Elevated Fracture Risk Observed in SLE, Lupus Nephritis

Patients with systemic lupus erythematosus (SLE) who are enrolled in Medicaid are at greater risk for fractures compared with patients without SLE, according to cohort study data published in Arthritis & Rheumatology.

Investigators abstracted claims data on adults aged 18 to 65 years from the Medicaid Analytic Extract database from 2007 to 2010 to assess fracture incidence rates and relative risk in patients with and without SLE. Patients with SLE were age- and sex-matched with non-SLE comparators. SLE in patients was defined as the presence of ≥3 ICD-9 codes for SLE in claims data. Patients with lupus nephritis had ≥2 additional codes for renal disease. As primary outcome measures, investigators captured any incident fractures of the pelvis, wrist, hip, or humerus. Sociodemographic characteristics, medication prescriptions, and comorbid medical conditions were assessed during the 180-day baseline period prior to index date. Incidence rates (IR) and adjusted hazard ratios (HR) were subsequently calculated in each patient cohort.

A total of 47,709 patients with SLE were identified and matched to 190,836 non-SLE comparators. Lupus nephritis was present in 19.8% of the SLE cohort. The mean age of participants with SLE was 41.4, and 92.6% were women. In patients with SLE, the IR for any fracture was 4.32 per 1000 person-years. In patients with SLE and lupus nephritis, the IR increased to 4.60 per 1000 person-years. Patients without SLE had a lower IR for any fracture: 2.40 per 1000 person-years. Pelvic fractures were the most frequent fracture type in patients with SLE (1.72/1000 person-years), while wrist fractures were the most common in comparators (1.04 per 100,000 person-years). 

According to comparative risk analyses, patients with SLE had a 2-fold greater risk for fracture compared with controls (HR, 2.09; 95% CI, 1.85-2.37). Patients with lupus nephritis had a significantly greater risk for fractures compared with controls (HR, 3.06; 95% CI, 2.24-4.17), as well as a 1.6-fold greater risk compared with patients with SLE without lupus nephritis (HR, 1.58; 95% CI, 1.20-2.07). When analyses were adjusted for glucocorticoid use and medical comorbidities, these risks were slightly attenuated but not eliminated.

These data underscore the elevated risk for fracture in patients with SLE, particularly patients with an additional diagnosis of lupus nephritis. Clinicians may find these results useful in identifying which patients may benefit from fracture prevention measures.

Reference

Tedeschi SK, Kim SC, Guan H, Grossman JM, Costenbader KH. Comparative fracture risks among US Medicaid enrollees with and without systemic lupus erythematosus [published online February 4, 2019]. Arthritis Rheumatol. doi:10.1002/art.40818