Rates commonly used in epidemiology

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See also standardisation (mortality).

Rate (per annum) Numerator Denominator Notes
General fertility rate No of births Women age 15-44 (1000s) 64.3 per thousand in UK in 1990
Crude birth rate No of births Total population includes men women and children (1000s) 13.9 per thousand in UK in 1990
Age-specific fertility rates No of births per women of specific age range No of women in that age range (1000s) -
Total period fertility rate Summarises age-specific rates: live births per woman if all women experienced the average number of births for each age range, throughout her reproductive life. Per woman. 1.84 in UK in 1990.

2.1 is replacement figure in UK (>2 due to deaths before reaching child-bearing age).

Stillbirth rate No of stillbirths (>24/40 since 1992, >27/40 previously) Total births (1000s) 4.6 per thousand in UK in 1990
Perinatal mortality rate (PNMR) Stillbirths + deaths in early neonatal period (within first week of life) Total births (1000s) -
Early neonatal mortality rate Deaths in early neonatal period (within first week of life) Live births (1000s) -
Late neonatal mortality rate Deaths in late neonatal period (between 7th and 28th day of life) Live births (1000s) (150 per thousand at end of last century; 58.7 in 1936; ~8 in 1990 (UK)
Neonatal mortality rate Deaths in first 28 days of life Live births (1000s) 4.5 per thousand in UK in 1990
Post neonatal mortality rate Deaths after 28 days but within the first year of life Live births (1000s) 3.2 per thousand in UK in 1990. Strongly associated with social class etc.
Infant mortality rate Deaths within the first year of life Live births (1000s) 7.7 per thousand in UK in 1990.
Maternal mortality rate Deaths occurring "while pregnant or within 42 days (6/52) of termination of pregnancy from any cause related to or aggravated by pregnancy or its management, but not from accidental or incidental causes". See also Maternal deaths. Total births (100 000s) 1/200 a turn of century; one in 13 000 in 1990.
Crude death rate No of deaths Total population (1000s or 10,000s) Expresses mortality as a single figure, but varies with demography. Rate >1/10k is an emergency
Case fatality rate No of deaths from a specific disease No of cases with the same disease (1000s) -
Incidence rate Number of new cases over a defined period Population at risk -
Prevalence Total number of cases at a point in time, or during a period of time (point or period prevalence) Population at risk -