1. Introduction
Suicide is known as one of the biggest medical and social problems in the world [1, 2]. In addition to personal and family injuries, this phenomenon causes social challenges as well [3, 4].
According to the definition of the World Health Organization (WHO), suicide is an act in which a person intentionally and without the intervention of others performs an abnormal behavior, such as self-harm or consuming a substance in an amount greater than the amount prescribed for treatment, and his goal is to achieve the expected changes [5]. This organization announced in June 2021 that more than 700,000 people die by suicide every year. For every suicide, more people commit suicide [6].
According to the long-term history of suicide to improve the public health of society, epidemiological investigations of suicide and its action are considered essential components of the mental health of society [7]. The issue of suicide becomes more prominent when, according to reports, suicide attempts are more common among teenagers and young people than among other age groups [8]. This phenomenon is reported as the fourth cause of death among teenagers aged 15-19 years in 2021.
The causes of suicide are different in people, and factors, such as despair or having inappropriate mental and psychological conditions, drug addiction and abuse, financial problems, family challenges, cultural issues, etc. can be considered to be involved in its creation. Various factors, such as age, sex, race, psychological factors, socioeconomic conditions, family conditions, and the level of access to counseling and mental health services, etc. can play a vital role in the formation of suicide attempts and their repetition in people [9]. A previous suicide attempt is the crucial risk factor for suicide in the general population. Eating pesticides, hanging, and firearms are among the most common methods of suicide in the world [6].
In the world, a suicide attempt occurs every three seconds [1]. The frequency of suicide varies depending on the geographical situation in different countries and regions so that 77% of the world’s suicides occur in low- and middle-income countries [6]. The rate of suicide has increased in Iran in recent years and has reached 9.4 per hundred thousand people. In terms of the global ranking of suicide, Iran ranks 58th, among which the three provinces of Ilam, Kermanshah, and Hamadan have the highest suicide rate [5]. Considering the increase in suicide-related behaviors in recent years in the country, investigating and recognizing patterns related to it can help to prevent and control this health problem [2].
Geographical and temporal changes in the rate of suicide mortality are closely related to different social statuses in the provinces and over time [10]. Also in a study conducted in Taiwan, a significant relationship was observed between air temperature, humidity, sunlight, atmospheric pressure, season, and year with suicide [11]. Climatic factors (changes in temperature, humidity, and season) and geographic and atmospheric factors can be effective in the rate of suicide [12]. Studies have shown that demographic factors, such as age, sex, cultural, social, and economic factors [13, 14, 15, 16] and marital status, physical health, alcohol addiction, drugs [17, 18], mental illnesses and depression, financial and legal problems and loss of relatives [19], even climate, geographical conditions, family history of suicide, and religion [20], each of them is somehow effective in the occurrence of suicide. The gender difference in suicide methods and the variety of suicide patterns are different in the geographical regions of the world [21].
Suicide prevention is not an easy process and this program is considered one of the vital priorities of the World Health Organization. Identifying the causes, methods of action, demographic, and epidemiological characteristics of suicides are vital in controlling and reducing this social challenge [22]. In other words, to have an effective program and intervention to reduce the cost and burden caused by this health problem in society, it is necessary to have accurate and appropriate information and identify the risk factors related to it [9].
Therefore, in this regard and considering that Mazandaran Province is one of the provinces with a high suicide rate, the present study was conducted to determine the epidemiology of relief missions following the suicide in the pre-hospital emergency system of Mazandaran University of Medical Sciences.

2. Materials and Methods
This study is descriptive and was conducted from September 2019 to September 2021 in the pre-hospital emergency area of Mazandaran University of Medical Sciences. Statistical information related to the missions carried out following suicide during the years under review using data contained in the national emergency mission form registered in Asayar software was extracted. Among the available information and by the demographic information questionnaire, age, sex, as well as from the emergency mission forms, items, such as the location of the accident, time of the accident, method of suicide, and the result of the mission were extracted.
To examine the results, frequency percentage, Mean± SD were used, and to examine the qualitative variables between the groups, the Chi-square test and Fisher’s exact test were used. The collected data were analyzed using SPSS software, version 26 (SPSS Inc., Chicago, IL, USA). A significance level of 0.05 was considered.
The Chi-square test was used to investigate the relationship between suicide method, time of suicide, and gender. Fisher’s exact test was also used to investigate the relationship between age groups and suicide methods.
The inclusion criteria included all the patients assisted with a diagnosis of suicide in the pre-hospital emergency department of Mazandaran and the exclusion criteria included patients assisted outside the time frame of the study.

3. Results 
According to the information obtained during the 2 years from September 2019 to the end of August 2021, 1327 patients diagnosed with suicide were admitted to the pre-hospital emergency system of Mazandaran. The highest frequency of suicide attempts during these two years occurred in 2020 among 524 people (39.5%) and in September among 87 people (6.6%).
In the present study, 712 people (53.7%) were men and 615 people (46.3%) were women. The mean age of the patients was 32.2±12.03 years, and the most common age of suicide attempt was 20-29 and 39-30 years, respectively. The lowest age of the admitted person was 11 years and the highest age was 87 years (Table 1).

According to the results of Fisher’s exact test, a statistically significant relationship was observed between age groups and suicide methods (P=0.02).
The Chi-square test was used to investigate the relationship between the suicide method and gender. According to the results of this test, a statistically significant relationship was observed between gender and suicide methods (P=0.00) (Table 2).

The most common method of suicide among patients was drug poisoning (32.1%), other cases (30.06%), and self-harm (20.6%).
In the survey of people in terms of the time of the accident, the highest frequency of suicide attempts was between evening and night among 497 people (37.5%) and the lowest was among 195 people (16.8%) between 6 AM and 12 AM (Figure 1).

The Chi-square test was used for the relationship between the year of suicide and suicide attempt methods. According to the results, a significant relationship was observed (P=0.03).
The most common cause of death was hanging in 32 cases and the age group of 50 to 59 years. A total of 83% of deaths in the pre-hospital emergency area were male. In total, 5.3% of the missions resulted in death. A total of 988 suicide cases (74.5%) were sent to health centers (Table 3).

4. Discussion
According to the findings of this research, the highest number of suicide cases occurred in the age group of 30-39 years, with 416 people, and the lowest number of suicide cases was reported in the elderly age group, with 39 cases. With increasing age, the percentage of suicide cases increased. The results of the present study were consistent with the findings of Mohammadi et al.’s study [1], but it was not consistent with the results of the study conducted by Shekarzadeh [9] and Rezaian [8] in 2014, which could be due to the different geographical location and also the difference in the investigated area (pre-hospital and hospital area).
In this study, men accounted for a greater share of suicide cases than women, men with 53.7% compared to women at 46.3%, which is consistent with the results of Zarenejad et al.’s study in Fars Province [20]. In the study conducted by Shokrzadeh et al. titled suicide attempt by drug poisoning, as well as in the study conducted by Mohammadi et al., women constituted a higher proportion of cases [1, 9].
Drug poisoning included the most cases of suicides. In women, the number of drug poisoning cases was more than in men. Intentional drug poisoning is one of the most common methods of committing suicide in many parts of the world [23]. In many investigations inside the country, including in Golestan [24], Semnan [25], Kermanshah [26], Ahvaz [27], Gilan [28], northwest Iran [29] and also some countries, including India [30], Turkey [31], and Romania [32] this trend has been observed. These results emphasize that the drug is considered one of the critical means of suicide in Iran and many parts of the world due to its easy access and ease of use.
Between 6 PM and 12 PM, the most cases of suicide were recorded, which is consistent with the study of Shekarzadeh and colleagues [9]. The highest frequency of deaths was reported between 12 AM and 6 PM.
Hanging, other cases of suicide, and self-harm had the largest contribution to the death of pre-hospital emergency system clients seeking suicide.
One of the limitations of this study is the lack of access to the demographic information of the patients due to the emergency of the patients and the need to quickly transfer and send them to the treatment center. Also, the medical records of the patient, the cause of the suicide attempt, the person’s history of suicide, the result of being sent to the health-treatment center, etc. are not available in the pre-hospital emergency area.

5. Conclusion
Suicide prevention is not an easy process, and this program is considered one of the crucial priorities of the WHO. Young and productive age groups are among the most vulnerable groups in suicide cases. Men died about 5 times more than women due to suicide in the pre-hospital emergency department. In the summer season, suicide is more common than in other seasons. Therefore, more planning is required, including mental health self-care training in families, schools, etc. implementation of psychological counseling, rapid diagnosis, and treatment in vulnerable groups. Due to the emergency conditions of patients and the lack of access to medical records and demographic information of patients, more detailed investigations are needed to determine the epidemiology of suicide in the pre-hospital emergency system.

Ethical Considerations
Compliance with ethical guidelines
This study approved by Ethic Committee of Mazandaran University of Medical Sciences (No.: IR.MAZUMS. REC.1400.11853 dated 2021).

Funding
This research was funded by Mazandaran University of Medical Science.

Authors' contributions
All authors equally contributed to preparing this article.

Conflict of interest
The authors declared no conflict of interest.

Acknowledgments
We express our gratitude to the honorable deputy of research and technology of Mazandaran University of Medical Sciences for the financial support of the project and the respected experts of the pre-hospital emergency center and accident management of Mazandaran University of Medical Sciences who helped us in conducting this research.


References

1. Mousavi Z. [Epidemiological study of suicide in Asadabad city in 2011-2017: A descriptive study (Persian)]. Journal of Rafsanjan University of Medical Sciences. 2020; 19(3):235-50. [DOI:10.29252/jrums.19.3.235]
2. Gorgi Z, Rezaeian M, Rezaei F, Sheikh Fathollahi M. [Epidemiology of suicide and suicide attempts in counties under the supervision of Shiraz University of Medical Sciences from 2009 to 2012 (Persian)]. Health and Development Journal. 2020; 5(1):58-70. [Link]
3. Ghoreyshi S, Mousavinasab S. [Systematic review of researches on suicide and suicide attempt in Iran (Persian)]. Iranian Journal of Psychiatry and Clinical Psychology. 2008; 14(2):115-21. [Link]
4. Mohammadi N, Karbakhsh M, Pajoumand A. [Epidemiologic aspects of deliberate self-poisoning in adolescents: A hospital-based study in Tehran (Persian)]. Tehran University Medical Journal. 2007; 65(4):59-64. [Link]
5. Moradi AR, Moradi R, Mostafavi E. [A survey of the rate and effective factors on suicide in Bahar (Persian)]. Journal of Research in Behavioural Sciences. 2012; 10(1):50-8. [Link]
6. Sicotte R, Iyer SN, Kiepura B, Abdel-Baki A. A systematic review of longitudinal studies of suicidal thoughts and behaviors in first-episode psychosis: Course and associated factors. Social Psychiatry and Psychiatric Epidemiology. 2021; 56(12):2117-54. [DOI:10.1007/s00127-021-02153-2] [PMID]
7. Dadfar M, Lester D, Abdel-Khalek AM. Religiosity, happiness and suicidal behaviour: A cross-sectional comparative study in Iran. Mental Health, Religion & Culture. 2021; 24(2):128-41. [DOI:10.1080/13674676.2020.1767554]
8. Khajedaluee M, Khadem-Rezaiyan M, Jarahi L, Khatibi-Moghadam H, Faridpak A. Suicidal continuum (ideation, planning, attempting) in an Islamic country; which should be focused on? Journal of Injury and Violence Research. 2021; 13(1):47-54. [DOI:10.5249/jivr.v13i1.1556]
9. Shokrzadeh M, Jafari D, Hoseinpoor R, Delaram A, Pouyan Sadr A, Masodi E, et al. Frequency of poisoning leading to hospitalization in the intensive care units in Northeastern Iran, 2008-2018. Journal of Research Development in Nursing and Midwifery. 2021; 18(1):26-9. [DOI:10.52547/jgbfnm.18.1.26]
10. Haghparast-Bidgoli H, Rinaldi G, Shahnavazi H, Bouraghi H, Kiadaliri AA. Socio-demographic and economics factors associated with suicide mortality in Iran, 2001-2010: Application of a decomposition model. International Journal for Equity in Health. 2018; 17(1):77. [DOI:10.1186/s12939-018-0794-0] [PMID] [PMCID]
11. Lee HC, Lin HC, Tsai SY, Li CY, Chen CC, Huang CC. Suicide rates and the association with climate: A population-based study. Journal of Affective Disorders. 2006; 92(2-3):221-6. [DOI:10.1016/j.jad.2006.01.026] [PMID]
12. Daliri S, Bazyar J, Sayehmiri K, Delpisheh A, Sayehmiri F. [The incidence rates of suicide attempts and successful suicides in seven climatic conditions in Iran from 2001 to 2014: A systematic review and meta-analysis (Persian)]. Scientific Journal of Kurdistan University of Medical Sciences. 2017; 21(6):1-15. [doi:10.22102/21.6.1]
13. Azizpour Y, Asadollahi K, Sayehmiri K, Kaikhavani S, Abangah G. Epidemiological survey of intentional poisoning suicide during 1993-2013 in Ilam Province, Iran. BMC Public Health. 2016; 16(1):902. [DOI:10.1186/s12889-016-3585-9] [PMID] [PMCID]
14. Nazarzadeh M, Bidel Z, Ranjbaran M, Hemmati R, Pejhan A, Asadollahi K, et al. Fatal suicide and modelling its risk factors in a prevalent area of Iran. Archives of Iranian Medicine. 2016; 19(8):571-6. [PMID]
15. Kangavari HN, Shojaei A, Nazari SSH. Suicide mortality trends in four provinces of Iran with the highest mortality, from 2006-2016. Journal of Research in Health Sciences. 2017; 17(2):e00382. [PMID]
16. Soltani S, Aghakhani K, Barzegar A, Ghadirzadeharani M, Fallah F. Epidemiology of completed suicides referred to forensic pathology organization of Tehran, Iran, during March 2011 to March 2016. International Journal of Medical Toxicology and Forensic Medicine. 2017; 7(3):151-8. [DOI:10.18869/nirp.ijmtfm.7.3.151]
17. Shakeri A, Jafarizadeh F. [The reasons for successful suicides in Fars province (Persian)]. Journal of Mazandaran University of Medical Sciences. 2013; 22(97):271-5. [Link]
18. Ahmadi M, Ranjbaran H, Azadbakht M, Gorji MH, Gorji AH. A survey of characteristics of self-immolation in the northern Iran. Annals of Medical and Health Sciences Research. 2014; 4(S 3):S228-32. [DOI:10.4103/2141-9248.141964] [PMID] [PMCID]
19. Jafari F, Ahmadi Livani A, Amiresmaili M, Moosazadeh M. [Seasonality pattern of suicide in Iran: A systematic review (Persian)]. Journal of School of Public Health & Institute of Public Health Research. 2014; 12(3):23-35. [Link]
20. Zarenezhad M, Gorgi Z, SheikhFathollahi M, Gholamzadeh S, Ghadipasha M, Rezaeian M. [Epidemiological survey of suicide in Fars province in the south of Iran during 2003 to 2011 (Persian)]. Journal of Rafsanjan University of Medical Sciences. 2015; 13(12):1129-40. [Link]
21. Bantjes J, Tomlinson M, Weiss R, Yen P, Goldstone D, Stewart J, et al. Non-fatal suicidal behaviour, depression and poverty among young men living in low-resource communities in South Africa. BMC public Health. 2018; 18(1):1195. [DOI:10.1186/s12889-018-6104-3] [PMID] [PMCID]
22. Fadum EA, Stanley B, Qin P, Diep LM, Mehlum L. Self-poisoning with medications in adolescents: A national register study of hospital admissions and readmissions. General Hospital Psychiatry. 2014; 36(6):709-15. [DOI:10.1016/j.genhosppsych.2014.09.004] [PMID]
23. Hamdan S, Melhem N, Orbach I, Farbstein I, El-Haib M, Apter A, et al. Risk factors for suicide attempt in an Arab kindred. Journal of Affective Disorders. 2011; 132(1-2):247-53. [DOI:10.1016/j.jad.2011.01.012] [PMID] [PMCID]
24. Taziki M, Semnani S, Golalipour M, Behnampour N, Taziki A, Rajaee S, et al. [Epidemiological survey of suicide in Golestan province in the North of Iran (2003) (Persian)]. Journal of Mazandaran University of Medical Sciences. 2006; 16(55):72-7. [Link]
25. Saberi-Zafarghandi M, Ghorbani R, Mousavi S. [Epidemiologic study on suicide attempt in affiliated hospitals of Semnan University of Medical Sciences (Persian)]. Koomesh. 2005; 6(4):311-8. [Link]
26. Rezaie L, Khazaie H, Soleimani A, Schwebel DC. Self-immolation a predictable method of suicide: A comparison study of warning signs for suicide by self-immolation and by self-poisoning. Burns. 2011; 37(8):1419-26. [DOI:10.1016/j.burns.2011.04.006] [PMID]
27. Rahmani AH, Jafari M, Farnam M, Zafari J. [Evaluation of epidemiologic of drug poisoning in the Ahvaz Razi Hospital in the years of 2004-2008 (Persian)]. Iranian Journal of Forensic Medicine. 2015; 21(1):43-6. [Link]
28. Monsef Kasmaie V, Asadi P, Maleki Ziabari S. [A demographic study of suicide methods in the patients aided by emergency Paramedics Guilan (Persian)]. Journal of Guilan University of Medical Sciences. 2013; 22(87):31-7. [Link]
29. Shams Vahdati S, Moradi N, Hemat Ghadim J, Tajoddini S. Evaluation of suicide attempts with drug poisoning in North-West of Iran. Journal of Emergency Practice and Trauma. 2015; 1(1):1-2. [DOI:10.15171/jept.2016.07]
30. Kanchan T, Menezes RG. Suicidal poisoning in Southern India: gender differences. Journal of forensic and legal medicine. 2008; 15(1):7-14. [DOI:10.1016/j.jflm.2007.05.006] [PMID]
31. Oguzturk H, Turtay MG, Pamukcu E, Ciftci O. Demographic features of acute drug poisoning admitted to Inonu University Hospital in Malatya, Turkey. Scientific research and essays. 2010; 5(18):2761-7. [Link]
32. Sorodoc V, Jaba IM, Lionte C, Mungiu OC, Sorodoc L. Epidemiology of acute drug poisoning in a tertiary center from Iasi County, Romania. Human & experimental toxicology. 2011; 30(12):1896-903. [DOI:10.1177/0960327111403172] [PMID]