Comparative analysis of respiratory muscle strength before and after bariatric surgery using 5 different predictive equations

Study objective: Obesity has detrimental effects on general health and respiratory function. This study aimed to evaluate respiratory muscle strength in the morbidly obese population, before and after bariatric surgery, and to compare these estimates with the predictive values using different mathematical equations available. Design: Prospective cohort study. Setting: Outpatient clinic for the treatment of obesity. Patients: Patients scheduled for elective bariatric surgery. Intervention: Bariatric surgery. Measurements: The maximal inspiratory pressure (MIP) was measured at screening and 3, 6, and 9 months postoperative. Predictive values were calculated using 5 different mathematical equations. Visual inspection of Bland-Altman plots was performed to determine the agreement between the equations studied. Main results: In total 125 patients were found eligible and 122 patients were available for the final analysis, among them were 104 women and 18 men, with a mean age of 43.02 +/- 11.11 years and mean BMI of 43.10 +/- 5.25 kg/m(2). In the preoperative period, the predicted MIPs according to the Harik-Khan, Neder, Costa, and Wilson equations were significantly different compared with the actual MIP (P .05). Postoperatively, there was a significant difference between the MIP values after 3 and 6 months and the predicted MIP values according to Harik Khan, Neder, and Enright equations. After 9 months, all predicted MIP values were significantly different from the predicted values. Bland-Altman analysis showed that the Enright equation was best suitable for predicting the MEP. Conclusion: Of the 5 mathematical equations studied, that of Enright and colleagues was found best suitable for predicting the MW in the obese population studied.