Bone Density Significantly Altered by Smoking History in Men Without COPD

Bone density, measured by chest computed tomography (CTBD), was significantly altered in men without chronic obstructive pulmonary disease (COPD) based on their smoking status and pack-years, according to a study published this week in Scientific Reports.¹

Smoking and bone mineral loss have been associated before, as male smokers with or without COPD were shown to have a definite risk of low CTBD and vertebral fractures.² However, because these studies were conducted on patients with COPD, or in a general population that included patients with COPD, cases of low CTBD could be associated with the development of osteoporosis and emphysema in patients with COPD rather than smoking history. Researchers sought to investigate the relationship between smoking and CTBD in men without COPD to distinguish its association.

The cross-sectional study compared 1011 men 50 years or older without COPD on their smoking status in relation to their bone density, measured through CTBD, and bone mineral density, measured by dual-energy x-ray absorptiometry (DEXA-BMD). Data derived from the Ansan cohort included in the Korean Genome and Epidemiology Study (KoGES). The correlation between CTBD and DEXA-BMD was compared, as was the association of CTBD with pack-years:

• Smoking status in subjects indicated as never, former, and current smokers
• Pack-year relationship with subjects indicated as light smokers (<15 pack-years), moderate smokers (15-<30 pack-years), and heavy smokers (≥30 pack-years)

Data showed an overall statistically significant lower CTBD of all vertebral bodies (VBs) for ever-smokers than in never-smokers. In participants younger than 65 years, CTBD levels of the T10 and L1 and mean CTBD of the T4, T7, and T10 were definitively lower in ever-smokers than in never-smokers (P <.05), whereas ever-smokers 65 years or older only showcased lower CTBD of L1. DEXA-BMD of all VBs, without L1, similarly showed definite differences among never, former, and current smokers.

CTBD was found to be lowest in heavy smokers, who showed significantly lower levels compared with light smokers (P <.05). Heavy and moderate smokers both exhibited a definite association with lower CTBD, which was not found in never-smokers. The correlations between CTBD and DEXA-BMD were significant at all VB levels (correlation coefficient, 0.448~0.640; P <.01), with an additional association with a smoker’s pack-years. This stark association between moderate and heavy smoking with lower CTBD, and CTBD’s subsequent correlation to DEXA-BMD, highlights the diminished bone quality in frequent smokers.

The study had limitations in its participants, as ever-smokers exhibited a heightened consumption of alcohol compared with never-smokers, which may contribute to lower CTBD. Its focus on a specific area in Korea may additionally represent data that do not apply to other populations.

Researchers provided extensive evidence of associations between smoking and lower CTBD in men, regardless of COPD diagnosis. The escalating correlation of CTBD and pack-years further reveals an individual’s increased risk based on their smoking history.

Reference

1. Kim C, Kim S, Lee KY, et al. Differences in bone density on chest CT according to smoking status in males without chronic obstructive lung disease. Sci Rep. 2019;9(1):10467. doi: 10.1038/s41598-019-46830-4.
2. Jaramillo JD, Wilson C, Stinson DJ, et al. Reduced bone density and vertebral fractures in smokers. Ann Am Thorac Soc. 2015;12(5):648-656. doi: 10.1513/AnnalsATS.201412-591OC.