Introduction
Delirium is an acute and fluctuating change in the mental state of the patient, which is associated with a decrease in consciousness and impaired attention. This disorder appears suddenly in a short period [1]. Delirium is a clinical syndrome that can occur at any age, but it is one of the most common disorders in older patients [2]. The prevalence of delirium in the elderly is higher due to underlying and predisposing risk factors [3]. Delirium is a medical emergency and is often associated with severe underlying diseases. Rapid diagnosis and treatment of underlying diseases should be the first goal of delirium management based on the patient-centered care approach [4]. Diagnosing and identifying factors related to this disease can prevent its negative consequences. This study aims to investigate the prevalence of delirium and its related factors in the elderly hospitalized in selected hospitals in Iran.
Methods
This is a descriptive-analytical study with a cross-sectional design. The study population consists of the elderly people hospitalized in the emergency and internal departments of Firozabadi and Rasoul Akram hospitals, affiliated to Iran University of Medical Sciences, in Tehran, Iran in 2020-2021. Using a simple random sampling method, 300 eligible patients were selected as the samples. Inclusion criteria were age 60 and above, willingness to participate in the study, and no surgery in the recent days. Exclusion criteria were: Suffering from aphasia, having balance disorders, and not having a companion in patients who were abnormal in terms of consciousness. The 4AT test was used to assess delirium in the patients. The questionnaires were completed by the researcher for the patients two hours after entering the emergency department. In cases where the patient was in an abnormal state of consciousness, the required information was collected from the companion of the patient. The 4AT test has four items including Alertness, Abbreviated Mental Test, Attention, and Acute change. The score ranges from 0 to 12; a score of 0 indicates no delirium, a score of 1-3 suggests the exposure to delirium, and a score of ≥4 indicates delirium with/without cognitive impairment. It takes about two minutes to complete (5, 6). After collecting the data, they were analyzed in SPSS software, version 24 using descriptive statistics (Mean±SD) and inferential statistics (Pearson’s correlation test). The significance level was set at 0.05.
Results
The mean age of the patients was 70.91±8.77 years; 53% were male, 98% were Iranian, 48% were illiterate, 31% had primary school education, 62% were married, and 80% were living with their families. Their mean body mass index was 25.84±5.34 kg/m2. Forty-two percent had a history of polypharmacy. Thirty-seven percent were dependent in performing daily life activities. Forty-two percent reported a history of hospitalization in the past month, and 42% had a history of urinary catheter in the hospital. Twenty-seven percent reported hearing loss and 46% reported vision loss, while only 4% were using hearing aids and 19% wore glasses. Ten percent reported a history of substance abuse and 11% reported a history of benzodiazepine drugs use. Eleven percent had cognitive impairment, 1% had a history of Parkinson’s disease, 15% had a history of specialized treatment for depression, 51% had a history of chronic pain, and 85% had a history of constipation in the last 6 months. Twenty-five percent experienced a fall in the past month.
The evaluation of the patients in terms of delirium syndrome showed that 85% were normal in terms of consciousness; 45% stated their age, date of birth, place (clinic or hospital name) and current year without error (attention dimension); 62% could not say the months of the year in reverse at all (attention dimension) and 73% had no fluctuating change (stumbling). Absence of delirium was confirmed in 26% of patients; 31% were exposed to delirium and 43% had delirium (score higher than 4). The delirium status of hospitalized patients had a significant relationship with the history of polypharmacy, independence in performing activities of daily living at home, history of hospitalization in the last month, cognitive impairment, Parkinson’s disease, history of specialized treatment for depression, and history of chronic pain (Table 1).


The delirium status had no significant relationship with age, sex, education, marital status, history of falls, smoking, benzodiazepine drugs use, and living alone.
Discussion
The prevalence of delirium in the hospitalized elderly in Tehran is about 40%, which is considered a high prevalence. Early detection and diagnosis of delirium can prevent the occurrence of adverse consequences caused by this syndrome. It is necessary to provide appropriate and comprehensive interventions to reduce the adverse effects of this syndrome for the elderly with delirium. It is recommended that due to the increasing prevalence and importance of this syndrome in the elderly, this syndrome should be considered and investigated in the integrated care package for the elderly given to physicians and non-physicians.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the ethics committee of Iran University of Medical Sciences (Code: IR.IUMS.FMD.REC.1398.171). 

Funding
This study was funded by Iran University of Medical Sciences.

Authors' contributions
The authors had equal contribution to the preparation of this article. 

Conflicts of interest
The authors declare no conflict of interest.

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