Developing a simple preinterventional score to predict hospital mortality in adult venovenous extracorporeal membrane oxygenation: A pilot study

Despite gaining popularity, venovenous extracorporeal membrane oxygenation (VV-ECMO) remains a controversial therapy for acute respiratory failure (ARF) in adult patients due to its equivocal survival benefits. The study was aimed at identifying the preinterventional prognostic predictors of hospital mortality in adult VV-ECMO patients and developing a practical mortality prediction score to facilitate clinical decision-making. This retrospective study included 116 adult patients who received VV-ECMO for severe ARF in a tertiary referral center, from 2007 to 2015. The definition of severe ARF was P(a)O(2)/ FiO(2) ratio < 70 mm Hg under advanced mechanical ventilation (MV). Preinterventional variables including demographic characteristics, ventilatory parameters, and severity of organ dysfunction were collected for analysis. The prognostic predictors of hospital mortality were generated with multivariate logistic regression and transformed into a scoring system. The discriminative power on hospital mortality of the scoring system was presented as the area under receiver operating characteristic curve (AUROC). The overall hospital mortality rate was 47% (n = 54). Pre-ECMO MV day > 4 (OR: 4.71; 95% CI: 1.98–11.23; P < 0.001), pre-ECMO sequential organ failure assessment (SOFA) score >9 (OR: 3.16; 95% CI: 1.36–7.36; P = 0.01), and immunocompromised status (OR: 2.91; 95% CI: 1.07–7.89; P = 0.04) were independent predictors of hospital mortality of adult VV-ECMO. A mortality prediction score comprising of the 3 binary predictors was developed and named VV-ECMO mortality score. The total score was estimated as follows: VV-ECMO mortality score = 2 × (Pre-ECMO MV day > 4) + 1 × (Pre-ECMO SOFA score >9) + 1 × (immunocompromised status). The AUROC of VV-ECMO mortality score was 0.76 (95% CI: 0.67–0.85; P < 0.001). The corresponding hospital mortality rates to VV-ECMO mortality scores were 18% (Score 0), 35% (Score 1), 56% (Score 2), 75% (Score 3), and 88% (Score 4), respectively. Duration of MV, severity of organ dysfunction, and immunocompromised status were important preinterventional prognostic predictors for adult VV-ECMO. The 3 prognostic predictors could also constitute a practical prognosticating tool in patients requiring this advanced respiratory support. Physicians in ECMO institutions are encouraged to perform external validations of this prognosticating tool and make contributions to score optimization.