Incidence is the number of new cases of a disease that arise in a group of people over a set period, usually expressed as a rate, such as cases per 100,000 people per year. It measures how often people develop a disease, as opposed to prevalence, which counts everyone who has it at a given time.
Origin
Counting new cases in a defined population is one of the oldest tools of epidemiology, developed alongside vital statistics in the 19th century. Population cancer registries, which began in the 20th century, made it possible to measure the incidence of rare cancers such as mesothelioma.
Significance in Asbestos Context
Incidence figures sit behind much of what is said about asbestos disease. Mesothelioma is rare in the general population, so a cluster of new cases among shipyard workers, insulators or people living near a mine stands out sharply. Studies compare the incidence in exposed groups with the incidence expected in the general population, often using a standardized incidence ratio. Incidence trends also show the long latency of asbestos disease: in many countries mesothelioma rates kept rising for decades after asbestos use fell, and in the United States the number of new cases each year has been roughly level for some time, with rates among women and in older age groups drawing attention. Reported rates depend on how cases are counted and coded, and mesothelioma is sometimes misdiagnosed, so registry numbers are estimates. For an individual claim, incidence is background; it describes populations, not whether a particular person's disease was caused by asbestos.
Example Sentence
The study found a mesothelioma incidence among former insulators many times higher than in the general population of the same age.
Related Terms
Prevalence, Epidemiology, Standardized Incidence Ratio (SIR), Cancer Registry, SEER, Cohort Study, Latency
Notes
- When you read an incidence figure, check the time period and the population it describes.
- A rate per 100,000 per year is not your personal risk; ask a doctor how it applies to your exposure.
In the research library
238 studies in our medical research library mention Incidence in the title or abstract. Among the most cited:
- Incidence rates of malignant mesothelioma in Denmark and predicted future number of cases among menJ. Kjaergaard, M. Andersson, 2000 · Scandinavian Journal of Work, Environment & Health · cited 39 times
- Explaining differences in incidence rates of pleural mesothelioma between Sweden and the NetherlandsA. Burdorf, B. Järvholm, A. Englund, 2005 · International Journal of Cancer · cited 24 times
- Mesothelioma Incidence Rates in Australia since 1982: Exploring Age, Period, and Cohort Effects and Future ProjectionsK. Walker-Bone, M.A. Goodwin, B. Bufton, et al, 2025 · Cancer Epidemiology, Biomarkers & Prevention · cited 8 times
- Recent trends in incidence rates of pleural mesothelioma in British ColumbiaH.I. Morrison, P.R. Band, R. Gallagher, et al, 1984 · Canadian Medical Association Journal · cited 6 times
- Occupation and cancer - follow-up of 15 million people in five Nordic countriesE. Pukkala, J.I. Martinsen, E. Lynge, et al, 2009 · Acta Oncologica · cited 522 times
The journals that publish most on it: Occupational and Environmental Medicine (17), American Journal of Industrial Medicine (15), Occupational Medicine (8).
Category: Epidemiological Methods · All Lexicon terms A–Z
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