Introduction
Malnutrition is one of the prominent public health problems, especially in the elderly. Physiological changes related to aging, if accompanied by other psychological, social and environmental factors, can lead the elderly towards malnutrition. Elderly people with psychological disorders are at risk of malnutrition [1]. There are few studies on the elderly with psychological disorders hospitalized in a psychiatric hospital; most of them have focused on their depression [2] and do not consider all mental disorders. Malnutrition is a multifactorial problem [3, 4]. Examining the nutritional status and identifying factors affecting it is one of the prevention and control measures. Therefore, this study aims to investigate the nutritional status of the elderly hospitalized in the Razi Psychiatric Center in Tehran, Iran and determine its relationship with the health status and essential micronutrients.
Methods
This is a descriptive-analytical study with a cross-sectional design conducted in 2018. All the elderly participated in the study had at least one of the psychological disorders (schizophrenia, bipolar disorder, obsessive-compulsive disorder, anxiety, etc.). The inclusion criteria were the willingness to participate in the study, age ≥60 years, and the permission of the attending physician. Unwillingness to continue participation, occurrence of severe physical and mental problems, and death were considered as exit criteria. These criteria were according to the patients’ clinical records, conducting an interview with them, or based on observation. For patients with cognitive disorders, including dementia, in addition to checking their medical records, data were obtained through asking questions from the attending nurse or physician. 
Data collection was conducted in three stages, including completing the questionnaire, collecting blood samples for clinical tests, and measuring body mass index (BMI). A three-part questionnaire was used, the first part was about demographic information, the second part was the mini nutritional assessment (MNA) tool, and the third part was assessing the health status (Dental health, physical activity, history of an underlying disease, as well as the level of micronutrients such as folic acid, vitamin B12, vitamin D, zinc, calcium, folate, transferrin, and albumin). The collected data were analyzed in SPSS v. 21 software using chi-square test, ANOVA, and logistic regression analysis.
Results
A total of 108 eligible and available older patients were selected for the study. Seven patients were excluded due to unwillingness to continue cooperation (n=5), heart attack (n=1) and death (n=1). Therefore, the data of 101 older patients were examined. Table 1 presents the demographic characteristics of the participants.


Most of the elderly had 60-75 years of age, female, and had a history of staying in the hospital for 21-40 years, and most of them (59.4%) were at risk of malnutrition. The results of Chi-square test showed no significant relationship of patients’ age, gender, and length of hospital stay with their nutritional status (P>0.05). There was no relationship between nutritional status and having cardiovascular diseases, respiratory disorders, diabetes mellitus, metabolic disorders, high blood fat, anemia and Parkinson’s disease (P>0.05). A significant relationship was reported only between nutritional status and the factors of physical activity and dental health (P<0.05). The results based on chi-square test and ANOVA showed a significant difference in the levels of BMI, vitamin D and vitamin B12 (P<0.05). The levels of albumin, calcium, zinc, transferrin and folic acid were almost the same in nutritional groups (P<0.05). It was found that 94% of the elderly had vitamin D deficiency.
In Table 1, the results of the binary logistic regression analysis (ENTER method) for predicting nutritional status based on five factors that had a significant relationship with nutritional status (physical activity, dental health, BMI, vitamin D, and vitamin B12) are presented. It should be noted that the dependent variable of nutritional status was converted into two groups of malnourished and normal by merging two groups of with malnutrition and at risk of malnutrition, and was used in binary regression. Omnibus test was used to evaluate the entire regression model, where the chi-square value was reported 59.73, which was significant (P<0.001). Hence, the overall regression model had a goof fit to the data (P<0.001). Of the five predictor variables, three variables of physical activity (OR=8.539, 95% CI:1.142-63.85), dental health (OR=23.119, 95%CI:1.401-38.78) and vitamin 12 level (12 OR=1.007, 95% CI:1.002-1.012) were able to significantly predict changes in nutritional status of the elderly (P<0.05).
Discussion
The results showed that more than two-thirds of hospitalized elderly were at risk of malnutrition or had malnutrition. Physical activity, dental health status, and vitamin B12 level were reported as predictors of malnutrition in the elderly.
One of the limitations of this study were the small sample size and the inability to generalize the findings; therefore, it is recommended to conduct similar studies in other cities with a larger sample size. Due to the cross-sectional nature of the study, it was not possible to provide a direction link between causes and effects in the model. Moreover, the range of confidence in physical activity and dental health status was very high, which somehow reduces the confidence in the odds ratio. In this study, the identified factors that had an impact on malnutrition of the elderly can be modified. Hence, screening, corrective measures, and regular management of nutritional status should be strengthened as an important pillar in therapeutic interventions for the elderly.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by Ethics Committee of the University of Social Welfare and Rehabilitation Sciences (Code: IR.USWR.REC.1395.159). 

Funding
This research is a part of the research project that was conducted at the Psychosis Research Center of the University of Rehabilitation Sciences and Social Health. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Authors' contributions
Conceptualization: Omid Rezaei, Laden Fattah Moghadam and Fereshte Rezaei; Research and review: Laden Fattah Moghadam, Dawood Arab Qahestani and Fereshte Rezaei; Editing and finalization: All authors.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
This research is a part of the research project that was conducted at the Psychosis Research Center of the University of Rehabilitation Sciences and Social Health. We hereby thank and appreciate all colleagues of Razi Psychiatric Hospital and Psychosis Research Center.


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