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

Table 1 Main sociodemographic and clinical characteristics of chronic kidney disease individuals, people living with human immunodeficiency virus and coagulopathy individuals

Variable		I_CKD	P_HIV	I_COAG
		n (%)	n (%)	n (%)
Gender	Female	101 (37.3)	37 (38.9)	1 (2.0)
	Male	170 (62.7)	58 (61.1)	50 (98.0)
Age	18-30	19 (7.0)	9 (9.5)	25 (50.0)
	30+	253 (93.0)	86 (90.5)	25 (50.0)
Marital status	Married	132 (49.3)	31 (35.2)	17 (33.3)
	Not married	136 (50.7)	57 (64.8)	34 (66.7)
Race	White	71 (27.6)	29 (46.0)	14 (29.2)
	Black	186 (72.4)	34 (54.0)	34 (70.8)
Length of education	Up to 8 yr	136 (51.1)	36 (38.7)	14 (27.5)
	9 or more	130 (48.9)	57 (61.3)	37 (72.5)
Acupuncture	Yes	21 (7.8)	9 (9.5)	15 (29.4)
	No	247 (92.2)	86 (90.5)	36 (70.6)
Tattoo	Yes	27 (10.1)	29 (31.2)	6 (12.0)
	No	240 (89.9)	64 (68.8)	44 (88.0)
Piercing	Yes	9 (3.4)	7 (7.5)	2 (4.1)
	No	259 (96.6)	86 (92.5)	47 (95.9)
Shared nail cutters/razor/toothbrush	Yes	190 (66.9)	70 (74.5)	22 (43.1)
	No	94 (33.1)	24 (25.5)	29 (56.9)
Blood or plasma transfusion	Yes	169 (63.3)	16 (17.2)	35 (70.0)
	No	98 (36.7)	77 (82.8)	15 (30.0)
Transfusion before 1994	Yes	34 (12.8)	7 (7.5)	25 (49.0)
	No	231 (87.2)	86 (92.5)	26 (51.0)
HBV vaccine	Yes	206 (72.5)	41 (43.2)	36 (70.6)
	No	78 (27.5)	54 (56.8)	15 (29.4)
Use of illicit drugs	Yes	18 (6.9)	22 (23.9)	6 (12.2)
	No	244 (93.1)	70 (76.1)	43 (87.8)
History of STI	Yes	61 (23.0)	44 (51.8)	10 (20.0)
	No	204 (77.0)	41 (48.2)	40 (80.0)
Alcohol consumption	Yes	48 (18.0)	31 (41.3)	30 (60.0)
	No	219 (82.0)	44 (58.7)	20 (40.0)
Condom use	Frequent	66 (25.6)	57 (64.0)	18 (39.1)
	Infrequent	192 (74.4)	32 (36.0)	28 (60.9)
Hemodialysis per week	3 times	236 (89.4)	-	-
	4 times or more	28 (10.6)	-	-
Hemodialysis time (mo)		76.1 (80.1)	-	-
Coagulopathy	Hemophilia	-	-	47 (92.2)
	von Willebrand 3	-	-	4 (7.8)
Type of hemophilia	Deficiency factor VIII	-	-	39 (84.8)
	Factor IV deficiency	-	-	7 (15.2)
Severity	Mild/moderate	-	-	13 (28.3)
	Serious	-	-	33 (71.7)
Inhibitory antibodies	Present	-	-	5 (11.4)
	Absent	-	-	39 (88.6)

I_CKD: Chronic kidney disease individuals; HBV: Hepatitis B virus; I_COAG: Coagulopathy individuals; P_HIV: People living with human immunodeficiency virus; STI: Sexually transmitted infection.

Table 2 Bivariate analysis of sociodemographic and clinical characteristics according to hepatitis B virus and hepatitis C virus markers in chronic kidney disease individuals

Variable	Adjustment	HBsAg		Anti-HBc		Anti-HCV
		DBS	Serum	DBS	Serum	DBS	Serum
Acupuncture	OR crude (95%CI)	-	-	-	4.0 (1.5-10.6)	-	-
	OR adjusted (95%CI)	-	-	-	5.1 (1.8-14.5)	-	-
Shared nail cutters/razor /toothbrush	OR crude (95%CI)	-	-	2.6 (1.4-4.6)	1.9 (1.1-3.2)	-	-
	OR adjusted (95%CI)	-	-	2.7 (1.5-4.8)	2.6 (1.5-4.7)	-	-
History of transplant	OR crude (95%CI)	-	-	2.9 (1.3-6.4)	-	5.8 (2.5-13.6)	5.8 (2.5-13.6)
	OR adjusted (95%CI)	-	-	2.7 (1.2-6.1)	-	2.8 (1.1-7.4)	2.8 (1.1-7.7)
Infrequent condom use	OR crude (95%CI)	5.6 (1.6-16.4)	4.4 (1.4-14.5)	-	-	-	-
	OR adjusted (95%CI)	5.6 (1.6-16.4)	4.4 (1.4-14.5)	-	-	-	-
Hemodialysis time (mo)	OR crude (95%CI)	-	-	-	1.01 (1.01-1.01)	1.01 (1.01-1.02)	1.01 (1.01-1.01)
	OR adjusted (95%CI)	-	-	-	1.01 (1.01-1.01)	1.01 (1.01-1.02)	1.01 (1.01-1.02)
Hemodialysis 4 times per week or more	OR crude (95%CI)	-	-	-	-	-	2.8 (1.1-6.9)
	OR adjusted (95%CI)	-	-	-	-	-	2.7 (1.1-7.4)

CI: Confidence interval; DBS: Dried blood spot; HBc: Hepatitis B core; HCV: Hepatitis C virus; OR: Odds ratio.

Table 3 Bivariate analysis of sociodemographic and clinical characteristics according to hepatitis B virus and hepatitis C virus markers in people living with human immunodeficiency virus

Variable	Adjustment	HBsAg		Anti-HBc		Anti-HCV
		DBS	Serum	DBS	Serum	DBS	Serum
Male gender	OR crude (95%CI)	-	4.7 (1.3-17.4)	3.2 (1.3-7.8)	2.9 (1.1-7.3)	-	-
	OR adjusted (95%CI)	-	4.9 (1.2-19.2)	3.2 (1.3-7.8)	2.9 (1.1-7.3)	-	-
Blood or plasma transfusion	OR crude (95%CI)	-	4.2 (1.3-13.5)	-	-	-	-
	OR adjusted (95%CI)	-	4.6 (1.3-16.0)	-	-	-	-

CI: Confidence interval; DBS: Dried blood spot; HBc: Hepatitis B core; HCV: Hepatitis C virus; OR: Odds ratio.

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.