Health Indicators — Mortality, Morbidity, DALY/QALY/HALE, Sullivan's Index, PQLI and HDI

A health indicator is a variable that can be measured and compared over time or between places to reflect the health of a population. Because good morbidity data are often unavailable, mortality rates are frequently used to identify vulnerable populations — WHO uses exactly this rationale for the infant and under-five mortality indicators. Exam questions group indicators into a few families:

Neonatal deaths are subdivided into early neonatal (first 7 days) and late neonatal (after day 7 but before 28 completed days). Strictly, WHO notes that IMR and U5MR are probabilities of dying derived from a life table rather than true rates, though everyone calls them rates. Case-fatality measures the severity of a disease, not the risk of catching it.

Stillbirth is not part of NMR, IMR or U5MR, because those rates count only deaths among live births. WHO defines stillbirth as fetal death at 28 weeks of gestation or more, whereas some countries (for example the USA) report fetal deaths from 20 weeks or 350 g, so stillbirth rates are not directly comparable between countries.

A maternal death (WHO) is the death of a woman from any cause related to or aggravated by pregnancy or its management — excluding accidental or incidental causes — during pregnancy and childbirth or within 42 days of termination of pregnancy.

See postpartum haemorrhage for a major direct cause of maternal death, and family planning methods for why fewer pregnancies lower the maternal mortality rate even when the ratio does not change.

• Incidence — the occurrence of new cases in a population over a specified period. Incidence proportion is also called attack rate, risk or cumulative incidence: the proportion of an initially disease-free population that develops disease in a limited period.
• Prevalence — the proportion of persons who have the disease (new and pre-existing cases) at a point in time (point prevalence) or over an interval (period prevalence).
• Morbidity in the broad sense covers disease, injury and disability, and can also describe the duration of illness.

In 1971, D. F. Sullivan published A single index of mortality and morbidity (HSMHA Health Reports). His method combines a period life table (mortality) with the prevalence of disability from a cross-sectional survey to give the expected number of years a person will live free of disability. That figure — life expectancy minus the expected years spent with disability — is known as Sullivan's index, or disability-free life expectancy (DFLE).

Sullivan's method remains the most widely used way to calculate health expectancies, and WHO's HALE is built on the same approach, using years lost to disability at each age to split life expectancy into years of full health and years lost.

UNDP itself notes that the HDI captures only part of human development — it does not reflect inequality, poverty, human security or empowerment, which is why companion indices exist.

Numerical questions give a small district's vital statistics and ask for one indicator. Work from the definition — numerator, denominator, multiplier — and ignore the distractor figures. Take a hypothetical district with a mid-year population of 2,00,000, 4,000 live births, 1,600 total deaths, 120 deaths under one year (of which 80 in the first 28 days), 160 deaths under five years and 6 maternal deaths in a year.

• Denominator questions — IMR, NMR, U5MR per 1,000 live births; MMR per 100,000 live births; crude death rate per mid-year population.
• MMR vs MMRate — live births vs women of reproductive age.
• Maternal death time limit — within 42 days of the end of pregnancy.
• Sullivan's index = disability-free life expectancy.
• PQLI components — infant mortality, life expectancy at age one, literacy.
• HDI components — life expectancy at birth, schooling, GNI per capita; geometric mean.
• DALY = YLL + YLD; one DALY = one lost year of healthy life.
• Case-fatality rate measures severity (virulence) of a disease.