Diagnosis of osteoporosis in COPD patients: Estimation of the 10-year probability of a major osteoporotic fracture (FRAX), and Dual-energy X-Ray Absorptiometry

The aim of the study was to evaluate various methods of osteoporosis diagnostics (FRAX® and Dual-energy Х-Ray absorptiometry – DXA) and the sequence of their application in the diagnostic algorithm in COPD patients without a history of large bone fractures. Methods. Cross-sectional study of 115 COPD patients without exacerbation (93 men and 22 women, mean age 67.2 ± 7.1 years). The study included clinical examination, FRAX® estimation and comparison of the 10-year probability of a major osteoporotic fracture (MOF) with the Russian intervention threshold, spirometry, DXA of lumbar spine and proximal femur, semi-quantitative radiographic morphometry by Genant. All patients were examined using several methods that are possible in clinical practice: 1) FRAX® without DXA; 2) FRAX® + DXA in patients with intermediate 10-year probability of MOF and recalculation of FRAX® probability including femoral neck bone mineral density (BMD); 3) FRAX® + DXA in patients with intermediate 10-year probability of MOF. Take into account DXA results; 4) DXA without FRAX® ; 5) DXA + recalculation of FRAX ® for individuals with normal BMD or osteopenia. Results. In the whole sample of patients 1 – 5 diagnostic methods revealed 5.1, 7.0, 15.7, 44.3, 45.2% of individuals with osteoporosis, respectively. In men, the methods using FRAX ® (1 – 3) gave unsatisfactory results – the number of patients requiring treatment did not exceed 4.3%, while DXA revealed osteoporosis in 43%. FRAX® + DXA analysis in patients with intermediate 10-year probability of MOF (3 th method) was the best for women. The main independent predictors of low bone mineral density were post-bronchodilator FEV 1 ≤ 30% predicted and/or long-term oral glucocorticoid use. Asymptomatic vertebral fractures were detected in 11 patients. Before the radiographic morphometry, treatment would have been prescribed only 1 patient for the 1th or 2th methods; 5 patients – 3th method and 9 patients using 4th or 5th methods. Conclusion. The use of the Russian FRAX® model in men with COPD revealed a very low percentage of people who need osteoporosis treatment; DXA was the optimal diagnostic method. If it`s not possible to perform DXA in the most COPD patients, it should be prescribed to people with very severe bronchial obstruction and/or taking long-term oral glucocorticoid therapy. Regardless of the BMD parameters, semi-quantitative X-ray morphometry should be performed to diagnose asymptomatic vertebral fractures.