2643605 ELTS EUTOS long-term survival 19 2643603 ELTS European treatment and outcome study long term survival 3 2643604 ELTS early life thermal stress 2 2643608 ELTS Early-life tobacco smoke 1 2643607 ELTS EUTOS long-term survival scores 1 2643606 ELTS EUTOS score for long-term survival 1