Seasonality of antidepressant prescriptions and sick leaves

The aim of the present study was to estimate the number of patients with a seasonal prescription pattern of antidepressants, which might be taken as a surrogate marker for medicated patients with seasonal affective disorder (SAD). Furthermore, we examined the time course of sick leaves for patients with seasonal and non-seasonal prescriptions of antidepressants. A retrospective analysis of prescription data of all patients insured by the Sickness Fund Burgenland (BGKK) between 2005 and 2016 was performed. Patients with treatment initiation of an antidepressant in the last and first quarter of the year for at least two consecutive years were selected (SAD-med). Patients with continuation treatment in the third quarter and patients with initiation of antidepressant medication in the second and third quarter of the year were excluded. The mean yearly prescription rate for antidepressants was 9.6% in the insured population. 3.0% of patients treated with antidepressants and 0.9% of insured cases satisfied the definition of SAD-med. The mean number of yearly sick leave days was similar for SAD-med patients and those with non-seasonal prescriptions. Time series analysis showed that sick leaves in SAD-med were influenced by seasonal fluctuations for several years after the first antidepressant prescription. Our study sheds light on antidepressant prescription and sick leave patterns in the general population. Compared to the prevalence of SAD, the estimated rate of SAD-med is substantial. Sick leaves appear to be closely linked to antidepressant prescriptions, and show a characteristic time course before and after the initial prescription.