Background: It is unknown whether newer, mainly selective serotonin reuptake inhibitors, and older tricyclic antidepressants are used similarly regardless of the geographical area of residence and education.
Methods: We included four randomly sampled cohorts of the Finnish working aged population (n = 998,540-1,033,135). The sampling (Dec 31st in 1995, 2000, 2004 and 2010) resulted in non-overlapping time windows where each participant was followed up for four years for the first antidepressant use. Using Cox proportional hazards models, we examined whether the hazard of antidepressant use differed between the capital area and three other areas (Southern, Western and Northern/Eastern Finland). Educational differences were examined using four sub-groups: capital area/high education (reference category); other areas/high education; capital area/low education; and other areas/low education.
Results: Hazard ratios for the use of newer antidepressants were significantly lower in all other areas compared to the capital area after adjustment for age, sex, marital status, employment status, education, income, and area-level unemployment. Findings remained consistent in all time windows, differences increasing slightly. In the sub-group analysis those with low education had the lowest level of use in all areas, also within the capital area. The results were opposite for older antidepressants in all but the last time window.
Limitations: Some degree of unmeasured confounding and exposure misclassification is likely to exist.
Conclusions: Newer antidepressants were more commonly used in the capital than in the other areas, and among those with high versus low education. These differences in antidepressant use suggest socioeconomic inequalities in the mental health treatment quality.
Keywords: Antidepressant; Education; Geographical area; Inequality; SSRI; Socioeconomic.
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