Dried blood spot sampling as an alternative for the improvement of hepatitis B and C diagnosis in key populations

Table 4 Test parameter values according to individuals with coagulopathies, chronic kidney disease and people living with human immunodeficiency virus

Diagnostic test parameters	I_COAG, n = 51			I_CKD, n = 284			P_HIV, n = 95
	HBsAg	Anti-HBc	Anti-HCV	HBsAg	Anti-HBc	Anti-HCV	HBsAg	Anti-HBc	Anti-HCV
True positive (n)	2	13	20	13	90	43	17	35	24
True negative (n)	49	35	26	270	165	235	71	48	70
False positive (n)	0	0	1	1	5	2	4	6	0
False negative (n)	0	3	4	0	23	3	3	1	0
Sensitivity (%)	100	81.3	83.3	100	79.6	93.5	85.0	97.2	100
Specificity (%)	100	100	96.3	99.6	97.1	99.2	94.7	88.9	100
PPV (%)	100	100	95.2	92.9	94.7	95.6	81.0	85.4	100
NPV (%)	100	92.1	86.7	100	87.8	98.7	95.9	98.0	100
Correct classification (accuracy) (%)	100	94.1	90.2	99.6	90.1	98.2	92.6	92.2	100
Incorrect classification (%)	0	5.9	9.8	0.4	9.9	1.8	7.4	7.8	0
Estimated prevalence/serum (%)	3.9	31.4	47.1	4.6	39.9	16.3	21.1	40.0	25.5
Estimated prevalence/DBS (%)	3.9	25.5	41.2	4.9	33.6	15.9	22.1	45.6	25.5

DBS: Dried blood spot; HBc: Hepatitis B core; HCV: Hepatitis C virus; I_CKD: Chronic kidney disease individuals; I_COAG: Coagulopathy individuals; NPV: Negative predictive value; P_HIV: People living with human immunodeficiency virus; PPV: Positive predictive value.