Table 4.

 Sensitivity and specificity of measurements of total bile acid concentrations in prediction of cholestatic hepatobiliary disease. Positive predictive value (PPV) and negative predictive value (NPV) of test, assuming prevalence of cholestasis of 1 in 500 or 1 in 2500

Cut off (μmol/l)	% Sensitivity (95% CI)	% Specificity (95% CI)	Prevalence of disease
			1 in 500			1 in 2500
			PPV %	NPV %		PPV %	NPV %
25.0	65.9 (59.6 to 71.2)	94.0 (92.0 to 94.7)	2.14	99.93		0.43	99.99
30.0	61.5 (55.4 to 67.9)	96.3 (94.9 to 97.2)	3.22	99.92		0.66	99.98
35.0	53.3 (47.1 to 59.8)	97.8 (97.2 to 99.1)	4.63	99.90		0.96	99.98
48.5	35.2 (29.3 to 41.1)	99.0 (98.1 to 99.5)	6.83	99.87		1.44	99.97
69.0	12.1 (8.4 to 16.9)	99.5 (98.7 to 99.8)	4.22	99.82		0.87	99.96
79.0	7.1 (4.3 to 11.1)	100.0 (99.6 to 100.0)	100	99.81		100	99.96