Antidepressant Drug Adherence From Bandolier, Feb 2001; 84-3

The starting point of this review¹ is the contention that SSRIs cause fewer and less severe side-effects that traditional antidepressants and the explicit or implicit expectation that, consequently, the use of SSRIs will enhance medication compliance. These questions, however, lead to broader issues, such as the measurement of compliance.

The Bandolier authors make the cogent point that this is especially important in the case of the treatment of depression because of cost-effectiveness. I.e., if SSRIs and older antidpressants are equally efficacious and safe, then the least expensive agent should legitimately be used. If, on the other hand, SSRIs are more effective because of better patient adherence, then the picture is not so clear.

The review under consideration looked at 136 randomized trials comparing SSRIs with other antidepressants in depressed patients. The compliance measurement used was the rate of withdrawal from the studies.

The analysis shows, at a 95% confidence level that there were indeed fewer total withdrawals secondary to adverse reactions with SSRIs than with amitriptyline, imipramine and clomipramine. While total withdrawals were 27% with SSRIs and 30% for tricyclics and heterocyclics, most SSRI withdrawals due to lack of efficacy rather than adverse events.

Bandolier goes on to point out that there is nonetheless significant uncertainty about the final effect because of three factors:

1. Dose. Higher doses of medicines are likely to elicit greater adverse event rates. The results presented make no allowance for dose.
2. Methodology of Data Collection. Different collection methods yield different results. For example, using diaries generates higher rates of adverse events than spontaneous reporting.
3. Size. Many of the studies used patient groups of less than 200 and the data was, as one would expect, highly variable.

Bandolier’s conclusion, echoing in many ways their take on compliance in general, is that while clinical trials featuring SSRIs cause fewer withdrawals because of adverse effects, it would be an egregious oversimplification to translate that as an enhancement to adherence in day to day clinical care.

Footnote

1. The article reviewed is
   C Barbui et al. Selective serotonin reuptake inhibitors versus tricyclic and heterocyclic antidepressants: comparison of drug adherence. In: The Cochrane Library, Issue 4, 2000. Oxford. [back]

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