Compliance with tricyclic antidepressants: the value of four different methods of assessment

Authors


Professor Sir Charles George, Clinical Pharmacology Group, University of Southampton, Biomedical Sciences Building, Bassett Crescent East, Southampton SO16 7PX. Tel.: 023 80594261; Fax: 023 80594262.

Abstract

Aims To assess the advantages and disadvantages of four methods for studying compliance with antidepressants: self-report scores, tablet counts, a microprocessor (MEMS) container system and the assay of nordothiepin and dothiepin concentrations in plasma.

Methods The techniques were used in 88 patients commencing tricyclic antidepressants in the setting of UK general practice.

Results The MEMS system proved to be the most informative technique allowing identification of the precise time of container opening, the demonstration of ‘drug holidays’ and early cessation of therapy. Self-report scores (Morisky) proved a useful screening technique with a sensitivity of 72.2% and specificity of 74.1% for ≥ 80% compliance. Although tablet counts were possible in 84 patients (95.5%) they were unreliable in 19 (21.6%). Blood concentration assays proved the least acceptable method to patients and were possible in only 53 (60.2%). A ratio of nordothiepin:dothiepin ≥ 1.1 claimed, by others, to identify noncompliance was only reliable when concentrations were low.

Conclusions Both the MEMS system and self-report scores proved useful methods for identifying noncompliant patients in the setting of UK general practice. Although compliance was higher than reported in previous studies with 70 patients (79.5%) completing 6 weeks treatment, general practitioners tended to prescribe subtherapeutic doses.

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