Characteristics and Outcomes After General Anaesthesia in Elderly Patients: A Nationwide Cohort Study

BACKGROUND: Elderly patients are more frail and have a higher burden of comorbidity, which could influence the risk of complications after anaesthesia. The aim of this study was to describe the elderly patient population undergoing general anaesthesia in Denmark. METHODS: This was a national registry-based observational cohort study of adult patients (≥ 18 years) undergoing general anaesthesia in Denmark in 2020 and 2021, with a primary focus on patients 80 years and above. Patient and procedure characteristics of interest were age, sex, BMI, ASA classification, Elixhauser Comorbidity Index, comorbidities, type of procedure, and class of priority. The primary outcome of interest was 30-day mortality. Secondary outcomes included acute kidney injury within 7 days, length of hospital stay, and number of days in the ICU. RESULTS: A total of 453,133 cases of general anaesthesia in 328,951 unique patients in Denmark during 2020 and 2021 were included in this study. Of these, 25,955 (8%) patients were 80 years of age and above. Elderly patients undergoing general anaesthesia were of higher ASA classification, suffered from a higher degree of comorbidity measured by Elixhauser Comorbidity Index, had a lower proportion of elective procedures and a higher proportion of expedited and urgent procedures. Mortality for all patients at 30 days was 1.5% (n = 4814). While mortality was low for cases aged between 18 and 65 years, 30-day mortality increased for each year after 65 years of age even after adjusting for covariates. Mortality was especially high for patients with high Elixhauser Comorbidity Index, high ASA classification, and for non-elective procedures. CONCLUSION: In this nationwide registry-based cohort study, we described the elderly patient population undergoing general anaesthesia in Denmark. We found that 30-day mortality increased for each year after 65 years of age even after adjusting for covariates. EDITORIAL COMMENT: This large cohort study from Denmark assesses perioperative case factors including age, comorbidity and more, then describing different risk levels for 30 day mortality, particularly with advanced age.