Objective: To determine the lung age of patients with morbid obesity and to compare it with the chronological age of these patients, emphasizing the premature damage that morbid obesity does to the lungs. Methods: An open, prospective cross-sectional study comprising 112 individuals: 78 patients with morbid obesity (study group); and 34 non-obese individuals with normal pulmonary function results (control group). All of the patients underwent spirometry for the determination of lung age. The lung age and the chronological age of the individuals in each group were compared in isolation and between the two groups. Results: The difference between lung age and chronological age in the group with morbid obesity was significant (p < 0.0001; 95% CI: 6.6-11.9 years), the mean difference being 9.1 ± 11.8 years. The difference between the study group and the control group in terms of lung age was significant (p < 0.0002; 95% CI: 7.5-16.9 years), the mean difference being 12.2 ± 2.4 years. Lung age correlated positively with chronological age and body mass index (BMI), whereas it correlated negatively with the spirometric variables (p < 0.0001 for all). Multiple linear regression analysis identified BMI and chronological age (p < 0.0001) as significant predictors of lung age. Conclusions: Lung age is increased in patients with morbid obesity, suggesting premature damage and accelerated lung aging, as evidenced by the discrepancy between chronological age and lung age. The determination of lung age might become a new tool for understanding pulmonary function results, for patients as well as for health professionals, in relation to obesity control.

Keywords: Spirometry; Obesity, morbid; Respiratory function tests.