Patterns of antidepressant use in Italy: therapy duration, adherence and switching

Abstract

Aim: This study aimed to describe the prescription pattern of selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs) in an Italian setting, focusing on therapy duration, switching and adherence.

Method: Historic cohort study, based on administrative databases of three Italian local health-units, was conducted. Patients with a prescription of antidepressants (ADs) in 2009 were enrolled and grouped into: (1) naïve, (2) already in treatment with the same drug and (3) already in treatment with a different drug. Therapy duration, switching and adherence [as medication possession ratio-(MPR)] were evaluated. A logistic regression model was performed to identify predictors of adherence.

Results: There were 88,755 subjects recruited: 37 % naïve, 58 % already in treatment with the same drug and 4 % with different drug. A treatment duration of ≤3 months was found in 41 % of naïve patients, whereas the majority of patients already in treatment had a duration of ≥6 months. Switches occurred in 0.7 % of the whole cohort and mostly occurred between two different SSRIs. The 63 % of naïve patients had a low adherence (MPR < 60 %), whereas a good adherence (MPR ≥ 80 %) was found in 58 % of patients already in treatment with the same drug and in 39 % of those already in treatment with different drug. Predictors of adherence were: female gender, increasing comorbidity and pain absence. All ADs, except for fluoxetine and venlafaxine, showed a better adherence than paroxetine.

Conclusion: Notwithstanding the difficulty to associate the AD prescription to the specific diagnosis of depression, this study highlighted a short duration and a low adherence of AD therapies, especially at the initiation of treatment. Physicians should carefully balance the need to prescribe these drugs, considering the great likelihood of a short duration of treatment and a very low level of adherence.