Question

Difficulty: EasyEpidemiologic Study Designs

A group of researchers is investigating the potential association between a rare autoimmune condition, systemic sclerosis, and prior occupational exposure to silica dust. The researchers identify 50 patients with confirmed systemic sclerosis from a regional rheumatology clinic. They then identify 100 healthy individuals without the disease from a general internal medicine clinic, matching them to the affected patients by age and biological sex. The researchers proceed to review the detailed occupational histories of all 150 participants to look for past silica dust exposure. Based on this scenario, which of the following statements correctly describe this study design? (Select all that apply)

  1. Participants are enrolled into the study based on their disease statusAnswer
  2. The study design is highly efficient for investigating rare diseasesAnswer
  3. C
    Participants are enrolled into the study based on their prior exposure to silica dust
  4. D
    The study allows for the direct calculation of disease incidence
  5. E
    Relative risk is the primary statistical measure of association used

Answer

The study enrolls participants based on their disease status and is highly efficient for investigating rare diseases.
The clinical vignette describes a case-control study. In a case-control study, individuals are specifically selected based on whether they currently have the disease of interest (cases) or do not have the disease (controls). Because the researchers guarantee a set number of diseased individuals at the start of the investigation, this design is exceptionally efficient for studying rare diseases. If a cohort study were used for a rare disease, it would require a massive sample size and a prolonged follow-up period to yield a statistically significant number of affected patients.

Step-by-Step Solution

1
Identify the study design from the vignette narrative.
The researchers identify cases (patients with systemic sclerosis) and controls (healthy individuals), then look back at their occupational history to assess exposure.
Determining the direction of inquiry (from disease to exposure) is necessary to classify the study as a case-control study.
2
Recall the fundamental characteristics of a case-control study.
Case-control studies select subjects based on disease outcome, are efficient for studying rare diseases, cannot measure true incidence, and utilize odds ratios as the measure of association.
Matching the identified study design to its core epidemiological features helps accurately evaluate the answer choices.

Key Concept

Characteristics of Case-Control Studies
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