Mexico

Incidence of road injuries in Mexico[Download detailed results tables: Mexico-WebTables]

Last Updated: April 16 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.  

Download PDF version of report: click here

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 Mexico. 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 20,339 deaths in Mexico representing an annual injury rate of 18.2 deaths per 100,000 people. In addition, almost two million people were victims of non-fatal injuries due to road crashes. Of the six countries in the Latin American region that were analyzed in this project, Mexico had the third highest road injury death rate (Figure 1). The road injury death rate of Mexico was 3.1 times the death rate in countries with the best road safety performance (Sweden, UK, and Netherlands). 

Injuries as a whole, including from unintentional and intentional causes, resulted in 52,536 deaths or 10.6% of all deaths in Mexico in 2005. Road traffic crashes are the leading cause of injury deaths in Mexico, resulting in almost twice as many deaths as homicides and five times as many deaths as suicides (Table 1). In 2005, road injuries account for 39% of all injury deaths in Mexico.

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 Mexico. 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 in Mexico using national death registration data obtained from the WHO Mortality Database. We estimated the incidence and distribution of non-fatal injuries using the results of the 2002/2003 World Health Surveys and the ENSANuT Health Survey.

Estimates of road injury deaths

Our review of data sources for estimating national road injury deaths in Mexico revealed two potential data systems: national death registration data and data from traffic police. In this study, we have computed estimates of national road injury deaths from the former (death registration) and compared them with those reported by the latter. We obtained death registration data from the publicly available WHO Mortality Database. These data are tabulations of deaths recorded by national civil registration systems. Typically these systems record age, sex, and causes of death coded using principles of the International Statistical Classification of Diseases (ICD).  A total of 53 years of data were available, most recently for the year 2006. We analyzed data since 1970 and present detailed results for the year 2005. 

Reclassification to GBD-2005 definitions: We reclassified age into 38 age-sex groups. The age definitions match those used by the GBD-2005 project and are available on the GBD-Injury expert group website. Click here to go directly to the age definitions. 

We reclassified the ICD coded deaths to the definitions of road injuries (and other injuries) as recommended by the GBD-Injury expert group [Click here for full details]. 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:

In addition, there are two partially-specified sub-categories of road injuries:

Table 2 shows the distribution of the 52,536 injury deaths reported in the death registration data for the year 2005. It should be noted that the 21 partially-specified categories have a hierarchical structure of specificity and many of these categories are not related with road injuries. 

We assessed the quality of the death registration data based on the distribution of the number of deaths in the partially specified categories. As shown in Table 2, the quality of the death registration as measured by the fraction of death registration cases assigned to partially specified categories is reasonably good for estimating total road injury deaths in Mexico. However, it should be noted that almost one-fifth (19.8%) of all injury deaths assigned to unintentional injuries, did not specify a mechanism. Further, about one-fourth (27.1%) of cases assigned to road injuries do not have a road-user specified. About one-third (35.1%) of road injury deaths that are assigned to vehicle occupants, do not identify the type of vehicle. This introduces the potential for some biases in estimating the incidence of road injuries, and particularly in the road-user disaggregation.  

Reallocation of injury deaths coded to partially-specified causes: 

The effect of these redistribution steps is evident in Figure 2, which shows the change in the estimated number of road deaths after each redistribution step. The death registration data has 16,148 deaths specified as road injuries to begin with. As expected from the distribution of deaths shown in Table 2, there is an increase in the estimates of road injury deaths during the redistribution of deaths coded to partially specified causes. The main increase occurs when deaths coded to unintentional injuries- unspecified mechanism are reallocated. This results in an increase of about 23% in the road injury deaths. 

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 Mexico, only a relatively small fraction (1.0%) 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 because 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 Mexico is 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 Mexico are 24% higher than those reported by official government statistics in the 2009 WHO Global Status Report on Road Safety (Figure 3). The official government statistics in the WHO report are provided by the National Institute of Statistics Geography and Information. Figure 3 also compares data from two data sources (SIMBAD, and International Road Federation) that are based on police reporting. The comparison shows that estimates of road deaths based on death registration data are approximately five times higher than deaths reported by traffic police.

Road deaths by age and sex

Most road deaths in Mexico occur among adult males (Figure 4a). Almost 3/4th (72%) of all road injury deaths were men and over 3/4th of these men (78%) were adults older than 20 years. Death rates (Figure 4b) among men are 3.7 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 10-14 years and 15-19 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 (45%) in Mexico occur among pedestrians (Figure 5). Car occupants comprise an additional 40%of all fatalities.  Although motorcyclists accounted for only 5% of all deaths in 2005, these deaths are rapidly rising in Mexico. Deaths among motorcycle riders in 2006, were three times deaths in the year 2000. Thus, the growing number of deaths among motorcyclists in Mexico is a  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 parts of Latin America as well. See attached web tables (Mexico-WebTables) for time-histories of road deaths by road-user type.

Estimates of non-fatal road injuries

The incidence of non-fatal road injuries can be estimated from various sources, including police reports, hospital administrative records, and population surveys. Among these, police reports are widely known to underreport road injury cases in low income countries as well as in high income countries. Hospital records have the advantage of providing detailed medical descriptions of injuries making classification of injuries by severity possible. However, estimation of population rates is difficult without investing substantial efforts in identifying the hospital catchment population. Thus, population based health and injury surveys are the most reliable sources of information for incidence of road injuries, especially in information-poor settings. 

We estimated the incidence of non-fatal road injuries in Mexico using the 2002-2003 World Health Surveys (WHS), a nationally represented household survey that included questions on road injury involvement. These surveys, which were conducted by the World Health Organization, provide a unique opportunity for cross-country comparisons of non-fatal injuries because they asked the same set of questions in 53 countries, most of which are low- or middle- income countries. The surveys included the following set of road injury related questions in their household module:

In Mexico, 38,618 interviews were conducted as part of the WHS, with a response rate of 100% and a negligibly small number of the surveys had missing responses for the question on bodily injury in road accidents. In our analysis of the WHS, we replaced the missing values for this question with the predicted value from a logistic regression model fit to the cases with a non-missing response. The model used the response to this question as the dependent variable and the following independent variables: gender, age groups, place of residence, permanent income quintile, country, marital status, education, occupation, self-rated health, visual acuity (seeing and recognizing a person from across road), and alcohol consumption as predictor dummy variables. We used survey (svy) commands in Stata 10 for the analysis of the WHS.

Non-fatal injuries by age, sex, and residence

Our analysis of the 2002/2003 WHS suggests that almost two million people in Mexico are involved in non-fatal road crashes annually. This corresponds to 1.9% [95% CI:1.6 -2.1] of the population, which is similar to the average (2.04%) for the combined population of the 50 WHS countries analyzed by us. 

Road injury incidence is significantly higher among residents of urban areas, with a point estimate that is 70% higher than among residents of rural areas (Figure 6). Men have significantly higher rates of non-fatal road injury incidence than women (Figure 7). Road injury incidence is significantly higher among young adults (18-44 years) than both of the older age groups (Figure 8). It should be noted that while the non-fatal injury rate among those older than 65 years is much lower than among young adults, the death rate among the elderly (Figure 4b)  is the highest, pointing to high case fatality rates among the elderly. 

 

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 Rafael Lozano, 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 Mexican Ministry of Health (Secretaría de Salud), particularly the Vice Ministry of Innovation and Quality, and the General Direction of Health Information (GDHI) for providing access to the datasets used in this analysis of road traffic injuries in Mexico. This analysis would not have been possible without the extensive efforts of the GDHI in the careful design and implementation of these data collection activities.