Azadeh Nouhi Siahroudi ^1* Seyed Saeed Hashemi Nazari ^2,3* Mahshid Namdari ¹ Mohammad Hossein Panahi ^1,4 Seyed Amirhosein Mahdavi ⁵ Ali Khademi ⁶

• ¹ Department of Epidemiology, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran, Iran, Tehran, Iran
• ² Department of Epidemiology, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran., Tehran, Iran
• ³ Prevention of Cardiovascular Disease Research Center, Department of Epidemiology, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran, Tehran, Iran
• ⁴ Safety Promotion and Injury Prevention Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran, Tehran, Iran
• ⁵ Legal Medicine Research Center, Legal Medicine Organization of IRAN MD, Tehran, Iran., Tehran, Iran
• ⁶ Legal Medicine Research Center, Iranian Legal Medicine Organization, Tehran, Iran, Tehran, Iran

Background Suicide represents a critical public health concern and one of the most devastating forms of death. Based on a report from the World Health Organization, around 700,000 deaths by suicide occur globally each year. In 2019, the worldwide suicide mortality rate was 9.0 per 100,000 people, while in Iran, this rate has been reported to be an average of 5.2 . Suicide is influenced by various factors spanning individual, relational, community, and social domains. One significant factor potentially impacting this issue was the COVID-19 pandemic, which may have affected these trends by disrupting individuals' social interactions. The present study was carried out to investigate the impact of the COVID-19 pandemic on the changes in suicide rates in Iran .This study was designed using an interrupted time series approach combined with negative binomial regression. Seasonal effect was adjusted for using the harmonic method. The research sample comprised 63,514 suicide recorded between April 20, 2009,- March 20, 2023. Suicide mortality data were sourced from the National Legal Medicine Organization. The study analyzed trends in suicide incidence both prior to and during the COVID-19 pandemic. The period used to evaluate pandemic-related changes in Iran began in May 2020, following the WHO declaration of COVID-19 as a global public health emergency. Descriptive analyses were performed using Stata software, and trend assessments through the Interrupted Time Series method were conducted using R software and the "lmtest" statistical package. The changes in the incidence of suicide during the study increased by 1.003 monthly (p<0.001). This rate increased by 1.1 (p<0.001) compared to the times before the onset of the pandemic after entering the effect of the COVID-19 pandemic in the model. When the interaction effect of time with the COVID-19 pandemic was added to the base model, no significant relationship was observed.Before the COVID-19 pandemic, suicides in Iran had a proportional increasing trend. However, three months after the pandemic, an increasing trend in the level of suicide deaths was observed. Most likely, the COVID-19 pandemic phenomenon had an impact on the occurrence of suicide.