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GHME 2013 Conference Session: Verbal autopsy Date: June 18 2013 Presenter: Peter Serina Institution: Institute for Health Metrics and Evaluation (IHME), University of Washington
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The development of a shortened verbal autopsy instrument for routine surveillance
June 18, 2013
Peter Serina
Post-Bachelor Fellow
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Outline
• The context
• Construction of a shortened instrument
• Measuring performance
• Next steps
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Cause of death data
• Cause of death is important
• Vital registration systems are limited
• An information gap exists
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One solution: verbal autopsy
• Trained interviewer
• Structured questionnaireo Signs
o Symptoms
o Demographic characteristics
• Lay respondent familiar with the deceased
• Population Health Metrics Research Consortium (PHMRC) instrument:o 153 questions
o 45 minutes
PHMRC GC13 Project
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Verbal autopsy: an evolution
• Survey structure
• Analytic techniques
• Data capture
Wikimedia commons
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Outline
• The Context
• Construction of a shortened instrument
• Measuring performance
• Next steps
• Conclusion
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Construction of shortened instrument
Two approaches:
1. Expert-driven
2. Data-driven
Cost (Time and
money)
Quality(Survey
performance)
Coverage (Population, causes, and
areas)
Data-driven approach
The data:
• Population Health Metrics Research Consortium (PHMRC)
• Gold standard verbal autopsy validity study
The method:
• Tariff
• Systematic reduction
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Country SiteGS
deaths
Mexico Mexico City 2,031
TanzaniaPemba Island 822
Dar es Salaam 3,239
IndiaUttar Pradesh 2,170
Andhra Pradesh 2,382
Philippines Bohol 1,898
Total 12,542
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Tariff method
AIDS Malaria Fall
Suffered a fall 0 0 32
Decedent had TB 5 0 0
Fever 1 1.5 -1
Decedent haddementia 0 -1 0
Tariff standard deviation
18.5
2.9
1.3
0.6
Sym
pto
ms
Causes
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Performance metrics
• Mean chance-corrected concordance for cause jo Performance at the individual level
• Cause-specific mortality fraction (CSMF) accuracyo Performance at the population level
𝐶𝐶𝐶 𝑗=( 𝑇𝑃 𝑗
𝑇𝑃 𝑗+𝐹𝑁 𝑗)−( 1𝑁 )
1−( 1𝑁 )
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Individual performance vs. question quantity for adults
Chance-corrected concordance
Number of questions
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Outline
• The context
• Construction of a shortened instrument
• Measuring performance
• Next steps
• Conclusion
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Questionnaire size
Neonate Child Adult
Full instrument 149 127 183
Full analyzed 117 84 170
Shortened analyzed 50 60 90
Shortened instrument 76 72 105
% reduction 49% 43% 43%
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Population-level performance
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Individual-level performance
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Outline
• The context
• Construction of a shortened instrument
• Measuring performance
• Next steps
• Conclusion
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Next steps
• Link survey size to time to implement
• Pilot surveys in:o Philippines
o Bangladesh
o Sri Lanka
2.2: Did Juan Garcia have a fever?
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Outline
• The Context
• Construction of a shortened instrument
• Measuring performance
• Next steps
• Conclusion
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Conclusion
Our findings:• > 40% fewer questions chosen in systematic, data-driven
process
• Negligible effects on performance with same population size
Impact:• Greater number of verbal autopsies can be collected
• Strengthen routine surveillance
• Address the information gap
