COPD Risk Inflated by Obesity, and Underweight

July 21, 2014

A new study shows that the risk of chronic obstructive pulmonary disease increases with obesity. Yet, the risk was increased in underweight persons as well.

Obesity, particularly abdominal obesity, represents an important risk factor for chronic obstructive pulmonary disease (COPD), according to a large, prospective study.

In a seemingly contradictory finding, the risk of COPD also was increased in underweight persons.

“Our findings suggest that next to smoking cessation and the prevention of smoking initiation, meeting guidelines for body weight, body shape, and physical activity level may represent important individual and public health opportunities to decrease the risk of COPD. Physicians should encourage their patients to adhere to these guidelines as a means of preventing chronic diseases in general and possibly COPD in particular,” according to lead author Gundula Behrens, PhD, Department of Epidemiology and Preventive Medicine, University of Regensburg, Germany, and her coauthors.

Dr Behrens and colleagues in Germany and the United States examined the relationship of waist-to-hip circumference, body mass index (BMI), and physical activity levels to new cases of COPD in a large group of US men and women who participated in the National Institutes of Health–AARP Diet and Health Study. The researchers looked at data on more than 113,000 persons aged 50 to 70 years who did not have COPD, cancer, or heart disease at the beginning of the study in 1995. The participants provided complete self-reported information on anthropometric measurements, physical activity, smoking, and COPD incidence during a 10-year follow-up period.

In that time, COPD developed in more than 3600 persons. The risk of COPD was increased by 72% in those who had a large waist circumference-110 cm or bigger in women and 118 cm or bigger in men.

“We observed a stronger positive relation with abdominal body fat than with total body fat and COPD,” stated Dr Behrens. “In particular, overweight as measured by BMI emerged as a significant predictor of increased risk of COPD only among those with a large waist circumference.”

A large waist was a robust predictor of COPD in smokers as well as in persons who had never smoked, she noted.

Pollution, smoking, and toxic particles in workplace dust are thought to cause COPD through chronic inflammation and impaired ability to heal injury to the lungs. “Increased local, abdominal, and overall fat depots increase local and systemic inflammation, thus potentially stimulating COPD-related processes in the lung,” stated Dr Behrens.

Large hip circumference and increased physical activity levels were related to decreased COPD risk. Persons who had a large hip circumference and were physically active at least 5 times a week were 29% less likely to experience COPD. The authors speculated that physical activity induces reductions in oxidative stress and chronic inflammation, factors that promote COPD. In addition, physical activity improves processes of lung repair and reduces obesity.

The risk of COPD in underweight persons was increased by 56%. Possible reasons for the finding, the authors stated, include malnutrition and reduced muscle mass leading to increased COPD susceptibility as well as progression through inflammatory processes and impaired lung repair capacity.

The researchers reported their results online on July 7, 2014 in the Canadian Medical Association Journal.