Utilization patterns of antidepressants between 1991 and 2011 in a population-based cohort of middle-aged and elderly

Background: In middle-aged and older patients in whom antidepressant use increased in last decades, patterns of use might be of concern The objective of this study was to investigate the patterns of prevalence, incidence and duration of antidepressant use in an ageing population.

Methods: All participants (aged>45 years) from the population-based Rotterdam Study were followed from January 1st 1991 until death, loss to follow-up, or end of the study period (December 31st 2011). Antidepressant drug dispensing, based on pharmacy records, were subdivided into Tricyclic Antidepressants (TCAs), Selective Serotonin Reuptake Inhibitors (SSRIs) and other antidepressants. One-year prevalence, 5-year incidence and duration of antidepressant use were calculated.

Results: Yearly prevalence of antidepressant use increased from 3.9% in 1991 to 8.3% of the population in 2011. The increase in SSRI use was 5.8-fold, whereas use of other antidepressants doubled and TCA use remained stable over time. Incidence of all antidepressants decreased from 23.9 to 14.2 per 1000 person-years between 1992 and 2011. The duration of a first treatment episode increased over time.

Conclusion: Despite the prevalence of antidepressant use increased over time, incidence did not, which is most likely explained by a longer treatment duration and recurrent episodes.