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Basic Research Design:
Published in Lynne M. Bianchi, Research during Medical Residency, 2022
Lynne M. Bianchi, Luke J. Rosielle, Justin Puller, Kristin Juhasz
Examples:Investigators conduct a prospective cohort study to see if participation in team sports prior to age 50 protects older adults from health conditions commonly associated with aging. They identify a cohort of young adults between the ages of 25 and 30 who play recreational sports in three communities across New Jersey and survey the participants every 5 years to monitor health status.An investigator completes a retrospective cohort study of a group of patients from a geographical region (risk factor) with a high prevalence of leukemia (outcome). Records are reviewed to identify risk factors/exposures, such as length of time living in the area and proximity of one's home to a former waste disposal site.
Study Limitations to Consider
Published in Lisa Chasan-Taber, Writing Grant Proposals in Epidemiology, Preventive Medicine, and Biostatistics, 2022
However, instead, selection bias is possible in a prospective study through differential loss to follow-up. Just as participants who do not agree to participate will not be in your final dataset, participants who are lost to follow-up will also not be present in your final dataset. That is why loss to follow-up in a prospective cohort study can also be viewed as a type of potential selection bias. I use the term potential because not all loss to follow-up is differential and therefore not all loss to follow-up meets the criteria for selection bias.
Environmental Exposures and Reproduction *
Published in Michele Kiely, Reproductive and Perinatal Epidemiology, 2019
In cohort studies, groups are defined by exposure status and followed up to observe the frequency of certain outcomes. While such studies may be based on record systems (e.g., workplace groups or union lists for historical cohort studies), this design allows more direct measurement of exposure and outcome and thus can provide the most representative data in a prospective cohort study. Unfortunately, such studies are very time consuming and expensive. Few environmental agents have been studied in this way; lead is a notable exception (e.g., see References 29 to 30). A major advantage to this study design is the ability to examine more than one outcome in the same population (see Section I); however, rare events are difficult to study unless the group studied is very large. The quality of the exposure data are affected by the same issues briefly described in the discussion of case-referent studies.
Characteristic analysis of early gastric cancer after Helicobacter pylori eradication: a multicenter retrospective propensity score-matched study
Published in Annals of Medicine, 2023
Xinyuan Liu, Xinyu Wang, Tao Mao, Xiaoyan Yin, Zhi Wei, Jindong Fu, Jie Wu, Xiaoyu Li
Our multicenter retrospective study comparatively analyzed the clinical, endoscopic, and histopathological features of GC after H. pylori eradication and H. pylori infection-related GC, providing a reference for the early detection and diagnosis of GC after H. pylori eradication. We matched the variables, including sex, age, smoking history, drinking history, family history of GC, CCI, and the number of endoscopic examinations, to eliminate the effect of confounding factors, especially since patients in HP-eradicated group might have received longer duration of follow-up after HP eradication with more clinic visit and endoscopic surveillance than those in the control group. Our study has several limitations. First, this was a retrospective study with no prognostic analysis, which was not as convincing as a prospective study. Second, the number of patients diagnosed with EGC after H. pylori eradication is indeed very small although this research was a multicenter study. In addition, our study has strict inclusion and exclusion criteria, so the sample size in Hp-eradicated group is small as well. In the near future, we will conduct a prospective cohort study, expand the sample size, and perform a comparative analysis of the survival rates.
A single-center experience of parathyroidectomy in 1500 cases for secondary hyperparathyroidism: a retrospective study
Published in Renal Failure, 2022
Shasha Zhao, Wei Gan, Wenjia Xie, Jinlong Cao, Liang Zhang, Ping Wen, Junwei Yang, Mingxia Xiong
Our study analyzed the curative effect of parathyroidectomy, common complications, outcomes, and pathological reports of resected parathyroid and thyroid tissues. However, there were many limitations to our study. First, the lack of long-term follow-up data is the biggest shortcoming of this study. We tried to collect sufficient data with a long-term follow-up but failed. It was truly a time- and labor-consuming project without a previously well-designed scheme. To overcome this defect, we are conducting a cohort study comparing long outcomes between the two operation methods. Other limitations still exist, such as the retrospective nature of the analysis from a single-center, incompleteness of clinical data, lack of hypocalcemia-related symptoms, and lack of improvement in bone pain and pruritus. Again, most of these data can be obtained by a well-designed prospective cohort study.
Trajectories of disability in activities of daily living in advanced cancer or respiratory disease: a systematic review
Published in Disability and Rehabilitation, 2022
Lucy Fettes, Josephine Neo, Stephen Ashford, Irene J. Higginson, Matthew Maddocks
A prospective cohort study is an effective and appropriate way to observe trajectories of ADL disability as it allows for as many variables as required to be studied in order to determine any association with the outcome and allow all relevant confounding variables to be rigorously collected [59]. The sample should accurately reflect advanced cancer or respiratory disease using appropriate inclusion criteria [59], and use of multiple sites helps to widen recruitment and generalizability, and small samples can be pooled for increased power [60–62]. It is important to be aware that the efficiency of a prospective cohort study increases as the incidence of a particular outcome increases [59], which means it is necessary to recruit participants who are at risk of functional loss. Gatekeeping of the more unwell or disabled participants by clinicians can be prevented by use of a trained research assistant to screen for eligible participants [63].