Background Survival of systemic lupus erythematosus (SLE) patients has improved dramatically due to improved treatment, and the morbidity pattern has shifted towards long-term complications as osteoporosis. SLE occurs in women during child-bearing years and the disease often persists to the postmenopausal period1. Assessment of fracture risk in SLE patients is important as fractures may occur while bone mineral density (BMD) is above the osteoporotic threshold or at the normal range2. Osteocalcin measurement helps to assess fracture risk and select patients for treatment.
Objectives To assess the fracture risk in a cohort of Egyptian female SLE patients by using BMD and osteocalcin level with correlation to disease activity, damage index and drugs in use.
Methods 70 females with SLE ≥40 years old satisfying the SLICC classification criteria were enrolled with detailed history taking including disease duration, drugs in use, traditional risk factors, regular exercise, history of previous fractures and menstrual history. Assessment of disease activity using Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and disease damage using the Systemic Lupus International Collaborative Clinics/ American College of Rheumatology Damage Index (SLICC/ACR DI). Serum calcium, phosphorus and alkaline phosphatise were measured. BMD measured by dual energy X-ray absorpiometry (DEXA) scans at lumbar spine (LS) (L2-L4) and femoral neck (FN), serum osteocalcin level and World Health Organization fracture risk assessment tool (FRAX®).
Results 14//70 (20%) patients had LS osteoporosis, 25//70 (35.7%) had LS osteopenia and 6/70 (8.6%) had FN osteoporosis, 30/70 (42.9%) had FN osteopenia. FRAX-Major ≥20% was observed in 10% of patients, FRAX-HIP ≥3% was seen in 27.1% of patients. Serum osteocalcin level was significantly decreased in SLE patients with lower BMD than those with normal BMD, and significantly decreased in patients with osteoporosis than those with osteopenia. A significant negative correlation was found between osteocalcin level and age of patients, disease duration, SLEDAI and SLICC scores, current, IV pulse and cumulative steroids, immunosuppressants, anticoagulants, but there was a positive correlation with antimalarials and calcium supplements.
Conclusions SLE patients are at greater risk for developing osteoporosis and osteopenia. Ten-year risk of major and hip fractures was high in SLE patients. Increasing age, disease duration, high anti-DNA titres, SLEDAI and SLICC were associated with a higher 10-year probability of major osteoporotic fracture. FRAX predicted incident hip and major osteoporotic fractures among SLE patients with normal and low bone mass not just those with frank osteoporosis. Physicians should be alerted to the higher risk of future fractures in SLE patients for periodic monitoring.
Furukawa M, Kiyohara C, Horiuchi T, Tsukamoto H, Mitoma H, Kimoto Y et al. Prevalence and risk factors of vertebral fracture in female Japanese patients with systemic lupus erythematosus. Mod Rheumatol, 2013; 4:765–73.
Van den Bergh J, Van Geel T, Lems W and Geusens P. Assessment of individual fracture risk: FRAX and beyond. Curr Osteoporos Rep, 2010; 8:131–7.
Disclosure of Interest None declared