Duration and adherence of antidepressant treatment (2003 to 2007) based on prescription database

Many patients discontinue antidepressant therapy long before the six-month minimum duration recommended for the treatment of major depression and many other diagnoses.

To estimate the duration of antidepressant treatment and to analyse the following factors in relation to treatment adherence: age, sex, polypharmacy and type of drug.

Retrospective cohort followed up for five years (2003-2007) based on prescription database.

Users who had received at least one antidepressant prescription in 2003 and who had not received antidepressants during the previous 12 months.

Age, sex, drug, polypharmacy, period of treatment, packs dispensed. Adequate adherence was defined as dispensation of medication during at least 80% of the treatment period, and compliance was defined as good when, in addition, the treatment lasted more than four months.

Of the 7525 patients selected, 56% abandoned medication during the first four months. Men were more likely to give up medication before time than women. Good compliance was recorded in 22% of patients and was twice as frequent in patients with high levels of polypharmacy than in those with low levels (31% vs. 15.3%). Patients receiving maprotiline, venlafaxine, mirtazapine, citalopram, clomipramine and fluoxetine presented the highest percentages of good compliance.

Only one out of five patients complied with treatment for over four months. Treatment periods were shorter in men. In chronic processes, patients receiving polypharmacy presented the best compliance.