Table 1 Definitions of epidemiological measures
From: Epidemiology of Sanfilippo syndrome: results of a systematic literature review
Measure | Definition |
|---|---|
Incidence rate | Number of new cases of a disease in a population during a given period of time divided by the total of the lengths of time that each individual in the population was at risk, expressed as person-time (e.g., person-years) |
Cumulative incidence | Number of new cases of a disease in a population during a given period of time divided by the total number of people at risk of developing the disease at the beginning of the same period of time |
Lifetime risk | Lifetime risk is a special case of cumulative incidence in which the period of time studied is the entire remaining lifetime; if one calculates the entire remaining lifetime from birth, the measure is called lifetime risk at birth |
Point prevalence | Proportion of people in a population who have a disease or condition at a particular time point |
Birth prevalence | Number of cases (including birth defects among live births, spontaneous fetal death, and induced terminations when available) divided by the total number of live births (or live births plus stillbirths) |