title: Does N-acetyl cystein affect the sensitivity and specificity of Helicobacter pylori stool antigen test?
abstract: BACKGROUND
  N-acetyl cystein, a mucolytic agent, might make Helicobacter pylori antigens shed more easily to stool, and might therefore contribute to the diagnostic accuracy of the Helicobacter pylori stool antigen test. The aim of this study is to investigate if N-acetyl cystein contributes to the diagnostic accuracy of the Helicobacter pylori stool antigen test by increasing the sensitivity and specificity of the test.
  
  
  METHODS
  107 patients were separated into treatment and placebo groups. The AC group (n = 53) was given 5 ml of acetyl cystein (4%) t.i.d. and the Placebo group (n = 54) was given placebo, for 3 days. Helicobacter pylori status was determined by both histology and CLOtest. Stool samples were assayed using a specific ELISA kit for Helicobacter pylori stool antigen.
  
  
  RESULTS
  The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy of Helicobacter pylori stool antigen test were 76%, 79%, 90%, 55%, and 77%, respectively, in AC group; and 85%, 89%, 93%, 76% and 86%, respectively, in placebo group.
  
  
  CONCLUSIONS
  N-acetyl cystein did not increase, and actually decreased, the sensitivity and specificity of the Helicobacter pylori stool antigen test according to our results. We believe that this finding can be taken into consideration when setting up the exclusion criteria for future studies, which will use Helicobacter pylori stool antigen tests.
authors.affiliation: Department of Gastroenterology G A TA Haydarpaşa Training Hospital, Istanbul/Turkey.
authors.forename: Levent
authors.initials: L
authors.lastname: Demirtürk
authors.forename: Yusuf
authors.initials: Y
authors.lastname: Yazgan
authors.forename: Orhan
authors.initials: O
authors.lastname: Tarçin
authors.forename: Melih
authors.initials: M
authors.lastname: Ozel
authors.forename: Muhittin
authors.initials: M
authors.lastname: Diler
authors.forename: Oral
authors.initials: O
authors.lastname: Oncül
authors.forename: Sükrü
authors.initials: S
authors.lastname: Yildirim
mesh_terms: D000111:Acetylcysteine / Q000008:administration & dosage*; D000284:Administration, Oral; D000328:Adult; D000942:Antigens, Bacterial / Q000032:analysis; D005100:Expectorants / Q000008:administration & dosage*; D005243:Feces / Q000737:chemistry / Q000382:microbiology*; D005260:Female; D016481:Helicobacter Infections / Q000175:diagnosis*; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity
chemical_list: D000942:Antigens, Bacterial; D005100:Expectorants; D000111:Acetylcysteine