Incidence of road injuries in Iran

[Download detailed results tables: Iran_2005]
Last Updated: April 17 2011

Important: Please note that the results presented here are preliminary. Additional adjustments will be necessary as the results are made consistent with the ongoing Global Burden of Disease (GBD-2005) project, for which the results presented here are an input. Final estimates of the GBD-2005 study will be released in late 2010.  

About this report

Reliable statistics of road injuries are an essential input for describing the public health burden of injuries, evaluating the impact of safety policies, and benchmarking achievements. While injury surveillance systems are common in high income countries, most low and middle income countries are unlikely to have such capacity for several decades. In the interim, estimates should be derived by harmonizing injury statistics from the wide array of data sources that may be available in a country or region. 

This report summarizes our findings for the incidence of deaths and non-fatal injuries from road crashes in Iran. It is one of a series of national road injury assessments that we are producing during the course of this project. The intended audience of these reports includes the global donor community, the international research community, and national health and transport policy makers. We are committed to keeping this project open-source and collaborative in nature. All readers are encouraged to provide feedback to help improve methods, incorporate other sources of information, and suggest more effective methods for communicating these results.

Summary Results

In 2005, road crashes resulted in 30,772 deaths in Iran representing an annual injury rate of 44.0 deaths per 100,000 people. In addition, over one million people were victims of non-fatal injuries due to road crashes. Of the 18 countries that were analyzed in this project, Iran had the highest road injury death rate (Figure 1). The road injury death rate of Iran was 7.5 times the death rate in countries with the best road safety performance (Sweden, UK, and Netherlands). 

Road traffic crashes are the leading cause of injury deaths in Iran, resulting in seven times as many deaths as suicides and almost 20 times as many deaths as homicides (Table 1). In 2005, road injuries accounted for almost two-thirds of all injury deaths in Iran.  Compared with other health problems faced by Iran, road traffic crashes present a significant challenge, killing more people annually than the death toll of the 2003 Bam earthquake Road injuries are the third leading cause of death in Iran resulting in over 10.3% of all deaths, almost five times the world average (2.1%).   

How did we compute these estimates?

Our general methodology for estimating deaths and non-fatal injuries involves piecing together data from a wide array of sources that typically include death registers, hospital records, funeral records, health surveys, and police reports. This requires filling information gaps, mapping from varying case definitions, deriving population based incidence estimates from sources that may not track denominator populations, and appropriately reapportioning cases assigned to poorly specified causes. For a general description of the broad methodology, please visit the Methods-overview section of our website.   The following sections describe the specific data sources used, the estimation methods, and the key results for our estimates of road injuries in Iran. The analytical adjustments to the data introduce uncertainty in the estimates. Thus, wherever possible, we have outlined the effects of the adjustments on the estimates. 

Overview of data sources

We estimated the incidence and distribution of road injury deaths using data from the national death registration system and  forensic medicine. We estimated the incidence and distribution of non-fatal injuries using a hospital registry that recorded admissions and outpatient visits, and the results of the 2000 Demographic and Health Survey (Figure 2).

Estimates of road injury deaths and non-fatal injuries

We obtained micro-data for the 2005 death registration records from the Iranian Ministry of Health and Medical Education (MOHME). The Death Registration System (DRS) collects mortality data from district health centers. In rural areas, deaths are registered in approximately 17,000 Health Houses and reported to the district health centers. At the district level, death registration data are obtained from five sources: (1) all public and private hospitals, (2) official district cemeteries, (3) the district office of the Forensic Medicine Organization, (4) household visits by community health workers in rural areas, and (5) information from community health volunteers, clergymen and printed obituaries. In most cases, a physician provides death certification with cause of death reported in a format similar to the International Statistical Classification of Diseases 10th Revision. In 2005, which is the study year, the death registration system covered all 30 provinces except Tehran. 

Because the death registration data did not include the province of Tehran, we attempted generating estimates for this province using several different methods. For instance, we computed the estimates for Tehran province by applying the age- sex- urban/rural- and victim mode- specific death rates to the population of Tehran (6,449 road traffic deaths). Because most of the population of Tehran province lives in the metropolitan city Tehran, we also obtained estimates by applying death rates from the next five most populous cities in Iran (Ahvaz, Esfhan, Mashhad, Shiraz and Tabriz). We found a variation of over 400% suggesting that road traffic death rates vary considerably between cities. Thus, we used an alternate data source, forensic medicine, which reported province totals of road traffic deaths in Iran that were broadly consistent with our estimates from the death registration system for the remaining 29 provinces. Since forensic medicine did not provide a further break down of the 2,645 RTI deaths in Tehran, we have assumed the age- sex- and victim mode- breakdown computed from the other 29 provinces apply to Tehran. 

We obtained micro-data from a hospital sample registry conducted by MOHME in 2005, which collected injury case information from all hospitals in 12 provinces in a specified time period. This data included all inpatient cases during the first week of the last month of each season (4 weeks in total), and all outpatient cases during one randomly assigned day of each of these four weeks (4 days in total). Data was collated from the medical records of the victim, the DRS record for fatal cases, and an interview with household members of the victims. Data collected included variables that characterized the demographic and socioeconomic characteristics of victims, vehicles involved, highway types, environmental conditions, and injury and care details. We analyzed a total of 2,572 records outpatient records and 9,123 inpatient records.  We extrapolated road traffic injures rates during the time period of data collection in the 12 provinces to generate the annual estimate for the national population. 

Finally, we obtained data for the nationally representative 2000 Demographic and Health Survey (DHS), which covered 56,674 urban households and 54,952 rural households. We analyzed responses to three consecutive questions: 1. “Has any member of your household suffered an accident during the past month?” (Response Categories: “Yes,” “No,” “Do not know”); 2. "What was the type of accident?” (“Traffic accident” was one of the response categories); and 3. “What treatment did s/he receive?” (Response categories:  “Inpatient”, “Outpatient,” “At home,” and “No treatment.”)

Reclassification to GBD-2005 definitions: We reclassified age into 22 age-sex groups. The age definitions match those used by the GBD-2005 project and are available on the GBD-Injury expert group website.  

We reclassified the ICD coded deaths to the definitions of road injuries (and other injuries) as recommended by the GBD-Injury expert group. These definitions map all ICD codes for external causes of injury to 48 fully-specified cause categories and 21 partially-specified and undetermined cause categories. The fully-specified cause categories include nine road-user categories:
Pedestrian (V01-V04, V06, V09), 
Bicyclist (V10-V19), 
Two-wheeler rider (V20-V29), 
Three-wheeler occupant (V30-V39), 
Car occupant (V40-V49), 
Van occupant (V50-V59), 
Truck occupant (V60-V69), 
Bus occupant (V70-V79), and,
Other road injury (V80, V82, V83, V84, V85). 
The deaths classified to partially-specified and undetermined cause categories were redistributed over the fully-specified categories. All redistributions were done in proportion to the number of cases in the fully-specified causes within age-sex groups. The redistribution is done in 21 steps, one for each partially-specified category. This respects the information content in the hierarchical structure of the partially-specified categories. Thus, several of these steps do not affect the road injury estimates.  For instance, the category of firearm: undetermined intent was redistributed over the categories for firearm: unintentional, firearm: self-inflicted, and firearm: inter-personal. This redistribution step has no effect on the road injury estimates. Only the redistribution of the following partially-specified categories has an effect on road injury estimates:
Road injury - unspecified occupant, i.e. not pedestrian or bicyclist, 
Road injury - unspecified road user,
Unspecified transport injury,
Unspecified unintentional injury,
Unspecified mechanism - undetermined intent, and
Unspecified mechanism - unspecified intent.
Adjustments that have not applied yet: Two key adjustments that are likely to modify the road injury death counts have not been applied yet. First, we have not reallocated deaths coded to unspecified causes outside the ICD injury chapter. This reallocation has not been done yet because research into the causes of deaths coded to this category is currently ongoing. However, it should be noted that in Iran, only a small fraction of deaths are coded to this category and the effect on road injury death counts is thus expected to be small.   Second, we have made no adjustments to account for incomplete death registration (other than the adjustment for Tehran described above) becau se estimates of completeness of global death registration data are currently being developed. However, our preliminary comparison of total all-cause deaths reported in the death registration data analyzed by us with deaths reported by the UN Population Division suggests that death registration in 29 provinces of Iran (i.e. excluding Tehran) was near complete. It should be noted that both of these adjustments would increase the estimated death counts. Thus, the mortality results presented here likely underestimate the true number of road injury deaths.

Comparison of our estimates with other sources

Our estimate of road injury deaths in Iran are a third higher than those reported by official government statistics in the 2009 WHO Global Status Report on Road Safety (Figure 3), which are based on national forensic medicine.  Our estimates of road injury deaths are over seven times the number of deaths reported by police (4441 deaths in 2005).






Road deaths by age and sex

Most road deaths in Iran occur among adult males (Figure 4a). Over 4/5th (81%) of all road injury deaths were men.   Death rates (Figure 4b) among men are over 4.4 times those among women overall. Men have higher death rates for all age groups but the gender differential is smaller among the elderly.  Both death counts and death rates rise dramatically in the transition in age from childhood to young adults (see age groups 5-14 years and 15-24 years). Death rates continue to rise with age and are highest among the elderly.



Such age and sex patterns in deaths and death rates are consistent with those seen in other countries. For the most part, the gender differentials in death rate are a result of higher exposure to road traffic among men in combination with higher risk-taking behavior. Similarly, the age pattern of death rates partly reflects patterns of exposure and partly case-fatality rates. While exposure to road traffic declines with age among older populations, the bio-mechanical tolerance to injury (i.e. the likelihood of death in the event of a crash) also declines, resulting in increasing death rates with age. 

Road deaths by type of road-user

Most road deaths (42%) in Iran occur among car occupants (Figure 5). Pedestrians and motorcycle riders account for another 26% and 14% of all deaths, respectively.  The large number of deaths among motorcyclists in Iran is of special concern. Motorcycles are among the most risky modes of transport. It is already well known that in South-East Asia motorcycles comprise a large proportion of the vehicle fleet and this is reflected in their road injury statistics. However, our analysis suggests that motorcycle fleets and the injuries resulting from their use are rapidly rising in many other parts of the world. In Iran the number of motorcycle riders have risen very rapidly in recent years, at a rate dramatically higher than other vehicles. The number of motorcycles in Iran in 2005 was over four times the number in 2001. 

Non-fatal road injuries

In 2005, 1.06 million people (1.5% of population) suffered injuries for which they were admitted to hospitals (248,341 people), received outpatient care (491,307 people), or treated at home (290,321 people). An additional 0.29 million people were involved in crashes that did not receive any care. Rates of hospital inpatient admissions and outpatient visits have an age trend that is different from that of deaths (Figure 6). While the death rate increases steadily with age, the rate of non-fatal injuries peaks in the age group of 15-24 years and declines for higher ages.  

The distribution of road traffic crashes by victim's mode of transport is substantially different for deaths and non-fatal cases (Figure 7). While car occupants comprise the largest death category, over half of all hospital admissions and outpatient visits for road traffic crashes are riders of motorized two-wheelers. Motorized two-wheeler crashes result in a dramatically higher number of inpatient admissions (27.8) and outpatient visits (55.8) per death than for all road traffic crashes (8.1 and 16.0, respectively). Thus, the public health burden imposed by motorized two-wheeler riders on the Iranian health care system is not apparent from death statistics. 

Acknowledgements

These country reports were produced as part of a project funded by the World Bank Global Road Safety Facility. The results presented here are based on secondary data analysis of data collected by various national and international agencies. Dr Mohsen Naghavi, now based at the Institute of Health Metrics and Evaluation, Seattle, played an instrumental role in data access, analysis and interpretation. We are grateful to the Iranian Ministry of Health and Medical Education (MOHME) and its divisions, in particular the Deputy of Health, the Network Development and Health Promotion Center, Dr Esmaeel Motlagh and Dr Nahid Jafari for providing access to data sets. 
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Kavi Bhalla,
Oct 3, 2009, 3:48 AM
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Kavi Bhalla,
Oct 3, 2009, 3:48 AM