Low SSRI dosing in clinical practice-a register-based longitudinal study

Since several recent meta-analyses report a dose-response relationship for the antidepressant effect of the selective serotonin reuptake inhibitors (SSRIs), we investigated how these drugs are dosed in clinical practice.

Through linkage of nation- or region-wide registers, we describe SSRI doses in 50,365 individuals residing in Region Västra Götaland, Sweden, with an incident diagnosis of depression and initiating SSRI treatment between 2007 and 2016. The primary question was to elucidate to what extent these individuals had been prescribed a daily dose that according to recent meta-analyses is required to elicit the maximum antidepressant effect, that is >20 mg citalopram, >10 mg escitalopram, >10 mg fluoxetine, >10 mg paroxetine or >50 mg sertraline.

In all, 21,049 (54%) out of 38,868 individuals <65 years of age, and 9,131 (79%) out of 11,497 individuals ≥65 years of age, never received an SSRI dose reported to exert maximum antidepressant effect. These prescribing practices were seen for citalopram, escitalopram and sertraline, but not for fluoxetine and paroxetine, and were frequent in both primary and secondary/tertiary care. Suggesting that doses here defined as maximum efficacy doses, when prescribed, are usually not intolerable, between 59% and 68% of individuals <65 years of age received such a dose also for the subsequent prescription, that is as frequently as in those prescribed a sub-maximum efficacy dose (52-69%).

Most patients being prescribed an SSRI to treat their depression never receive the dose that according to recent meta-analyses is most likely to effectively combat their condition. The lack of consensus regarding effective dosing of SSRIs may have contributed to this state of affairs.