Describe the characteristics and design of a cohort study. Based on a disease or health condition identified from the “2020 LHI Topics” on the Healthy People 2020 website, or an article from the library, discuss a real example of a cohort study (include the link to the article in your post to the forum). Include the participants, exposures or treatment groups, time frame, and outcomes that were measured. Why is a cohort study described as an “observational” study rather than an “experimental” study design?
Word count needs to be at least 300 words. Please cite any references being used.
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Introduction:
Cohort studies are among the most common study designs in medical research, where researchers follow a group of individuals over time to determine the incidence and risk factors for a particular health outcome. This study design is observational, where the researcher observes the group under investigation without any interference in their natural routine.
Characteristics and Design of a Cohort Study:
In cohort studies, participants are selected based on their exposure status, and the researcher observes the participants for a specific time to determine the differences in health outcomes between the exposed and non-exposed groups. The participants can either be exposed to a particular risk factor or non-exposed individuals. The researcher aims to study the incidence of the outcome among the exposed group compared to those who are not exposed.
The design of a cohort study requires a specific protocol, including the selection of participants, exposed and non-exposed groups, follow-up plan, and the outcome measure. The participants’ selection must be random or representative of the population of interest to ensure the study’s generalizability. The researcher defines and measures the exposure or treatment group and the outcome measure. In the comparison of the exposed and non-exposed groups, the researcher can also measure confounding variables that may affect the outcome, such as age, sex, or socioeconomic status. In the follow-up plan, the researcher must observe and record the participants’ outcome to measure the risk of developing the condition or disease of interest.
Real Example of Cohort Study:
According to the Healthy People 2020 objective, “Maternal, Infant, and Child Health,” preterm birth is a significant concern in the United States. In a study published by JAMA Pediatrics, researchers investigated the effect of maternal vitamin D supplementation on the risk of preterm birth. The researchers conducted a randomized controlled trial study, where participants were assigned randomly to either a vitamin D group or placebo group. The study included pregnant women aged 18 to 40 years and randomized 200 women to receive vitamin D supplementation and 200 women to receive a placebo. The participants received 1,200,000 IU of vitamin D or placebo in the 24 to 28 weeks of gestation. The researchers observed the participants until delivery and measured the preterm birth incidence in both groups. The results suggested that maternal vitamin D supplementation reduced the incidence of preterm birth by 45% compared to the placebo group.
Cohort Study as Observational Study:
Cohort studies are observational studies because the researcher does not manipulate the variables to study the outcome. Unlike experimental studies, where the researcher intervenes and controls the variables to show a causal relationship, in an observational study, the researcher only observes and records the variable of interest in the population, understanding possible confounding factors that may affect the outcome. This study design allows the researcher to study the incidence of disease or outcomes in a population without any external interference.
Conclusion:
Cohort studies are an observational study design that plays a vital role in medical research to explore the incidence and risk factors for different health outcomes among different populations. This design is beneficial in identifying risk factors for disease development and helps develop a preventative measure for the desired outcome.
