Background Osteoporosis (OP) is 2–3 times more frequent in rheumatoid arthritis (RA) patients as compared to general population with associated 1,5–2,5 – fold increased risk of fractures. Femoral neck fracture is the most unfavorable prognosis and outcome in these patients, compromising their quality of life.
Objectives To identify major risk factors of femoral neck OP in female RA patients.
Methods The study included 206 female RA patients (ACR criteria), aged 20–75 years (mean age 56,6±11,2 years). An individual patient's file contained social and demographic data, anthropometric parameters, case history, clinical examination and lab findings, traditional OP risk factors, patient's joint status and comorbidities. Hand and distal feet X-ray was taken in each case. Van der Heijde modified Sharp method was used to score the erosions and joint space narrowing in hands and feet. Axial bone mineral density (BMD) was measured using DEXA scan. DEXA T-score was used in post-menopausal women, and Z-score – in menstruating women.
Results Femoral neck OP was diagnosed in 68 patients (33%), while in 138 (67%) no OP was found. Patients with and without OP were of comparable age (58,7 ± 12,3 vs 55,5 ± 10,2 years, p=0,06), but differed in disease duration (12 (7; 22) vs 11 (7; 15) years, p=0,04) and total Sharp score (181,5 (92; 267) vs 112 (59; 173), p=0,006). OP patients were taking higher average daily dose of glucocorticosteroids (GC) during the previous year (5 (2,5; 7,5) vs 2,5 (1,3; 5) mg/day, p=0,03) and were prescribed greater number of intra-articular (i/a) GC injections vs patients without OP (8 (3; 18) vs 6 (2; 10), p=0,04, respectively). Analysis of traditional OP risk factors identified lower body weight in OP patients (62,8 ± 11,4 vs 69,6 ± 12,4 kg, p<0,001) and post-menopause status in the majority of them (89,7 vs 74,6%, RR =1,2, 95% CI 1,06–1,36, p=0,007). Higher incidence of femoral neck fractures within the immediate family members was found in OP patients family history (16,4 vs 2,9%, RR =5,57, 95% CI 1,82–17,07, p=0,001). Multifactorial analysis identified the following major femoral neck OP risk factors: total Sharp score, average daily GC dose during the previous year, total number of intra-articular GC injections, and menopause; the contribution of these variables in OP development was assessed (discriminant function coefficients: 0,006; 0,37; 0,07; 2,91, respectively) to suggest a model (with the area under the ROC curve equal to 0,926), allowing prediction of femoral neck OP with high accuracy, equal to 89,7%.
Conclusions The degree of erosive joint destruction in hand and feet (based on total Sharp score), average daily GC dose during the previous year, total number of intra-articular GC injections, and menopause are major risk factors of femoral neck OP in female patients with RA.
Disclosure of Interest None declared
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