Severe atrophic gastritis in aged Helicobacter pylori-positive patients leads to the decrease of the level of amount of H. pylori in gastric mucosa. Cut-off value for E-plate（ a serum H. pylori antibody kit） has been set regardless the age of the subjects. The aim of this study was to estimate appropriate cut-off values for E-plate in younger and elderly subjects. A total of 994 healthy adults who received a health survey in Iwaki area of Hirosaki City in 2005 were tested. We divided the subjects into two groups; the elderly group included 594 subjects who were born before 1950 and the younger group included 400 subjects who were born after 1950. We evaluated appropriate cut-off values of E-plate by stool antigen test as gold standard. The ROC curves showed the best cut-off level to be 12.5 U/ml （sensitivity: 94.2%, specificity: 84.0%） in elderly group and 14.5 U/ml（ sensitivity: 93.4%, specificity: 89.4%） in younger group. False positive results of E-plate were more frequent in elderly group （P < 0.001）. Cut-off values of E-plate should be decided according to the age of the subjects.弘前医学. 63, 2012, p.48-54journal articl

Chiba, Daisuke

Fukuda, Shinsaku

Iino, Chikara

Iwane, Kaori

Matsuzaka, Masashi

Oyama, Takao

Shimoyama, Tadashi

Takahashi, Ippei

Umeda, Takashi

English

Hirosaki University Repository for Academic Resources

Hirosaki Med．J.　63：48―54，2012ORIGINAL ARTICLEEVALUATION OF THE APPROPRIATE CUT-OFF VALUE FOR SEROLOGICAL DIAGNOSIS OF HELICOBACTER PYLORI INFECTION BY COMPARISON WITH A STOOL ANTIGEN TESTChikara Iino1），Tadashi Shimoyama1），Takao Oyama1），Daisuke Chiba1）， Takashi Umeda2），Ippei Takahashi2），Masashi Matsuzaka2），Kaori Iwane2）  and Shinsaku Fukuda1）Abstract　Severe atrophic gastritis in aged Helicobacter pylori-positive patients leads to the decrease of the level of amount of H. pylori in gastric mucosa.  Cut-off value for E-plate （a serum H. pylori antibody kit） has been set regardless the age of the subjects.  The aim of this study was to estimate appropriate cut-off values for E-plate in younger and elderly subjects.  A total of 994 healthy adults who received a health survey in Iwaki area of Hirosaki City in 2005 were tested.  We divided the subjects into two groups; the elderly group included 594 subjects who were born before 1950 and the younger group included 400 subjects who were born after 1950.  We evaluated appropriate cut-off values of E-plate by stool antigen test as gold standard.  The ROC curves showed the best cut-off level to be 12.5 U/ml （sensitivity: 94.2%, specificity: 84.0%） in elderly group and 14.5 U/ml （sensitivity: 93.4%, specificity: 89.4%） in younger group. False positive results of E-plate were more frequent in elderly group （P < 0.001）.  Cut-off values of E-plate should be decided according to the age of the subjects. Hirosaki Med．J.　63：48―54，2012　Key words:  Helicobacter pylori; E-plate; cut-off value.原　著Helicobacter pylori 便中抗原との比較による Helicobacter pylori 血清抗体（E-plate）のカットオフ値についての検討飯　野　　　勢1）　　下　山　　　克1）　　小　山　隆　男1）　　千　葉　大　輔1） 梅　田　　　孝2）　　高　橋　一　平2）　　松　坂　方　士2）　　岩　根　かほり2） 福　田　眞　作1）抄録　Helicobacter pylori 感染高齢者の多くは萎縮性胃炎が高度となり，感染菌量が減少・消失するが，これまで H. pylori 血清抗体測定法のカットオフ値は年齢の影響が考慮されてこなかった．2005年の青森県岩木地区の健診受診者を対象とし，1950年以前の出生者594人を高齢群，以降の出生者400人を若年群について，便中抗原測定法を gold standard とした場合の両群での E-plate の至適カットオフ値を調べた．ROC 曲線より，E-plate の至適カットオフ値は高齢群で12.5 U/ml （感度94.2%，特異度84.0%），若年群では14.5 U/ml （感度93.4%，特異度89.4%）となり，高齢者で低かった．高齢群では E-plate の偽陽性の頻度も高かった（P <0.001）．E-plate のカットオフ値は対象者の年齢も考慮して設定すべきである． 弘前医学　63：48―54，2012　キーワード：Helicobacter pylori；E-plate；cut-off value.1）Department of Gastroenterology and Hematology, Hirosaki University Graduate School of Medicine2）Department of Social Medicine, Hirosaki University Graduate School of MedicineCorrespondence: T. ShimoyamaReceived for publication, December 22, 2011Accepted for publication, December 28, 20111）弘前大学大学院医学研究科消化器・血液内科学講座2）弘前大学大学院医学研究科社会医学講座別刷請求先：下山　克平成23年12月22日受付平成23年12月28日受理49Appropriate Cut-Off Value for E-plateIntroduction　 Infection of Helicobacter pylori induces chron-ic active inflammation of the gastric mucosa and associated with the development of sev-eral upper gastrointestinal diseases such as atrophic gastritis, peptic ulcer, gastric cancer, MALT lymphoma and hyperplastic polyp 1, 2）. Eradication of H. pylori prevents recurrence of peptic ulcer 3） and reduces metachronous gastric cancer after endoscopic resection of gastric cancer 4）.  Eradication of H. pylori is also the treatment of the first choice for gastric MALT lymphoma 5）.  Furthermore, H. pylori infection is associated with extragastric disorders such as immune thrombocytopenic purpura 6）, iron deficiency anemia 7） and chronic urticaria 8）.  In 2009, the Japanese Society for Helicobacter Research revised the guidelines for the management of Helicobacter pylori infection and recommended H. pylori eradication for all the infected patients 9）.  As the indication for the treatment of H. pylori infection has been expanded, diagnosis of infection and evaluation of the results of eradication therapy have become more significant.  　Measurement of serum antibody is one of the most widely-used methods for the management of H. pylori infection.  More recently, serum antibody is used in the screening for gastric cancer known as ABC method 10）, which is the combination of the detection of serum H. pylori antibody and determination of atrophic gastritis by serum pepsinogen （PG） levels.  Among serum antibody tests, E-plate is the most commonly used test in Japan because this test was developed using Japanese H. pylori strains and highly accurate for Japanese patients 11）. To date, cut-off value of E-plate test has been the same in any ages.  In patients with H. pylori infection, the prevalence of atrophic gastritis increases with age 12）.  Severe atrophic gastritis leads the decrease of H. pylori colonization and the decrease of H. pylori antibodies occurs 13）.  Therefore, the appropriate cut-off value of E-plate would be different between younger and elderly populations.  Particularly, low level of serum antibody can cause false-negative results of ABC screening for gastric cancer, and some people may miss the chance of having detailed examination without being aware of the risk of gastric cancer.　 The aim of this study was to examine the difference of appropriate cut-off value for E-plate in younger and elderly patients by the comparison of a monoclonal antibody-based stool antigen test.Materials and Methods　 Among 1070 healthy adults who received health survey （Iwaki Health Promote Project） in Iwaki area of Hirosaki City in April 2005, 994 subjects agreed to participate in this study. Subjects took their stool samples in the morning of the day of health survey.  The subjects were 381 men and 613 women; the mean age was 56.9 ±13.9 years old.  Subjects who had previous history of gastric surgery, successful H. pylori eradication were excluded.  We divided the subjects into elderly and younger groups. The elderly group included 594 subjects, who were born before 1950 and the younger group included 400 subjects, who were born after 1950.  We evaluated appropriate cut-off value of E-plate by using the stool antigen test as a gold standard.  Stool samples were stored at -80°C and tested for the prevalence of H. pylori antigen with enzyme immunoassay （EIA） by using a monoclonal antibody kit （Testmate pylori antigen enzyme immunoassay; TPAg EIA, Wakamoto Pharmaceutical Co. Ltd. Kanagawa, Japan & Kyowa Medex, Tokyo, Japan） 13）. Serum samples were stored at -20°C and tested for the prevalence of IgG antibody to H. pylori by E-plate （Eiken, Tokyo, Japan） 11）.  The 50 C. Iinolevels of PG I and PG II were also measured by radioimmunoassay.  The result was considered indicative of atrophic gastritis when both a PG I level of < 70 μg/l and a PG I/II ratio of < 3.0 were obtained and severe atrophic gastritis when both a PG I level of < 30 μg/l and a PG I/II ratio of < 2.0 14）.  Differences of the results of E-plate between younger and elderly groups were examined by χ2 analysis.  A p-value of < 0.05 was considered statistically significant. Receiver operating characteristic （ROC） curves were used to determine the appropriate cut-off value.  　All the subjects provided their written informed consent, and this study was approved by the ethics committee of Hirosaki University.Results　 In younger group and elderly group, 29% and 53% of the subjects had atrophic gastritis and 4% and 21% of the subjects had severe atrophic gastritis by serum PGs （Table 1）. The prevalence of subjects who had severe atrophic gastritis was significantly higher in elderly group than younger group （P < 0.001）. When diagnosis of H. pylori infection was determined by TPAg EIA, 42% of subjects in younger group and 64% of subjects in elderly group were tested positive （Table 1）.  In all the 994 subjects, when present cut-off value of E-plate was used, 551 subjects were positive for TPAg EIA including 22 subjects negative for E-plate and 443 subjects were negative for TPAg EIA including 75 subjects positive for E-plate （Table 2）.  Sensitivity, specificity and accuracy of E-plate were 96.0%, 83.1% and 90.2%, respectively, in all the 994 subjects.  Although the sensitivity and accuracy were not different, the specificity was 79.1% in elderly group and 86.1% in younger group, respectively.  The specificity of E-plate was significantly lower in Table 1  The characteristics of younger subjects and elderly subjects.YoungersubjectsElderlysubjectsMale / Female 163 / 237 218 / 376 Age （mean ± SD） 42.9 ± 9.16 66.2 ± 6.81H. pylori infection（stool antigen positive） 42 % 64 % *Atrophic gastritis 29 % 53 % *Severe atrophic gastritis 4 % 21 % **: P <0.001Table 2  Comparison of serology and stool antigen test for detection of H. pylori infection.E-plateTPAg EIA sensitivity（%）specificity（%）accuracy（%）+ ve ‒ veAll + ve 529 75 96.0 83.1 90.2‒  ve 22 368younger   subjects+ ve 162 32 95.8 86.1 90.3‒  ve 7 199*elderly subjects+ ve 367 43 96.1 79.7 90.2‒  ve 15 169*: P <0.001. Cut-off value is set as 10 U/ml according to the manufacturer's instructions.51Appropriate Cut-Off Value for E-plateelderly group comparing with younger group （P < 0.001）. 　Appropriate cut-off value determined by ROC curve analysis was 12.5 U/ml （sensitivity: 94.2%, specificity: 84.0%, accuracy: 90.6%） in elderly group （Figure 1） and 14.5 U/ml （sensitivity: 93.4%, specificity: 89.4%, accuracy: 91.0%） in younger group （Figure 1）. Discussion　 The present study demonstrated that appropriate cut-off value of E-plate determined by ROC curve was higher in younger subjects Figure 1　ROC curve of E-plate using TPAg EIA as the standard.  A） for elderly subjects and B） for younger subjects, respectively.Figure 1B)A)52 C. Iinothan elderly subjects.  The difference would be caused by the prevalence and extent of atrophic gastritis in H. pylori infected patients increased with age 12）.  In this study, the proportion of the subjects who had severe atrophic gastritis increased in elderly group.  In patients with severe atrophic gastritis, H. pylori colonization is decreased or spontaneously disappeared resulting in the decrease of serum antibody. Therefore, in some patients with severe atrophic gastritis, the value of E-plate became under the cut-off value.  There were also other patients with severe atrophic gastritis, the value of E-plate remains above the cut-off level while H. pylori colonization had been already disappeared.  False positive results of serology in such patients would cause low specificity of E-plate in elderly subjects.  Actually, although sensitivity and accuracy were not different between elderly and younger groups, specificity of E-plate was significantly lower in elderly group by both present cut-off and appropriate cut-off determined by ROC curves.  Severe atrophic gastritis presented in aged subjects may cause false positive and negative serology. Thus, serological diagnosis of H. pylori infection, including E-plate, may be more reliable in younger populations.  　In this study, a monoclonal antibody-based stool antigen test was used as a gold standard. According to the guidelines for the management of Helicobacter pylori infection in Japan, stool antigen tests based on monoclonal antibody appear to be an accurate test for evaluating the results of H. pylori eradication therapy as well as urea breath test 9）.  TPAg EIA was developed in Japan and has been shown to have high sensitivity and specificity 15, 16）.  Since this study was taken place as a part of a health survey, the methods of estimation of H. pylori infection had to be easy and costless.  Thus, we used TPAg EIA as a gold standard to estimate appropriate cut-off value of E-plate. 　 ABC method is a new gastric cancer screening developed in Japan by combination of the detection of serum anti-H. pylori antibody and the measurement of serum PG levels 10）.  In ABC method, subjects are classified into one of 4 risk groups （group A, B, C, and D） according to the presence of atrophic gastritis identified by serum PGs and H. pylori seropositivity. Group A comprised the subjects whose results are negative for both anti-H. pylori antibody and atrophic gastritis.  Group B comprised the subjects whose results are seropositive for H. pylori but negative for atrophic gastritis.  Group C comprised the subjects whose results are positive for both anti-H. pylori antibody and atrophic gastritis.  Group D comprised the subjects with atrophic gastritis and anti-H. pylori antibody levels lower than the cut-off value. Several studies have shown the usefulness of this method for assessment of the risk of gastric cancer 17, 18）. However, one of the problems of ABC method is false negative result of H. pylori serology.  Some elderly subjects who show false negative results by serology would be classified into group A which is recognized to have very low risk of gastric cancer.  Such subjects would lose the chance of receiving endoscopy.  Actually, in our department, the level of E-plate was estimated slightly below the recommended cut-off level in some elderly patients with early gastric cancer.  Since the purpose of cancer screening is to reduce the mortality rate, it is important to distinguish the patients with early gastric cancer as the subjects who need endoscopy.  Gastric cancer is more frequently occur in elderly patients who have severe atrophic gastritis.  However, ABC method was performed without consideration of the possibility of the decrease of serum antibody level in elderly patients.  Therefore, more consideration is necessary for the cut-off level of H. pylori serology particularly in elderly subjects.  53Appropriate Cut-Off Value for E-plateConclusion 　Appropriate cut-off value of E-plate test was lower in elderly people than in younger people by using the stool antigen test as a gold standard. The specificity of E-plate was significantly lower in elderly group.  Appropriate cut-off value of E-plate should be examined according to age of the subjects and the purpose of serodiagnosis such as ABC screening particularly in elderly populations.Acknowledgements　 This study was partly supported by Grant-in-Aids from the Ministry of Education, Culture, Sports, Science and Technology, Japan （no. 18200044-00 and 23659342）, and was based on the Iwaki Health Promotion Project as a project by Hirosaki University Graduate School of Medicine, in collaboration with Aomori Heath Evaluation and Promotion Center and Hirosaki City Office, Department of Health Promotion.References1）Uemura N, Okamoto S, Yamamoto S, Matsumura N, Yamaguchi S, Yamakido M, Taniyama K, et al. Helicobacter pylori infection and the development of gastric cancer. N Engl J Med 2001;345:784-9.2）Ohkusa T, Takashimizu I, Fujiki K, Suzuki S, Shimoi K, Horiuchi T, Sakurazawa T, et al. Disappearance of hyperplastic polyps in the stomach after eradication of Helicobacter pylori. 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Evaluation of the Appropriate Cut-Off Value for Serological Diagnosis of Helicobacter Pylori Infection by Comparison with a Stool Antigen Test

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Evaluation of the Appropriate Cut-Off Value for Serological Diagnosis of Helicobacter Pylori Infection by Comparison with a Stool Antigen Test

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