Introduction
Borderline personality disorder (BPS) is a serious mental disorder that is characterized by instability in self-image, interpersonal relationships, and emotions [1]. The prevalence of this disorder in the general population is estimated to be about 1%, and in psychiatric outpatients and inpatients to be 12 and 22%, respectively [6]. The pathology of this disorder is such that some patients are prone to hospitalization and rehospitalization [15]. The prevalence of suicidal thoughts and attempts among BPD patients have been estimated to be over 60% [16]. About 50% of patients admitted for suicide and self-harm risk management have BPD [17]. Psychotic symptoms, including auditory hallucinations, are another important reason for hospitalization and a risk factor for suicide in some BPD patients [18, 19]. Transient paranoia experienced under stress and characterized by exaggerated beliefs, alongside hearing “voices” (auditory hallucinations), is a psychiatric symptom that predicts hospitalization in BPD patients. Risky and uncontrolled behaviors, including extreme aggression, impulsive sexual activity, and self-medication, can also be reasons for hospitalization in BPD patients [20-22]. 
Not only the clinical symptoms of BPD inpatients can differ from those of BPD outpatients, but they also differ between male and female patients with BPD, although some studies have not reported any differences between the sexes [24, 25], while there are studies suggesting that emotional instability and interpersonal problems more common in female BPD patients and impulsivity and aggression more common in males [9, 11, 26]. In this study, we aim to investigate the clinical symptoms of BPD in hospitalized patients in Iran, and compare male and female inpatients in clinical symptoms and comorbid personality disorders.

Methods
The study population consists of inpatients admitted to three psychiatric centers in Iran (Iran Psychiatric Hospital, the Neurology Department of Taleghani Hospital, and Razi Psychiatric Hospital). During one year, 120 inpatients were introduced to the research team, of whom 26 inpatients did not meet the diagnostic criteria for BPD, and 7 inpatients were excluded due to incomplete responses to the questionnaires. Finally, data from 87 inpatients (64 females and 23 males) were included in the analysis. The data were collected using the Personality Inventory for DSM-5 (PID-5), the Structured Clinical Interview for DSM-5 Screening Personality Questionnaire, and the Structured Clinical Interview for DSM-5 Personality Disorders. To examine the difference in clinical variables based on sex, the chi-square test was used. To compare men and women in PID-5 scores, the one-way analysis of variance (ANOVA) was used.

Results
The mean age of the inpatients was 27.23±7.31 years. The frequencies of clinical symptoms of BPD and comorbid personality disorders in inpatients are shown in Table 1.


Overall, emotional swings (95.4%), shifting self-image (95.4%), and explosive anger (93.1%) had the highest prevalence, while paranoia/transient dissociation (59.8%) had the lowest prevalence rate. In females, emotional swings (95.3%) had the highest prevalence, while paranoia/transient dissociation (70%) had the lowest prevalence rate. All males (100%) had both shifting self-image and explosive anger, while paranoia/transient dissociation (56.5%) was the least prevalent symptom. Based on the Chi-square test, there was no significant difference in BPD symptoms and comorbid personality disorders between males and females (Table 1). Table 2 shows the mean scores of PID-5 in males and females.




The mean scores of females in attention seeking were significantly higher than that of males, while the scores of males in grandiosity were significantly higher than that of females (P<0.05). 

Conclusion
Overall, the results showed that emotional liability, anger, and shifting self-image are the most prominent clinical symptoms in BPD inpatients in Iran. Self-harm/suicide and impulsive behaviors are also prevalent in more than 80% of these inpatients. There is no significant difference between male and female inpatients with BPD in clinical symptoms and comorbid personality disorders. Further studies in Iran are recommended with the participation of outpatients with BPD and investigating the effect of cultural factors on the clinical symptoms of BPD.

Ethical Considerations
Compliance with ethical guidelines
The study was approved by the University of Social Welfare and Rehabilitation Sciences, Tehran, Iran (Code: IR. USWR.RECI1398.049). All participants declared a written informed consent, and their information was kept confidential. 

Funding
This article was extracted from the PhD thesis of Maryam Kami at the Department of Clinical Psychology, University of Social Welfare and Rehabilitation Sciences. This research did not receive any specific grant from funding agencies in the public, commercial, or non-profit sectors.  

Authors contributions
Conceptualization: Abbas Pourshahbaz, Masoud Nosratabadi, and Maryam Kami; Sampling: Maryam Kami, Zahra Dehghanizadeh, and Marzie Olamaie Koopaie; referring the inpatients and supervision: Omid Rezaei , Amir-Abbas Keshavarz-Akhlaghi, and Seyed Shahab Banihashem; Data analysis and writing the initial draft: Maryam Kami; Editing, review, and final approval: All authors.

Conflicts of interest
The authors declare no conflict of interest.

Acknowledgments
The authors would like to thank all participants and treatment staff of the Iran Psychiatric Hospital, Taleghani Hospital, and Razi Psychiatric Hospital for their cooperation.