Association of systemic lupus erythematosus with a higher risk of cervical but not trochanteric hip fracture: A nationwide population-based study

Objective: To determine the incidence rates and risk factors of cervical and trochanteric hip fractures (HFs) among patients with systemic lupus erythematosus (SLE) based on a nationwide population-based data set. Methods: We conducted a cohort study using data from the Taiwan National Health Insurance database. Patients with SLE and their age- and sex-matched counterparts without SLE were identified. The primary end point was the first occurrence of HF. Cox proportional hazards model was used to evaluate the respective risk factors of cervical and trochanteric HFs in the lupus cohort. Results: Among 14,544 patients with SLE (90% women, mean age 38.1 years) with a mean followup of 6 years, 75 developed HF (incidence rate 8.60 per 10,000 person-years). Compared to controls, the incidence rate ratios (IRRs) for developing HF among lupus patients were 3.17 (95% confidence interval [95% CI] 1.92-5.39, P < 0.001) for cervical HF and 1.11 (95% CI 0.58-2.11, P = 0.571) for trochanteric HF. The IRRs for HF were 2.38 (95% CI 1.58-3.63, P < 0.001) for women and 1.06 (95% CI 0.21-4.93, P = 0.922) for men. Lupus patients with cervical HF were younger than controls with cervical HF (mean age 56.7 versus 67.8 years; P = 0.007). Multivariable Cox regression analyses showed that age, use of intravenous cyclophosphamide, higher dose of steroid, and stroke were associated with cervical HF, whereas age was the only associated factor for trochanteric HF. Conclusion: SLE is associated with a higher risk for cervical but not trochanteric HF, and these 2 types of HFs have different risk factors.