Uncorrected Proof Shiraz E-Med J. 2021 October; 22(10):e109972. Published online 2021 May 18. doi: 10.5812/semj.109972. Research Article Cognitive Dysfunction and Survival in Hospitalized Patients with Delirium: A 12-Month Prospective Cohort Study Mousa Kiani Chelmardi 1 , Raheleh Rafaiee 2 , Seyed Davood Hosseini Talari 3 , Nadia Abedi Omali 4 and Seyed Hamzeh Hosseini 1, * 1 Department of Psychiatry, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran 2 Department of Neuroscience, School of Advanced Technologies in Medicine, Mazandaran University of Medical Sciences, Sari, Iran 3 Department of Psychiatry, School of Medicine, Babol University of Medical Sciences, Babol, Iran 4 Psychiatry and Behavioral Sciences Research Center, Addiction Research Institute, Mazandaran University of Medical Sciences, Sari, Iran * Corresponding author: Department of Psychiatry, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran. Email: hosseinish20@gmail.com Received 2020 October 03; Revised 2021 January 26; Accepted 2021 January 29. Abstract Background: The effect of delirium of hospitalized inpatients on post-discharge cognitive status and survival of older patients remains unclear, and little is known about the related risk factors of cognitive impairment after delirium. Objectives: To determine one-year survival of patients with delirium and cognitive dysfunction in elderly inpatients after initial hospital admission. Methods: This prospective cohort study was conducted on 100 patients with delirium admitted to a general hospital from October 2018 to November 2019. Cognitive dysfunction and death were the primary outcomes. The mini-mental state examination (MMSE) was used to measure cognitive function. Results: In this study, 12 patients died in hospital and cumulative three-month mortality was 40%. Finally, 60 patients were followed for one year. The one-year survival rate through the Kaplan-Meyer approach was 31%. The rate of one-year mortality was found with a significant association with underlying parameters, such as cancer (P = 0.008), cirrhosis (P = 0.04), trauma (P = 0.001), BUN ≥ 50 mg/dL (P = 0.02), Cr ≥ 1.2 mg/dL (P = 0.04), hypocalcemia (P = 0.0), and thrombocytopenia (P = 0.002). According to the MMSE scores, participants had normal cognition (46.7%), mild dementia (6.7%), moderate dementia (33.3%), and severe dementia (3.3%). The cognitive impairment showed a significant association with underlying parameters, such as pulmonary infections (P = 0.02), trauma (P = 0.02), and renal failure (P = 0.04). Conclusions: Assessment and screening for delirium is necessary in all older hospitalized inpatients. Cognitive measurement is effective to identify delirium, accelerate proper control, and decrease its negative effects. Family members should be trained and involved in care, particularly for monitoring of risk factors upon discharge. Keywords: Delirium, Cognitive Dysfunction, Death, Cohort 1. Background Delirium is commonly observed in the elderly in acute and non-acute care settings and is associated with poor outcomes (1-3). Prevalence estimates typically range from 9 - 32% of older hospitalized inpatients (4). According to studies, around 70% of patients in intensive care units (ICU) are affected by delirium (5) and the hospital mortal- ity rate is 25 - 33% (6). The one-year mortality rate of 35 - 40% is observed for hospitalized seniors with delirium (7), which is similar to the mortality linked to sepsis or acute myocardial infarction (8). The delirium rate in Iran is 21.8%, while its rate in hospitalized cases in ICU and general ward is 24.7% and 17.5%, respectively (9). Investigating the outcomes after delirium in the el- derly and providing interventions to improve patient out- comes are of particular interest (10, 11). Although it is an acute disease, it is linked to many long-term complications as well as an increase in healthcare burden and costs (12). Delirium is linked with persistent impairments in brain function, including cognitive decline and increased risk of dementia and death (13, 14). Although numerous studies have documented that persistent cognitive impairment af- fects 30 - 80% of survivors (15-20), it is necessary to deter- mine the risk factors and predictors of this pernicious com- plication of critical illness (21). Despite a high rate of delirium in cases admitted to hospitals in Iran (9), little has been investigated about the future cognitive dysfunction after delirium and related risk factors. Identifying manageable risk factors regarding Copyright © 2021, Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.