Relationship between femur neck bone mineral density and prevalent chronic obstructive pulmonary disease (COPD) or COPD mortality in older non-Hispanic white adults from NHANES III

Abstract

The relationship between femur neck bone mineral density (FNBMD), prevalent COPD, and COPD mortality was examined in older non-Hispanic white adults from NHANES III. FNBMD was significantly related to prevalent COPD and COPD mortality before and after adjusting for shared risk factors. Bone mineral density (BMD) has been linked to chronic obstructive pulmonary disease (COPD), but little is known about its relationship with COPD mortality. The present study examined the relationship between FNBMD, prevalent COPD, and COPD mortality in older non-Hispanic white adults from the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994). COPD status at baseline was defined by self-reported physician's diagnosis and by airway obstruction based on spirometry measurements in 3,275 non-Hispanic whites aged 50 years and older. COPD mortality cases were identified using linked mortality records obtained through 2006. FNBMD was measured by dual-energy x-ray absorptiometry. Multiple regression was used to examine the baseline relationship between COPD and FNBMD. Cox proportional hazards models were used to estimate the hazards ratio (HR) for COPD mortality by FNBMD. Twelve percent self-reported a physician's diagnosis of COPD, 23 % had mild or moderate airway obstruction, and 9 % had severe or very severe airway obstruction. There were 180 COPD mortality cases in the sample. FNBMD was significantly lower in those with self-reported COPD diagnosis or airway obstruction before and after adjusting for shared risk factors (p < 0.05). COPD mortality risk was significantly increased for each standard deviation decline in FNBMD before (by 68 %) and after (by 26-38 %) adjusting for shared risk factors. Low FNBMD was associated with both baseline COPD and future COPD mortality. Shared risk factors appeared to explain some, but not all, of these relationships.