Importance  Extracorporeal membrane oxygenation (ECMO) is used as temporary cardiorespiratory support in critically ill patients, but little is known regarding long-term psychiatric sequelae among survivors after ECMO.

Objective  To investigate the association between ECMO survivorship and postdischarge mental health diagnoses among adult survivors of critical illness.

Design, Setting, and Participants  Population-based retrospective cohort study in Ontario, Canada, from April 1, 2010, through March 31, 2020. Adult patients (N=4462; age ≥18 years) admitted to the intensive care unit (ICU), and surviving to hospital discharge were included.

Exposures  Receipt of ECMO.

Main Outcomes and Measures  The primary outcome was a new mental health diagnosis (a composite of mood disorders, anxiety disorders, posttraumatic stress disorder; schizophrenia, other psychotic disorders; other mental health disorders; and social problems) following discharge. There were 8 secondary outcomes including incidence of substance misuse, deliberate self-harm, death by suicide, and individual components of the composite primary outcome. Patients were compared with ICU survivors not receiving ECMO using overlap propensity score–weighted cause-specific proportional hazard models.

Results  Among 642 survivors who received ECMO (mean age, 50.7 years; 40.7% female), median length of follow-up was 730 days; among 3820 matched ICU survivors who did not receive ECMO (mean age, 51.0 years; 40.0% female), median length of follow-up was 1390 days. Incidence of new mental health conditions among survivors who received ECMO was 22.1 per 100-person years (95% confidence interval [CI] 19.5-25.1), and 14.5 per 100-person years (95% CI, 13.8-15.2) among non-ECMO ICU survivors (absolute rate difference of 7.6 per 100-person years [95% CI, 4.7-10.5]). Following propensity weighting, ECMO survivorship was significantly associated with an increased risk of new mental health diagnosis (hazard ratio [HR] 1.24 [95% CI, 1.01-1.52]). There were no significant differences between survivors who received ECMO vs ICU survivors who did not receive ECMO in substance misuse (1.6 [95% CI, 1.1 to 2.4] per 100 person-years vs 1.4 [95% CI, 1.2 to 1.6] per 100 person-years; absolute rate difference, 0.2 per 100 person-years [95% CI, −0.4 to 0.8]; HR, 0.86 [95% CI, 0.48 to 1.53]) or deliberate self-harm (0.4 [95% CI, 0.2 to 0.9] per 100 person-years vs 0.3 [95% CI, 0.2 to 0.3] per 100 person-years; absolute rate difference, 0.1 per 100 person-years [95% CI, −0.2 to 0.4]; HR, 0.68 [95% CI, 0.21 to 2.23]). There were fewer than 5 total cases of death by suicide in the entire cohort.

Conclusions and Relevance  Among adult survivors of critical illness, receipt of ECMO, compared with ICU hospitalization without ECMO, was significantly associated with a modestly increased risk of new mental health diagnosis or social problem diagnosis after discharge. Further research is necessary to elucidate the potential mechanisms underlying this relationship.