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Epidemiology
Published in Samuel C. Morris, Cancer Risk Assessment, 2020
Case-control studies first identify people with a particular disease (the cases) and another group of people without the disease (the controls). Then information on past exposures and other factors is collected from interviews, questionnaires, medical records, work records, and other sources. If a higher proportion of cases were exposed, then a link between exposure and disease is suggested. This is a uniquely epidemiological design which has no parallel in the classic experimental approach as used in toxicology. It is, in many ways, the most powerful design in the armamentarium of the epidemiologist. Comparing it to prospective studies, Sartwell (1983) describes the advantages of the case-control design as (1) enormously more efficient in requirements of manpower, cost, and time; (2) not requiring follow-up; (3) permitting careful examination of a wide array of factors; (4) the ability to take into consideration changes in the amount of exposure over time up to the onset of the disease. Its efficiency and ability to examine exposure and other factors more closely for each subject is because one only must be concerned with, say, 300 cases and 600 controls when in a prospective study it might be necessary to deal with 10,000 subjects to ultimately end up with the same number of cases. There are three key areas to look for in a case-control study: (1) selection of cases; (2) selection of controls; and (3) ascertainment of exposure and other cofactors.
Epidemiological Methods for Studying the Role of Beta Receptor Agonist Therapy in Asthma Mortality
Published in Richard Beasley, Neil E. Pearce, The Role of Beta Receptor Agonist Therapy in Asthma Mortality, 2020
Case-control studies are the most practicable and efficient form of epidemiological research when studying rare outcomes, and for this reason alone case-control studies are the optimal approach for investigating the causes of asthma mortality. As a result of their great efficiency, new (and therefore often unexpected and controversial) results are usually first shown in case-control studies.15 However, the methodological issues are often complex, and some relatively poor case-control studies have been conducted, particularly in the years when this technique was first being developed. Partly as a consequence, case-control studies were initially regarded as an inherently inferior form of formal epidemiological research. However, it is now recognized that a well-designed case-control study only differs from a full cohort study in one respect: that cases are compared with a sample of the cohort rather than the full cohort. In all other respects, the case-control approach has all the advantages (and disadvantages) of the cohort approach. In addition, the case-control design has one important advantage: it is considerably more efficient. This increase in efficiency usually means that a much larger study (in terms of the number of cases) can be conducted.
Big Data Analytics
Published in Shein-Chung Chow, Innovative Statistics in Regulatory Science, 2019
In clinical research, one of the major concerns of a case-control study is selection bias, which often caused by significant difference or imbalance between the case and control groups, especially for large observational studies (Rosenbaum and Rubin, 1983, 1984; Austin, 2011). In this case, the target patient population under study in the control group may not be comparable to that of the case group. This selection bias could alter the conclusion of the treatment effect due to possible confounding effect. Consequently, the conclusion may be biased and hence misleading. To overcome this problem, Rosenbaum and Rubin (1983) proposed the concept of propensity score as a method to reduce selection bias in observational studies. Propensity score is a conditional probability (or score) of the subject being in a particular group when given chosen characteristics. That is, consider the case group as those who received a certain treatment (T = 1), and the control group as those who did not receive this treatment (T = 0). Let X be a vector represents baseline demographics and/or patient characteristics that are important (e.g., possible confounding factors) for matching the case and control populations for reducing the selection bias. The propensity score is then given by
Heightened risks of cardiovascular disease in South Asian populations: causes and consequences
Published in Expert Review of Cardiovascular Therapy, 2023
Maria Stefil, Jack Bell, Peter Calvert, Gregory YH Lip
The INTERHEART study [81] was a landmark case–control study examining global patterns of ASCVD risk factors in 15,152 patients with MI and 14,820 controls from across 52 countries, including 3,936 individuals from 5 South Asian countries. South Asian countries were similar to the global pattern in that nine traditional risk factors (abnormal lipids, smoking, hypertension, diabetes, abdominal obesity, psychosocial factors, consumption of fruits, vegetables, and alcohol, and regular physical activity) together accounted for 92% of the population attributable risk for MI. In South Asian countries, the risk factors with the highest population attributable risks were dyslipidaemia (58.7%), abdominal obesity (37.7%), smoking (37.4%), exercise levels (27.1%), hypertension (19.3%), and fruit and vegetable intake (18.3%). In South Asian countries, the prevalence of alcohol intake, particularly in the predominantly Muslim countries of Pakistan and Bangladesh, was low, and alcohol intake was not associated with MI[81]. These findings should be interpreted within the limits of the case–control study design and the fact that many risk factors were self-reported.
Social determinants associated with loss of an eye in the United States using the All of Us nationwide database
Published in Orbit, 2022
Alison X. Chan, Bharanidharan Radha Saseendrakumar, Daniel J. Ozzello, Michelle Ting, Jin Sook Yoon, Catherine Y. Liu, Bobby S. Korn, Don O. Kikkawa, Sally L. Baxter
A major strength of using the All of Us database is the enrollment of underrepresented minorities. This is especially relevant given that African Americans and Hispanics are historically underrepresented in ophthalmology research and clinical trials.29 As a testament to the program’s commitment to diversity, our initial analyses of the database revealed that 21.94% of enrolled adults identified as African American. The national scale of All of Us is an additional strength, as the program has multiple enrollment sites in both academic and community settings across the country. Finally, the All of Us database offers sociodemographic information (i.e. highest attained education level, annual income, etc.) and survey data that are not readily available in routine EHRs. Limitations of this study include the inability to establish a causal relationship due to the case-control study design. Cohort definitions relied upon diagnostic billing codes, and it is possible misclassification or inconsistencies in diagnoses occurred, although this is a limitation common to analyses of claims and EHR data. Clinical notes documenting visual acuity and the severity of injury, tumor invasion, or infection are also not currently available through the database.
Evaluating the extent of change in near point of convergence in traumatic brain injury: a systematic review and meta-analysis
Published in Brain Injury, 2022
Revathy Mani, Steven Ngo, Jacinta Walz, Sieu K. Khuu
Most of the studies involved in the systematic review were of the case-control study design, as it would be ethically questionable to design and perform a randomized control trial where subjects are expected to sustain a TBI. While all of the case-control studies were age-matched and comparisons can be inferred between the control and experimental groups, the nature of the case-control study design is that it is retrospective and is dependent on data that has not been collected. A good compromise would be a longitudinal study design similar to a prospective cohort study, and not unlike the one performed by Vernau et al. (40) This would involve enrolling a cohort where TBI is a common occurrence, such as a contact sports league or the military, into the study to measure baselines for the control. Any who would then suffer a TBI would have the measurements taken again. This would result in a naturally large sample size in a simple to set up study which would have strong, conclusive results.