Patient adherence in the treatment of depression

Background Non-adherence with antidepressant treatment is very common. Increasing adherence to pharmacological treatment may affect response rate. Aims To review and summarise quantitative evidence on factors associated with adherence and of adherence-enhancing interventions. Method A systematic review of computerised databases was carried out to identify quantitative studies of adherence in depression. Papers retained addressed unipolar depression and considered adherence as the primary end-point. Results Of studies published between 1973 and 1999, 32 met the review criteria: epidemiological descriptive studies (n=14): non-random comparisons of control and intervention groups (n=3); randomised interventions (n=14); and meta-analysis (n=l). Patient education and medication clinics were the interventions most commonly tested, combined with a variety of other interventions. Conclusions The studies did not give consistent indications of which interventions may be effective. Carefully designed clinical trials are needed to clarify the effect of single and combined interventions. Declaration of interest The study was partially supported by Centro Studi e Ricerche in Psichiatria,Turin; Istituto Superiore di Sanit, Rome; and Ravizza Pharmaceuticals, Milan. Adherence may be defined as the extent to which a person's behaviour conforms to medical or health advice (Bruer, 1982). Four meta-analyses (Anderson Tomenson, 1995; Montgomery Kasper, 1995; Steffens et al, 1997; Anderson, 1998) have demonstrated that for tricyclic antidepressants (TCAs) and selective scrotonin reuptake inhibitors (SSRIs), drop-out rates are in the range of 21-33%, irrespective of the drug class. A subsequent meta-analysis showed that 20% of patients did not improve and 30% dropped out of treatment for a variety of reasons (Bollini et al, 1999). The drop-out rate is contributed to by factors such as illness and patients' characteristics, side-effects, time taken to improve or the patient-doctor relationship (Demyttenaere, 1997). The magnitude and complexity of the problem prompted this review of the available literature. The aim was to collect and synthesise quantitative information concerning factors associated with and interventions affecting adherence to antidepressants.