Methods to Measure Mortality
Methods to Measure Mortality. SMART Meeting July 14, 2004. Quadrat Sampling. Beldangi Camp, Nepal. Community Map (IDP camp in Gulu, Uganda). Measuring Mortality. What is the context/setting in which we are gathering information? Type of disaster/emergency Phase of emergency
Methods to Measure Mortality
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Presentation Transcript
Methods to Measure Mortality SMART Meeting July 14, 2004
Measuring Mortality • What is the context/setting in which we are gathering information? • Type of disaster/emergency • Phase of emergency • Setting (urban/rural, scattered/concentrated, mixed/unmixed) • Resources: human, financial • Constraints: time, security, geography
Measuring Mortality • What level of precision do we need? • What are the impacts of an imprecise estimate? • We could fail to deliver a life-saving intervention to people who need it • We could waste resources
Measuring Mortality • What methods are most appropriate and in what sequence? • Preparedness planning • Observation • Participatory appraisal • Surveys • Surveillance • In-depth sector assessments • Validation/cross-checking/triangulation
Methods to Assess Mortality Sphere Project’s Minimum Standards in Health Services: Initial Assessment • Total disaster-affected population • Sex and age breakdown (at least <5 and >5) • Average family and household size • Crude mortality ( deaths per 10,000 per day) • Under-5 mortality (deaths per 10,000 per day) • Age and sex-specific incidence rates of major problems and diseases
Methods to Assess Mortality • Observation • Body counts, burial/cremation site activity • Participatory Appraisal • Community/key informant estimates: ask numbers of deaths in last day/week/month, general age groups, pre-arrival/post-arrival, cause of death • Community mapping: locate health clinics, places of worship). Ask about mortality patterns, customs about death (rituals, taboos, disposal of the body, etc.)
Methods to Assess Mortality • Surveillance • Passive: Clinic data • Active: Burial sites, body counts, neighborhood interviews • Surveys • Cross-checking of data sources
Active vs. Passive Surveillance, Bangladesh Camps, 1992 (Diskett, 2003)
Cambodia (Kampuchea), 1962 (Holck and Cates, 1982)
Mortality Rates • Mortality • Crude Death Rate (CDR or CMR) = deaths during interval/mid-interval population • Infant Mortality Rate (IMR) = deaths of infants under 1 year/ 1,000 live births • Under-Five Mortality Rate (U5MR) = deaths of children <5/ 1,000 live births (as used by UNICEF, WHO, etc. expresses the probability of dying by exact age 5 [ 5q0]) • Not to be confused with Age-Specific Death Rate of Children <5 (ASDR-U5 or U5DR)= deaths of children <5/ mid-interval pop. of children <5
Methods to Assess Mortality • Calculating Crude Death Rate CDR=deaths during interval/mid-interval population • Question: A local official tells you of reports of 50 deaths among 10,000 IDPs. What is the CDR, calculated as deaths/10,000/day?
Methods to Assess Mortality • Calculating Crude Death Rate CDR=deaths during interval/mid-interval population • Answer: Trick question. You cannot calculate the Crude Death Rate because you are given no time period within which these deaths reportedly occurred.
Methods to Assess Mortality • Calculating Crude Death Rate CDR=deaths during interval/mid-interval population • Question: You have done a survey of IDPs and found that in a sample of 5,000 people, 15 deaths were reported in the last month. What is the CDR, calculated as deaths/10,000/day?
Methods to Assess Mortality • Answer: 15 deaths/5,000/30 days = 30 deaths/10,000/30 days= 1 death/10,000/day or 15/deaths/5,000/30 days= 0.5/deaths/5,000/day= 1 death/10,000/day
Methods to Assess Mortality • Units of expression are adjustable: For example, 1 death/10,000/day=36.5 deaths/1,000/year = 3.65% of the population died in one year • The Crude Mortality Rate includes all causes of death for all age groups, thus is sensitive to age composition.
Methods to Assess Mortality • Mortality rates should be standardized from camps/settlements/critical areas to national, baseline rates or other comparative data. • Mortality survey instruments should gather data on events that contribute to exposure time: deaths, births, in-migration and out-migration.
Methods to Assess Mortality • Things to think about in designing mortality surveys: • Is this for response or “for the record?” • What level of precision is needed? • What period of reporting or recall is used? • What events contribute to h’hold change, exposure time? • What kinds of death may be more critical to the life of the population? • How to define h’hold, family? • How frequently surveys are conducted?
Methods to Assess Mortality • Reporting/recall periods • periods may be shorter (30 days) or longer (1 year) but must be consistent and stable • shorter periods: • miss earlier mortality trends • highly sensitive to “calendar” error • may capture relatively small number of deaths (1 death/10,000/day = 15 deaths/5,000/month)
Methods to Assess Mortality • Mortality surveys are sensitive to error: • recall error • “calendar” error • age heaping/digit preference (numbers ending in 0 or 5) • age misreporting (children <1 often identified as 1, adults tend to overstate age) • sensitivity/taboos about death
Methods to Assess Mortality • Mortality surveys are sensitive to error: • Mistranslation • Interviewer error • Data-entry error • Analytic error
Methods to Assess Mortality • Mortality surveys • Recommended sample size: 900 households (30 x 30 cluster sample) • Recommended recall period: 6 months - 1 year • Capture key events that contribute to household change, exposure time • Get age, sex, date, cause of death • If using a questionnaire, pre-test, back-translate • Use timeline and/or seasonal calendar to help people recall ages, dates.
Methods to Assess Mortality • Mortality surveys • Participate with decision-makers, stake-holders to define objectives, necessary precision • Establish survey, sampling methodology • Identify and document survey, sampling design (note departures from plan) • Establish and document training curriculum • Establish and document analysis plan • Document and share results promptly