SP095PREVALENCE OF LOW BONE DENSITY AND FRAGILITY FRACTURES IN PATIENTS WITH LUPUS NEPHRITIS

Abstract

INTRODUCTION AND AIMS: Survival of patients with systemic lupus erythematosus (SLE) has improved, albeit with significant morbidity. An increased prevalence of osteopenia, osteoporosis and fractures has been reported. Studies in lupus nephritis (LN) patients are scarce. LN is one of the most severe manifestations of SLE, occurring in up to 60% of adults. The aetiology of bone loss is multifactorial. Densitometry is often used to diagnosis osteoporosis. Aims: evaluate the bone mineral density (BMD) and the presence of fragility fractures in patients with lupus nephritis. METHODS: A cross-sectional study including 35 patients with LN followed in our centre. We collected sociodemographic, clinical, laboratory characteristics of the population. BMD was determined using DXA. Osteopenia and osteoporosis were defined according to the WHO criteria. The presence of fragility fractures was assessed using dorsal and lumbar spine X-Ray. Statistical analysis was performed using SPSS. RESULTS: Seventeen patients (48,5%) had osteopenia and only one had osteoporosis measured in the lumbar spine and/or femoral neck. We included the patients with osteopenia and osteoporosis in the same group (OP). Mean lumbar spine BMD was 1,06 0,39 g/cm2 and mean femoral neck BMD was 0,99±0,13 g/cm2. The group with OP were older (mean age 42,4±11,2 years) and had longer duration of disease (142,2±91,4; 91,1±78,8 months), although without statistical significance. There were no statistical differences relatively to gender, menopause status, IMC, smoke and alcohol intake between the groups. The groups had similar scores of activity and damage (SLEDAI-2K; SLICC/ACR). The most frequent class of LN was IV (77,1%), followed by V (14,3%) and the combination of IV+V (8,6%). eGFR was slightly superior in the group with normal BMD (107,8±31,3 vs. 91,4±34,8; P>0,05). The evaluation of calcium, phosphorus, PTHi and 25(OH)Vitamin D didn't show any statistical difference. The group with OP used more frequently cyclophosphamide as induction therapy (10 in 16 patients). The majority of the patients were medicated with mycophenolate mofetil as maintenance treatment (81,3%) and with steroids, with a mean dose of prednisolone of 12 mg daily in the group with a normal BMD and 4 mg daily in the group with OP (NS). Almost all the patients were treated with vitamin D, calcium supplements and hydroxychloroquine (82,9%; 65,7%; 85,7%). There were no statistical significant differences between the groups. The distribution of antiphospholipid syndrome and oral anticoagulation was similar between the groups (n=4 in each group). Only 24 patients were evaluated with dorsal and lumbar x-rays. Five patients (14,2%) had evidence of a fracture (3 patients in the group with normal BMD and 2 in the group with OP). Patients with fractures presented a lower lumbar spine BMD compared to the patients without fractures (P=0,004). CONCLUSIONS: Although osteopenia is frequent in LN patients, the prevalence of fragility fractures is low, which may be related to improvement of immunosuppression therapy, specifically a better attention for a tapering scheme of steroids, in addition to prophylaxis, without compromising the prognosis of renal disease, being the majority of patients classified as chronic kidney disease grades 1 and 2.