RT Journal Article SR Electronic T1 Transfer factor of the lung for carbon monoxide (TLCO) in morbid obese subjects JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP PA4615 DO 10.1183/13993003.congress-2015.PA4615 VO 46 IS suppl 59 A1 Arismendi, Ebymar A1 Ríos, José A1 Roca, Josep A1 Burgos, Felip A1 Rivas, Eva A1 Rodriguez-Roisin, Roberto YR 2015 UL http://erj.ersjournals.com/content/46/suppl_59/PA4615.abstract AB Rationale and objectives: The impact of severe obesity on transfer factor of the lung for carbon monoxide (TLCO) remains uncertain. We hypothesized that, in addition to the potential intrinsic effects of obesity on lung function, morbidly obese subjects may require specific TLCO reference values. To this end, TLCO was measured in obese subjects before and after bariatric surgery (BS) and adjustment of the data to reported TLCO reference values was assessed.Methods: We explored 220 morbidly obese subjects (BMI ≥40 kg/m2) before BS and 129 of them were studied one year after BS. The Lin's concordance coefficient (LCC) (1) was used to assess adjustment between TLCO measurements and the corresponding predicted values derived from different sets of reference equations.Results: TLCO measurements significantly increased after BS (p<0.001). A poor LCC (between 0.25 to 0.58) was observed for most of the reference equations analyzed. Accordingly, we calculated a set of new reference equations using a cohort of 148 obese non-smokers before BS (123 were females; 43±13 yrs; BMI, 46±6 kg/m2) which markedly increased LCC (0.74, from 0.67-0.79).Conclusions: The results indicate that obesity has a significant negative impact on TLCO. Moreover, current reference equations are not adequate for lung function assessment of these subjects. The new TLCO reference equations herein developed may contribute to enhance evaluation of morbidly obese subjects.References: 1) Lin LI. A note on the concordance correlation coefficient. Biometrics 2000; 56:324-325.