Understanding of global health and changing morbidity and mortality is limited by inadequate measurement of population health. With fewer than one-third of deaths worldwide being assigned a cause, this long-standing dearth of information, almost exclusively in the world's poorest countries, hinders understanding of population health and limits opportunities for planning, monitoring, and evaluating interventions. In the absence of routine death registration, verbal autopsy (VA) methods are used to derive probable causes of death. Much effort has been put into refining the approach for specific purposes; however, there has been a lack of harmony regarding such efforts. Subsequently, a variety of methods and principles have been developed, often focusing on a single aspect of VA, and the resulting literature provides an inconsistent picture. By reviewing methodological and conceptual issues in VA, it is evident that VA cannot be reduced to a single one-size-fits-all tool. VA must be contextualized; given the lack of "gold standards," methodological developments should not be considered in terms of absolute validity but rather in terms of consistency, comparability, and adequacy for the intended purpose. There is an urgent need for clarified thinking about the overall objectives of population-level cause-of-death measurement and harmonized efforts in empirical methodological research.

Background Verbal autopsy methods are critically important for evaluating the leading causes of death in populations without adequate vital registration systems. With a myriad of analytical and data collection approaches, it is essential to create a high quality validation dataset from different populations to evaluate comparative method performance and make recommendations for future verbal autopsy implementation. This study was undertaken to compile a set of strictly defined gold standard deaths for which verbal autopsies were collected to validate the accuracy of different methods of verbal autopsy cause of death assignment. Methods Data collection was implemented in six sites in four countries: Andhra Pradesh, India; Bohol, Philippines; Dar es Salaam, Tanzania; Mexico City, Mexico; Pemba Island, Tanzania; and Uttar Pradesh, India. The Population Health Metrics Research Consortium (PHMRC) developed stringent diagnostic criteria including laboratory, pathology, and medical imaging findings to identify gold standard deaths in health facilities as well as an enhanced verbal autopsy instrument based on World Health Organization (WHO) standards. A cause list was constructed based on the WHO Global Burden of Disease estimates of the leading causes of death, potential to identify unique signs and symptoms, and the likely existence of sufficient medical technology to ascertain gold standard cases. Blinded verbal autopsies were collected on all gold standard deaths. Results Over 12,000 verbal autopsies on deaths with gold standard diagnoses were collected (7,836 adults, 2,075 children, 1,629 neonates, and 1,002 stillbirths). Difficulties in finding sufficient cases to meet gold standard criteria as well as problems with misclassification for certain causes meant that the target list of causes for analysis was reduced to 34 for adults, 21 for children, and 10 for neonates, excluding stillbirths. To ensure strict independence for the validation of methods and assessment of comparative performance, 500 test-train datasets were created from the universe of cases, covering a range of cause-specific compositions. Conclusions This unique, robust validation dataset will allow scholars to evaluate the performance of different verbal autopsy analytic methods as well as instrument design. This dataset can be used to inform the implementation of verbal autopsies to more reliably ascertain cause of death in national health information systems.