Prevalence and risk factors of osteoporosis in lupus nephritis patients in China: a cross-sectional study

BackgroundOsteoporosis is a significant concern among individuals with lupus nephritis (LN), with reported prevalence rates exhibiting considerable variation. This study investigates the prevalence and identifies risk factors contributing to osteoporosis in premenopausal and postmenopausal LN patients, addressing the paucity of data specific to the Chinese population.MethodsThis cross-sectional study enrolled patients with renal biopsy-proven LN, who underwent bone mineral density (BMD) measurements using dual X-ray absorptiometry at the lumbar spine, total hip, and femoral neck. The study was conducted at Tongji hospital from May 2011 to June 2018.ResultsA total of 130 patients were evaluated, with a mean age of 46.2 +/- 12.9 years, including 2 males and 128 females. A significant majority, 52.3% (n = 67) of the female patients, were identified as postmenopausal. BMD measurements revealed that 40.0% of patients had osteoporosis in at least one site. The spearman rank correlation of BMD with clinical characteristics indicated that age at menopause, weight, height, and body mass index were positively correlated with BMD, while age, age at diagnosis of LN, and menopause duration were negatively correlated with BMD in lumbar spine, total hip, and/or femoral neck. Multivariable linear regression analysis demonstrated that body mass index was positively associated with BMD, whereas disease duration and menopause duration were negatively associated with BMD in all and postmenopausal patients. Postmenopausal patients consistently had a higher prevalence of osteoporosis across all measured sites. Factors such as older age, lower weight, and the absence of bisphosphonates therapy were independently associated with an increased risk of osteoporosis in LN patients.ConclusionOur findings underscore a substantial prevalence of osteoporosis in LN patients, especially among postmenopausal individuals. The study identifies older age, lower weight, and absence of bisphosphonates treatment as risk factors for osteoporosis in this patient population.