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Measuring cause specific mortality: the use of verbal autopsies Alan Lopez Chalapati Rao.

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Presentation on theme: "Measuring cause specific mortality: the use of verbal autopsies Alan Lopez Chalapati Rao."— Presentation transcript:

1 Measuring cause specific mortality: the use of verbal autopsies Alan Lopez Chalapati Rao

2 Uses of cause of death data To study and explain levels, trends and differentials in age specific mortality (Preston and disciples) To guide priorities for resource allocation for intervention programs, biomedical and sociomedical research To monitor public health programs To provide clues for epidemiological research

3 Sources of national cause-specific mortality data –vital registration systems – GOLD STANDARD –sample registration systems –household surveys –population laboratories and surveillance systems –epidemiological estimates For deaths registered in these systems, cause of death is either –certified by a medical practitioner –based on "verbal autopsies" –not given at all

4 VR: Data availability, around 2000

5 Data quality

6 Strategies to improve COD data availability Accelerate development of civil registration –SLOW, EXPENSIVE, LOW GOVERNMENT PRIORITY Introduce / improve physician certification, ICD coding, and statistical processing of data –CRITICAL, NEEDS BIG ‘WHO’ PUSH, NO CHAMPIONS – Introduce and develop local applications of verbal autopsy procedures for data acquisition through vital registration sample registration demographic surveillance systems household surveys

7 What is VA ? VERBAL AUTOPSY (VA), a two step procedure –Data collection : interview of bereaved relatives to collect information on symptoms experienced by deceased before death, using some form of survey instrument –COD assignment : methods include –physician review of VA data –ICD certification, coding, and tabulation –computerised algorithms for population fractions

8 Principles of VA Based on recall by relatives of symptoms \ illness prior to death, sometimes difficult for adult deaths (similar symptoms) Requires identification of clearly distinguishable symptom complexes for each cause of interest, not available for some adult causes –lung cancer, TB, diabetes, different forms of liver disease etc So far, found useful and validated for infant and maternal deaths; deaths due to injuries Recent experiences suggest utility of gathering information from medical documents if available within household

9 Historical use of VA Measuring cause specific mortality in populations –SCDR / SRS - India – DSP / VR – China – AMMP (Tanzania) Investigating COD in specific age-sex cause groups –infant / child deaths –maternal causes of death –Injury related deaths Investigating outbreaks / epidemics –Ebola fever epidemic in West Africa –Diarrhoeal disease in Bangladesh

10 Historical use (contd) Assessing coverage and effectiveness of disease specific interventions –insecticide impregnated bed nets in Africa –Pneumococcal vaccine trials in Bohol –Home based neonatal care in India In developed countries –confidential enquiries of maternal mortality –Sudden infant death syndrome –QOL / mental health status in terminal illness among elderly

11 VA in India Survey of causes of death – rural (SCDR) 1967 – 1998 (1400 PHCs, rep) Structured instrument, lay assignment of cause, ICD classification since 1996 problems with incomplete coverage, inadequate investigator training / physician verification of cause New system being implemented in SRS, covering 8 million New instruments, field protocols, training support Five year retrospective survey planned soon independent field studies by Ind C Med Res in 5 zones,  1 million pop each Need for integrated approach, involving civil registration systems

12 SCDR Results

13 VA in China Two mortality statistics systems – NMS, DSP NMS (VR) – medical certification (urban) / lay reporting (rural) 120 m pop DSP –– 1981, now 145 points, nationally representative, 10 m pop medical certification / VA for household deaths (80%) Semi structured instrument, physician COD assignment, ICD classification since 1987 Household visit by township hospital staff Much reliance on free text response to ‘ What was the cause of death in this person?’ Use of supportive medical documentation available at home / from hospital records Needs to be tested for reliability, and if possible, validity Research projects underway (UQ, Harvard)

14 DSP Results

15 VA in Tanzania Adult morbidity and mortality project in 3 districts 1992 onwards Instruments developed by LSHTM – AMMP Physician assignment of cause Non ICD mortality classification Recent introduction of ICD certification / coding (2003) Validation study underway (UQ, Harvard, LSHTM)

16 AMMP results - 2000

17 Important issues in VA Standard survey instruments including modules for –Free text narrative –Structured questions –Recording household medical document information Interviewer –Education background, training Choice of respondent –Proximity to deceased, education, age and sex, cultural factors Recall periods –Minimum and maximum intervals Cause of death assignment and ICD coding –Physician / trained health professional review using standard protocols –Computerized programs –ICD mortality tabulation lists Validation studies

18 To develop standard verbal autopsy instruments and procedures that are applicable in different epidemiological and cultural settings with minimal modifications To measure biases in community cause of death patterns when using VA instruments validated in hospital based studies To improve understanding of quality of cause of death information for estimating global and regional mortality patterns

19 Methods VA validation study in Tanzania VA validation and mortality statistics evaluation study in China

20 Study design - Tanzania For each death 3000 deaths Medical recordVerbal autopsy DC/ underlying cause from reviewer 1 MR Underlying cause VA Underlying cause Agreement Verbal autopsy validation DC/ underlying cause from reviewer 2 Disagreement reconciled by consensus DC/ underlying cause from reviewer 1 Agreement DC/ underlying cause from reviewer 2

21 Study design - China Medical record Death certificate Verbal autopsy death certificate Verbal autopsy validation Routine system death certificate Routine system reliability – rural areas Routine system validation – urban areas 1900 deaths 3500 deaths 2700 deaths

22 Future research Gates proposal – Africa, Bangladesh, Philippines New UQ sites in Indonesia, Thailand Egypt, Syria, other EMRO countries ? Expression of interest by Indian SRS to adopt WHO VA methodology ? Other opportunities in Africa through PEPFAR?

23 Conclusions Information on symptoms could be combined with available clinical evidence for judging cause of death at individual level Scope for application of Bayesian principles in deriving population level cause specific mortality fractions from data gathered in surveys For adult deaths, could be useful for understanding broad cause group mortality at population level A measure of discriminatory power of individual questions / algorithms for identifying specific causes of adult deaths would be useful

24 Conclusions (contd) Need to evaluate biases from VA instrument validation in hospital studies, and cross cultural comparability of responses to specific questionnaire items Need for standardization of protocols for both data collection and cause of death assignment All VA implementation should contain elements of validation Examples of potential application –Sentinel sites in northern Brazil –Representative sites in Tanzania –Data quality improvement in Thailand, China No other option to rapidly increase usability of cause of death data from developing countries

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