Les Roberts

Mortality after the 2003 invasion of Iraq: a cross-sectional cluster sample survey

BACKGROUND An excess mortality of nearly 100 000 deaths was reported in Iraq for the period March, 2003-September, 2004, attributed to the invasion of Iraq. Our aim was to update this estimate. METHODS Between May and July, 2006, we did a national cross-sectional cluster sample survey of mortality in Iraq. 50 clusters were randomly selected from 16 Governorates, with every cluster consisting of 40 households. Information on deaths from these households was gathered. FINDINGS Three misattributed clusters were excluded from the final analysis; data from 1849 households that contained 12 801 individuals in 47 clusters was gathered. 1474 births and 629 deaths were reported during the observation period. Pre-invasion mortality rates were 5.5 per 1000 people per year (95% CI 4.3-7.1), compared with 13.3 per 1000 people per year (10.9-16.1) in the 40 months post-invasion. We estimate that as of July, 2006, there have been 654 965 (392 979-942 636) excess Iraqi deaths as a consequence of the war, which corresponds to 2.5% of the population in the study area. Of post-invasion deaths, 601 027 (426 369-793 663) were due to violence, the most common cause being gunfire. INTERPRETATION The number of people dying in Iraq has continued to escalate. The proportion of deaths ascribed to coalition forces has diminished in 2006, although the actual numbers have increased every year. Gunfire remains the most common cause of death, although deaths from car bombing have increased.

Mortality before and after the 2003 invasion of Iraq: cluster sample survey

BACKGROUND In March, 2003, military forces, mainly from the USA and the UK, invaded Iraq. We did a survey to compare mortality during the period of 14.6 months before the invasion with the 17.8 months after it. METHODS A cluster sample survey was undertaken throughout Iraq during September, 2004. 33 clusters of 30 households each were interviewed about household composition, births, and deaths since January, 2002. In those households reporting deaths, the date, cause, and circumstances of violent deaths were recorded. We assessed the relative risk of death associated with the 2003 invasion and occupation by comparing mortality in the 17.8 months after the invasion with the 14.6-month period preceding it. FINDINGS The risk of death was estimated to be 2.5-fold (95% CI 1.6-4.2) higher after the invasion when compared with the preinvasion period. Two-thirds of all violent deaths were reported in one cluster in the city of Falluja. If we exclude the Falluja data, the risk of death is 1.5-fold (1.1-2.3) higher after the invasion. We estimate that 98000 more deaths than expected (8000-194000) happened after the invasion outside of Falluja and far more if the outlier Falluja cluster is included. The major causes of death before the invasion were myocardial infarction, cerebrovascular accidents, and other chronic disorders whereas after the invasion violence was the primary cause of death. Violent deaths were widespread, reported in 15 of 33 clusters, and were mainly attributed to coalition forces. Most individuals reportedly killed by coalition forces were women and children. The risk of death from violence in the period after the invasion was 58 times higher (95% CI 8.1-419) than in the period before the war. INTERPRETATION Making conservative assumptions, we think that about 100000 excess deaths, or more have happened since the 2003 invasion of Iraq. Violence accounted for most of the excess deaths and air strikes from coalition forces accounted for most violent deaths. We have shown that collection of public-health information is possible even during periods of extreme violence. Our results need further verification and should lead to changes to reduce non-combatant deaths from air strikes.

Mortality in Iraq - Authors' reply

The authors respond to several critics of their report [G Burnham, R Lafta, D Doocy and L Roberts, Mortality after the 2003 invasion of Iraq: across-sectional cluster sample survey, Lancet 368 (2006), pp. 1421–1428]. The original article and the letters of criticism may be read by following the doi link and then linking to each letter or report. Language: en

Mortality in Iraq [1] (multiple letters)

In their Article on mortality before and after the 2003 invasion of Iraq (Nov 20, p 1857), Les Roberts and colleagues use several questionable sampling techniques that should have been more thoroughly examined before publication. Although sampling of 988 households randomly selected from a list of all households in a country would be routinely acceptable for a survey, this was far from the method actually used—a point basically lost in the news releases such a report inevitably engenders. The survey actually only included 33 randomised selections, with 30 households interviewed surrounding each selected cluster point. Again, this technique would be adequate for rough estimates of variables expected to be fairly homogeneous within a geographic region, such as political opinion or even natural mortality, but it is wholly inadequate for variables (such as violent death) that can be expected to show extreme local variation within each geographic region. In such a situation, multiple random sample points are required within each geographic region, not one per 739 000 individuals. In my opinion, such a flaw by itself is fatal, and should have precluded publication in a peer-reviewed journal. However, the authors’ sampling technique is also questionable in other ways. When a town or village was selected from the “cumulative population lists for the Governorate”, the survey team then “drove to the edges of the area and stored the site coordinates”. In personally deciding what constituted the edges of the grid rectangle for “the area”, the team leader could potentially introduce bias into the selecting of an area to sample. In any case, it seems quite likely that the grid rectangles created by driving around in a war zone were much smaller than the original census tracts used in the “cumulative population lists”. Additionally, there is no way to verify that the 30 closest households were those actually interviewed. It is always easier to interview the more vocal households, and there is some leeway in deciding which doorways are closest. The claimed 99·5% response rate makes it seem highly suspect that the 30 closest doorways were actually those rigorously selected. Lastly, when interviewing a “household” about violent deaths, one is likely to hear reports included from an extended family unit. Individuals might be included from a network of family by marriage, including many dozens if not hundreds of individuals. Although such individuals might have even lived in the household at some point, that does not mean they would have actually been living at that location at the time of the survey if they had not been killed. Such a phenomenon is much more likely when reporting violent deaths (due to the extreme emotional import of such occurrences) than when reporting natural deaths. I think such considerations should have been uncovered during a thorough review by statistical experts (as I assume occurred before electronic publication of this article immediately before a US presidential election). If not precluding publication altogether, these fairly obvious points should have been included in a fair editorial analysis accompanying the article.The uncertainty of estimates from retrospective mortality surveys in humanitarian emergencies is composed of both sampling and reporting errors. Gilbert Burnham and colleagues, in their mortality study in Iraq (Lancet 2006; 368(9545): 1421-1428), quantify the sampling error, but the security situation did not allow for the supervision and repeat interviews needed to estimate reporting errors. Over-reporting of deaths was regarded as limited because 92% of reported deaths were supported by death certificates, but Burnham and colleagues do not report who issued these certificates. Neither do they discuss why the availability of death certificates increased from 81% in 2004. The existence of a substantial reporting error is supported by the finding of low child mortality. The study population only reported 54 non-violent deaths in those younger than 15 years, and 1474 births—ie, an under-15 mortality of 36 per 1000 births. This is a third of the estimated preinvasion under-5 mortality. Since nothing indicates that child mortality has decreased, the results suggest that fewer than half of child deaths were reported. Without an explanation for the high availability of death certificates, one could assume that the reporting error is of the same size as the sampling error (±30%). This assumption still yields at least a five-fold higher number of violent deaths than the passive surveillance mortality numbers. If the death certificates are valid and the availability above 90%, it seems better to monitor mortality by compiling data from the local agencies that issue these certificates than by doing further dangerous household surveys. Language: en