A screening test for cervical cancer has a sensitivity of 80% and specificity of 90%. In a population of 10,000 women where the prevalence of cervical cancer is 2%, what is the Positive Predictive Value (PPV) of the test?
- A 14.2% ✓
- B 80%
- C 90%
- D 62%
Explanation
With prevalence 2%: true positives = 200 × 0.80 = 160; false positives = 9800 × 0.10 = 980. PPV = TP/(TP+FP) = 160/(160+980) = 160/1140 ≈ 14.0%. This illustrates the critical effect of disease prevalence on PPV: even a test with 80% sensitivity and 90% specificity has a low PPV when the disease is rare, because most positives will be false. PPV rises with increasing prevalence. In low-prevalence populations, widespread screening generates many false positives, leading to unnecessary investigations, anxiety, and cost — the core argument against screening in low-risk populations.
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.