Prevalence of Delirium After Abdominal Surgery and Association With Ketamine: A Retrospective, Propensity-Matched Cohort Study

Hina Faisal; Fatima Qamar; En Shuo Hsu; Jiaqiong Xu; Eugene C Lai; Stephen T Wong; Faisal N Masud

doi:10.1097/CCE.0000000000001032

Prevalence of Delirium After Abdominal Surgery and Association With Ketamine: A Retrospective, Propensity-Matched Cohort Study

Crit Care Explor. 2024 Jan 11;6(1):e1032. doi: 10.1097/CCE.0000000000001032. eCollection 2024 Jan.

Authors

Hina Faisal^{1

2}, Fatima Qamar³, En Shuo Hsu⁴, Jiaqiong Xu⁴, Eugene C Lai⁵, Stephen T Wong⁶, Faisal N Masud^{7

8}

Affiliations

¹ Department of Surgery, Houston Methodist, Houston, TX.
² Department of Surgery, Weill Cornell Medicine, New York, NY.
³ Department of Cardiothoracic Surgery, Houston Methodist, Houston, TX.
⁴ Center for Health Data Science and Analytics, Houston Methodist, Houston, TX.
⁵ Stanley H. Appel Department of Neurology, Houston Methodist, Houston, TX.
⁶ Department of Systems Medicine and Bioengineering and Houston Methodist Neal Cancer Center, Houston Methodist, Houston, TX.
⁷ Center for Critical Care, Houston Methodist, Houston, TX, USA.
⁸ Department of Anesthesiology, Weill Cornell Medical College, New York, NY.

Abstract

Importance: Delirium is a common postoperative complication for older patients in the ICU. Ketamine, used primarily as an analgesic, has been thought to prevent delirium.

Objective: Determine the prevalence and association of delirium with low-dose ketamine use in ICU patients after abdominal surgery.

Design: Single-center, retrospective, propensity-matched cohort study.

Setting: Eight hospital academic medical center.

Patients: Cohort comprising 1836 patients admitted to the ICU after abdominal surgery between June 23, 2018 and September 1, 2022.

Main outcomes and measures: Propensity score matching (PSM) with a 3:1 ratio between no-ketamine use and ketamine use was performed through a greedy algorithm (caliper of 0.005). Outcomes of interest included: delirium (assessed by Confusion Assessment Method-ICU), mean pain score (Numeric Pain Scale or Critical Care Pain Observation Tool score as available), mean opioid consumption (morphine milligram equivalents), length of stay (d), and mortality.

Results: Prevalence of delirium was 47.71% (95% CI, 45.41-50.03%) in the cohort. Of 1836 patients, 120 (6.54%) used low-dose ketamine infusion. After PSM, the prevalence of delirium was 56.02% (95% CI, 51.05-60.91%) in all abdominal surgery patients. The ketamine group had 41% less odds of delirium (odds ratio [OR] = 0.59; 95% CI, 0.37-0.94; p = 0.026) than patients with no-ketamine use. Patients with ketamine use had higher mean pain scores (3.57 ± 2.86 vs. 2.21 ± 2.09, p < 0.001). In the subgroup analysis, patients in the ketamine-use group 60 years old or younger had 64% less odds of delirium (OR = 0.36; 95% CI, 0.13-0.95; p = 0.039). The mean pain scores were higher in the ketamine group for patients 60 years old or older. There was no significant difference in mortality and opioid consumption.

Conclusions and relevance: Low-dose ketamine infusion was associated with lower prevalence of delirium in ICU patients following abdominal surgery. Prospective studies should further evaluate ketamine use and delirium.

Keywords: critical care; delirium; healthcare delivery; ketamine; outcomes assessment; surgical procedures.