Cost implications of initial antidepressant selection in primary care.

While fluoxetine is considerably more expensive than tricyclic antidepressants (TCAs), some previous studies have suggested that general medical expenditures are lower among patients treated with fluoxetine. In this study, computerised pharmacy and cost-accounting records of a large health plan were used to examine overall treatment costs for 5169 primary-care patients beginning antidepressant treatment with fluoxetine or one of 2 TCAs, imipramine or desipramine. Comparison was based on initial medication prescribed, regardless of subsequent switches or discontinuation. Patients treated with fluoxetine were older, with a higher burden of medical illness and higher overall health-service costs before starting antidepressant treatment, compared with patients receiving the other 2 drugs. Initial choice of fluoxetine was associated with approximately $US140 higher mean antidepressant costs and approximately $US300 higher mean costs for all other health services (1995 costs). Alternative methods of accounting for baseline differences (age, medical comorbidity, prior costs) indicated that adjusted 'non-antidepressant' costs (total costs minus costs of antidepressant therapy) in the fluoxetine group were $US75 to $US300 lower than in either of the TCA groups, but these differences were not statistically significant. Subgroup analyses suggested that the use of fluoxetine was associated with lower overall costs only among those incurring high costs in the pretreatment period. These findings support earlier studies suggesting that the use of fluoxetine as a first-line antidepressant in primary care will increase antidepressant drug costs, but will not significantly increase total treatment costs.