To examine the effect of defining different cut points for abnormality on the yield of screening including the PPV and the number needed to test to avoid 1 future case of CTS we examined the sensitivity and specificity for the cut points shown in ตารางทีื 2
As expected for a relatively rare condition, specifcity and negative predictive value were high(75.9% to 93.1% and 97.5% to 98.8% respectively)however sensitivity was low (36.4% to 65.5%) and PPV very low (6.4% to 18.5 %).
The most sensitve cut point greater than 0.5 ms detected 65.5% of those who would later be diagnosed with CTS.