MADRID – Morbidly obese asthmatics may require less inhaler therapy after bariatric surgery, a retrospective chart review and longitudinal cohort study suggests.
Among patients who used any form of inhaler therapy prior to surgery, one or more classes of inhalers were discontinued in 30% (P less than .05), Dr. Randall Schwartz reported at the world congress of the American College of Chest Physicians.
Patrice Wendling/Frontline Medical News
Dr. Randall Schwartz
Specifically, short-acting beta agonist (SABA) use decreased significantly by 13.1% from baseline (64.5% to 51.4%; P less than .0001) and long-acting beta agonist/inhaled corticosteroid (LABA/ICS) combinations by 8.1% (40.2% to 32.1%; P = .0034). Fewer patients were on short- or long-acting muscarinic antagonists (SAMA/LAMA), which declined 1.6% (9.4% to 7.8%; P = .305).
The corresponding number need to treat was 8 patients for SABA, 12 for LABA/ICS combinations, and 7 for SAMA/LAMA.
Prior studies have shown a decrease in asthma severity after gastric surgery but haven’t specifically looked at inhaler usage.
Though there was a 30% reduction among those using inhalers, 10% of patients actually required more inhaler therapy after surgery, said Dr. Schwartz, chief internal medicine resident, Cleveland Clinic Florida, Weston.
"Our supposition is that the overwhelming majority of these patients have obesity-related asthma – neutrophilic mediated inflammation; whereas some of those who ended up having to go up in their inhaler therapy might have had classic atopic eosinophilic-mediated asthma," he explained in an interview.
Unfortunately, only 203 of the 505 patients had formal pulmonary function tests (PFT) and only 9 had fractional exhaled nitric oxide measured. "I think nitric oxide would be a really non-invasive and simple thing we could do to follow-up with these patients because PFTs represent a bit of a challenge in this population because of body mechanics," Dr. Schwartz said. "I would bet we’re going to see a disproportionate amount of elevated phenotypes in those who actually had to increase their inhaler usage and probably not significant eosinophilic inflammation in the majority of patients, particularly those who decreased their inhaler usage."
Of those who started a LABA/ICS for the first time after surgery, 72% had already been on a SAMA/LAMA prior to surgery.
Of those starting a SAMA/LAMA for the first time after surgery, 100% were on a SABA or LABA/ICS prior to surgery.
Overall, there was a 20% reduction in postoperative inhaler use, with a number needed to treat of only seven patients, according to the poster presentation (Chest 2014;145:15A [doi:10.1378/chest.1824454]).
Because of the retrospective nature of the study, it was not possible to determine whether type of gastric surgery or amount of weight loss influenced postoperative inhaler use, he said. Other possible factors could be improved body mechanics and decreased inflammation from less adipose tissue.
The mean change in body mass index was –16.2 kg/m2, which occurred at an average of 19 months after surgery.
The review included 716 patients who underwent gastric bypass surgery or sleeve gastrectomy with an accompanying diagnosis of asthma. A total of 211 patients were excluded because of concomitant or suspected chronic obstructive pulmonary disease.
At baseline, the average BMI was 50.7 kg/m2, average forced expiratory volume in 1 second was 79%, and average FEV1/forced vital capacity was 91%.
Going forward, the investigators reported that they hope to perform follow-up testing in the existing cohort and prospectively study post–gastric bypass inhaler use, including asthma severity, fractional exhaled nitric oxide testing, and a cost-benefit analysis.
"Gastric surgery costs about $20,000 and it can cost $3,000-$6,000 a year depending on whether patients are using one or two inhalers to control their asthma," Dr. Schwartz said. "So over the course of a few years, you make up that difference with asthma alone, not to mention the cardiovascular benefits."
The investigators reported having nothing to disclose.