Postoperative outcomes in older patients with postoperative delirium in the UK: SNAP-3, a snapshot observational study.

BACKGROUND: Delirium occurs in about 6% of older surgical patients and more frequently in those who are older or frail or undergo urgent surgery. It is associated with adverse postoperative outcomes. However, it remains unclear to what extent delirium is the cause of worse outcomes and to what extent it is a marker of other pre-existing vulnerabilities. METHODS: We conducted a prospective observational cohort study of UK patients aged 60 yr and above undergoing surgery (excluding minor procedures) over 5 days in March 2022. Data were collected on patient characteristics and clinical variables, postoperative delirium, length of stay (LOS) in hospital, morbidity, and mortality. Delirium was assessed on postoperative days 3 and 7 using the four A's Test or Confusion Assessment Method for the Intensive Care Unit tools, supplemented by structured notes review. We analysed the impact of delirium on postoperative outcomes using quantile regression and mixed effects logistic regression, with adjustment for confounding informed by directed acyclic graphs and covariate missing data handled using multiple imputation. RESULTS: Analysis included 7128 patients from 214 hospitals. The incidence of delirium was 6.7% (479/7128). Delirium was associated with longer LOS (increase in median LOS of 5.2 days, effect estimate 95% confidence interval [CI], 3.8-6.5), higher odds of postoperative morbidity (adjusted odds ratio [aOR], 10.2; 95% CI, 7.4-13.9), 120-day mortality (aOR, 1.8; 95% CI, 1.2-2.6), and 1-yr mortality (aOR, 2.0; 95% CI, 1.5-2.7). Sensitivity analysis excluding lower-risk daycase patients found similar results to the main analysis. CONCLUSIONS: Delirium, which is common in older people having surgery, negatively impacts on postoperative outcomes and thus must be included in perioperative shared decision-making with patients considering surgical interventions.