PurposeVery elderly (over 80 yr of age) critically ill patients admitted to medical-surgical intensive care units (ICUs) have a high incidence of mortality, prolonged hospital length of stay, and dependent living conditions should they survive. The primary purpose of this study is to describe the outcomes and differences in outcomes between very elderly medical patients and their surgical counterparts admitted to Canadian ICUs, thereby informing decision-making for clinicians and substitute decision-makers.MethodsThis was a prospective multicentre cohort study of very elderly medical and surgical patients admitted to 22 Canadian academic and non-academic ICUs. Outcome measures included ICU length of stay and mortality, hospital length of stay and mortality, and disposition following hospital discharge.ResultsThere were 1,671 patients evaluated in this study. Patient demographics included a mean age of 84.5 yr, baseline Acute Physiology and Chronic Health Evaluation (APACHE) II score of 22.4, baseline Sequential Organ Failure Assessment (SOFA) score of 5.3, overall ICU mortality of 21.8%, and overall hospital mortality of 35.0%. Medical patient median ICU length of stay was 4.1 days, hospital length of stay was 16.2 days, ICU mortality was 26.5%, and hospital mortality was 41.5%. Surgical patient median ICU length of stay was 3.8 days, hospital length of stay was 20.1 days, ICU mortality was 18.7%, and hospital mortality was 31.6%. Only 45.0% of medical patients and 41.6% of surgical emergency patients were able to return home to live.ConclusionsIn this large sample of critically ill medical and surgical patients, the admission SOFA score and hospital lengths of stay were not different between the two groups, but medical patients had longer ICU lengths of stay and higher ICU and hospital mortality than surgical patients.