Positive Predictive Value (PPV) of a screening test is MOST affected by:

• A Sensitivity of the test
• B Specificity of the test
• C Prevalence of the disease in the population being screened ✓
• D The total sample size used in validation studies

Explanation

PPV (proportion of test-positive individuals who truly have disease) is heavily influenced by disease prevalence. Even a test with 99% sensitivity and specificity will have poor PPV in a low-prevalence population because false positives outnumber true positives. This explains why mass screening is less efficient for rare diseases — PPV rises dramatically as prevalence increases. Sensitivity and specificity are intrinsic properties of the test, not the population.

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.