By Annette M. Boyle
TEMPLE, TX—When counseling a patient with chronic obstructive pulmonary disease (COPD), many clinicians start with two words of advice: “Stop smoking.” Sharing the results of recent research from the Central Texas VA might provide additional encouragement to veterans with COPD to follow that advice, particularly if they are underweight.
The Texas team found that, among underweight patients on long-term oxygen therapy (LTOT), smokers had more than nine times the death rate of nonsmokers.
“The results of our study are unique due to the drastic increase in mortality in actively smoking underweight veterans with COPD who require LTOT,” said co-author Udaya M Bhat, MD, chief of pulmonary, critical care and sleep medicine at the Central Texas Veterans Health Care System.
Smoking is the leading risk factor for development of COPD, which includes emphysema and chronic bronchitis. About 75% of patients with COPD are current or former smokers, and nearly 40% of patients diagnosed with the disease continue to smoke, according to the U.S. Centers for Disease Control and Prevention. Other risk factors include long-term exposure to dust or other lung irritants and certain genetic mutations.
“COPD is the fifth most common chronic medical problem in the VA system and affects up to 15% of all VA patients,” Bhat told U.S. Medicine. The prevalence is generally attributed to the higher rate of smoking among military personnel, particularly those who have been deployed.
VA has a large population of patients with COPD receiving oxygen therapy, according to Bhat. The VA/DoD Clinical Practice Guideline for COPD recommends oxygen for patients with daytime oxygen saturation below 88% or below 90% if there is evidence of tissue hypoxia. Oxygen therapy reduces breathlessness and patients with severe COPD
“While oxygen therapy and smoking cessation have known benefits in COPD patients, low BMI is a predictor of poor outcomes. LTOT is of proven benefit, but has substantial risk to patients who continue to smoke,” Bhat said.
The researchers sought to determine the predictors of mortality in patients on long-term oxygen therapy by examining the impact of smoking status, age, race, hypertension, cardiovascular disease, stroke, depression, post-traumatic stress disorder, body mass index (BMI) and forced expiratory volume in one second (FEV1). Their retrospective analysis included 158 patients who started long-term oxygen therapy for COPD between October 2010 and September 2015 at their facility.
BMI Predicted Survival
They found that smoking was not associated with a statistically significant reduction in probability of survival. Body mass index, however, strongly predicted survival.
Every underweight smoker in the study died within 32 weeks of beginning long-term oxygen therapy. Four of the 18 normal weight smokers died in that time frame, as did three of the 26 smokers in the overweight and obese category.
“For every one unit increase in BMI, the rate of death decreased by 8%, holding all other variables constant,” the researchers wrote. As a result, “the overweight category had an 88% decreased rate of death compared to underweight category,” they noted.
Among the nonsmokers, 2 of 9 in the underweight category died, compared with 12 of 27 patients in the normal weight group and 6 of 66 in the overweight and obese category.
Previous studies have found a dose-response relationship between BMI and risk of death in COPD. A meta-analysis of 17 observational studies with a total of 30,182 COPD patients found that underweight patients had a 40% increase in mortality risk compared to normal weight patients, while overweight and obese patients had a 20% and 23% reduction in risk, respectively.2
Patients with severe COPD might lose weight as a consequence of fatigue and chronic shortness of breath, according to the National Heart, Lung and Blood Institute. Bhat advised that patients with low BMI be referred to a pulmonologist and nutritionist. The VA guideline recommends a nutrition referral for calorie supplementation for patients with a BMI less than 20 kg/m2.
While current mortality prediction models do not assess smoking and BMI in combination, the Texas team concluded that considering both factors together provided “extremely useful prognostic information regarding underweight actively smoking patients with COPD receiving LTOT.”
For the day-to-day interaction with patients with COPD, Bhat recommended stressing the basics. “From the perspective of a general practitioner, clinicians should make every effort to counsel patients regarding tobacco cessation and provide cessation aids. This should be readdressed during every clinic visit,” he said.
Patients with COPD who have low BMI and continue to smoke should be made aware of their prognosis, if long-term oxygen therapy is indicated. “Realistic expectation of the prognosis and the natural progression of the disease should be discussed with the patient and family members,” Bhat said.
As a team, the researchers went further. “According to our results, we suggest the pulmonary clinician’s care plan should include discussions of palliative care, goals of care, and hospice referrals with patients in this subgroup when the criteria for LTOT is met,” they wrote.
- Pattison R, Lat T, Sikka P, Coppin J, Bhat U. Predictors of Mortality in Actively Smoking Veterans with Chronic Obstructive lung Disease Receiving Long-Term Oxygen Therapy. Chest. October 2017;152(4):SA810.
Guo Y, Zhang T, Wang Z, et al. Body mass index and mortality in chronic obstructive pulmonary disease: A dose–response meta-analysis. Liu. J, ed. Medicine. 2016;95(28):e4225.