Table 2. Hazard ratio for the risk factors included in the ANN model. Confounding variables ranked in order of importance for the ANN model.

	Mandatory risk variable	HR mean (95% CI)
	Donor age	1.107 (1.107–1.107)
	Recipient age	1.126 (1.125–1.126)
	Donor blood group 0	0.979 (0.979–0.980)
	Donor blood group B	1.055 (1.055–1.056)
	Donor blood group AB	1.024 (1.023–1.025)
	Recipient blood group A	1.008 (1.008–1.009)
	Recipient blood group B	1.027 (1.027–1.028)
	Recipient blood group 0	1.084 (1.083–1.084)
	Donor female gender	1.034 (1.034–1.035)
	Recipient female gender	1.025 (1.024–1.025)
	Recipient-donor height match	0.998 (0.998–0.999)
	Recipient-donor weight match	1.013 (1.013–1.013)

ANN, artificial neural network; COPD, chronic obstructive pulmonary disease; ECMO, extracorporeal membrane oxygenation; HLA, Human Leukocyte Antigen; HR, hazard ratio; ICU, intensive care unit; PVR, pulmonary vascular resistance.