Vertebral bone attenuation in Hounsfield Units and prevalent vertebral fractures are associated with the short-term risk of vertebral fractures in current and ex-smokers with and without COPD: a 3-year chest CT follow-up study.

ABSTRACT

CT scans performed to evaluate chronic obstructive pulmonary disease (COPD) also enable evaluation of bone attenuation (BA; a measure of bone density) and vertebral fractures (VFs). In 1239 current/former smokers with (n = 999) and without (n = 240) COPD, the combination of BA and prevalent VFs was associated with the incident VF risk. INTRODUCTION: Chest CT scans are increasingly used to evaluate pulmonary diseases, including COPD. COPD patients have increased risk of osteoporosis and VFs. BA on CT scans is correlated with bone mineral density and prevalent VFs. The aim of this study was to evaluate the association between BA and prevalent VFs on chest CT scans, and the risk of incident VFs in current and former smokers with and without COPD. METHODS: In participants of the ECLIPSE study with baseline and 1-year and 3-year follow-up CT scans, we evaluated BA in vertebrae T4-T12 and prevalent and incident VFs. RESULTS: A total of 1239 subjects were included (mean age 61.3 ± 8.0, 61.1% men, 999 (80.6%) COPD patients). The mean BA was 155.6 ± 47.5 Hounsfield Units (HU); 253 (20.5%) had a prevalent VF and 296 (23.9%) sustained an incident VF within 3 years. BA and prevalent VFs were associated with incident VFs within 1 (per - 1SD HR = 1.38 [1.08-1.76] and HR = 3.97 [2.65-5.93] resp.) and 3 years (per - 1SD HR = 1.25 [1.08-1.45] and HR = 3.10 [2.41-3.99] resp.), while age, sex, body mass index (BMI), smoking status and history, or presence of COPD was not. In subjects without prevalent VFs and BA, and for 1-year incidence, BMI values were associated with incident fractures (1 year, BA per - 1SD HR = 1.52 [1.05-2.19], BMI per SD HR = 1.54 [1.13-2.11]; 3 years, per - 1SD HR = 1.37 [1.12-1.68]). CONCLUSIONS: On CT scans performed for pulmonary evaluation in (former) smokers with and without COPD, the combination of BA and prevalent VFs was strongly associated with the short-term risk of incident VFs.