An Alternative Method for Predicting the Risk of Postoperative Complications in Lung Resection

ObjectivesThe aims of this study were to design a best fit linear regression model to estimate VO2max (estimated VO2) and to compare the ability of VO2 values (measured and estimated) predicting cardiorespiratory complications in a series of patients undergoing lung resection for lung cancer.MethodThis was a prospective, observational study performed in 83 patients. Variables analyzed were: demographic characteristics, comorbidity, body mass index (BMI), FEV1%, FVC%, diffusion capacity (DLCO%), mean daily distance walked in kilometers, VO2max measured by cardio-pulmonary exercise test (CPET) and postoperative complications. Descriptive and comparative statistical analysis of the variables was performed using the Mann–Whitney test for categorical variables and the Student's t-test for continuous variables. A new linear regression model was designed, where the dependent variable (measured VO2max) was estimated by the distance, DLCO% and age, resulting in the estimated VO2. The predictive power of the measured and estimated consumption was analyzed using the Student's t-test, grouping by the occurrence or absence of cardiorespiratory complications.ResultsBoth groups were homogeneous for age, sex, BMI, FEV1%, DLCO%, comorbidity, type of resection performed and mean distance walked per day. Estimated VO2 and measured VO2 were normally distributed (K–Smirnov test, P>.32). VO2 means estimated by the model (age, DLCO% and mean distance walked per day) were significantly different between patients with and without complications (Student's t-test, P=.037) compared with measured VO2 values, which did not differentiate groups (Student's t-test, P=.42).ConclusionThe VO2max estimated by the model is more predictive in this case series than the VO2max measured during a standard exercise test.

ResumenObjetivosLos objetivos de este trabajo son rediseñar un modelo de regresión lineal para estimar el valor de VO2max (VO2 estimado) ya publicado y comparar la capacidad predictiva de los valores VO2 medido y VO2 estimado en la aparición de complicaciones cardiorrespiratorias en una serie de pacientes sometidos a resección pulmonar por cáncer de pulmón.MétodoEstudio prospectivo y observacional en 83 pacientes. Variables analizadas: demográficas, comorbilidad, IMC, FEV1%, FVC%, DLCO%, distancia recorrida media diaria (km), VO2max medido en el test de ejercicio cardiopulmonar (CPET) y complicación postoperatoria. Estadística descriptiva y comparativa de variables usando Mann-Whitney test para categóricas y t de Student para continuas normales. Se diseña un modelo de regresión lineal donde VO2max, la variable dependiente, se estima desde la distancia recorrida, DLCO% y edad del paciente y su resultado es la VO2 estimada. Se compara la capacidad predictiva de los VO2max medido y estimado mediante t de Student, agrupando por ocurrencia o no de complicaciones cardiorrespiratorias.ResultadosLos 2 grupos son homogéneos en edad, distribución de sexos, IMC, FEV1%, DLCO%, comorbilidad, cirugía realizada y distancia media recorrida/día. VO2 medida y VO2 estimada tienen distribución normal (K-Smirnov p > 0,32). En la predicción de complicaciones, las medias del VO2 estimado a partir del modelo son significativamente diferentes entre los pacientes con/sin complicación (t de Student p = 0,037); frente a los valores de VO2 medido que no distinguen grupos (t de Student p = 0,42).ConclusionesEl VO2max estimado por el modelo es más predictivo en esta serie de casos que el VO2max medido en una CPET.