Prevalence and predictors of asymptomatic vertebral fractures in inflammatory myositis

Abstract

Aim: To assess the frequency and risk factors of asymptomatic vertebral fractures in inflammatory myositis.

Patients and methods: Dorsal and lumbar spine lateral radiographs were taken for adults with inflammatory myositis and scored using Genant's semi-quantitative technique. Demographic data, weight, height, postmenopausal status, duration of corticosteroid use, drug intake, co-morbidities and past history of fractures were recorded. Bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry (DEXA). Myositis Damage Index (MDI) was also assessed. All results are expressed in median and interquartile range.

Results: One hundred patients (82 female) with myositis of median age 35.5 (28.5-46) years and disease duration 3.0 (1.81-8.0) years were studied. Thirty-five patients had adult dermatomyositis (DM), 26 polymyositis, 31 connective tissue disease-associated myositis and eight had juvenile onset myositis. Seventeen were postmenopausal women. Forty-six patients had asymptomatic vertebral fractures and 19 had more than one fracture. Half the fractures occurred in those with disease duration of <5 years. Of the 69 fractures, 47 (68.1%), 16 (23.2%) and 6 (8.7%) were mild, moderate and severe, respectively. The 11th and 12th thoracic vertebrae were together the most commonly (30.4%) affected. Of the 70 who underwent BMD assessment, 62.7% were osteopenic and 26.9% were osteoporotic. T scores of DEXA scan at the lower third of the radius correlated negatively with fracture number (r = -0.27 (-0.50 to -0.005), P = 0.04). Gender, age, disease duration, years of corticosteroid intake, body mass index, years post-menopause and MDI had no correlation with number of fractures.

Conclusion: Patients with inflammatory myositis have high prevalence of asymptomatic vertebral fractures.

Keywords: bone; fracture; myositis.