Verbal autopsy as a tool for identifying children dying of sickle cell disease: a validation study conducted in Kilifi district, Kenya

Abstract

Background: Sickle cell disease (SCD) is common in many parts of sub-Saharan Africa (SSA), where it is associated with high early mortality. In the absence of newborn screening, most deaths among children with SCD go unrecognized and unrecorded. As a result, SCD does not receive the attention it deserves as a leading cause of death among children in SSA. In the current study, we explored the potential utility of verbal autopsy (VA) as a tool for attributing underlying cause of death (COD) in children to SCD.

Methods: We used the 2007 WHO Sample Vital Registration with Verbal Autopsy (SAVVY) VA tool to determine COD among child residents of the Kilifi Health and Demographic Surveillance System (KHDSS), Kenya, who died between January 2008 and April 2011. VAs were coded both by physician review (physician coded verbal autopsy, PCVA) using COD categories based on the WHO International Classification of Diseases 10th Edition (ICD-10) and by using the InterVA-4 probabilistic model after extracting data according to the 2012 WHO VA standard. Both of these methods were validated against one of two gold standards: hospital ICD-10 physician-assigned COD for children who died in Kilifi District Hospital (KDH) and, where available, laboratory confirmed SCD status for those who died in the community.

Results: Overall, 6% and 5% of deaths were attributed to SCD on the basis of PCVA and the InterVA-4 model, respectively. Of the total deaths, 22% occurred in hospital, where the agreement coefficient (AC1) for SCD between PCVA and hospital physician diagnosis was 95.5%, and agreement between InterVA-4 and hospital physician diagnosis was 96.9%. Confirmatory laboratory evidence of SCD status was available for 15% of deaths, in which the AC1 against PCVA was 87.5%.

Conclusions: Other recent studies and provisional data from this study, outlining the importance of SCD as a cause of death in children in many parts of the developing world, contributed to the inclusion of specific SCD questions in the 2012 version of the WHO VA instruments, and a specific code for SCD has now been included in the WHO and InterVA-4 COD listings. With these modifications, VA may provide a useful approach to quantifying the contribution of SCD to childhood mortality in rural African communities. Further studies will be needed to evaluate the generalizability of our findings beyond our local context.

Figure 1

Cause-specific mortality fractions (CSMFs) for 610 child deaths interpreted by verbal autopsy (VA) coders. CSMFs for 610 deaths of children aged less than 14 years in the Kilifi Health and Demographic Surveillance System (KHDSS) study area, derived from verbal autopsies interpreted by two independent physician coders.

Figure 2

Cause-specific mortality fractions (CSMFs) for 610 child deaths interpreted by physician coded verbal autopsy (PCVA) and the InterVA-4 model. CSMFs for 610 deaths of children aged less than 14 years in the Kilifi Health and Demographic Surveillance System (KHDSS) study area, derived from verbal autopsies interpreted by PCVA and the InterVA-4 model.

Figure 3

Cause-specific mortality fractions (CSMFs) for 134 child deaths assigned by physician coded verbal autopsy (PCVA), the InterVA-4 model and pediatric hospital cause of death (COD). The figure shows CSMFs for 134 child deaths. Underlying CODs determined by PCVA and the InterVA-4 model were compared against the COD given by physicians for those who died on the pediatric ward at Kilifi District Hospital (KDH).