Determining causes of mortality in children enrolled in a vaccine field trial in a rural area in the Western Cape Province of South Africa

AIM: A mortality surveillance system was developed to identify and document causes of death among children enrolled in a tuberculosis vaccine field trial in South Africa. The aims of this study were to describe causes of mortality in children enrolled in a phase IV trial comparing intradermal with percutaneous administration of Bacille Calmette Guerin, and to compare causes of mortality recorded on death certificates with those obtained by clinical record review combined with verbal autopsies (CR/VA). METHODS: For children who died, certified causes of death were compared with those determined by CR/VA. RESULTS: Among 11677 children enrolled, 177 deaths were notified over 4 years. The incidence rate of death was 6.8/1000 person-years. Follow-up time ranged from 0.03 to 35.3 months (median 4 months; interquartile range 1.4-8.5). The infant mortality rate was 12.5/1000 live births and the neonatal mortality was 3/1000 live births. Pneumonia, gastroenteritis and septicaemia were among top causes of mortality by both methods. 'Sudden unexplained' and 'ill-defined' causes were among top causes of mortality based on CR/VA, while tuberculosis and 'natural causes' were among top causes based on death certificates. Important underlying causes of mortality by CR/VA include HIV/AIDS, prematurity/low birth weight and malnutrition. In 47% of deaths there was agreement on immediate causes of death. This increased to 54% when 'natural causes' and 'sudden unexplained deaths' were included. CONCLUSION: In this cohort mortality was largely due to infectious diseases. While CR/VA provided additional information on most deaths, this was not always sufficient to assign specific causes of death.