Prevalence of Osteoporosis in 100 Iraqi Patients with Systemic Lupus Erythematosus: A Case Control Study

Abstract

Back ground: In recent years, survival of patients with systemic lupus erythematous (SLE) has raised significantly so long-term complications, as osteoporosis, are currently of major importance.

Objective: To assess the prevalence of osteoporosis in Iraqi patients with SLE.

Patients and Methods: This case control study was conducted on 100 SLE patients and 100 healthy controls matched in age, sex, and body mass index. Bone mineral density (BMD) obtained at the lumber spine (L1-L4) and right and left femurs using dual energy X-ray absorptiometry (DXA) machine (Dexxum). Osteoporosis was diagnosed according to WHO guidelines criteria for diagnosis of osteoporosis and Z-scores was used in premenopausal women and men younger than 50 years.

Results: Mean age of SLE patients was 32.01±10.14 years and 32.46±6.29 years in the control group. Females represented 91% of patients and 92% of controls. The mean BMI of patients was 27.41±6.04 kg/m² compared to 28.8±5.26 kg/m² of controls. There was no statistical significant differences between both groups in demographic characteristics (P>0.05). BMD at lumbar spine was significantly lower in SLE patients than controls (82(82%) vs 61(61%), p< 0.001, OR (95%CI): 3.04(1.59-5.81).Of those patients with low BMD, 46% had osteoporosis. Additionally, BMD at total femur was significantly lower in SLE patients than controls (59 (59%) vs 24(24%), p<0.001, OR (95%CI): 4.56(2.48-8.37). Of those patients with low BMD at total femur, 15 (15%) had osteoporosis. Multiple logistic regression analysis showed non-significant association between low BMD in SLE patients and various baseline characteristics (P>0.05).

Conclusions: Prevalence of osteoporosis in Iraqi patients with SLE was 46% at lumbar spine and 15 % at total femur. This may suggest to do early screening for low BMD in patients with SLE for early diagnosis and appropriate treatment.

Keywords: SLE, Osteoporosis, Dual x-ray absorptiometry, Bone mineral density