High ASA Physical Status and Low Serum Uric Acid to Creatinine Ratio are Independent Risk Factors for Postoperative Delirium Among Older Adults Undergoing Urinary Calculi Surgery

PURPOSE: This study was to investigate the incidence and potential predictive factors for postoperative delirium (POD) in older people following urinary calculi surgery, and to establish the corresponding risk stratification score by the significant factors to predict the risk of POD. PATIENTS AND METHODS: We retrospectively analyzed the perioperative data of 195 patients aged 65 or older who underwent elective urinary calculi surgery between September 2020 and September 2022. POD was defined by chart-based method, and the serum uric acid to creatinine (SUA/Cr) ratio as well as neutrophil-to-lymphocyte ratio (NLR) were calculated, respectively. Identification of the risk factors for POD was performed by univariate and multivariate logistic regression analysis. Moreover, the risk stratification score was developed based on the regression coefficients of the associated variables. RESULTS: In 195 eligible patients following urinary calculi surgery, the median age was 69 (66–72) and 19 patients ultimately developed POD (9.7%). The results by univariate analysis showed that patients with advanced age, high American Society of Anesthesiologists (ASA) physical status (≥3) and low SUA/Cr ratio (≤3.3) were more likely to develop POD, but dexmedetomidine can significantly decrease the risk of the occurrence of POD. The multivariate analysis further indicated that high ASA physical status (≥3) and low SUA/Cr ratio (≤3.3) were independently associated with POD, and the POD incidence could obviously be elevated with the increase of risk stratification score. Moreover, patients with delirium had longer hospital stays. CONCLUSION: POD is frequent in geriatric patients following urinary calculi surgery (9.7%). The high ASA physical status (≥3) and low SUA/Cr ratio (≤3.3) were effective predictors of POD. The corresponding risk stratification based on these factors could be beneficial to determining patients who are susceptible to POD, and thus better preventing and reducing the occurrence of POD. However, large prospective studies are needed to confirm this finding.