A prospective cohort study is a

longitudinal Longitudinal is a geometric term of location which may refer to: * Longitude ** Line of longitude, also called a meridian * Longitudinal engine, an internal combustion engine in which the crankshaft is oriented along the long axis of the vehicle, ...

cohort study A cohort study is a particular form of longitudinal study that samples a cohort (a group of people who share a defining characteristic, typically those who experienced a common event in a selected period, such as birth or graduation), performing ...

that follows over time a group of similar individuals ( cohorts) who differ with respect to certain factors under study, to determine how these factors affect rates of a certain

outcome Outcome may refer to: * Outcome (probability), the result of an experiment in probability theory * Outcome (game theory), the result of players' decisions in game theory * ''The Outcome'', a 2005 Spanish film * An outcome measure (or endpoint) ...

. For example, one might follow a cohort of middle-aged truck drivers who vary in terms of smoking habits, to test the hypothesis that the 20-year incidence rate of lung cancer will be highest among heavy smokers, followed by moderate smokers, and then nonsmokers. The prospective study is important for research on the

etiology Etiology (pronounced ; alternatively: aetiology or ætiology) is the study of causation or origination. The word is derived from the Greek (''aitiología'') "giving a reason for" (, ''aitía'', "cause"); and ('' -logía''). More completely, e ...

of diseases and disorders. The distinguishing feature of a prospective cohort study is that at the time that the investigators begin enrolling subjects and collecting baseline exposure information, none of the subjects have developed any of the outcomes of interest. After baseline information is collected, subjects in a prospective cohort study are then followed "longitudinally," i.e. over a period of time, usually for years, to determine if and when they become diseased and whether their exposure status changes outcomes. In this way, investigators can eventually use the data to answer many questions about the associations between "risk factors" and disease outcomes. For example, one could identify smokers and non-smokers at baseline and compare their subsequent incidence of developing heart disease. Alternatively, one could group subjects based on their body mass index (BMI) and compare their risk of developing heart disease or cancer. Prospective cohort studies are typically ranked higher in the hierarchy of evidence than retrospective cohort studies and can be more expensive than a case–control study. One of the advantages of prospective cohort studies is they can help determine risk factors for being infected with a new disease because they are a longitudinal observation over time, and the collection of results is at regular time intervals, so recall error is minimized.

Reporting

The Strengthening the Reporting of OBservational studies in Epidemiology (

STROBE A strobe light or stroboscopic lamp, commonly called a strobe, is a device used to produce regular flashes of light. It is one of a number of devices that can be used as a stroboscope. The word originated from the Ancient Greek ('), meaning ...

) recommends that authors refrain from calling a study ‘prospective’ or ‘

retrospective A retrospective (from Latin ''retrospectare'', "look back"), generally, is a look back at events that took place, or works that were produced, in the past. As a noun, ''retrospective'' has specific meanings in medicine, software development, popu ...

’ due to these terms having contradictory and overlapping definitions. STROBE also recommends that whenever authors use these words, they specify which definition they use, including a detailed description of how and when data collection took place.

Examples

Caerphilly Heart Disease Study The Caerphilly Heart Disease Study, also known as the Caerphilly Prospective Study (CaPS), is an epidemiological prospective cohort, set up in 1979 in a representative population sample drawn from Caerphilly, a typical small town in South Wales, ...

, UK.
Canadian Longitudinal Study on Aging / Étude longitudinale canadienne sur le vieillissement (CLSA-ÉLCV)

The CARTaGENE cohort / Quebec's largest prospective study
Quebec, Canada
Cebu Longitudinal Health and Nutrition Survey
the Philippines *

Framingham Heart Study The Framingham Heart Study is a long-term, ongoing cardiovascular cohort study of residents of the city of Framingham, Massachusetts. The study began in 1948 with 5,209 adult subjects from Framingham, and is now on its third generation of parti ...

, USA. *

Million Women Study The Million Women Study is a study of women’s health analysing data from more than one million women aged 50 and over, led by Dame Valerie Beral and a team of researchers at the Cancer Epidemiology Unit, University of Oxford. It is a collabo ...

, UK. *

Rotterdam Study The Rotterdam Study or ERGO ( Dutch: ''Erasmus Rotterdam Gezondheid Onderzoek'') is a prospective, population-based cohort study. The aim of the Rotterdam Study is to investigate etiology, preclinical phase, prognosis and potential intervention t ...

, Netherlands.
Tsimane’ Amazonian Panel Study
Bolivia
The UK biobank
UK

References

{{DEFAULTSORT:Prospective Cohort Study Cohort study methods

Reporting

Examples

See also

References