Screening And Diagnostic Value Of Volatile Markers In Exhaled Breath Of Patients With Gastroesophageal Reflux Disease

Objective:To screen out specific VOCs associated with GERD and different phenotypes of GERD and further evaluate their value in the diagnosis of GERD.Methods:A total of 106 breath specimens were collected from patients with different subtypes of GERD(24 patients in group A,16 patients in group B,28 patients in group C and 9 patients in group E)and control group(29 patients in group D)using endoscopic and esophageal 24h pH monitoring results as criteria.The VOCs in the samples were analyzed by combined SPEM/GC-MS technique,and the specific VOCs markers of GERD and GERD subtypes were analyzed and screened by MPP software,and their value in the diagnosis of GERD was evaluated by ROC curve.Results:General data results:Patients in groups A,B,C and E weighed(67.7±7.8,66.1±10.3,67.9±8.6,69.4±7.1 kg),BMI(24.5±0.8,24.7±1.9,24.2±1.6,24.9±1.1 kg/m~2)versus group D weight(60.1±10.7 kg),BMI(22.1±1.7 kg/m~2)was statistically different(P<0.05),while the mean age(54.2±11.8,48.0±12.5,53.1±9.7,49.6±6.9 years)was not statistically different compared with group D(49.2±13.3 years),(P>0.05).GC-MS results showed that four VOCs with significant differences,including n-dodecane,n-hexadecane,5-methyl-undecane and 5-ethyldecane,were screened in the experimental group(group ABCE)compared with the control group(group D).In group A,four VOCs with significant differences,including n-tetradecane,n-hexadecane,5-methyl-undecane and5-propylnonane,were screened compared with group D.In group B,three VOCs with significant differences,including o-trifluoromethylbenzoic acid,2-methyl-undecane and n-dodecane,were screened compared with group D.In group C,three VOCs with significant differences,including 5-methyl-undecane,5-ethyl-decane and5-propyl-nonane,were screened compared with group D.By making ROC curves,we found that the sensitivity of 5-ethyl-decane for the diagnosis of GERD was 80.90%,specificity 47.61%,P>0.05,no reference value.5-methyl-undecane had 88.40%sensitivity and 48.40%specificity.The sensitivity of n-dodecane was 91.20%and the specificity was 53.85%.The sensitivity of n-hexadecane was 91.20%and the specificity was 53.86%.Conclusion:The traditional tests for GERD have limitations and often delay the early diagnosis of the disease,so it is important to find a new simple,non-invasive and comfortable method for early diagnosis,and it is feasible to perform breath analysis on the basis of metabolomics to find diagnostic indicators of GERD.5-methyl-undecane,n-dodecane and n-hexadecane can be used as landmark VOCs for early discrimination between GERD patients and healthy populations,among which n-dodecane may serve as a new reference indicator for early diagnosis of GERD.