What common epidemiologic measures are used in surveillance besides incidence and prevalence?

• A. Attack rate, case fatality rate, mortality rate, and time-to-event measures.
• B. Only incidence and prevalence.
• C. Sensitivity and specificity.
• D. Population growth rate and birth rate.

Answer: (A)

Beyond simply counting new cases and total existing cases, surveillance uses measures that describe risk, severity, and timing of outcomes. The attack rate is a measure of risk during an outbreak in a defined group, usually reflecting the proportion of people who become ill over a short period and helping us gauge how quickly an outbreak spreads in that setting. The case fatality rate tells us the proportion of diagnosed cases that die, showing how deadly the disease is among those affected and informing whether care or treatments are making a difference. The mortality rate expands the view to the whole population, indicating how many deaths occur per unit of population and time, which guides public health planning and resource allocation. Time-to-event measures add the dimension of timing, focusing on how long it takes to reach outcomes like death or recovery after exposure or diagnosis, which is important for understanding prognosis and the impact of interventions over time. These measures complement incidence and prevalence to give a fuller picture of an outbreak’s dynamics, disease severity, and burden. Diagnostic test characteristics like sensitivity and specificity are about test accuracy, not population-level surveillance outcomes, and demographic rates like population growth or birth rate aren’t specific disease surveillance measures.