the development of a shortened verbal autopsy instrument for routine surveillance

The development of a shortened verbal autopsy instrument for routine surveillance

June 18, 2013

Peter Serina

Post-Bachelor Fellow

2

Outline

• The context

• Construction of a shortened instrument

• Measuring performance

• Next steps

3

Cause of death data

• Cause of death is important

• Vital registration systems are limited

• An information gap exists

4

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

5

Verbal autopsy: an evolution

• Survey structure

• Analytic techniques

• Data capture

Wikimedia commons

6

Outline

• The Context

• Construction of a shortened instrument

• Measuring performance

• Next steps

• Conclusion

7

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

12

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

17

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

Thank you

Peter Serina

ptserina@uw.edu