Increased bone turnover, osteopenia common among men with COPD
MedWire News: Study findings show that men with chronic obstructive pulmonary disease (COPD) have a greater prevalence of osteopenia than healthy individuals, which may be a result of increased bone turnover.
"Osteoporosis is common in patients with COPD but the likely multifactorial causes contributing to this condition (eg, gender, age smoking, therapy) mask the potential contribution from elements related to COPD," say James Duckers (Cardiff University, UK) and co-authors.
The team therefore assessed osteoporosis and bone mineral density (BMD) related to COPD in a group of 30 clinically stable male ex-smokers with confirmed COPD, and 15 age-matched ex-smoker male controls.
None of the patients were on inhaled corticosteroids or had received more than one short course (<1 week in duration) in their lifetime.
All patients were assessed for BMD at the lumbar spine and hip, forced expiratory volume in one second (FEV1), biochemistry, inflammation, and circulating bone markers for formation and resorption.
Overall, the mean FEV1 percentage was 64%, with the majority of patients having a Global Initiative for Chronic Obstructive Lung Disease (GOLD) Stage II airflow obstruction (20 patients at Stage II, 10 patients at Stage I or III).
Total BMD at the hip and also at the three hip sub regions was significantly lower in patients than controls, while the BMD at the lumbar spine was not different. In patients, both fat-free mass index (FFMI) and FEV1 were significantly related to hip BMD but not to lumbar spine BMD.
Regression analysis showed that FEV1 and FFMI were both predictive of hip BMD, while at the lumbar site, smoking pack year history was predictive of BMD.
The researchers say that osteopenia was more prevalent in patients than controls. Indeed five patients and one control were osteoprotic, with a further 17 patients and five controls diagnosed with osteopenia.
The team found that circulating bone markers were comparable between patients and controls.
However, all bone biomarkers were inversely related to hip BMD in patients, but did not relate to lumbar spine BMD. Osteoporotic patients showed significantly higher osteoprotegerin than non-osteoporotic patients after controlling for age.
The study also showed that mean vitamin D was significantly lower in patients compared with controls, at 16.1 versus 11.4 µg/l, and 80% of patients had insufficient levels (<20 µg/l) compared with 60% of patients.
Although chronic inflammation has been postulated as a mechanism in the loss of BMD in COPD, no significant difference was found in interleukin-6 levels between patients and controls.
"Our findings highlight the potential value of studying milder severity patients free from potential causative confounders, and reinforce the need for earlier identification and targeting of risk factors for osteoporosis as part of the management of COPD," say the authors in the journal Respiratory Research.
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By Ingrid Grasmo