For a disease with low prevalence in the general population, which characteristic of a screening test becomes MOST critical to avoid an unacceptable rate of false positives?

• A High specificity ✓
• B High sensitivity
• C High positive likelihood ratio
• D Short test-retest interval

Explanation

When disease prevalence is low, even a modestly poor specificity generates many false positives because the number of true negatives in the population is very large. By Bayes' theorem, PPV is heavily influenced by prevalence; low prevalence reduces PPV dramatically. High specificity (few false positives) is therefore critical for population-level screening of rare conditions to maintain an acceptable false-positive rate and avoid unnecessary workup and harm.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.