Miscellaneous: Study Design

Study Design

Descriptive Studies

Case Report
- Report of a Single Patient Case
Case Series
- Compares: A Single Group of Patients Similar in Some Form (Receiving an Intervention or with a Certain Disease)
  - No Control Group
- Describes: Risk Factors or Outcomes

Analytical Studies Mn

Case-Control Study
- Compares: Diseased vs. Healthy
- Determines: Past Risk Factors
Cross-Sectional Study
- Compares: A Group with a Current Risk Factor vs. a Group Without the Risk Factor
- Determines: Prevalence of an Outcome Now
Cohort Study
- Compares: A Group with the Risk Factor vs. a Group Without the Risk Factor
- Determines: Incidence of Outcome
- Types:
  - Retrospective Cohort – Looks at Patients with Past Risk Factors to Evaluate Incidence to Now Retrospectively
  - Prospective Cohort – Looks at Patients with Current Risk Factors to Evaluate Incidence into the Future Prospectively
Clinical Trial
- Compares: Treatment Group vs. Control Group
- Determines: Outcomes in Future Prospectively
- Randomized Control Trial (RCT) – Essentially the Gold Standard Study
Reviews of Multiple Studies:
- Meta-Analysis
  - Combines Data from Different Studies
- Systematic Review
  - Qualitatively Reviews Multiple Studies

Other Study Design Considerations

Clinical Equipoise – There Must Be No Clear Preference Between the Different Tested Interventions
Blinding:
- Blinded Study – Patients Do Not Know Which Treatment They are Receiving
  - Eliminates Placebo Effect
- Double-Blinded Study – Neither Patients nor Physicians Know Which Treatment They are Receiving
Intention-to-Treat Analysis – Data Analyzed by the Group they are Randomized To
- Regardless of Whether They Receive the Intended Treatment or Not
- Includes Noncompliance, Withdrawal from Study, Loss to Follow Up or Protocol Violations

Research Clinical Trials

Visual Comparison of Study Types