. Adh erence was measured electronically with the MEMS (Medication Event Monitori ng System). Design: Nine-week double blind, randomized controlled trial. Se tting: Ambulatory psychiatric care. Patients: Random sample of 66 depressed (DSM-RI-R criteria) patients. Intervention: Fluoxetine 20 mg or amitriptyl ine 150 mg. Main outcome measures: Time course of adherence and its relatio n to severe adverse events, drop-outs and outcome. Results: Non-adherence t o the treatment regimen occurred frequently in both treatment groups: 31% o f patients had at least one 3-day drug holiday, and 34% of patients had at least one episode of three pills in a 24-h period. Over-consumption occurre d more frequently during the -early phases of treatment while underconsumpt ion occurred more frequently during the later phases. Patients on amitripty line (P = 0.03) and patients with a higher pill intake (P = 0.01) experienc ed more severe adverse events. Patients on amitriptyline (P = 0.009) and pa tients with a lower adherence to the treatment regimen (P = 0.004) disconti nued from treatment more frequently. The final Hamilton score was significa ntly predicted by a longer duration of treatment and by a better adherence, but only in amitriptyline. users. Conclusions: Non-adherence to the treatm ent regimen has important clinical consequences. Pharmacodynamics. and huma n behavior predict risk for severe adverse events and drop-outs. Moreover, in amitriptyline users but not in fluoxetine users, better adherence predic ts a better outcome. (C) 2001 Elsevier Science BY All rights reserved.