This study tried to looks back on the trend of mortality of young people during the last decades and also how the main causes of deaths, which classified based on the ICD-10 format, have been changed during the same period. Although the mortality rate reduced by 54% during the period, a surprising upward rate was observed in 2003 (Fig. 1). It is believed that the cause of this sudden increase in mortality in 2003 might be attributed to the massive earthquake of Bam city on December 26, 2003, which killed about 25,514 people, including many young people (24).
According to the findings, the mortality rate was higher among young men compared to women. In other studies, young men of all ages in the world has also higher death rates than women except in Africa and Southeast Asia, which is mostly attributed to maternity- related factors (8). The results of a study by Murray and Lopez in eight regions of the world showed that 53% of deaths occurred in men and the highest frequency was related to Ischemic Heart disease (25). The results of a study by Boroumand-nia et al. (2019), which examined the mortality rate in Iranian men, showed that ischemic heart disease, RTI and ischemic stroke were the most common causes of death among Iranian adult men in 2016 (26). Figure 4, compares the mortality rate of young people aged 15–24 in Iran, the EMRO, the region where Iran is located, and the world, in which, Iran's data are aggregated within the EMRO data and the EMRO data are aggregated within the world data. According to this Figure, the mortality rate of women in all three regions is lower than that of men. Furthermore, the mortality rate of Iranian women is lower than women in the whole world and in the EMRO, while the mortality rate of women in the EMRO is higher than the other two places. Also, the mortality rate of men in the EMRO has surpassed the mortality rate of men in the world since 2002 and had the highest mortality rate. However, in 2003 alone, the mortality rate of Iranian men due to the above-mentioned cause was higher than that of other two regions.
Findings showed that the most common cause of mortality among Iranian youth has been “injuries” during the study period and the “RTI” was the most prevalent sub-cause (Fig. 2). Injuries and specially RTI are also one of the leading causes of death and disability among young people in the world, killing more than 4.4 million people in 2017 and putting a major strain on global health (27). According to statistics, almost 90% of injuries occur in low and middle-income countries (LMICs) (28) and Iran have the highest rate compared to other LMICs (29, 30). The results of other studies in Iran showed that the highest number of deaths due to RTI is among men and in the age group of 15–24 years and 34–35 years (42% of the total mortality) (31, 32). A high percentage of deaths in this age group could be due to more involvement in road transport, greater tendency for high-risk activities, and less tendency to follow traffic rules (33, 34). RTI in Iran are estimated to cause a loss of 2271 years of life each year, as well as financial loss of $ 6 billion (35, 36).
According to the results of the present study, after RTI, “unintentional injuries” have been in the second rank of death cause and the SH and IPV have been responsible of most deaths after the mentioned causes during the last decades (Fig. 3). An earlier study in Iran showed that the number of deaths due to attacks with firearms and sharp objects increased during the study period 1990–2015 (37). The results of a meta-analysis also showed that the trend of suicide attempt or SH is increasing in Iran (38). There is an evidence that in the EMRO, the number of deaths due to IPV has more increased in recent years compared to rest of the world due to the recent widespread conflicts in this region (39). Findings of a systematic review in the EMRO showed that although the mortality rate in people aged 0–19 years due to “RTI” and “other unintentional injuries” decreased during the years 1990 to 2017, mortality due to "SH and IPV" increased in this age group and tripled during this period (40). The results of a study by Patton et al., which examined the global pattern of mortality in young people, also showed that SH and suicide were increased in young men and women and was the second most common cause of death in this age (8). Therefore these statistics necessitate attention to this matter among young people, who are the reproductive generation of any society. The role of parental divorce, hormonal fluctuations that disrupt their mental state and access to firearms are SH-related factors in this population (41). However, regression analyses conducted in this study indicated that all of the four sub-causes of “injuries”, had a statistically significant downward trend, except death due to substance use disorders (SUD) which had a significant upward trend during the last decades (Table 2). Thus, although the other three sub-causes of injuries, especially RTI, leads to considerably more deaths among young people, and thus requires serious preventive actions, the SUD, on the other hand, needs special attention due to its increasing rate. Recent studies in Iran indicates an increasing rate of tendency to drug abuse such as Tramadol, Ritalin, Pethidine, and Morphine, especially among young people (42). It also needs consideration that, SUDs are concurrence with other problems such as depression, mood disorders, anxiety disorders, and personality disorders that make the situation more difficult to resolve (43). Evidence shows that poverty, family problems, marital discord, inappropriate patterns of assimilation, unemployment, academic failure and psychological problems and underlying factors for the tendency towards addiction among young people (44). Restricting access to drug use, increasing awareness on high-risk age groups are recommended to combat with drug abuse (45).
The NCDs have been the second main causes of death of young people during the last three decades (Fig. 2), and of its sub-causes, death due to the CVDs and neoplasm caused the highest mortality rate among people aged 15–24 years (Fig. 3). Worldwide, deaths due to the NCDs projected to increase from 38 million in 2012 to 52 million in 2035, mostly due to the population ageing (46). Most deaths by the CVDs are due to ischemic heart disease and stroke, one third of which occur in people under 70 years of age (47). Data have shown that the CVDs will lead to death in more than 23 million people (approximately 30.5%) worldwide by 2030 (49). Based on the analytical findings in this study, death due to the ‘Neoplasm’ has an increasing trend with an annual regression coefficient of 0.065 in young people during the study period (Table 2). Based on predictions, assuming that there is no change in diagnostic methods and the status of risk factors, the number of new cases of cancer in Iran will increase to 54% by 2035 (51). Therefore, increasing awareness of risk factors, signs and symptoms of cancers should be considered as a priority in cancer control planning, especially in younger female population, subject to be in higher risk of breast cancer (52). The NCDs is actually very important for considerations, as of the three main categories of death causes, only death due to the NCDs showed a significantly increasing trend during the last decades. Also, except death due to the CVDs, which was the only sub-category of the NCDs with a significant downward trend, the other sub-categories including ‘Neoplasm’, ‘Diabetes and kidney diseases’, ‘Mental disorders’, ‘Musculoskeletal disorders’, ‘Chronic respiratory diseases’ and ‘Skin and subcutaneous diseases’ all showed a growing trend, thus, needs more and special considerations (Table 2).
The third leading cause of death among young people is called as ‘communicable, maternal, neonatal, and nutritional diseases’, which has a lower mortality rate among young people than the other two main causes mentioned. Over the past decades, the prevalence of infectious diseases has decreased significantly. Improvements is socio-economic strategies and success in the primary health care system to control communicable diseases, infants, mothers and nutrition, as well as population aging, urbanization, industrialization and lifestyle changes have put Iran in a state of transition from communicable diseases to the NCDs (53). However, in the category of communicable diseases, “HIV/AIDS and sexually transmitted infections” was the only sub-category witnessing a significant rising trend. The result of a recent study indicated that, of all causes of maternal mortality in Iran, HIV/AIDS have been the only one, making more deaths and have had a growing trend during the last three decades (22). Therefore, special attention should be paid to this cause by health authorities in Iran.
Examining past trends in death rates and causes strengthens insights into the state and future trends in health and death-related indicators, which are crucial for policy-making, especially in developing countries with limited resources. The results of this study, due to considering data from about three decades in the country and comparing it with other countries in the same period, are of great importance, especially compared to cross-sectional or short-term studies and can be used by health policy makers in the country in predicting the causes of youth death in the future. Examining past trends in rates and causes of mortality strengthens insights into the future trends in health- and death-related indicators, which are crucial for policy-making, especially in developing countries with limited resources. The findings of this study are highly reliable due to the use of accurate and complex statistical analysis and can provide a basis for researchers to perform many other studies. However, this study also has some limitations, the most important of which is the estimated data of the GBD, which is the basis of this study. Since the data related to the causes of death are not available anywhere else and these data are not complete and accurate even at the level of Ministry of Health of countries, and are also considered highly confidential and not available to researchers, the only solution is to use estimated international data sources such as the GBD. Considering the results regarding the trend of youth mortality causes in the last 28 years in Iran and comparing them with similar data from other regions of the world, important outcomes can be achieved, and programs and policies can be considered to reduce youth mortality in Iran by paying special attention to the causes.