In an interesting article, Pampallona et al (Reference Katon, Von Korff and Lin2002) reviewed the literature concerning patient adherence in the treatment of depression. The outcome of most studies revealed that interventions to improve adherence tend to be successful in most cases, although it is not completely clear which interventions may be the most helpful.

In our view, the most important goal in trying to enhance adherence is to improve treatment outcome. Pampallona et al stated that ‘the important relationship between adherence and outcome of treatment has been evaluated only in one study’.

When we reviewed the articles that Pampallona et al included in their article, however, we identified at least four studies that addressed the relationship between adherence and treatment outcome.

Katon et al (Reference Lawton-Smith1995, Reference Katon, Von Korff and Lin1996) demonstrated that multifaceted interventions improved adherence to antidepressant regimens in patients with major and with minor depression. The interventions resulted in more favourable outcomes in patients with major, but not minor, depression. In a more recent study of the same group (Reference Katon, Robinson and Von KorffKaton et al, 1999) patients in the intervention group also had significantly better adherence to antidepressive medication and showed a significantly greater decrease in severity of depressive symptoms over time and were more likely to have fully recovered during follow-up at 3 and 6 months. Peveler et al (Reference Pampallona, Bollini and Tibaldi1999) found that counselling about drug treatment significantly improved adherence. Clinical benefit, however, was seen only in patients with major depressive disorder receiving doses ≥75 mg of a tricyclic antidepressant.

These findings provide evidence that interventions can enhance adherence and can increase the response rate in patients with major depression who are treated with an adequate dosage of an antidepressant agent. With respect to minor depression results are less convincing.