Corticosteroid Is Associated with Both Hip Fracture and Fracture-Unrelated Arthropathy

OBJECTIVE: We aimed to investigate whether and how corticosteroid use was associated with serious hip arthropathy. METHODS AND MATERIALS: This population-based cohort study analyzed the Taiwan National Health Insurance Research Database and screened the one-million random sample from the entire population for eligibility. The steroid cohort consisted of 21,995 individuals who had used systemic corticosteroid for a minimum of 6 months between January 1, 1997 and December 31, 2006. They were matched 1:1 in propensity score on the index calendar date with controls who never used steroid. All participants were followed up until occurrence of serious hip arthropathy that required arthroplasty, withdrawal from the national health insurance, or the end of 2011. Surgical indication was classified as fracture-related and -unrelated. The cumulative incidence of hip arthroplasty was estimated by the Kaplan Meier method. The association with steroid exposure was explored by the Cox proportional hazard model. RESULTS: Cumulative incidences of hip arthroplasty after 12 years of follow-up were 2.96% (95% confidence interval [CI], 2.73–3.2%) and 1.34% (95% CI, 1.2–1.51%) in the steroid users and non-users, respectively (P<0.0001). The difference was evident in fracture-related arthroplasty with 1.89% (95% CI, 1.71–2.09%) versus 1.10% (95% CI, 0.97–1.25%), but more pronounced in fracture-unrelated surgery, 1.09% (95% CI, 0.95–1.24%) versus 0.24% (95% CI, 0.19–0.32%). Multivariate-adjusted Cox regression analysis confirmed steroid use was independently associated with both fracture-related (adjusted hazard ratio [HR], 1.65; 95% CI, 1.43–1.91) and unrelated arthroplasty (adjusted HR, 4.21; 95% CI, 3.2–5.53). Moreover, the risk for fracture-unrelated arthropathy rose with steroid dosage, as the adjusted HR increased from 3.30 (95% CI, 2.44–4.46) in the low-dose subgroup, 4.54 (95% CI, 3.05–6.77) in intermediate-dose users, to 6.54 (95% CI, 4.74–9.02) in the high-dose counterpart (P(trend)<0.0001). CONCLUSIONS: Corticosteroid use is associated with long-term risk of hip arthroplasty, particularly for fracture-unrelated arthropathy.