9 Incidence and determinants of vertebral and peripheral fractures in patients with systemic lupus erythematosus: a prospective longitudinal cohort study

Abstract

Background Systemic lupus erythematosus (SLE) is associated with an increased risk of fractures1. However, data on the incidence of vertebral and peripheral fractures are limited. In particular, data on (morphometric) vertebral fracture incidence and determinants of such fractures are scarce and show conflicting results. The objective of this study was to assess the incidence of fractures in a population of patients with SLE, and to identify determinants that predict incident vertebral and peripheral fractures. Methods A prospective longitudinal cohort study in 145 patients with SLE was performed. Serial bone mineral density (BMD) measurements using dual x-ray absorptiometry, and radiographs of the thoracic and lumbar spine were performed at inclusion and after a median of 5 years (IQR 35) followup. Demographic and clinical data were collected. Vertebral fractures were scored according to the semi-quantitative method by Genant et al. Reported peripheral fractures were confirmed by x-rays. Analyses were performed with logistic regression (forward selection procedure). Outcome measures were incident fracture in general (yes/no), vertebral fracture (yes/no), and peripheral fracture (yes/no). Results Of the 145 included patients, 131 (90%) were females and 100 (69%) Caucasian. The mean age was 41 years (SD 12) at baseline, and median follow-up was 7.2 years (IQR 612). A total of 42 incident fractures (vertebral and peripheral) occurred during 998 patient years. The incidence rate of vertebral and peripheral fractures was 2.0 per 100 patient years (95% CI 1.303.13), and 2.20 per 100 patient years (95% CI 1.453.35), respectively. Any fracture (both vertebral and peripheral) was predicted by postmenopausal status and Caucasian ethnicity. Vertebral fractures were predicted by age, in which the older the SLE patient, the higher the odds of getting vertebral fractures. Peripheral fractures were predicted by history of stroke, postmenopausal status and moderate alcohol use (112 units per week). Use of higher dosages of alcohol (>13 units per week) did not reduce peripheral fracture occurrence. Table 1 shows the final prediction models. Conclusions The results of our study suggest a twofold increased risk of both vertebral and peripheral fractures in SLE patients compared to the general population.1 2 Age, Caucasian ethnicity and postmenopausal status are important risk factors for incident fractures in SLE. In addition, special attention should be paid to SLE patients with a history of stroke since this subgroup of patients is at high risk of peripheral fractures.