NR 503 Week 3 Discussion Epidemiological Methods and Measurements

Sample Answer

1. What is the fundamental difference between the method you have chosen (either the case-control or cohort method) and the randomized controlled trial?

Case-control studies define an outcome of interest first. Participants are selected for the study based on their disease status in relation to the chosen outcome. The 1st group will have the outcome while the control group does not have the chosen outcome. Investigators look back in time to compare the two groups for a risk factor, exposure, or treatment of interest (Dupepe et. al., 2019). This type of study is comparative but considered retrospective primarily. Case-control studies do not answer questions about prevalence or incidence, but instead allow investigators to test hypothesis regarding causation and therapeutic efficacy (Depepe et. al., 2019).

Dupepe et. al. (2019) explains that case-control studies provide an estimate of the strength of association between a variable and the outcome of interest in the form of an odds ratio (OR). Odds ratio in case-control studies has to do with the odds of being an exposed case compared with the odds of being exposed control (Curley, 2019). If the outcome of interest is uncommon and both the controls and cases are low risk for developing the outcome, the OR can approximate relative risk, which demonstrates a stronger association and inference of causality (Depepe et. al., 2019).

Randomized control trials (RCTs) are the highest quality of study design but are not always practical due to study protocols, higher costs, length of study, and difficulty enrolling enough participants (Dupepe et. al., 2019).

According to Hariton & Locascio (2018) the singular advantage of RCTs over other evaluation methods is the ability to reliably establish a causal link when comparing interventions to an outcome, while eliminating bias that comes with other evaluation methods. The reason that randomized control trials are preferred is the ability to remove bias from evaluation. RCTs include participants that are chosen randomly from an eligible population with a control group that is chosen from the same population. Through randomization large groups of participants have a balance of characteristics which allow attribution of differences in intervention and outcome (Hariton & Locascio, 2018).

Both randomized control trials and case-control trials focus on an outcome prior to beginning the study.

2. What are the advantages and disadvantages of the study method you chose (case-control or cohort study)?

An advantage of case-control studies is that they require a smaller number of participants, is less expensive to produce, and can be conducted over a shorter period. The studies are retrospective which allows investigators to study multiple potential exposures or risk factors, rare outcomes, and outcomes that require longer latency periods (Depepe et. al., 2019). Case-control studies are ideal for studying rare conditions like neurosurgical conditions which occur in the general population in small incidences but may have long latency periods. Randomized control trials would not be feasible to evaluate these type of rarer conditions (Depepe et. al., 2019).

Disadvantages of case-control design is vulnerability to bias because in retrospective studies the investigator control is limited in selecting cases and introduces sample bias (Depepe et. al., 2019). In nested control-case studies there would be an exception because it combines cohort studies with case-control studies in which risk factor selection prior to occurrence of outcome can eliminate bias. Initially, this would prevent this disadvantage if participants were chosen in a random fashion (Depepe et. al., 2019).

3. What are the characteristics of a correlational study?

Correlational studies are used to conduct studies of a population’s characteristics. Rates are calculated for characteristics that describe populations and are used to compare frequencies between different groups at various times (Curley, 2019, p. 72). Correlation studies could report if a correlation exists but cannot show if an association exists when comparison is made to compare population data (Curley, 2019, p.72).

4. Where does the method you chose (case-control or cohort study) fall on the research pyramid? What does its location on the research pyramid mean?

In accordance with the research pyramid of evidence, my method of case-control study falls under level 4. The purpose of the evidence pyramid is to identify the strength of the evidence in all types of research. The research levels at the tip of the pyramid have the most credibility, while those at the base of the pyramid are less credible, and more exposed to bias (Curley, 2019, p.113). Case-control studies fall at level number 4 meaning that they are credible, but not as valid as random-control trials or cohort studies. To be clear all evidence on the pyramid is considered credible, but some of the research has higher credibility.

According to Havey (2020) the issue with the evidence pyramid is that it sets meta-analyses and systematic reviews as the standard, which requires well executed random control trials. Even though cohorts and case-studies are lower on the pyramid, they are more commonly used as medical evidence due to the advantages of cost and patient participation.

Reference

• RN, A.L.C. P. (2019). Population-Based Nursing (3rd ed.). Springer Publishing LLC. https //ambassadored.vitalsource.com/books/9780826136749Links to an external site.
• Dupépé, Kicielinski, K. P., Gordon, A. S., & Walters, B. C. (2019). What is a Case-Control Study? Neurosurgery, 84(4), 819–826. https //doi.org/10.1093/neuros/nyy590Links to an external site.
• Hariton, & Locascio, J. J. (2018). Randomised controlled trials – the gold standard for effectiveness research Study design randomised controlled trials. BJOG  an International Journal of Obstetrics and Gynaecology, 125(13), 1716–1716. https //doi.org/10.1111/1471-0528.15199Links to an external site.
• Harvey. (2020). Can we use levels of evidence to make a decision? Canadian Journal of Surgery, 63(1), E86–E86. https //doi.org/10.1503/cjs.001920