Incidence of road injuries in Mozambique
Last Updated: April 13 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. Please also note that this analysis for Mozambique is closely related with another ongoing project to estimate the burden of injuries in Sub-Saharan Africa.
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 Mozambique. 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.
In 2007, road crashes resulted in approximately 3,050 deaths in Mozambique representing an annual injury rate of 15.3 deaths per 100,000 people (Figure 1). In addition, nearly 200,000 people were victims of non-fatal injuries due to road crashes. These estimates of deaths and non-fatal injuries are substantially higher than previously reported. In particular, the road injury death rate is twice the death rate reported in official statistics, which are based on police reports. The road injury death rate 2.5 times that of countries with the best road safety performance (Sweden, UK, and Netherlands).
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 data sources, estimation methods, and the key results for our estimates of road injuries in Mozambique. 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 Mozambique using estimates of urban and rural injury death rates from a a nationally representative post-census mortality study. We disaggregated these further by external cause using Maputo Central Hospital Mortuary (1994-2003) for urban deaths; and the Manhica Health and Demographic Surveillance Site (HDSS) for rural deaths (1999-2001). We estimated the incidence and distribution of non-fatal injuries using the results of the 2003 Mozambique Demographic and Health Survey (DHS) and injury surveillance data from the Maputo Central Hospital Injury Surveillance System collected in 2001 and 2002.
Estimates of road injury deaths
Our review of data sources for estimating national road injury deaths in Mozambique revealed the following data sources: (1) 2007 post-census mortality survey, Inquerito Nacional Sobre Causas de Mortalidade (INCAM); (2) the Maputo Central Hospital Mortuary, and (3) the Manhica HDSS; and (4) national police statistics. In this study, we have computed estimates of national road injury deaths from the former three (INCAM survey, urban mortuary and rural HDSS) and compared the results with the statistics reported by the police.
The INCAM survey was a nationally representative survey of causes of death conducted using verbal autopsy after the 2007 household census in Mozambique. "Accidents and Injuries" was one of the causes of death listed. Based on the results of this study, 4.7% (95% CI:4.1-5.3) of all urban deaths in Mozambique are from injuries and 3.5% (95% CI:3.0-4.0) of all rural deaths in Mozambique are from injuries. We coupled these injury-death fractions with total all-cause deaths reported estimated from the 2007 household census to construct urban and rural injury mortality envelopes.
The data from the Maputo Central Hospital Mortuary (1994-2003) are tabulations of deaths as recorded using their fatal injury surveillance instrument. Typically the data captures in such injury surveillance captures age, sex, and injury deaths coded using locally selected and appropriate injury intent and injury mechanism categories. The Manhica HDSS data (1999-2001) is tabulated using broad categories based on the principles of the International Statistical Classification of Diseases (ICD) 10th revision. The variables include age, sex and ICD-10 code. The police report the total number of road deaths in Mozambique as reported to them (several years are available but for the purposes of this comparison we used 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. The GBD-Injury expert group also recommends definitions for sub-categories of road injuries by road-user type.
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.
Unfortunately, our two main data sources for estimating deaths (Maputo Central Hospital Mortuary, and Manhica HDSS site) did not code data at sufficient detail to estimate road-user subcategories for road injury deaths. Thus, our analysis was limited to estimating total road injury deaths in Mozambique.
Table 1 shows the distribution of the 11,663 injury deaths recorded at the Maputo Central Hospital Mortuary between 1994-2003. Almost half (47%) of all injury deaths received at this urban mortuary during this 10 year period were due to road traffic injuries. Road injuries accounted for over five times as many deaths as due to firearm injuries, which was the second leading cause of injury deaths.
Similarly, Table 2 shows the distribution of the 112 injury deaths for which data was collected at the Manhica HDSS. Poisonings were the leading cause of injury deaths in this rural setting. Road injuries ranked second and accounted for 18% of all injury deaths.
We assumed that the distribution of injury deaths recorded in the Maputo city mortuary data and at the Manhica HDSS are representative of injury deaths in an urban and rural setting respectively. Thus, we estimated total rural and urban fatal injuries in Mozambique from the INCAM survey and disaggregated these totals further by using the Maputo city mortuary and Manhica HDSS injury death fractions. The urban and rural numbers were then added together to form the total fatal road injury estimate for Mozambique in 2007.
Comparison of our estimates with other sources
Our estimate of road injury deaths in Mozambique are twice those from official government statistics as reported by the 2009 WHO Global Status Report on Road Safety and the National Institute for Road Safety (Figure 3). The official government statistics are based on the national police. While the details of the methods used by the police to collect information on fatal road injuries are not clear, the discrepancy is likely due to under-reporting of road traffic deaths by police.
Road deaths rates in urban and rural settings
While almost two-thirds of the population of Mozambique lives in rural areas, the country is undergoing rapid urbanization. The road injury death rate (Figure 3) in urban areas (23.2 per 100 000 people) is more than twice that among the rural population (11.3) and substantially higher than the national rate (15.3).
Estimates of non-fatal road injuries
Typically, 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 Mozambique using data from the Injury Module of the 2003 Demographic and Health Survey (DHS), a nationally represented household survey that included questions. Note that the standard 2003 DHS questionnaire does not include questions on road injury involvement. However an injury module was included in the 2003 Mozambique DHS. This nationally representative population-based health survey surveyed 63,496 individuals. The survey instrument included questions about non-fatal injuries: injury mechanism, intent, health care utilization and disability.
While the 2003 DHS Injury Module included several questions on injuries, we analyzed the following set of road injury related questions for our analysis:
In the past 30 days, has any member of this household suffered from any type of injury? [Yes/No]
When (in the last 30 days) did the accident happen? [Within the last 1 week/ 1-2 weeks/ 3 weeks or more]
What was the cause or mechanism of the injury? [Road traffic accident]
Did you receive any medical care or treatment for your injuries? [Yes/No/Don’t know]
Did you suffer a disability as a result of the injury? [Yes/No/Don’t know]
The DHS data was analyzed using survey (svy) commands in Stata 10.
Our analysis of the 2003 DHS suggests that approximately 193,000 people in Mozambique are injured in non-fatal road crashes annually. This corresponds to 1.3% [95% CI:0.8-1.8%] of the population.
Figure 4 illustrates that road injury incidence among residents of rural areas and residents of urban areas are statistically significantly higher among urban residents (1.7%[95%CI:0.94-2.4%]) than among rural residents (0.5%[95%CI:0.2-0.8%]). Note that this result is in line with the death rates estimated in this study. While men have higher rates of non-fatal road injury incidence than women, the difference is not statistically significant (Figure 5). Similarly, the road injury rates among adults aged 15-64 years is higher than that of children (<15 years), but the difference is not statistically significant.
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 analysis of data collected by various national and international agencies.
This report on road injuries in Mozambique was developed in close collaboration with Ms Kidist Bartolomeos from the Department of Violence and Injury Prevention at the World Health Organization. We are grateful to the Ministério da Saúde and the Instituto Nacional de Estatística for providing access to the datasets used in this analysis of road traffic injuries in Mozambique. This analysis would not have been possible without the extensive efforts of Dr. Carla de Silva, Dr. Fatima Zacharias and Dr. Eugenio Zacharias.