Effect of bariatric surgery on airway response and lung function in obese subjects with asthma.

Background: Obesity is a risk factor for self-reported asthma and makes asthma management more difficult. The effects of bariatric surgery on asthma in severely obese subjects remain to be documented.

Methods: In this prospective study, 12 asthmatic patients with severe obesity were evaluated before, 6 and 12 months after bariatric surgery. Each had methacholine inhalation tests, measures of expiratory flows and lung volumes, measurements of C-reactive protein and questionnaires on asthma medication, asthma symptoms and co-morbid conditions. Eleven severely obese patients with asthma (considered as controls) underwent the same evaluations. Primary endpoint was airway responsiveness to methacholine and secondary endpoints were lung volumes and markers of systemic inflammation.

Results: Mean body mass index decreased from 51.2 to 34.4 kg/m(2) twelve months post-surgery. Mean PC(20) methacholine improved from 0.84 to 6.2 mg/ml (P < 0.001); FEV(1), FVC, FRC, FRC/TLC and ERV all improved (P ≤ 0.006). C-reactive protein decreased from 8.6 to 1.7 mg/L (P < 0.001) Asthma symptoms total score was significantly reduced (P = 0.03) and asthma medication needs decreased, ten patients being able to stop all asthma drugs. No significant changes of these parameters from baseline were observed in asthmatic controls. Improvements in airway responsiveness and lung volumes happened in parallel and correlated with reductions of body mass index (r = 0.58, P = 0.049), C-reactive protein levels (r = -0.74, P = 0.004).

Conclusion: Airway responsiveness, lung volumes and asthma severity/control markedly improved with weight loss following bariatric surgery in severely obese patients.