What factors influence long-term antidepressant use in primary care? Findings from the Australian diamond cohort study.

Antidepressants are one of the most commonly prescribed drugs in primary care. The rise in use is mostly due to an increasing number of long-term users of antidepressants (LTU AD). Little is known about the factors driving increased long-term use. We examined the socio-demographic, clinical factors and health service use characteristics associated with LTU AD to extend our understanding of the factors that may be driving the increase in antidepressant use. Cross-sectional analysis of 789 participants with probable depression (CES-D≥16) recruited from 30 randomly selected Australian general practices to take part in a ten-year cohort study about depression were surveyed about their antidepressant use. 165 (21.0%) participants reported <2 years of antidepressant use and 145 (18.4%) reported ≥2 years of antidepressant use. After adjusting for depression severity, LTU AD was associated with: single (OR 1.56, 95%CI 1.05-2.32) or recurrent episode of depression (3.44, 2.06-5.74); using SSRIs (3.85, 2.03-7.33), sedatives (2.04, 1.29-3.22), or antipsychotics (4.51, 1.67-12.17); functional limitations due to long-term illness (2.81, 1.55-5.08), poor/fair self-rated health (1.57, 1.14-2.15), inability to work (2.49, 1.37-4.53), benefits as main source of income (2.15, 1.33-3.49), GP visits longer than 20min (1.79, 1.17-2.73); rating GP visits as moderately to extremely helpful (2.71, 1.79-4.11), and more self-help practices (1.16, 1.09-1.23). All measures were self-report. Sample may not be representative of culturally different or adolescent populations. Cross-sectional design raises possibility of "confounding by indication". Long-term antidepressant use is relatively common in primary care. It occurs within the context of complex mental, physical and social morbidities. Whilst most long-term use is associated with a history of recurrent depression there remains a significant opportunity for treatment re-evaluation and timely discontinuation