A Mediation Analysis Examining High Risk, Anticholinergic Medication Use, Delirium, and Dementia After Major Surgery.

INTRODUCTION: Anticholinergic medications are known to cause adverse cognitive effects in community-dwelling older adults and medical inpatients, including dementia. The prevalence with which such medications are prescribed in older adults undergoing major surgery is not well described nor is their mediating relationship with delirium and dementia. We sought to determine the prevalence of high-risk medication use in major surgery patients and their relationship with the subsequent development of dementia. METHODS: This was a retrospective cohort study which used data between January 2013 and December 2019, in a large midwestern health system, including sixteen hospitals. All patients over age 50 undergoing surgery requiring an inpatient stay were included. The primary exposure was the number of doses of anticholinergic medications delivered during the hospital stay. The primary outcome was a new diagnosis of Alzheimer's disease and related dementias at 1-y postsurgery. Regression methods and a mediation analysis were used to explore relationships between anticholinergic medication usage, delirium, and dementia. RESULTS: There were 39,665 patients included, with a median age of 66. Most patients were exposed to anticholinergic medications (35,957/39,665; 91%), and 7588/39,665 (19.1%) patients received six or more doses during their hospital stay. Patients with at least six doses of these medications were more likely to be female, black, and with a lower American Society of Anesthesiologists class. Upon adjusted analysis, high doses of anticholinergic medications were associated with increased odds of dementia at 1 y relative to those with no exposure (odds ratio 2.7; 95% confidence interval 2.2-3.3). On mediation analysis, postoperative delirium mediated the effect of anticholinergic medications on dementia, explaining an estimated 57.6% of their association. CONCLUSIONS: High doses of anticholinergic medications are common in major surgery patients and, in part via a mediating relationship with postoperative delirium, are associated with the development of dementia 1 y following surgery. Strategies to decrease the use of these medications and encourage the use of alternatives may improve long-term cognitive recovery.

Rivastigmine for the management of anticholinergic delirium.

INTRODUCTION: Anticholinergic agents are commonly taken in overdose, often causing delirium. The spectrum of anticholinergic delirium ranges from mild agitation to severe behavioural disturbance. Physostigmine is an effective treatment for anticholinergic delirium, but its availability is limited. As rivastigmine is readily available, it has been used to manage anticholinergic delirium; however, there is limited research investigating its use. METHOD: This was a retrospective review of patients with anticholinergic delirium treated in two toxicology units with rivastigmine (oral capsule or transdermal patch) from January 2019 to June 2023. The primary outcome was the use of further parenteral treatment (sedation or physostigmine) for delirium post rivastigmine administration. RESULTS: Fifty patients were administered rivastigmine for the management of anticholinergic delirium. The median age was 36 years (interquartile range: 25-49 years) and 27 (54 per cent) were females. Features consistent with anticholinergic toxicity included tachycardia in 44 (88 per cent) and urinary retention requiring catheterisation in 40 (80 per cent). Forty-three patients (86 per cent) were treated with physostigmine before rivastigmine administration. Twenty-two were managed with transdermal rivastigmine (most commonly 9.5 mg/24 hour patch), and 28 with oral rivastigmine 6 mg. Further parenteral sedation and/or physostigmine treatment were required more often in patients given transdermal than oral rivastigmine [16/22 (73 per cent) versus 9/28 (32 per cent), P = 0.010)]. No patients had bradycardia or gastrointestinal symptoms following rivastigmine administration. One patient with a history of epilepsy had a seizure, 1.5 hours post physostigmine administration and 7 hours post transdermal rivastigmine. DISCUSSION: Rivastigmine has been increasingly used for the management of patients with anticholinergic delirium, due to the lack of availability of physostigmine. In this case series, rivastigmine transdermal patch appeared to be less effective than oral rivastigmine capsules, likely due to its slow onset of action and/or insufficient dose. CONCLUSION: Rivastigmine can be used to treat anticholinergic delirium. In our case series oral rivastigmine appeared more effective than transdermal rivastigmine.

The risk of delirium after sedation with propofol or midazolam in intensive care unit patients.

AIM: Knowledge of risk factors may provide strategies to reduce the high burden of delirium in intensive care unit (ICU) patients. We aimed to compare the risk of delirium after deep sedation with propofol versus midazolam in ICU patients. METHODS: In this prospective cohort study, ICU patients who were in an unarousable state for ≥24 h due to continuous sedation with propofol and/or midazolam were included. Patients admitted ≤24 h, those with an acute neurological disorder and those receiving palliative sedation were excluded. ICU patients were assessed daily for delirium during the 7 days following an unarousable state due to continuous sedation. RESULTS: Among 950 included patients, 605 (64%) subjects were delirious during the 7 days after awaking. The proportion of subsequent delirium was higher after midazolam sedation (152/207 [73%] patients) and after both propofol and midazolam sedation (257/377 [68%] patients), compared to propofol sedation only (196/366 [54%] patients). Midazolam sedation (adjusted cause-specific hazard ratio [adj. cause-specific HR] 1.32, 95% confidence interval [CI] 1.05-1.66) and propofol and midazolam sedation (adj. cause-specific HR 1.29, 95% CI 1.06-1.56) were associated with a higher risk of subsequent delirium compared to propofol sedation only. CONCLUSION: This study among sedated ICU patients suggests that, compared to propofol sedation, midazolam sedation is associated with a higher risk of subsequent delirium. This risk seems more apparent in patients with high cumulative midazolam intravenous doses. Our findings underpin the recommendations of the Society of Critical Care Medicine Pain, Agitation/sedation, Delirium, Immobility (rehabilitation/mobilization), and Sleep (disruption) guidelines to use propofol over benzodiazepines for sedation in ICU patients.

Effectiveness of antipsychotics for managing agitated delirium in patients with advanced cancer: a secondary analysis of a multicenter prospective observational study in Japan (Phase-R).

PURPOSE: Delirium is a common and serious comorbidity in patients with advanced cancer, necessitating effective management. Nonetheless, effective drugs for managing agitated delirium in patients with advanced cancer remain unclear in real-world settings. Thus, the present study aimed to explore an effective pharmacotherapy for this condition. METHODS: We conducted a secondary analysis of a multicenter prospective observational study in Japan. The analysis included patients with advanced cancer who presented with agitated delirium and received pharmacotherapy. Agitation was defined as a score of the Richmond Agitation-Sedation Scale for palliative care (RASS-PAL) of ≥ 1. The outcome was defined as -2 ≤ RASS-PAL ≤ 0 at 72 h after the initiation of pharmacotherapy. Multiple propensity scores were quantified using a multinomial logistic regression model, and adjusted odds ratios (ORs) were calculated for haloperidol, chlorpromazine, olanzapine, quetiapine, and risperidone. RESULTS: The analysis included 271 patients with agitated delirium, and 87 (32%) showed -2 ≤ RASS-PAL ≤ 0 on day 3. The propensity score-adjusted OR of olanzapine was statistically significant (OR, 2.91; 95% confidence interval, 1.12 to 7.80; P = 0.030). CONCLUSIONS: The findings suggest that olanzapine may effectively improve delirium agitation in patients with advanced cancer.

Ertapenem-induced encephalopathy in a patient with liver abscess and acute kidney injury.

A man in his late 70s, retired and independent, generally fit and well with a history of normal cognitive function baseline presented with liver abscess and acute kidney injury. He received meropenem 1 g three times a day for 15 days then subsequently changed to ertapenem 1 g one time a day in preparation for outpatient antibiotic treatment. After 2 days of starting ertapenem, the patient developed night-time delirium, decreased orientation and insomnia, loss of appetite, jerking and hallucination. Investigations have been done to investigate the cause of acute delirium, including lumbar puncture, CT brain, MRI brain, repeat CT abdomen and pelvis to monitor the liver abscess, and electroencephalogram but results were all unremarkable. Medication history during admission was reviewed and discontinued one by one the medications that were suspected to have caused the encephalopathy. Two days following the discontinuation of ertapenem, the patient's symptoms improved with a rapid return to his baseline and without neurological deficit.

Antipsychotics and the QTc Interval During Delirium in the Intensive Care Unit: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Antipsychotic medications, often prescribed for delirium in intensive care units (ICUs), may contribute to QTc interval prolongation. Objective: To determine whether antipsychotics increase the QTc interval in patients with delirium in the ICU. Design, Setting, and Participants: An a priori analysis of a randomized clinical trial in medical/surgical ICUs within 16 centers across the US was conducted. Participants included adults with delirium in the ICU with baseline QTc interval less than 550 ms. The study was conducted from December 2011 to August 2017. Data analysis was performed from April 25 to August 18, 2021. Interventions: Patients were randomized 1:1:1 to intravenous haloperidol, ziprasidone, or saline placebo administered twice daily until resolution of delirium, ICU discharge, or 14 days. Main Outcomes and Measures: Twelve-lead electrocardiograms were used to measure baseline QTc before study drug initiation and telemetry was used to measure QTc before each subsequent dose of study drug. Unadjusted day-to-day changes in QTc were calculated and multivariable proportional odds regression was used to estimate the effects of antipsychotics vs placebo on next-day maximum QTc interval, adjusting for prespecified baseline covariates and potential interactions with sex. Safety end points, including the occurrence of torsade de pointes, were evaluated. All analyses were conducted based on the intention to treat principle. Results: A total of 566 patients were randomized to haloperidol (n = 192), ziprasidone (n = 190), or placebo (n = 184). Median age was 60.1 (IQR, 51.4-68.7) years; 323 were men (57%). Baseline median QTc intervals across the groups were similar: haloperidol, 458.0 (IQR, 432.0-479.0) ms; ziprasidone, 451.0 (IQR, 424.0-472.0) ms; and placebo, 452.0 (IQR, 432.0-472.0) ms. From day 1 to day 2, median QTc changed minimally: haloperidol, -1.0 (IQR, -28.0 to 15.0) ms; ziprasidone, 0 (IQR, -23.0 to 20.0) ms; and placebo, -3.5 (IQR, -24.8 to 17.0) ms. Compared with placebo, neither haloperidol (odds ratio [OR], 0.95; 95% CI, 0.66-1.37; P = .78) nor ziprasidone (OR, 1.09; 95% CI, 0.75-1.57; P = .78) was associated with next-day QTc intervals. Effects were not significantly modified by sex (P = .41 for interaction). There were 2 occurrences of nonfatal torsade de pointes, both in the haloperidol group. Neither was associated with study drug administration. Conclusions and Relevance: The findings of this trial suggest that daily QTc interval monitoring during antipsychotic use may have limited value in patients in the ICU with normal baseline QTc and few risk factors for QTc prolongation. Trial Registration: ClinicalTrials.gov Identifier: NCT01211522.

Comparison of phenobarbital monotherapy to a benzodiazepine-based regimen for management of alcohol withdrawal syndrome in trauma patients.

BACKGROUND: Alcohol withdrawal syndrome (AWS) is associated with increased morbidity and mortality in the trauma population. Benzodiazepines (BZDs) are standard of care for AWS; however, given the risk of delirium with BZDs and reports of BZD-refractory withdrawal, phenobarbital (PHB) has emerged as an alternative therapy for AWS. Safety and efficacy studies of PHB for AWS in trauma patients are lacking. Our aim was to compare a BZD versus PHB protocol in the management of AWS in trauma patients. METHODS: We performed a retrospective cohort study at a level 1 trauma center of patients at risk for AWS managed with either a BZD or a low-dose oral PHB regimen. Patients were excluded if they were taking BZDs or barbiturates before admission, received propofol or dexmedetomidine before initiation of the study drug, presented with delirium tremens or seizures, or died or discharged within 24 hours of presentation. The primary outcome was complicated AWS (seizures or alcohol withdrawal delirium/delirium tremens). Secondary outcomes included uncomplicated AWS; therapy escalation; oversedation; delirium-, intensive care unit-, and ventilator-free days; and length of stay. RESULTS: A total of 411 patients were identified; 118 received BZD, and 293 received PHB. The odds of developing complicated AWS with PHB versus BZD-based therapy were not statistically significant (odds ratio [OR], 0.52; 95% confidence interval [CI], 0.21-1.39); however, patients receiving PHB were less likely to develop uncomplicated AWS (OR, 0.08; 95% CI, 0.04-0.14) and less likely to require escalation of therapy (OR, 0.45; 95% CI, 0.24-0.84). The PHB group had a length of stay 3.1 days shorter than the BZD group ( p = 0.002). There was no difference in intensive care unit-, ventilator-, or delirium-free days. CONCLUSION: A PHB-based protocol for the management of AWS is a safe and effective alternative to BZD-based regimens in trauma patients. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level IV.

Comparison of Volatile Anesthetics Versus Propofol on Postoperative Cognitive Function After Cardiac Surgery: A Systematic Review and Meta-analysis.

OBJECTIVE: To compare the effects of volatile anesthetics and propofol on neurocognitive function after cardiac surgery. DESIGN: A systematic review and meta-analysis of randomized controlled trials. SETTING: A literature search of PubMed, EMBASE, CENTRAL, CINAHL, Scopus, and Web of Science databases was conducted. PARTICIPANTS: A total of 10 randomized controlled trials comparing volatile anesthetics and propofol in cardiac surgery were included in the study. INTERVENTIONS: The standardized mean difference and risk ratio were calculated to estimate pooled effect sizes. MEASUREMENTS AND MAIN RESULTS: The primary outcome was the postoperative neurocognitive function score, and the secondary outcome was the incidence of delirium after cardiac surgery. The analysis did not show significant differences in postoperative neurocognitive function scores (standardized mean difference -0.06, 95% CI -0.81-0.69; p = 0.879). The incidences of delirium (risk ratio 1.10, 95% CI 0.81-1.50) between the volatile anesthetics and propofol groups were not significant (p = 0.533). CONCLUSIONS: Unlike noncardiac surgery, there are no differences between volatile anesthetics and propofol regarding postoperative neurocognitive dysfunction after cardiac surgery.

Efficacy and Safety of Risperidone in Patients With Delirium: The RIDDLE Pilot Study.

BACKGROUND: The cornerstone treatment of delirium is to assess and treat its underlying causes and prevent further complications. Drug therapy may be necessary to control agitation and behavioral symptoms associated with delirium. The aim of this pilot study was to evaluate the feasibility of a randomized placebo controlled trial to evaluate the efficacy and safety of risperidone in the treatment of delirium. METHODS: This was a randomized double-blinded placebo-controlled trial. Patients were enrolled in the study if they were hospitalized and 65 years or older and had a diagnosis of delirium. Delirium Rating Scale revised 98 was used to determine delirium and motor agitation. RESULTS: A total of 14 participants with 57% being men and having a mean age of 86 years were included. There were no statistically significant differences between the risperidone and placebo group for the Delirium Rating Scale revised 98 score. There were no severe adverse reactions reported in the study, and no patients discontinued the study for adverse reactions. CONCLUSIONS: Risperidone at low doses (1 mg daily or less) was well tolerated for the treatment of delirium. Future large-scale trials are needed to evaluate the safety and efficacy of risperidone in the treatment of delirium. This pilot study taught us that the phase 2 RIsperDone DELirium trial will need a multicenter design with more research personnel to increase the number of participants enrolled.

Association Between Antidiabetic Drugs and Delirium: A Study Based on the Adverse Drug Event Reporting Database in Japan.

BACKGROUND AND OBJECTIVE: Several associations between diabetes mellitus and delirium have been reported; however, they have been inconsistent, and evidence on the effects of antidiabetic medications on delirium is also limited. This study aimed to investigate whether the use of antidiabetic drugs is a risk factor for delirium development. METHODS: Using the Japanese Adverse Event Reporting Database, we analyzed 662,899 reports between 2004 and 2022. Reporting odds ratios (RORs) and 95% confidence intervals (CIs) for delirium associated with diabetes and using each antidiabetic medication were calculated after adjusting for potential confounders. RESULTS: Overall, 8892 of the reports analyzed were associated with delirium. A comparison of the incidence of delirium between patients with and without diabetes showed no significant difference, with 1.34% in patients without diabetes and 1.37% in those with diabetes. In each antidiabetic medication, signals for delirium were detected for sulfonylurea (crude ROR, 1.35; 95% CI 1.21-1.51) and insulin (crude ROR, 1.28; 95% CI 1.13-1.44). These results were maintained even after adjusting for factors with potential confounders (sulfonylurea: adjusted ROR, 1.75; 95% CI 1.54-2.00, insulin: adjusted ROR, 1.35; 95% CI 1.20-1.54). CONCLUSIONS: Our results suggest no association between diabetes and delirium; however, using sulfonylurea and insulin may be associated with delirium development. Nonetheless, these findings should be validated in future studies.

Delirium following pregabalin discontinuation in an individual with no psychiatric or substance use history.

We report about a man in his mid-50s who was prescribed pregabalin (150 mg/day) for neuropathic pain due to a herniated intervertebral disc. Four weeks later, he presented to the emergency room with symptoms consistent with delirium. After ruling out acute intoxication with a substance and neurological causes, collateral information from the family and review of his medical chart indicated potential discontinuation syndrome owing to pregabalin. Following the successful treatment and resolution of delirium, the patient revealed he had been consistently consuming pregabalin doses upwards of 2 g/day over the past 2 weeks, leading to the premature exhaustion of his prescription and an abrupt cessation. The case findings underscore the necessity for physicians to recognise the potential for pregabalin misuse and the associated withdrawal risks, including delirium.

Effects of xenon anesthesia on postoperative neurocognitive disorders: a systematic review and meta-analysis.

The latest clinical trials have reported conflicting outcomes regarding the effectiveness of xenon anesthesia in preventing postoperative neurocognitive dysfunction; thus, this study assessed the existing evidence. We searched the PubMed, Embase, Cochrane Library, and Web of Science databases from inception to April 9, 2023, for randomized controlled trials of xenon anesthesia in postoperative patients. We included English-language randomized controlled studies of adult patients undergoing surgery with xenon anesthesia that compared its effects to those of other anesthetics. Duplicate studies, pediatric studies, and ongoing clinical trials were excluded. Nine studies with 754 participants were identified. A forest plot revealed that the incidence of postoperative neurocognitive dysfunction did not differ between the xenon anesthesia and control groups (P = 0.43). Additionally, xenon anesthesia significantly shortened the emergence time for time to opening eyes (P < 0.001), time to extubation (P < 0.001), time to react on demand (P = 0.01), and time to time and spatial orientation (P = 0.04). However, the Aldrete score significantly increased with xenon anesthesia (P = 0.005). Postoperative complications did not differ between the anesthesia groups. Egger's test for bias showed no small-study effect, and a trim-and-fill analysis showed no apparent publication bias. In conclusion, xenon anesthesia probably did not affect the occurrence of postoperative neurocognitive dysfunction. However, xenon anesthesia may effectively shorten the emergence time of certain parameters without adverse effects.

Toxidrome of an Easily Obtainable Nootropic: A Case Report of Phenibut Intoxication and Withdrawal Delirium.

PURPOSE/BACKGROUND: Phenibut (4-amino-3-phenyl-butyric acid) is a structural analog of GABA with central nervous system depressant and anxiolytic properties, developed in the former Soviet Union for anxiety, insomnia, and alcohol withdrawal. Its primary mechanism of action is believed to be a GABA-B receptor agonist-with high affinity at the α 2 δ subunit-containing voltage-dependent calcium channels and therefore gabapentinoid activity-as well as, to a lesser extent, GABA-A agonist activity. While not approved or regulated by the FDA, phenibut is easily obtainable online, where it is marketed as a nootropic, or cognitive enhancer. However, phenibut can lead to problems related to intoxication, dependency, and withdrawal, similar to other sedatives. METHODS/PROCEDURES: We present a case of phenibut intoxication and withdrawal delirium that provided diagnostic and management challenges because of a patient that was initially not forthcoming about his phenibut use which resulted in five presentations to the hospital including two admissions. FINDINGS/RESULTS: Initial differential including adrenergic, serotonergic or anticholinergic toxidrome based on clinical picture and history reported at that time, however phenibut use of 50 g daily was eventually revealed, an amount exceeding the highest reported cases in our review of the English literature. IMPLICATIONS/CONCLUSIONS: High-dose phenibut intoxication and withdrawal can appear as dramatic and dangerous as high-dose sedative withdrawal, however given its specified receptor affinity and binding profile we found that a pharmacotherapeutic approach targeting GABA-B, GABA-A, and gabapentenoid receptors were effective in stabilizing this patient, eventually leading to the patient's full and sustained recovery.

Severe Alprazolam Withdrawal With Delirium and Psychosis: A Case Report and Literature Review.

ABSTRACT: In our report, and review of the literature, we present an important clinical lesson for the recognition and treatment of alprazolam withdrawal with complicated delirium and psychosis, and present a strong case for future treatment algorithms. Our case is unique due to the severity of behavioral disturbance associated with acute psychosis secondary to alprazolam withdrawal and the significant quantity of alprazolam consumed. The use of high cumulative doses of longer-acting benzodiazepines resulted in rapid improvement in symptoms with full resolution of psychosis. Within 4 days of treatment in hospital, delirium and psychosis had fully resolved. Detoxification continued in the community and the patient was followed up in clinic for monitoring of mental state. There was no recurrence of psychotic symptoms.

Delayed-Onset Psychosis Secondary to Tacrolimus Neurotoxicity After Lung Transplant: A Case Report and Systematic Review.

BACKGROUND: Tacrolimus is the most common immunosuppressant used after transplant, yet it can result in moderate-to-severe neurotoxicity in up to 32% of patients. Signs of neurotoxicity can vary from mild (tremor or headache) to severe (posterior reversible encephalopathy syndrome or psychosis. Prompt recognition and management is needed to lead to symptom resolution. OBJECTIVE: The objective of this study is to describe the clinical presentation of tacrolimus-induced psychosis, a type of tacrolimus-inducted neurotoxicity, and distinguish it from other central nervous system disturbances, including delirium. METHODS AND RESULTS: We present a case of delayed onset tacrolimus-induced psychosis with focus on unique clinical features and management strategies. We conducted a systematic review of cases of tacrolimus-induced psychosis using the PubMed database and included 15 manuscripts in our review. CONCLUSIONS: Tacrolimus-induced psychosis is a unique presentation of tacrolimus-related neurotoxicity and can present without the cardinal symptoms of delirium. The data on isolated psychotic symptoms are limited with current literature focusing on more common presentations of tacrolimus-induced neurotoxicity, such as delirium and tremor. Development of psychosis can occur later in the treatment course and at normal tacrolimus serum levels. It can improve with antipsychotic therapies, but primary management should include cross-titration to an alternate immunosuppressant regimen.

GHB: a life-threatening drug complications and outcome of GHB detoxification treatment-an observational clinical study.

BACKGROUND: GHB (gammahydroxybutyrate) and its precursors are popular recreational drugs due to their sedative, anxiolytic and sexually stimulating effects. Their use has been steadily increasing in recent years. The detoxification process is complex and prone to high rates of complications while little is known about the pathophysiology. This study aims to elucidate the characteristics of GHB-addicted patients and to evaluate the risks and complications of GHB withdrawal treatment. METHODS: This observational study describes prospectively the socioeconomic status, clinical history and course of inpatient detoxification treatment of a group of 39 patients suffering from GHB substance use disorder. Detoxification treatment took place in a highly specialized psychiatric inpatient unit for substance use disorders. RESULTS: GHB patients were characterised by being young, well-educated and by living alone. More than 50% of the patients had no regular income. The patients were male and female in equal numbers. Detoxification treatment was complicated, with high rates of delirium (30.8%) and high need for intensive care (20.5%). CONCLUSIONS: In our sample, GHB users were young, well-educated people and male and female in equal number. Detoxification proved to be dangerous for GHB-addicted patients. The presence of delirium and the need for transfer to an intensive care unit during detoxification treatment was extraordinarily high, even with appropriate clinical treatment. The reasons for this remain unknown. Therefore an intensive care unit should be available for GHB detoxification treatment. Further studies are needed to evaluate the options for prophylactic treatment of delirium during detoxification.

Effectiveness and safety of the co-administration of Yokukan-San (Japanese herbal medicine) with antipsychotics in hospitalized older patients with pneumonia.

AIM: Behavioral and psychological symptoms and delirium frequently occur in hospitalized older patients with pneumonia and are associated with longer hospital stays. Yokukan-San (YKS, traditional Japanese [Kampo] medicine) and antipsychotics are often used to treat delirium and behavioral and psychological symptoms in Japan. Hence, this study aimed to assess the effectiveness and safety of the co-administration of YKS with atypical antipsychotics in older patients with pneumonia. METHODS: We used the Japanese Diagnosis Procedure Combination inpatient database to retrospectively identify older patients (≥65 years) hospitalized for pneumonia who received antipsychotics within 3 days of hospitalization. The patients were divided into two groups: those who received atypical antipsychotics alone (control group) and those who received both atypical antipsychotics and YKS (YKS group). We compared length of hospital stay, in-hospital mortality, bone fractures, and administration of potassium products between the two groups using propensity score overlap weighting. RESULT: We identified 4789 patients in the YKS group and 61 641 in the control group. After propensity score overlap weighting, length of hospital stay was statistically significantly shorter in the YKS group (percentage difference -3.0%; 95% confidence interval -5.8% to -0.3%). The proportion of patients who received potassium products was higher in the YKS group (odds ratio 1.34; 95% confidence interval 1.15-1.55). In-hospital death and bone fractures were not significantly different. CONCLUSION: Co-administration of YKS with atypical antipsychotics could be a reasonable treatment option for hospitalized older patients with pneumonia and aggressive psychiatric symptoms. Geriatr Gerontol Int 2023; 23: 849-854.