Haghparast-Bidgoli et al. International Journal for Equity in Health (2018) 17:77 https://doi.org/10.1186/s12939-018-0794-0 RESEARCH Open Access Socio-demographic and economics factors associated with suicide mortality in Iran, 2001–2010: application of a decomposition model Hassan Haghparast-Bidgoli1* , Giulia Rinaldi2, Hossein Shahnavazi3, Hamid Bouraghi4 and Aliasghar A. Kiadaliri5 Abstract Background: Suicide is a major global health problem, especially among youth. Suicide is known to be associated with a variety of social, economic, political and religious factors, vary across geographical and cultural regions. The current study aimed to investigate the effects of socioeconomic factors on suicide mortality rate across different regions in Iran. Methods: The data on distribution of population and socio-economic factors (such as unemployment rate, divorce rate, urbanization rate, average household expenditure etc.) at province level were obtained from the Statistical Centre of Iran and the National Organization for Civil Registration. The data on the annual number of deaths caused by suicide in each province was extracted from the published reports of the Iranian Forensic Medicine Organization. We used a decomposition model to distinguish between spatial and temporal variation in suicide mortality. Results: The average rate of suicide mortality was 5.5 per 100,000 population over the study period. Across the provinces (spatial variation), suicide mortality rate was positively associated with household expenditure and the proportion of people aged 15–24 and older than 65 years and was negatively associated with the proportion of literate people. Within the provinces (temporal variation), higher divorce rate was associated with higher suicide mortality. By excluding the outlier provinces, the results showed that in addition to the proportion of people aged 15–24 and older than 65, divorce and unemployment rates were also significant predictors of spatial variation in suicide mortality while divorce rate was associated with higher suicide mortality within provinces. Conclusion: The findings indicate that both spatial and temporal variations in suicide mortality rates across the provinces and over time are determined by a number of socio-economic factors. The study provides information that can be of importance in developing preventive strategies. Keywords: Suicide mortality, Temporal variation, Spatial analysis, Panel data, Iran Background between 1980 and 2015. Although rates of fatal suicide Suicide is a major global health problem, especially have found to be overall decreasing in countries across among youth, where suicide is in the top three causes of the world from the 1990s to the present [3–8], this is death in people aged 10–24 years [1]. Overall, suicide not the case in certain countries and age groups [9–13]. and self-harm is the 18th highest cause of disability ad- Countries with the highest suicide rates are Eastern justed life years (DALYs) loss globally [2]. Evidence also European neighbors (including Russia, Estonia, Latvia shows that DALYs loss contributed to self-harm has de- and Lithuania) as well as countries such as Sri Lank, creased by 17% from 2005 to 2015 and that the death Korea and Cuba [14]. Teenagers and young adults carry rates due to self-harm have also decreased by 16.3% the high rates of suicide mortality in these countries with 46.5 and 23.6 suicide deaths per 100,000 population in Sri * Correspondence: [email protected] Lanka and Russia, respectively, recorded per year amongst 1Institute for Global Health, University College London, 30 Guilford Street, 15–19 year olds [15]. Suicide rate in the Eastern Mediter- London WC1N 1EH, UK ranean Region (EMR) countries is reported to be lower Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Haghparast-Bidgoli et al. International Journal for Equity in Health (2018) 17:77 Page 2 of 7 than the average global suicide rates, ranging from 0.55 to Statistical analysis 5.4 per 100,000 population [16]. However, mental disor- A decomposition model, similar to Phillips [42] was used ders, such as depression and anxiety in the EMR region for the data analysis. This model was used in order to are present at a higher rate than average global level [9]. differentiate between spatial (across provinces) and tem- In Iran, suicide rates have increased from 4.4 to 5.2 poral (over time) variations in suicide mortality rates per 100,000 population from 2006 to 2010, with the lar- and to determine how socio-demographic and economic gest burden being amongst males and amongst those 20 factors associate with suicide mortality rates in these to 29 years old [12, 17]. Fatal suicide attempts were two contexts. The model is expressed as follows: higher in males, but non-fatal attempts were higher in females [18]. Around 83% of deaths by suicide in Iran yit ¼ α þ βXi þ η ðÞþxit−Xi νi þ γt þ εit are in urban areas [18] and among them 79.9% of the in- dividuals were not working (including housewives, stu- yit represents suicide mortality rate; α is the intercept; β dents or unemployed men) [19]. Suicide rates in age captures the effect of between-province differences, rep- groups are vague with evidence reporting the highest resented by province means (shown in capital letters) for suicide rates amongst 15–65 year olds [18]. a specific characteristic over the entire period; xit repre- Suicide is known to be affected by a variety of social, sent the explanatory variables for each province i and economic, political and religious factors in different pop- year t; η measures the effect of within-province changes, ulations [20–22]. Factors associated with suicide vary i.e. province-year deviations from the overall province across geographical and cultural regions. Contradictory mean. Therefore, the β coefficients show how socio- evidence shows that lower socioeconomic status can be demographic and economic factors are associated with positively or negatively associated with suicide rates de- cross-sectional change in suicide mortality rates (across pending on the location [22–32]. Similarly, certain popu- provinces) and the η coefficients show how the covari- lations have the highest suicide rates amongst the young ates associate with temporal variation in suicide mortal- [12, 24, 33] and others amongst the elderly [7, 25, 34, 35]. ity rates (over time within provinces). The model also Studies assessing associations of suicide have been carried includes a province-specific residual term, νi, which is out in many countries [21, 22, 24–30, 36–38], but handled as a random variable and allows correlation there is a need to explore the associations of suicide among observations from the same province, γt are year- within Iran. This study aims to investigate the effects specific dummy variables to capture aggregate time ef- of socio-demographic and economic factors on suicide fects that influence all provinces, and a residual error mortality rate across and within different regions in term, εit, which permits correlation over time among Iran. It specifically, assessed spatial and temporal vari- observations from the same province. The model was es- ations in suicide rate across different provinces, for a timated using maximum likelihood techniques with ro- period of 10 years (2001–2010). bust standard errors [42]. Methods Results Data and data sources Table 1 presents descriptive statistics for dependent and The data on the distribution of population by province and independents variables. Between 2001 and 2010, the year were obtained from the Statistical Centre of Iran [39]. mean suicide mortality rate across the 28 provinces, was Data on annual suicide mortality in each province were col- 5.47 per 100,000. The variation in suicide mortality rates lected from the published reports of the Iranian Forensic across provinces was greater than those within states Medicine Organization (IFMO) affiliated to the Judicial Au- over time, indicated by the larger spatial standard devi- thority in Iran [40]. The IFMO is responsible for recording ation compared to the temporal standard deviation. all suicide cases in a national registry. All recorded suicide There are also substantial differences in economic var- cases are certified by autopsy [41]. We then calculated the iables across and within the provinces over time. For ex- suicide rate per 100,000 people by province and year. ample, urbanization rate with standard deviation of 12 Annual province-specific data on socio-demographic and 2.3% varies considerably across provinces and over and economic variables including unemployment rate, time, respectively. divorce rate, urbanization rate, average household ex- Table 2 shows the cross-sectional and temporal varia- penditure, literacy rate, and percentage of male in popu- tions in the suicide mortality rate and the covariates be- lation were collected from the Statistical Centre of Iran tween 2001 and 2010. Detailed summary statistics for all for all 28 provinces for the study period (2001–2010). It the variables and for each province are presented in should be noted that in 2004, a province (Khorasan Additional file 1. Overall, there are substantial variations province) split in 3 provinces and we pooled data for in suicide mortality rate and covariates across the prov- these three provinces for years 2005–2010. inces in both 2001 and 2010. For example, in 2001, suicide Haghparast-Bidgoli et al.