++
Learning Objectives
After completing this chapter, the reader will be able to:
Differentiate between four types of observational studies: case report/case series, cross-sectional study, case-control study, and cohort study (retrospective and prospective).
Determine if the results of an observational study are valid based on a critical evaluation of its methods.
Differentiate between three types of reviews: narrative (nonsystematic) review, qualitative systematic review, and quantitative systematic review (meta-analysis).
Determine if the results of a systematic review are valid based on a critical evaluation of its methods.
Differentiate between various other study designs: N-of-1 trials, health outcomes research, stability studies, bioequivalence studies, postmarketing studies, quality improvement research, survey research, and educational research.
Evaluate the appropriateness of the methodology in various other study designs.
Identify issues encountered in natural medicines medical literature that require special attention.
++
Key Concepts
The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement is a guidance document that describes the information that should be reported for a cross-sectional study, case-control study, or cohort study. Although developed to assist authors and reviewers/editors of journals, it can also serve as a tool to help readers identify important items for critical appraisal.
In the process of creating two or more groups of patients in observational studies, investigators may use a process called matching.
A confounding factor, or confounder, is something other than the independent variable that may affect the outcome in an observational study.
The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement is a guidance document that describes the information that should be reported for a systematic review. Although developed to assist authors and reviewers/editors of journals, it can also serve as a tool to help readers identify important items for critical appraisal.
Assessment of heterogeneity, the extent of dissimilarity in study results, is an important consideration for quantitative systematic reviews.
Failure to identify all relevant studies on a topic is a threat to the validity of a quantitative systematic review; thus, an assessment for publication bias should be performed.
Important research with which a health care professional should be familiar can be broadly organized by the reason the study or research is performed. These include studies conducted to help make therapeutic decisions, meet regulatory requirements, and examine and evaluate practice.
The principles and criteria used to analyze the quality of drug literature are used to analyze natural medicines medical literature; however, unique additional points such as standardization and purity must be considered.
++
The randomized controlled trial is the strongest study design for clinical research, but several other designs, such as observational studies and reviews, are also commonly used. Each study design is useful for specific situations, has inherent strengths and weaknesses, and involves some unique methodologies. Because all relevant literature should be considered when practicing evidence-based medicine (EBM), it is vital to understand how to evaluate all study designs. The purpose of this ...