Frequency of fractures in women with systemic lupus erythematosus: comparison with United States population data.

OBJECTIVE: To describe the frequency of self-reported fractures in a large population-based cohort of women with lupus, to compare the frequency of self-reported fractures between lupus patients and women of similar age in the general population by use of data from the 1994 National Health Interview Survey (NHIS), and to describe the associated risk factors for fracture in women with lupus. This study is a secondary analysis of data collected to assess cardiovascular risk in women with lupus.
METHODS: Fractures and associated risk factors were ascertained by self report in this retrospective cohort study of 702 living women with lupus who were followed up for 5,951 person-years. Self-reported fractures were verified in a subset of patients. A Weibull regression model was used to assess risk factors associated with time from lupus diagnosis to fracture in the univariate and multivariate analyses. Age-specific standard morbidity ratios (SMRs) were calculated to determine whether fracture occurrence was greater than expected in women with lupus.
RESULTS: Eighty-six (12.3%) of 702 women reported at least 1 fracture following the diagnosis of lupus. The sites of the first fracture were the leg (n = 32), foot (n = 16), arm (n = 15), spine (n = 9), rib (n = 7), hip (n = 2), pelvis (n = 2), hand (n = 1), shoulder (n = 1), and finger (n = 1). Fracture risk was increased in the lupus cohort compared with women of similar age from the United States population, using weighted data from the 1994 NHIS (SMR 4.7; 95% confidence interval 3.8, 5.8). Variables in the univariate analysis that were significantly associated (P < 0.05) with time from lupus diagnosis to fracture were older age at lupus diagnosis, longer disease duration, longer duration of corticosteroid use, less use of oral contraceptives, and menopause status. In the multivariate analysis, independent determinants of time from lupus diagnosis to fracture were older age at lupus diagnosis and longer duration of corticosteroid use.
CONCLUSION: Fractures occurred in 12.3% of lupus patients who were followed up for 5,951 person-years. There was nearly a 5-fold increase in fracture occurrence in the women with lupus compared with women from the US population. Older age at lupus diagnosis and longer use of corticosteroids were associated with time from lupus diagnosis to fracture. With increased life expectancy of lupus patients, fracture occurrence is a major threat to the health of these women. Prevention strategies must be directed toward minimizing the occurrence of fractures in these patients.