Lancet Surveys of Iraq War Casualties - The First Study (2004)

The First Study (2004)

The survey was sponsored by the Center for International Emergency Disaster and Refugee Studies, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA (authors L Roberts PhD, G Burnham MD) and the Department of Community Medicine, College of Medicine, Al-Mustansiriya University, Baghdad, Iraq. Roberts' team was chosen for their experience in estimating total mortality in war zones, for example his estimate of 1.7 million deaths due to the war in the Congo which not only met with widespread acceptance and no challenge when published in 2000, but resulted and was cited in a U.N. Security Council resolution that all foreign armies must leave Congo, a United Nations request for $140 million in aid, and the US State Department pledging an additional $10 million in aid. Similar studies have been accepted uncritically as estimates of wartime mortality in Darfur and Bosnia.

Roberts' regular technique is to estimate total mortality by personal surveys of a sample of the households in the area under study; this method being chosen in order to avoid the under-counting inherent in using only reported deaths in areas so chaotic that many deaths are unreported, and to include those deaths not directly attributable to violence but nevertheless the result of the conflict through indirect means, such as contamination of water supply or unavailability of medical care. The baseline mortality rate calculated from the interviewees' reports for the period prior to the conflict is subtracted from that reported during the conflict, to estimate the excess mortality which may be attributed to the presence of the conflict, directly or indirectly. This technique has been accepted uncritically in the previous mortality surveys discussed above.

Because of the impracticality of carrying out an evenly distributed survey, particularly during a war, Roberts' surveys use "cluster sampling", dividing the area into a number of randomly-selected, approximately equally-populated regions; a random point is chosen within each region, and a fixed number of the households closest to that point are surveyed as a "cluster". While not as accurate as an evenly distributed survey of the same number of households, this technique is more accurate than merely surveying one household for each selected point.

In his study of Iraq, Roberts divided the country into 33 regions, attempting to sample 30 households for each cluster, and selecting 988 households, with 7868 residents. In September 2004, each surveyed household was interviewed about household composition, births, and deaths since January, 2002. Of 78 households where members were asked to show documentation to confirm their claims after the interview was finished, 63 were able to present death certificates. According to the authors, 5 (0.5%) of the 988 households that were randomly chosen to be surveyed refused to be interviewed.

The relative risk of death due to the 2003 invasion and occupation was estimated by comparing mortality in the 17.8 months after the invasion with the 14.6 months preceding it. The authors stated, "Making conservative assumptions, we think that about 100,000 excess deaths, or more have happened since the 2003 invasion of Iraq." Among such "conservative assumptions" is the exclusion of data from Fallujah in many of its findings. Since interpreting the results of the study would be complicated by the inclusion of an outlier cluster in Fallujah, where heavy fighting caused far more casualties than elsewhere in Iraq, the study focused mainly on the results that excluded the Fallujah cluster. While the authors argued that the Fallujah cluster's inclusion could be justified as a normal part of the sampling strategy (the authors noted that other "hotspots" like Najaf had not ended up being surveyed), and the authors presented two sets of results in some cases (one set including the Fallujah data and one not), the article, and most press coverage of the article, stresses the data that excluded the Fallujah cluster.

The main debate in the media in the U.S. and UK focused on whether 98,000 (95% CI 8000–194,000) more Iraqis died as a result of coalition intervention, calculated from their estimate of an increased mortality of 1.5 times (95% CI 1.1-2.3) the prewar rate (excluding the Fallujah data). Had the Fallujah sample been included, the survey's estimate that mortality rates had increased about 2.5 times since the invasion (with a 95% CI 1.6-4.2) including the Fallujah data would have resulted in an excess of about 298,000 deaths (95% CI ?-?), with 200,000 concentrated in the 3% of Iraq around Fallujah (Roberts et al. p. 5).

According to the article, violence was responsible for most of the extra deaths whether or not the Fallujah data was excluded. Coalition airstrikes would be the main cause of these violent deaths if Fallujah data were included. The study makes the controversial conclusion that: "Violent deaths were widespread, reported in 15 of 33 clusters, and were mainly attributed to coalition forces." and "Violence accounted for most of the excess deaths and air strikes from coalition forces accounted for most violent deaths." The study estimates that the risk of death specifically from violence in Iraq during the period after the invasion was approximately 58 times higher than in the period before the war, with the CI95 being 8.1-419, meaning that there is a 97.5% chance that the risk of death from violence after the invasion is at least 8.1 times higher than it was before. Newsday reported:

"The most common causes of death before the invasion of Iraq were heart attacks, strokes and other chronic diseases. However, after the invasion, violence was recorded as the primary cause of death and was mainly attributed to coalition forces—with about 95 percent of those deaths caused by bombs or fire from helicopter gunships".

It was noted that the large estimate of excess death is even more shocking in view of the widely accepted belief that deaths in Iraq were already very high at 0.5% per year, particularly among children, due to UN sanctions against Iraq.