Impact of ankylosing spondylitis on depression: a nationwide cohort study

The aim of this study is to determine the relationship between AS and subsequent depression. This study was conducted using a nationwide dataset available in Korean National Health Insurance System (KNHIS). We identified 11,465 newly diagnosed AS patients and 57,325 patients without AS in the ratio of 1:5 matched by sex, age, and index date, between 2010 and 2014. We investigated any latent characteristics in the patients' demographic information and chronic comorbidities that could trigger a depression when diagnosed with AS. By comparing the cohort data, the hazard ratio of developing subsequent depression in AS patients was calculated and adjusted based on several risk factors. Despite the adjustment of demographic variables and chronic comorbidities, the risk of depression was 2.21 times higher in the AS cohort than in the control group. Multivariate analysis showed that AS patients with female gender, old age and low-income status showed higher risks of developing depression. Additionally, the presence of chronic comorbidities including diabetes mellitus, hypertension, hyperlipidemia, cancer, stroke, and chronic kidney disease increased the patients' risk of depression. The AS patients with stroke were reported to have the highest risk of depression. This population-based cohort study showed that AS significantly increased the subsequent risk of developing depression. Moreover, the development of a depression is influenced by certain demographic variables and different chronic comorbidities.