A comprehensive analysis of in-hospital adverse events after scopolamine administration: insights from a retrospective cohort study using a large nationwide inpatient database

BACKGROUND: Scopolamine is a widely used antiemetic in anesthetic practice, particularly for postoperative and post-discharge nausea and vomiting. Despite its frequent usage and recognized efficacy, concerns have emerged regarding the potential for increased side effects, particularly in elderly patients. Further research is needed to assess safety and determine age thresholds for adverse events. This study hypothesizes associations between perioperative scopolamine use, worse clinical outcomes, increased pneumonia, delirium, urinary retention, and readmissions. METHODS: A large, retrospective cohort study was performed using the TriNetX Analytics Network database on patients undergoing major surgical procedures between Jan 1, 2009, and March 21, 2018, to examine the impact of perioperative scopolamine use on in-hospital adverse events. Patients were divided into age groups and compared to a control group. The primary outcomes assessed were delirium, pneumonia, in-hospital death, new antipsychotic use, readmission, and new onset urinary retention within 7 days post-surgery. 1:1 propensity score matching was performed to reduce bias. Relative risk and risk differences with 95% confidence intervals were estimated. RESULTS: After 1:1 propensity score matching, we identified a total of 403,816 (201,908 pairs) perioperative scopolamine users and nonusers. The cohorts of 20-29, 30-39, 40-49, 50-59, 60-69, and 70 + contained 22,910 (11,455 pairs), 44,170 (22,085 pairs), 58,590 (29,295 pairs), 71,660 (35,830 pairs), 88,386 (44,193 pairs), and 118,100 (59,050 pairs) patients respectively. Across older age cohorts, after propensity score matching, perioperative scopolamine recipients had significantly increased relative risk and risk difference of delirium, pneumonia, in-hospital mortality, new antipsychotic use, readmission, and new-onset urinary retention. CONCLUSIONS: In this cohort study, perioperative scopolamine usage was associated with a significantly increased risk of in-hospital adverse events, both within the 70 + age cohort and among the 20-29, 30-39, 40-49, 50-59, and 60-69 age cohorts after major surgery. These findings highlight the need for careful assessment of scopolamine's risks and benefits, especially for patients aged 40 and older. Scopolamine may be most suited for post-discharge nausea and vomiting in ambulatory patients and clinicians should reassess its standard use for postoperative nausea and vomiting, favoring shorter-acting agents with fewer side effects.