Patterns of mortality rates in Darfur conflict

Background: Several mortality estimates for the Darfur conflict have been reported since 2004, but few accounted for conflict dynamics such as changing displacement and causes of deaths. We analyse changes over time for crude and cause-specific mortality rates, and assess the effect of displacement on mortality rates.

Methods: Retrospective mortality surveys were gathered from an online database. Quasi-Poisson models were used to assess mortality rates with place and period in which the survey was done, and the proportions of displaced people in the samples were the explanatory variables. Predicted mortality rates for five periods were computed and applied to population data taken from the UN's series about Darfur to obtain the number of deaths.

Findings: 63 of 107 mortality surveys met all criteria for analysis. Our results show significant reductions in mortality rates from early 2004 to the end of 2008, although rates were higher during deployment of fewer humanitarian aid workers. In general, the reduction in rate was more important for violence-related than for diarrhoea-related mortality. Displacement correlated with increased rates of deaths associated with diarrhoea, but also with reduction in violent deaths. We estimated the excess number of deaths to be 298 271 (95% CI 178 258-461 520).

Interpretation: Although violence was the main cause of death during 2004, diseases have been the cause of most deaths since 2005, with displaced populations being the most susceptible. Any reduction in humanitarian assistance could lead to worsening mortality rates, as was the case between mid 2006 and mid 2007.