A laboratory lowers the diagnostic cut-off value of fasting plasma glucose for diabetes screening from 126 mg/dL to 110 mg/dL. Compared with the original cut-off, the change will most likely produce:

• A Decreased sensitivity and increased specificity
• B No change in either, only altered predictive values
• C Increased both sensitivity and specificity
• D Increased sensitivity and decreased specificity ✓

Explanation

Lowering the diagnostic threshold moves more people into the screen-positive category, capturing additional true diabetics whose values fall between 110 and 126 mg/dL, so sensitivity rises. Simultaneously more normoglycaemic people fall above the lower cut-off, increasing false positives, so specificity falls. Sensitivity and specificity move in opposite directions whenever a single cut-off shifts along a continuous test variable, and predictive values then also change with prevalence.

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.