Deaths due to malaria by age, region, country, and year (Global), 1980-2010

In February 2012, IHME published in The Lancet global estimates for malaria mortality: Global malaria mortality between 1980 and 2010: a systematic analysis [13]. The new estimates differed from multiple previous assessments of malaria mortality at the global level and in individual countries, the most recent being the World Malaria Report 2011 [14] by the World Health Organization (WHO).

Our Approach

• We based our estimates on the broadest range of available data to date for 105 countries: a total of 1,150 site years of data from 1980 to 2010. This includes data from vital registration systems and from verbal autopsy [15] studies.
   
• Both WHO and IHME use verbal autopsy studies for estimating mortality from all causes and for estimating mortality from malaria specifically. The World Malaria Report 2011 [14] relied on verbal autopsy data for its child mortality estimates for some of the regions it studied. The report says, “Child malaria deaths were estimated using a verbal autopsy multi-cause model (VAMCM) developed by the WHO Child Health Epidemiology Reference Group (CHERG) to estimate causes of death for children aged 1-59 months in countries with less than 80% of vital registration coverage.” IHME used a wider range of verbal autopsy studies to generate its estimates and included adult deaths.
   
• WHO does not use verbal autopsy studies for estimates of adult deaths from malaria in sub-Saharan Africa, but it does use verbal autopsy studies for estimates of adult deaths in other areas. This is based on two assumptions. The first is the assumption – taught in medical and public health schools – that adults develop immunity from early exposure to malaria and do not die from the disease. The second is the assumption that verbal autopsy studies are not accurate enough to diagnose malaria, because the symptoms of malaria can be similar to other causes of death. IHME, using vital registration data and verbal autopsy studies for both children and adults, found that verbal autopsy studies yield conservative estimates of malaria mortality, meaning that the true number could be even higher.
   
• For African countries, WHO estimates are based on a model of malaria mortality that takes into account only population growth and the effects of vector control. IHME’s estimates include the effect of chloroquine resistance, the scale-up of artemisinin-combination treatment, environmental factors such as rainfall, and broader socioeconomic determinants.
   
• To overcome misclassification of malaria deaths attributed to other cases, IHME used an approach developed by IHME Assistant Professor Dr. Mohsen Naghavi and colleagues [16] to account for changes in the International Classification of Diseases and Injuries. With this approach, IHME redistributed deaths that had been called “fever of other and unknown origin,” “disseminated intravascular coagulation,” “other and unspecified infectious diseases,” and “sequelae of other and unspecified infectious and parasitic diseases.” As a result, some of those deaths were reclassified as malaria deaths.
   
• IHME’s estimates confirm some findings from previous studies. For example, they show that malaria deaths increased by three times through the 1980s and 1990s to a peak in 2004. Previous studies also show an increase in malaria deaths in this period of two to three times. Both the IHME study and previous studies have noted an association with increasing chloroquine resistance.
   

For a detailed discussion of our methods, please see the Web Appendix with the journal article [17].