External validation of scores proposed for estimation of survival probability of patients with severe adult respiratory distress syndrome undergoing extracorporeal membrane oxygenation therapy: a retrospective study

Introduction: This study was designed as an external validation of the recently proposed Predicting Death for Severe ARDS on V-V ECMO (PRESERVE) score, The respiratory extracorporeal membrane oxygenation survival prediction (RESP) score and a scoring system developed for externally retrieved patients on extracorporeal membrane oxygenation (ECMO) at our institution. All scores are proposed for the estimation of survival probability after ECMO treatment for severe adult respiratory distress syndrome. Methods: Data from 51 patients (2008 to 2013) were analyzed in this retrospective single-center study. A calculation of an adapted PRESERVE score, the RESP score as well as the score developed for externally retrieved ECMO patients was performed. Results: Seventy one percent of patients received veno-venous (v-v) and 29% venous-arterial (v-a) ECMO support during the study period. Overall survival at 6 months was 55%, with a 61% survival rate for v-v cannulated patients and a 40% survival rate for v-a cannulated patients. The PRESERVE score discriminated survivors and non-survivors with an area under the curve of 0.67 (95% CI 0.52 to 0.82, P = 0.03). Analyzing survival prediction according to cannulation modus, the PRESERVE score and the RESP score significantly predicted survival for patients on v-v ECMO with an area under the curve of 0.75 (95% CI 0.57 to 0.92, P = 0.01) and 0.81 (95% CI 0.67 to 0.95, P = 0.035), respectively, while the scoring system developed for externally retrieved ECMO patients failed to predict survival in our study population. All scores failed to predict mortality for patients on v-a ECMO. Conclusion: Our single-center validation confirms that the proposed PRESERVE and RESP score predict survival for patients treated with v-v ECMO for severe adult respiratory distress syndrome.