No increased risk of alopecia in ankylosing spondylitis patients: A population-based cohort study in Taiwan.

AIM: To investigate the association between ankylosing spondylitis (AS) and alopecia. METHODS: In this cohort study, data from over 1 000 000 patients in the Taiwan Longitudinal Health Insurance Database were extracted. We selected newly diagnosed (outpatient department visit three or more times or admission at least once) patients with AS (ICD-9-CM = 720.0) from 2000 to 2012. For the non-AS comparison group, patients never diagnosed with AS were chosen from 1999 to 2013. In all, 3640 AS patients and 14 560 non-AS controls were selected. Cox proportional hazard model and Kaplan-Meier analysis were used to present the results. The adjusted hazard ratio (HR) in the Cox proportional hazard model was adjusted for age, sex, hypertension, hyperlipidemia, diabetes, atopic dermatitis, and mental disorder. RESULTS: No increased risk of alopecia in AS patients was shown in the Cox proportional hazard model (crude HR 1.16, P = 0.595; adjusted HR 1.16, P = 0.599). Negative results are found as well in subgroup analysis of different age, sex (age 20-40 y: HR 1.03, P = 0.925; Age ≥40 y: HR 1.49, P = 0.406; Female: HR 1.17, P = 0.759; Male: HR 1.15, P = 0.667), and phenotypes of alopecia (androgenetic alopecia: HR 1.19, 95% confidence interval [CI] 0.58-2.41; alopecia areata: HR 0.98, 95% CI 0.37-2.62). A significant positive correlation is found between atopic dermatitis and alopecia (adjusted HR 8.05, P = 0.039). CONCLUSION: In this population-based cohort study, we found no association of risk of alopecia and AS.