Patients with newly diagnosed systemic lupus erythematosus (SLE) have a 62% increased risk for sustaining hip fractures, independent of traditional risk factors including glucocorticoid use, according to study results published in Arthritis Care and Research.

In this population-based 1:5 matched cohort study, researchers estimated the overall risk for hip fractures among patients with incident SLE (n=5047) compared with randomly selected age-, sex-, and index year-matched individuals from the general population (n=25,235). In the SLE cohort, 99.4% of patients were diagnosed by rheumatologists or from hospitalizations; incident hip fractures were identified using hospitalization data.

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During a mean follow-up of 10.75 years, 73 incident hip fractures were observed in the SLE cohort (0.93 events per 1000 person-years [PYs]), compared with 272 in the non-SLE cohort during a mean follow-up of 11.32 years (0.69 events per 1000 PYs). Compared with the non-SLE cohort, the overall risk for hip fractures was significantly higher with SLE diagnosis (hazard ratio, 1.62; 95% CI, 1.06-2.48) after adjusting for baseline risk factors.

Study limitations included the uncertainty of the accuracy of SLE case definition, potential misclassification despite the use of a stringent algorithm that required ≥2 principal codes for SLE, and uncertain ascertainment of the hip fracture case definition. Furthermore, applying the marginal structural model in this study may not truly estimate the causal effect of SLE on hip fractures.

Researchers indicated the important implications of this study for the prevention, screening, and treatment of osteoporosis that may lead to hip fractures. “As proposed by previous studies, the etiology of bone loss and the occurrence of clinical fractures in SLE is likely to be multifactorial, involving both nondisease and disease-related factors… High systemic inflammation in severe SLE may contribute to bone loss by increasing osteoclastic bone resorption and by reducing osteoblastic bone formation,” the researchers noted.

Reference

Li L, Xie H, Lu N, Esdaile JM, Aviña-Zubieta JA. The impact of systemic lupus erythematosus on the risk of newly diagnosed hip fracture [published online November 23, 2019]. Arthritis Care Res (Hoboken). doi:10.1002/acr.24112