Assessing the quality of evidence for verbal autopsy diagnosis of stroke in Vietnam

BACKGROUND: Information on the leading causes of mortality will continue to rely on verbal autopsy (VA) in developing countries. The accuracy of VA methods in correctly ascertaining the cause for each individual death is crucial in order to have confidence in the data collected through the procedure. Accuracy of the VA procedure is generally established by carrying out validation studies involving a comparison of the underlying cause of death derived from the VA with a reference underlying cause from medical records. Such validation is only possible in cases for which clinical records are available, and this is clearly not the case for most deaths in developing countries. We attempt to verify the accuracy of VA evidence by reviewing the responses to specific symptom questions and other information recorded in verbal autopsy questionnaires that were assigned cerebrovascular conditions (stroke) as causes of death upon physician review in Vietnam. MATERIALS AND METHODS: A national sample mortality surveillance activity identified deaths and causes of death that had occurred during 2008 in selected communes in 16 provinces distributed across Vietnam. All cases from the northern provinces of Hanoi, Hai Duong, Quang Ninh and Thanh Hoa with ICD codes pertaining to cerebrovascular diseases were identified. A total of 326 VA questionnaires for deaths from cerebrovascular diseases were reviewed and analysed in detail for the presence of symptoms pertaining to stroke. The respondents’ narration of the chronological disease history and the hospital diagnosis was also examined with an aim to explore supporting signs for diagnosis and to verify the quality of VA interview. Differences between responses among cases with and without hospital admission were examined using Chi-squared test of statistical significance. RESULTS: Ninty percent of the cases diagnosed as stroke were found to have positive response to the key symptoms; viz., paralysis (in structured question or free text) and history of stroke. For the remaining 10% of cases, stroke was assigned as a cause-of-death based on other suggestive cardiac signs and symptoms such as hypertension, unconsciousness, or headache, etc. Community had different perspectives of “paralysis” and “stroke” which might have affected the diagnosis of stroke in some aspects. Respondents of cases with hospital admission or visit were found to have a better recall of disease symptoms than those without hospital admission. CONCLUSION: The results of this study suggest the possible utility of VA content analysis method to back up the low coverage of conventional validation studies in developing countries owing to nonavailability of medical records. The understanding of the VA content would also form the basis for improvement in the quality of interviews and collection of data to achieve better quality information in future.