Obesity is associated with improved survival among patients with chronic obstructive pulmonary disease (COPD) who use long-term noninvasive ventilation (NIV), according to a study in Respiratory Medicine.
Investigators explored how obesity and other factors relate to mortality in patients with COPD on long-term NIV. The retrospective analysis included patients with COPD enrolled in a home ventilation program in Quebec, Canada, from 2014 to 2018. Participants were categorized by body mass index (BMI) into the obese group (BMI ³30 kg/m2) or non-obese group (BMI <30 kg/m2).
Survival was compared between the obese and non-obese groups with the Kaplan-Meier method, and log-rank tests were used to assess intergroup differences.
The analysis included 266 patients (mean [SD] age, 65.3 [9.2] years; 50% male), with 205 patients in the obese group, and 61 in the non-obese group. The overall mean NIV adherence was 415.5 [205.2] minutes/day. The median follow-up was 49 months (range, 0-95) and was longer in the obese group (54 months) vs the non-obese group (20 months).
During the follow-up, 120 patients died, of whom 80 were in the obese group (39.0% of entire group) and 40 were in the non-obese group (65.6% of entire group). Patients with obesity had a median survival of 80.0 (95% CI, 71.0-NA) months, and patients without obesity had a median survival of 30.0 (95% CI, 19.0-42.0) months.
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[O]ur study provides unique insights into the real-world outcomes in patients with COPD enrolled in a regional home NIV program. We identify that participants with a higher BMI, including those with BMI ³40 kg/m2, have reduced mortality compared to their counterparts with lower (including normal) BMI.
After the participants were further subcategorized into 4 BMI groups, survival was higher with each increasing level of BMI. Individuals with BMI less than 20 kg/m2 had a median survival of 14.0 (95% CI, 2.0-33.0) months; those with a BMI of 20 to 30 kg/m2 had a median survival of 39.0 (95% CI, 20.0-74.0) months; those with a BMI 30 to 40 kg/m2 had a median survival of 70.0 (95% CI, 53-81) months; and among those with a BMI 40 kg/m2 or greater, median survival was longer than the follow-up, although 37 (32.5%) individuals in this group had died at the time of analysis.
Sensitivity analyses in only patients verified as having partial pressure of carbon dioxide (PCO2) of at least 45 mmHg showed overall lower survival in all groups, with comparable findings regarding the effect of obesity.
Multivariable Cox proportional regression analysis with Least Absolute Selection and Shrinkage Operator (LASSO) regularization identified factors associated with mortality in all participants, including use of home oxygen (hazard ratio [HR], 1.82); fixed vs variable mode of ventilation (HR, 1.55); male sex (HR 1.44); comorbid thoracic cancer (HR, 1.27); and chronic opioid or benzodiazepine use (HR, 1.07).
In participants with obesity, multivariable Cox proportional regression analysis showed that patients who were on home oxygen or had thoracic cancers were more likely to have died during follow-up. For participants without obesity, univariable analysis showed that male sex and nonasthma respiratory comorbidities were associated with increased mortality, and multivariable analysis could not be completed.
Among several limitations, missing data for certain clinical variables reduced the power of the analyses. Spirometric data were unavailable for some patients in the database, polysomnography data were not systematically available, data were missing for exacerbation events, and the sample size of patients without obesity was relatively small.
“[O]ur study provides unique insights into the real-world outcomes in patients with COPD enrolled in a regional home NIV program,” stated the investigators. “We identify that participants with a higher BMI, including those with BMI ³40 kg/m2, have reduced mortality compared to their counterparts with lower (including normal) BMI.”
Disclosure: Some of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
