Helicobacter pylori infection in subjects negative for high titer serum antibody

Table 1 Characteristics of enrolled subjects

	Total	H. pylori infected1	H. pylori uninfected	P value3
n (%)	136	23 (17)	113 (83)
Demographic characteristics
Age median (IQR), yr	45 (37-56)	53 (44-68)	42 (35-53)	0.0057
Male sex (%)	53 (39)	7 (30)	46 (41)	0.48
Body mass index median (IQR), kg/m2	21.2 (19.6-23.7)	22.7 (20.4-25.6)	21.2 (19.5-23.3)	0.028
Family history of gastric cancer, present/absent	12/124	3/20	9/104	0.43
Smoking, present/absent	4/132	0/23	4/109	1.0
Drinking, present/absent	25/111	4/19	21/92	1.0
Laboratory data
Anti-H. pylori antibody median (IQR), U/mL	4.7 (3.7-6.6)	5.4 (4.2-7.9)	4.7 (3.7-6.4)	0.048
13C-urea breath test result median (IQR), per mil	0.3 (0.1-0.8)	19.3 (9.3-26.3)	0.3 (0.1-0.4)	3.6 × 10-14
Endoscopic findings
Kyoto classification of gastritis4, 5/4/3/2/1/0	1/3/14/9/13/96	1/3/8/6/2/3	0/0/6/3/11/93	3.8 × 10-13
Atrophy, 2/1/0	15/20/101	10/4/2009	6/10/97	5.8 × 10-12
Intestinal metaplasia, 1/0	14/122	9/14	5/108	2.9 × 10-5
Enlarged folds, 1/0	5/131	4/19	1/112	0.0029
Nodularity, 1/0	2/134	2/21	0/113	0.028
Redness, 1/0	19/117	12/11	7/106	7.3 × 10-7
Gastric sticky mucus, present/absent	22/114	8/15	14/99	0.013
Gastric ulcer, present/absent	1/135	1/22	0/113	0.17
Duodenal ulcer, present/absent	3/133	1/22	2/111	0.43
Gastroesophageal reflux disease, present/absent	20/116	2/21	18/95	0.53
Hiatal hernia, present/absent	18/118	2/21	16/97	0.74
Fundic gland polyp, present/absent	41/95	1/22	40/73	0.0022
Histological findings5
H. pylori density, present/absent	18/118	18/5	0/113	2.8 × 10-18
Chronic inflammation, present/absent	46/90	21/2	25/88	4.5 × 10-10
Neutrophil activity, present/absent	15/121	15/8	0/113	1.4 × 10-14
Intestinal metaplasia, present/absent	4/132	1/22	3/110	0.53
Glandular atrophy, present/absent	4/132	1/22	3/110	0.53

^{1 13}C-urea breath test-positive subjects were defined as H. pylori-infected patients;

³Fisher’s exact test, Cochran-Armitage test, or Mann-Whitney U test was used as appropriate;

⁴Kyoto classification of gastritis was estimated by gastric atrophy, intestinal metaplasia, enlarged folds, nodularity, and redness[13];

⁵We defined one or more score classified by the updated Sydney system in either the great curvature of the corpus or the antrum as present. H. pylori: Helicobacter pylori; IQR: Interquartile range.

Table 2 Area under the receiver operating characteristic curve for predicting Helicobacter pylori infection

	AUC	95%CI	P value
Age	0.684	0.564-0.804	0.0027
Body mass index	0.646	0.518-0.774	0.026
Serum antibody titer	0.631	0.500-0.763	0.051
Kyoto classification of gastritis	0.886	0.803-0.968	3.7 × 10-20
Endoscopic atrophy	0.848	0.760-0.936	7.7 × 10-15
Endoscopic intestinal metaplasia	0.674	0.570-0.777	0.0010
Enlarged fold	0.583	0.503-0.662	0.042
Nodularity	0.543	0.485-0.602	0.15
Redness	0.730	0.623-0.837	2.4 × 10-5
Gastric sticky mucus	0.612	0.508-0.716	0.035
Fundic gland polyp	0.655	0.594-0.717	7.4 × 10-7
H. pylori density	0.891	0.805-0.977	5.6 × 10-19
Chronic inflammation	0.846	0.776-0.916	5.3 × 10-22
Neutrophil activity	0.826	0.727-0.926	1.3 × 10-10

Positive urea breath test was defined as H. pylori infection. The values of the AUC were compared with the value of 0.5 using the chi-square test. AUC: Area under the receiver operating characteristics curve; CI: Confidence interval; H. pylori: Helicobacter pylori.

Table 3 Performance of endoscopic and histological findings for Helicobacter pylori infection

	Accuracy	Sensitivity	Specificity	PPV	NPV
Endoscopic findings
Kyoto classification of gastritis1	89.7	78.3	92.0	66.7	95.4
Atrophy2	85.3	82.6	85.8	54.3	96.0
Intestinal metaplasia	86.0	39.1	95.6	64.3	88.5
Enlarged folds	85.3	17.4	99.1	80.0	85.5
Nodularity	84.6	8.7	100	100	84.3
Redness	86.8	52.2	93.8	63.2	90.6
Gastric sticky mucus	78.7	34.8	87.6	36.4	86.8
Gastric ulcer	83.8	4.3	100	50.0	83.7
Duodenal ulcer	82.4	4.3	98.2	33.3	83.5
Gastroesophageal reflux disease	71.3	8.7	84.1	10.0	81.9
Hiatal hernia	72.8	8.7	85.8	11.1	82.2
Fundic gland polyp	54.4	4.3	64.6	2.4	76.8
Histological findings
H. pylori density	96.3	78.3	100	100	95.8
Chronic inflammation	80.1	91.3	77.9	45.7	97.8
Neutrophil activity	94.1	65.2	100	100	93.4
Intestinal metaplasia	81.6	4.3	97.3	25.0	83.3
Glandular atrophy	81.6	4.3	97.3	25.0	83.3

¹A score of 2 or more was defined as positive;

²A score of 1 or more was defined as positive. The data are presented as %. Positive urea breath test was defined as H. pylori infection. PPV: Positive predictive value; NPV: Negative predictive value; H. pylori: Helicobacter pylori.

Table 4 Multivariate analysis for independent predictors of Helicobacter pylori infection

	Odds ratio	95%CI	P value
Age	0.98	0.93-1.03	0.49
Body mass index	1.06	0.90-1.24	0.50
Serum antibody titer	1.21	0.87-1.68	0.26
Kyoto classification of gastritis	4.23	2.33-7.67	2.2 × 10-6