Objectives: The aim of the present study was to evaluate the association between psoriasis and osteoporosis using two different studies. Methods: Data from the Korean National Health Insurance Service-Health Screening Cohort of participants who were ≥ 40 years old were collected from 2002 to 2013. Psoriasis and osteoporosis were included using ICD-10 codes. In study I (a follow-up study), a total of 25,306 psoriasis participants were matched to 101,224 controls with respect to age group, sex, income group, and region of residence, and the occurrence of osteoporosis was analyzed. Crude (simple) and adjusted hazard ratios (HRs) were analyzed using a stratified Cox proportional hazard model. In study II (a nested case–control study), a total of 79,212 osteoporosis patients were matched to 79,212 controls, and a previous history of psoriasis was analyzed. Crude and adjusted odds ratios (ORs) were analyzed using a conditional logistic regression analysis. Subgroup analyses were conducted according to age group and sex. Results: The adjusted HR of osteoporosis was 1.11 (95% confidence interval [CI] = 1.07-1.15, P < 0.001) in study I. In the subgroup analysis according to age and sex, the results were consistent except for the ≥ 60-year-old women. The adjusted OR of psoriasis was 1.22 (95% CI = 1.16-1.28, P < 0.001) in study II. All subgroups demonstrated high adjusted ORs of osteoporosis for psoriasis. Conclusions: Psoriasis increased the risk of osteoporosis in the population of participants aged ≥ 40 years in Korea.
