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13 results for “epidemiology”

Formulae (13)

IR = \frac{\text{New Cases}}{\text{Population at Risk}} \times k

Rate at which new cases of a disease appear in a population over a given period.

P = \frac{\text{Existing Cases}}{\text{Total Population}} \times k

Proportion of a population that has a particular condition at a point in time.

R_0 = \beta \times D

Average number of secondary infections produced by one infected individual in a fully susceptible population.

H = 1 - \frac{1}{R_0}

Minimum fraction of the population that must be immune to prevent sustained spread.

R_e = R_0 \times S

Actual average infections per case when part of the population is already immune.

\frac{dS}{dt} = -\beta S I

Rate of change of the susceptible population in the SIR compartmental model.

\frac{dI}{dt} = \beta S I - \gamma I

Rate of change of the infected population — new infections minus recoveries.

\frac{dR}{dt} = \gamma I

Rate at which infected individuals recover and gain immunity.

CFR = \frac{\text{Deaths}}{\text{Confirmed Cases}} \times 100

Proportion of diagnosed individuals who die from the disease.

AR = \frac{\text{Cases during outbreak}}{\text{Population exposed}} \times 100

Proportion of an exposed population that develops the illness during an outbreak.

RR = \frac{\text{Risk in Exposed}}{\text{Risk in Unexposed}}

How many times more likely the exposed group is to develop the disease compared to the unexposed group.

OR = \frac{a \times d}{b \times c}

Ratio of the odds of exposure among cases versus controls in a case-control study.

NNT = \frac{1}{ARR}

Number of patients who must receive a treatment for one additional patient to benefit.