Lung Risk Factors May Boost Hip Fracture Risk in Smokers

By Marilynn Larkin

August 13, 2020

NEW YORK (Reuters Health) - People who smoke may have lung-specific risk factors such as emphysema that increase the risk of hip fracture, according to an observational study.

"Our group and others have shown that low bone mineral density is associated with lung disease-specific factors, such as emphysema and exacerbations of chronic obstructive pulmonary disease (COPD), independent of risk factors - e.g., smoking, age, sex - we typically use to assess fracture risk and need for osteoporosis screening," Dr. Jessica Bon of the University of Pittsburgh told Reuters Health by email. "Whether these same lung disease-specific factors are likewise associated with fracture risk was unknown."

As reported in the Journal of Bone and Mineral Research, Dr. Bon and colleagues analyzed data from 9,187 current and former smokers participating in the Genetic Epidemiology of chronic obstructive pulmonary disease (COPD) observational study.

Participants were 51.4% male with a median age of 60. Nearly half were actively smoking at study entry; less than half had airflow obstruction and about one-third had emphysema. They were followed for a median of 7.4 years, during which 361 hip fractures occurred.

The presence of traditional risk factors was low: reported fracture (6.5%), systemic steroid use (2.5%), and rheumatoid arthritis (7.3%). The prevalence of diabetes was 13.2%, and of self-reported osteoporosis, 9.6%.

Lung-specific risk factors included post-bronchodilator percent forced expiratory volume in 1 second (FEV1%) predicted (odds ratio, 0.95); Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification (OR, 1.09); CT-determined emphysema (OR, 1.34); symptom scores (OR, 1.10); 6-min walk distance (OR, 0.92); body mass index, airflow obstruction, dyspnea, and exercise (BODE) index (OR, 1.07); total exacerbations (OR, 1.13); and annual exacerbations (OR, 1.37).

In multivariable models, age, black race, osteoporosis, prevalent hip and spine fracture, rheumatoid arthritis, and diabetes were associated with incident hip fracture. When added to traditional risks, emphysema, 6-min walk distance, and total number of exacerbations improved risk discrimination.

The authors state, "These findings suggest that the incorporation of lung-specific risk factors into fracture risk-assessment tools may more accurately predict fracture risk in smokers."

Dr. Bon said, "Many of our COPD patients have significant emphysema or frequent exacerbations, yet are under the recommended age for DXA screening for osteoporosis and do not have other major risk factors that would warrant early bone mineral density assessment. We hope that our study prompts clinicians caring for patients with COPD to consider DXA that osteoporosis can be detected and primary prevention strategies for hip fracture initiated early."

"While early screening before the age of 65 in all COPD patients is likely not cost-effective, guidelines should consider COPD with high-risk features to be a major risk factor for fracture and recommend early DXA screening," she added.

Dr. Ali Sadoughi, director of Interventional Pulmonology and Bronchoscopy at Montefiore Health System and assistant professor for Pulmonary and Critical Care at Albert Einstein College of Medicine, in New York City, commented, "This research, as well as the updates to the guidelines, are needed and long overdue."

"Increased awareness of bone loss-related comorbidities among smokers with lung disease is an important step which can be added to smoking-cessation guidelines and efforts," he told Reuters Health by email. "This study showed the importance of an established screening protocol in routine care of this population with lung disease."

"Targeted therapy against the associated risk factors is advised," he added. "This includes judicious use of steroids to treat COPD exacerbations, attention to physical wellness and functional status, and treating comorbidities that affect bone health in these patients."

SOURCE: Journal of Bone and Mineral Research, online August 4, 2020.