Module 2: Study Designs

Case-control studies are useful in rare diseases because they allow researchers to efficiently investigate the relationship between exposure and outcome. In rare diseases, it is often difficult to gather a large number of cases, making it impractical to conduct a prospective cohort study. By using a case-control design, researchers can select a small number of cases with the disease and match them with controls without the disease. This allows for a more efficient study design and can provide valuable insights into the causes and risk factors of rare diseases.

The acronym "PICO" is commonly used in formulating research questions in evidence-based practice. It stands for Population, Intervention, Control, and Outcome. This framework helps researchers to clearly define the specific population or group they are studying, the intervention or treatment being investigated, the control group or comparison being used, and the desired outcome or result they are looking for. By using the PICO framework, researchers can develop focused and well-defined research questions that can be effectively studied and answered.

Observational studies do not always lead to the detection of causality. While they can provide valuable insights and generate hypotheses, they cannot establish a cause-and-effect relationship between variables. Observational studies observe and analyze existing data without manipulating any variables, which limits their ability to determine causation. Other types of studies, such as experimental studies, are better suited for establishing causality as they involve controlled interventions and randomization. Therefore, the given answer "False" is correct.

Systematic review and meta-analysis are considered more powerful in the EBM (Evidence-Based Medicine) pyramid because they provide the highest level of evidence. These types of studies involve the comprehensive review and analysis of multiple primary research studies on a specific topic. They aim to synthesize the available evidence and provide a more reliable and robust conclusion. Systematic reviews and meta-analyses are considered to have a higher level of evidence compared to individual observational studies like case-control and cohort studies, as well as opinion-based articles like editorials.

In a cohort study of the efficacy of drug "X" for myocardial infarction, the correct answer is A) we follow up patients and observe the case. This means that the study involves tracking and monitoring a group of patients over a period of time to observe the outcomes and effects of drug "X" on myocardial infarction. This type of study allows researchers to gather data on the real-world effectiveness of the drug in a specific population.

Interventional studies provide the highest level of evidence because they involve manipulating variables and controlling for confounding factors. These studies typically involve randomized controlled trials (RCTs), where participants are randomly assigned to different interventions or treatment groups. This design allows researchers to establish cause-and-effect relationships and draw more definitive conclusions about the effectiveness of a particular intervention. On the other hand, observational studies, both analytical and descriptive, only observe and record data without manipulating variables or controlling for confounding factors, making their evidence less robust.

The correct answer is B) Summary of all paper's parts. This means that a paper abstract should provide a concise overview of all the different sections or parts of the paper. It should briefly summarize the introduction, methods, results, and conclusions of the research study. The abstract serves as a snapshot of the entire paper, giving readers a clear understanding of what the study is about and what the main findings are, without going into too much detail.

The given answer states that "Can establish causal sequence" is not a disadvantage of a cohort study. This means that cohort studies are able to establish a causal sequence, which is a strength rather than a disadvantage. Cohort studies are known for their ability to determine cause and effect relationships between exposures and outcomes over a period of time. However, the other options listed - time-consuming, expensive, and high loss of follow-up - are all considered disadvantages of cohort studies.

Cross-sectional studies are a type of observational research that examines a population at a specific point in time. The two disadvantages mentioned in the answer are high risk of bias and the inability to establish a causal sequence. Cross-sectional studies are prone to bias because they do not control for confounding variables or establish a temporal relationship between the exposure and outcome. Additionally, they cannot determine the cause-effect relationship between variables since they only provide a snapshot of data at a single time point.

The correct answer is D) Case report is better than it. This answer is correct because the statement contradicts the common understanding in literature review that case reports are generally considered to be of lower quality evidence compared to other study designs. Literature reviews typically prioritize higher quality evidence such as systematic reviews, randomized controlled trials, and cohort studies over case reports. Therefore, it is incorrect to state that case reports are better than other types of evidence in a literature review.