Epidemiology and volume-outcome relationship of extracorporeal membrane oxygenation for respiratory failure in Japan: A retrospective observational study using a national administrative database

Aim: To describe the epidemiology of patients on extracorporeal membrane oxygenation (ECMO) and investigate the possible association between outcomes for respiratory ECMO patients and hospital volume of ECMO treatment for any indications.

Methods: Using data from the Diagnosis Procedure Combination database, a nationwide Japanese inpatient database, between 1 July 2010 and 31 March 2018, we identified inpatients aged ≥18 years who underwent ECMO. Institutional case volume was defined as the mean annual number of ECMO cases; eligible patients were categorized into institutional case volume tertile groups. The primary outcome was in-hospital mortality. For ECMO patients with respiratory failure, the association between institutional case volume group and in-hospital mortality rate was analyzed using a multilevel logistic regression model including multiple imputation.

Results: Extracorporeal membrane oxygenation was carried out on 25,384 patients during the study period; of those, 1,227 cases were for respiratory failure. Respiratory cases were categorized into low- (<8 cases/year), medium- (8-16 cases/year), and high-volume groups (≥17 cases/year). The overall in-hospital mortality rate for respiratory ECMO was 62.5% in low-, 54.7% in medium-, and 50.4% in high-volume institutions. With reference to low-volume institutions, the adjusted odds ratios (95% confidence interval) of the medium- and high-volume institutions for in-hospital mortality were 0.72 (0.50-1.04; P = 0.082) and 0.65 (0.45-0.95; P = 0.024), respectively.

Conclusions: The present study showed that accumulating the experience of using ECMO for any indications could positively affect the outcome of ECMO treatment for respiratory failure, which suggests the effectiveness of consolidating ECMO cases in high-volume centers in Japan.