Adjusting CA19-9 values to predict malignancy in obstructive jaundice: Influence of bilirubin and C-reactive protein

Table 1 Patient characteristics in the two groups of obstructive jaundice

	Benign	Malignant	P value
No. of patients	51	51
Bilirubin serum level (median and range) (g/dL)	5.2 (2.12-24.03) 95% CI = 5.0-7.2	9.7 (4.07-24.25) 95% CI = 9.6-12.5	< 0.0001
CA19-9 serum level (median and range) (U/mL)	36 (2-27019) 95% CI = 0-2.508	405 (2.5-62974) 95% CI = 699-6282	0.02
> 32 (%)	28/51 (54.9)	42/51 (82.3)	0.003
> 100 (%)	18/51 (35.3)	35/51 (68.6)	0.0007
CRP (median and range) (U/mL)	6.91 (0.1-30) 95% CI = 4.6-8.3	2.97 (0.1-13.2) 95% CI = 2.3-4.1	0.0002
> 1.5 (%)	34/51 (66.6)	25/51 (49.0)	0.005
> 5 (%)	21/51 (41.2)	7/51 (13.7)	0.004

CRP: C-reactive protein; CI: Confidence interval.

Table 2 Bilirubin, CA19-9 and C-reactive protein levels according to jaundice cause at time of hospital admission n (%)

Cause	No. of cases	Bilirubin(g/dL), median	CA19-9 (U/mL)				CRP (U/mL)
			Median	P value1	> 32	> 100	Median	P value2	> 1.5	> 5
Malignant	51	9.7	405		42 (8.3)	35 (68.6)	2		25 (49)	7 (13.7)
Pancreatic cancer	25 (49)	11.29	461	-	23 (92)	19 (76)	1.96	0.04	12 (48)	3 (12)
Bile duct cancer	10 (19.6)	9.94	313	0.28	7 (70)	6 (60)	1.26	0.06	1 (10)	0
Gallbladder cancer	7 (13.7)	8.94	3361	0.59	6 (85.7)	5 (71.4)	4.13a	0.91	5 (71.4)	2 (28.5)
Ampullary cancer	5 (9.8)	6.49	196	0.42	4 (80)	3 (60)	4.5	0.69	4 (80)	1 (0.2)
Intrahepatic cholangio carcinoma	1 (1.9)	16.13	2600	NA	1	1	5.96	NA	1	1
Others	3 (5.8)	7.65	16	0.53	1	1	4.95	0.84	2 (66.6)	1 (33.3)
Benign	51	5.2	36		28 (54.9)	18 (35.3)	4.5		34 (66.6)	21 (41.2)
CBD stones	34 (66.6)	5.63	42	0.10	19 (55.8)	12 (35.2)	3.47	-	22 (64.7)	11 (32.3)
Gallbladder stones with cholangitis	8 (15.7)	5.26	55	0.54	4 (50)	3 (37.5)	2.31	0.73	5 (62.5)	3 (37.5)
Biliary pancreatitis	8 (15.7)	3.85	61	0.27	4 (50)	3 (37.5)	10.33	0.04	7 (87.5)	7 (87.5)
Chronic papillitis	1 (1.9)	6.6	35	NA	1	0	0.7	NA	0	0

^aP = 0.04 vs other cancers.

¹Wilcoxon test compared to pancreatic cancer;

²Wilcoxon test compared to common bile duct (CBD) stones. CRP: C-reactive protein; NA: Not applicable.

Table 3 Adjustments of the value of CA19-9: Differences in sensitivity, specificity and positive predictive value (%)

	Sensitivity	Specificity	PPV
CA19-9 > 32 U/mL	82.3	45.0	59.1
CA19-9 > 100 U/mL	68.6	64.7	66.0
CA19-9/BIL	49.0	78.4	69.4
CA19-9/CRP	76.5	68.6	70.9

PPV: Positive predictive value; BIL: Bilirubin; CRP: C-reactive protein.