Top Ten Causes of Death and Life Expectancy in Zahedan ( South-East Iran ) in 2014

Introduction: Life expectancy is an overall measure of population health. Sistan and Balouchestan is the biggest in terms of geographical size and one of the least developed provinces in Iran. We tried to determine the top 10 causes of death and life expectancy in Zahedan in 2014 and compare them with other parts of Iran and global pattern. Methods: It is a cross-sectional study. Our population included residents of Zahedan in 2014. We used data from the death registration system according to ICD10 codes to determine the top 10 causes of death in Zahedan. We tried in this study to apply William Brass method to modify mortalities undercount. Then we estimated the life expectancy for men and women in Zahedan by providing lifetime tables. Results: Thetop ten causes of death in Zahedan were, respectively: 1injury, poisoning and other certain consequences of external causes, 2certain conditions originating in the prenatal period, 3-strokes, 4ischemic heart diseases, 5-neoplasm, 6Alzheimer disease, 7hypertension-related diseases, 8congenital malformations, deformations and chromosomal abnormalities, 9certain infectious and parasitic diseases and 10respiratory system infections. The death registration coverage in Zahedanhad been 83% for men and 73% for women in 2014 based on William Brass method. After applying undercount deaths and based on life tablescalculation we determined life expectancy 64.39 years and 67.51 years respectively for men and women in Zahedan city in 2014. Conclusion: In regard to ranks of strokes, ischemic heart disease, road accidents and cancers in our study; our resultsare similar to countries with middle income and higher income. Also, it is pertinent to also state it that thesecond rank of prenatal disease in our population is similar to that of the low-income countries.The relatively low life expectancy in Zahedan indicates the less developed condition and a purposeful intervention to improve the development condition and the prevention of the main causes of death in Zahedan are necessary to improve life expectancy in this region.


Introduction
Life expectancy is an overall measure of population health.The approximate doubling of life expectancy over the last century is a demonstration of substantial scientific and public health progress (Hum, Verguet, Cheng, McGahan, &Jha, 2015).
Life expectancy is the average number of years a person can expect to live given the current age-specific mortality rates (WHO, 2015a).
Significant variations in life expectancy still persist between high and low-income communities.Life expectancy is increasing and this has been attributed to improvements in sanitation and access to safe water; medical advances, including childhood vaccines, and massive increases in agricultural production.Life expectancy reflects the health status of a country's people and the quality ofhealth care they receive.
Life expectancy at birth has been increasing for both sexes in recent decades in Iran.It has steadily increased from 37.5 years in 195637.5 years in to 47.5 years in 196637.5 years in , 55.7 years in 197637.5 years in to 58.9 years in 198637.5 years in , 64.7 years in 199637.5 years in , 71 years in 200637.5 years in and 74 years in 201237.5 years in (WHO, 201137.5 years in , 2013)).
According to the WHO reports (2013), the mortality pattern has changed in Iran and in the world and the causes of death have transformed from infectious diseases like AIDS and malaria to chronic ones like cardiovascular diseases and cancers (WHO, 2013).The four main causes of death according to the prediction of WHO, for the future will be heart failure, stroke, chronic lung obstructive diseases and the lower respiratory system infection in 2030.Coronary artery diseases and cancers incidence due to aging population indicates the lower mortality rate due to infectious diseases (Heidari & Heidari, 2009).
Naghavi et al duringa period of 1990-2010 in Iran found a decreasing trend in age-specific mortality rate for both sexes, this mortality rate reduction was more significant in women (Naghavi et al., 2014).
Abdollahzade et al performed a study for classifying regional development in Iran.They used several indicators such as; social, population and cultural (14 indicators), economics (13 indicators), infrastructural and services (14 indicators).They concluded that Tehran, Semnan and Esfahan provinces were ranked in the first position and Kohkiloyeh-Boyrahmad, Lorestan and Sistan-Bluchestan provinces were ranked in the last position.(Abdollahzade & Sharifzadeh, 2012) Another study by Zarrabiand ShaykhBaygloo at 2011 compared health indicators between Iran provinces .They applied five main indices thatincluded, expert human resources, rural health services, medical facilities, governmental health services and private sector services.They showed that Tehran is the most developed and Ilam, Kohkiloyeh-Boyrahmad, South Khorasan and Sistan-Bluchestan provinces are the most deprived provinces in Iran based on health indicators (Zarrabi & Shaykh Baygloo, 2011).
Sistan and Balouchestan is the widest and one of the least developed provinces in Iran (southeast).Based on 2011 Iran statistics center, it had the lowest life expectancy as compared to the other provinces (Teyfouri & Akbari, 2013).Also, Tehran and Gilan provinces have the highest and Sistan and Balouchestan province has the least life expectancy based on the results of the last ministry of health researches in Iran (Teyfouri & Akbari, 2013).
Zahedan is the capital of Sistan and Balouchestan province and it had more complete and more reliable death registry system in comparison with other cities in the province.Then we went further to design our study only on the Zahedan population.
We tried to determine the top 10 causes of death and life expectancy in Zahedan in 2014 and compare them with Iran and global pattern.

Materials and Method
It is a cross-sectional study.Our population included residents of Zahedan in 2014.Population statistics obtained from population and housing census in 2011 that was carried out by Iran statistics center, and then we estimated it for 2014 by applying population growth rate.
Mortality data was extracted out ofthe death registration system in the provincial health center.We used data from the death registration system according to ICD10 codes to determine the top 10 causes of death in Zahedan.ICD10 is the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD), a medical classification list by the World Health Organization.It contains codes for diseases, signs and symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or diseases (WHO, 2014).
There is a death registration system software has been designed by Iran ministry of health.All death data after being adjusted with the information of civil registration organization and also the cemeteries were recorded in this software.
Taking cognizance of mortalities undercount and the existence of unofficial graveyards, we tried in this study to apply William Brass method (Mathers, Vos, Lopez, Salomon, & Ezzati, 2001) to modify mortalities undercount.In 1975 William Brass introduced a method to estimate the completeness of adult death registration.In this method we should use the number of death registered by age in a five-year period, also we need mid-year population size by every period of age.The outcome of this method is an average estimate of the extent of under-reporting of death above age 5. Separate calculations have been done for male and female as under-reportinghad been calculated for both sexes.Then we proceeded by estimating the life expectancy for men and women in Zahedan by providing lifetime tables.

Results
We evaluated 2890 registered deaths in 2014 that included 1710 men and 1180 women.The most common causes of death are summarized in table 1  The top ten causes of death in Zahedan based on main groups of diseases in ICD10 coding are shown in Table1.
We used life-table calculations based on available death registration system data, and life expectancy was calculated 68.3 years in Zahedan (66.8 years for men and 70.4 years forwomen).But due to the undercount of available data in the death registration system center, we tried to estimate the undercount percent by using the brass method.Tables 2, show Brass method calculations for thedetermination of undercount percent for both sexes.
Table 2. William Brass calculations for the determination of undercount percent for both sexes As we can also see in Table 2, death registration completion in Zahedan had been 83% (17% undercount) for men and 73% (27% undercount) for women in 2014 based on William Brass method.Also, we can see in figure1 and 2; outlier data that indicate the incompleteness of death registration.
PBR: Partial Birth Rate, PDR: Partial Death Rate To calculate the life expectancy, we first multiplied the number of deathsby K (1.202 for men and 1.359 for women), then life expectancy for men and women was calculated based on lifetime table (Tables 3 and 4).After applying undercount deaths and based on life table calculations, we determined life expectancy 64.39 years and 67.51 years respectively for men and women in Zahedan city in 2014.

Discussion
Having ignored the undercount cases of death, it was recognized in our study that total life expectancy for men and women in Zahedan is 68.3 years which is approximately the same as the published results of Iran ministry of health study for Sistan and Baloochestan province in 2011 (68.42 years) (Neisi, 2010).But applying mortality undercount by William Brass method, the life expectancy of men and women in Zahedan at birth is 64.3 and 67.5 years which is lower than the reported one by the ministry of health in 2011 and is closer to the reality.
Based on Iran's ministry of health report, Kurdistan, Kerman and Ilam provinces have the least life expectancy 69, 35, 69.4 and 69.39 respectively after Sistan and Balouchestan province.Tehran, Yazd, Isfahan and Ghazvin have had the highest life expectancy in the country with 71.39, 71.42, 71.59 and 72.3 years respectively (Neisi, 2010).
Life expectancy is one of the most important development indexes based on WHO third millennium goals.
It is known that the socio-economic variables such as per capita income, education and government expenditure on health are strong determinants of life expectancy in developing countries (Sede & Ohemeng, 2015) Sistan-Bluchestan provincewas ranked in the last position of development indicators in Iran in comparison with other provinces.(Abdollahzade & Sharifzadeh, 2012).Also, it is one of the most deprived provinces in Iran based on Health indicators (Zarrabi & Shaykh Baygloo, 2011).
Then low life expectancy in the center of Sistan and Balouchestan province obviously indicates an undesired developmental condition and deprived health services.
The gap in gender life expectancy is observed all over the world, as almost in all countries of the world women live longer (Barford, Dorling, Davey Smith, & Shaw, 2006), but the degree differs among countries or regions.This gap has been engendered by health behaviors, socio-economic status, culture related dietary habits, fertility preferences, environmental or genetic and physiologic factors (Lindahl-Jacobsen et al., 2013), with the interaction of the effect of several bio-psycho-social risk factors on the survival .Also based on our result women life expectancy was 3 years more than men in our study.
According to Iran ministry of health report in 2011, the average of life expectancy for men and women were respectively 72.1 and 74.6years (Neisi, 2010).Then in comparison with the country's average, we found a gap in life expectancy as 7.8 and 7.1 years respectively for Zahedani men and women.These differences can be related to the different pattern of mortality, as we found in this study significant differences regarding the main causes of death in Zahedan with the most common causes of death in Iran and in the world.
The top five causes of death in our study were respectively: 1).Injury, poisoning and other certain consequences of external causes (64.14% % related to traffic accidents), 2).Certain conditions originating in the prenatal period, 3).Strokes, 4).Ischemic heart diseases, 5).Cancers.The top five causes of death based on the report of Iran ministry of health in 2010 included 1).Ischemic heart diseases, 2).stroke, 3).Injury and poisoning, 4).Hypertension-relateddiseases, 5).Cancers (Khosravi et al., 2011).The first rank of injuries and the second rank of prenatal diseases are completely different from country patterns.
Also the top ten main causes of death in the world based on 2014 WHO report are, ischemic heart disease, stroke, lung obstruction diseases, lower respiratory system infection, lung and respiratory tract cancer, HIV/AIDS, diarrhea-related diseases, diabetes mellitus, road accidents and hypertension.This ranking is different for countries based on their income.While the main causes of death in low-income countries are, lower respiratory system infection, HIV/AIDS, diarrhea-related diseases, stroke, ischemic heart disease, malaria, premature birth disorders, tuberculosis, asphyxia during birth trauma and protein-energy malnutrition.
In middle-income countries, they include ischemic heart disease, stroke, lower respiratory system infection, lung obstruction diseases, diarrhea-related diseases, premature birth disorders, HIV/AIDS, diabetes, tuberculosis, and cirrhosis.
While for countries with upper middle income, stroke, ischemic heart disease, lung obstruction diseases, lung and respiratory tract cancer, diabetes mellitus, lower respiratory system infection, road accidents, hypertension -related heart diseases, liver and stomach cancer are the main cause of death.
Finally in high-income countries, the maincauses of death are, ischemic heart disease, stroke, respiratory tract and lung cancer, Alzheimer disease, dementia, lung obstruction diseases, lower respiratory system infection, colon cancer, rectum cancer, diabetes mellitus, hypertension-related heart diseases and breast cancer (WHO, 2015b).
In regard to ranks of strokes, Ischemic heart disease, road accidents and cancers in our study; our results is similar to countries with middle and higher income bracket.But the second rank of prenatal disease in our population indicates the less developed condition and undesirable health care services especially for pregnant women and newborns that can be more similar to low-income countries.
Based on our results, accidents and injuries had the first rank of mortality in Zahedan and 67.22% of all mortalities due to injurieshad been caused by traffic accidents.
TaravatManesh et al studied the epidemiology of fatal traffic injuries in Sistan and Balouchestan province in 2011 and described that this province in comparison with other provinces of Iran had the most unsafe roads and is one of the provinces with high traffic injuries.They reported that among all traffic fatal injuries, 78.8%had occurred in males and 21.3% in women.The mean age of these deaths was 30.19± 16.9 (Taravatmanesh, Hashemi-Nazari, Ghadirzadeh, &Taravatmanesh, 2015).This fact can be one of justifying factors of low life expectancy in Zahedan and also lower life expectancy in men than women.
As well prenatal period diseases as the second rank of mortality are obviously another reason for low life expectancy in this city.
Naghavi et al investigated Iran health transition based on global burden of diseases in 2010 and found that major causes of disability-adjusted life year (DALYs), such as injuries, interpersonal violence, and suicide, showed increasing trends, while rates of communicable diseases, neonatal disorders, and nutritional deficiencies have declined significantly (Naghavi et al., 2014), and as we found in our study, the injuries are the first cause of death in Zahedan population.
Tarkiainen et al. studied trends in life expectancy by income from 1988 to 2007 in the Finnish general population and reported that the gap in life expectancy between the highest and the lowest income population widened during the study period by 5.1 years among men and 2.9 years among women.The increasing gap in life expectancy was mainly due to increasesof mortality in the lowest income population and most importantly because of the increasing mortality in alcohol-related diseases.Their result determined an essential need to eliminate the specific health problems of the poorest (Tarkiainen, Martikainen, Laaksonen, & Valkonen, 2012).
In developed countries like the U.S.A, the decrease in deaths from heart disease, cancer, and HIV were confirmed to increase life expectancy for both sexes, among all racial or ethnic groups and for both US born and the foreign born (Li, Maduro, & Begier, 2015).
In the United States of America, life expectancy for the black population was 3.8 years lower than thewhite population.This difference was related to higher mortality rates for the black population due to heart disease, cancer, homicide, diabetes and prenatal conditions (Kochanek, Arias, & Anderson, 2013).
Mackenbach et al investigated the causes of the sudden improvement in life expectancy in Central and Eastern Europe in the 1990s.They concluded that the increase in life expectancy in Central and Eastern Europe had started at different times, but the main cause of this aforementioned improvement relates to the prevention or treatment of ischemic heart disease in all six countries and also changes in alcohol consumption and road traffic safety in some countries (Mackenbach, Karanikolos, Lopez Bernal, & McKee, 2015).
We also reported in our results, a lower life expectancy in comparison with other parts of Iran and the global pattern due to the different ranking cause of death in Zahedan.

Conclusion
With reference to the ranks of strokes, Ischemic heart disease, road accidents and cancers in our study; our results are similar to countries with middle and higher income.Conclusively it is also important to state it that the second rank of prenatal disease in our population is similar to those of the low-income countries.The relatively low life expectancy in Zahedan indicatesa less developed condition and purposeful intervention a holistic approach to improving the development condition and prevention of the main causes of death in Zahedan are necessary to improve life expectancy in this region.
): registered Death for any age period; N(X): reported population for any age period; D(X+): registered death over age X; N(X+): population aged X and over.C: the final estimate of the completion of death registration.

Figure 1 .
Figure 1.Completeness of Death Registration usingBrassGrowth Balance Method for male in Zahedan, 2014 m(x): probability of dying during interval x =n(x)[d(x)p(x)]; I(x); number of defaults surviving at the beginning of interval x; D(x); number of deaths in default population= m(x)I(x); L(x): person-year lived in the interval x= n(x)[L(x+1)+ a(x)D(x)]; T(x); Total persons-year cumulated from bottom; E(x); Life expectancy=T(x)/L(x).
m(x): probability of dying during interval x =n(x)[d(x)p(x)]; I(x): number of defaults surviving at the beginning of interval x; D(x):number of deaths in default population= m(x)I(x); L(x): person-year lived in the interval x= n(x)[L(x+1)+ a(x)D(x)]; T(x): Total persons-year cumulated from bottom; E(x): Life expectancy=T(x)/L(x); e(x): Life expectancy; based on the ICD 10 classification.Table1.Top ten causes of death in Zahedan population in 2014

Table 4 .
Life table for women inZahedan (2014) a(x): Proportion alive at the beginning of age interval x; p(x): Number alive at the beginning of the age interval x; d(x): number of deaths at age interval x;