Patient Characteristics Associated With Outcomes After General Anaesthesia in Denmark: A Nationwide Observational Study.

Abstract

Surgery under general anaesthesia is generally safe, although some patients are vulnerable to postoperative complications. Identifying predictors of poor outcomes after general anaesthesia in all settings is relevant for preoperative risk assessment, postoperative monitoring and patient counselling. The aim of this study was to identify patient groups with poor outcomes after general anaesthesia in Denmark. This was a nationwide, registry-based, observational cohort study of patients aged 18 years and above undergoing general anaesthesia in Denmark. Associations between patient characteristics (age, sex, body mass index, ASA classification and 23 comorbidities) and outcomes were analysed. The primary outcome was 30-day mortality. Secondary outcomes included acute kidney injury within 7 and 30 days, hospital length of stay, any ICU stay, length of ICU stay, 90-day mortality, in-hospital cardiac arrest within 30 days, and need for mechanical ventilation within 7 days. A total of 328,951 unique patients undergoing 453,133 cases of general anaesthesia in Denmark during 2020 and 2021 were identified. The adjusted odds of 30-day mortality were higher for cases with higher age, male sex and higher ASA classification. Compared with ASA II, the adjusted odds ratio for 30-day mortality was 0.19 (CI: 0.13-0.29) for ASA I, 7.00 (CI: 5.28-9.29) for ASA III, 40.7 (CI: 29.5-56.0) for ASA IV, and 223 (CI: 161-307) for ASA V. In this nationwide observational cohort study, higher ASA classification, higher age and male sex were independently associated with increased odds of 30-day mortality and several secondary outcomes after general anaesthesia. This study helps identify at-risk patient groups suitable for further studies investigating ways to reduce the risk of complications. From a national cohort, this analysis presents patient factors which have associations with postoperative mortality. This supports a simple classification for patient grouping where focus for complication prevention or mitigation can be applied.