The quantity of saliva and tongue fur in the spleen–stomach area (%) may forecast the risk and severity of gastroesophageal reflux disease (GERD) and might be noninvasive indicators of GERD. 

GERD, a prevalent digestive disorder, substantially impacts patients of all age groups. Heartburn, regurgitation, and reflux chest pain syndrome are the typical GERD symptoms while the extra-esophageal GERD symptoms include chronic laryngitis, dental erosion, coughing, hoarseness, asthma, dyspepsia, or nausea.

This debilitating disorder can substantially impair the individual's quality of life, sleep quality, and personal working performance, and can also cause mental disorders. GERD is a vital issue to be addressed because it not only exerts a psychological and physiological influence, but also places an economic challenge on healthcare resources.

The American College of Gastroenterology guidelines suggests that there is no gold standard methodology for diagnosing GERD. However, the diagnosis is commonly made based on the disease’s clinical manifestation and objective testing with endoscopy, ambulatory reflux monitoring, or the individual’s response to acid-suppressive treatment.

A six-to-eight-week course of empiric proton-pump inhibitor treatment, known as the proton-pump inhibitor trial, may validate GERD presence when individuals have the typical symptoms. However, this strategy is linked with few limitations: (i) the proton-pump inhibitor trial has a specificity of 54% and sensitivity of 78%, and (ii) negative findings cannot rule out GERD. The major tool to determine esophagogastroduodenoscopy is the various stages of disorder severity in the esophageal and gastrointestinal mucosa for a prolonged period.

Endoscopy, an invasive and nonsurgical procedure, aids to examine an individual’s digestive tract in detail. Utilizing endoscopy, failure to respond to antisecretory treatment should be determined. The  endoscopy role in managing GERD is to make a favorable diagnosis and rule out esophageal adenocarcinoma, erosive esophagitis, Barrett’s esophagus, and peptic stricture. But, the majority of individuals having the typical symptoms do not have erosion. This limits endoscopy as an initial diagnostic approach.

To detect the abnormal exposure of esophageal acid, ambulatory pH-impedance monitoring is a crucial method. It is indicated for individuals who do not respond to proton-pump inhibitor therapy and those with extra-esophageal symptoms, specifically those with non-erosive reflux disease prior to surgery. Although this technique has excellent specificity (85– 100%) and sensitivity (77–100%), it takes a long time to conduct the assessment and elevated costs also considerably limit the availability worldwide.

Endoscopy may have a few vital complications like infection, gut perforation, bleeding, or sedation effect. Early noninvasive diagnostic or screening methodology is required. The tongue-based diagnosis, which is one of the diagnostic procedures in traditional Chinese medicine, plays a pivotal role in the differentiation of symptoms and aids the physician to accurately diagnose and treat. The internal organs connect to the tongue via meridians. Thus, the tongue can mirror the status of the body and flow of blood and qi, and even help examine the disorder severity.

But, the diagnosis method utilizing such an observation often depends on the clinician’s subjective judgment and personal experience, and environmental factors. To mitigate these limitations, many computerized tongue evaluation systems have been developed to quantitatively and objectively diagnose the tongue condition.

The automatic tongue diagnosis system (ATDS) is composed of feature analysis, image capturing, color calibration, and tongue segmentation. The intra-agreement of this computerized analysis system was considerably raised compared to the traditional Chinese medicine doctors’ opinions alone.

ATDS and traditional Chinese medicine doctors’ opinions illustrated a moderate inter-agreement

ATDS offers objective information about the tongue, and also acts as a vital educational tool for students who are learning how to diagnose the tongue condition. In the future, the computer-aided diagnosis might aid to develop artificial intelligence with machine learning and deep learning. Numerous investigations have been performed to determine the relation between tongue imaging findings and diseases like dysmenorrhea, rheumatoid arthritis, breast cancer, and metabolic syndrome.

Rationale behind research

No study has explored the diagnostic accuracy of tongue features to diagnose GERD. Thus, this study was performed.

Objective

A cross-sectional, case-controlled observational analysis was carried to: (i) explore the tongue manifestations of individuals diagnosed with GERD utilizing an objective computerized tongue analysis system, (ii) examine the possible link between GERD and the tongue condition, and (iii) if tongue imaging could be the initial diagnosis of GERD noninvasively. 

Study outcomes

• The outcomes were: (i) thickness of the tongue’s fur, (ii) amount and area of saliva, and (iii) Risk of GERD

Outcomes

Baseline: There were no vital differences reported at baseline.

Study outcomes

In GERD patients, the thickness of the tongue’s fur and the saliva amount, especially that in the spleen–stomach area (%), were remarkably higher in comparison with non-GERD patients. The areas under the receiver operating characteristic (ROC) curve of the quantity of saliva and tongue fur in the spleen–stomach area (%) were found to be 0.606±0.049 and 0.615± 0.050, respectively.

Furthermore, as the value of the quantity of saliva and tongue fur in the spleen–stomach area (%) elevated, the GERD risk elevated by 3.621 and 1.019 times, respectively. The tongue fur in the spleen–stomach area (%) associated with GERD seriousness from grade 0 to higher than grade B were 51.67±18.72, 58.10±24.60, and 67.29±24.84, respectively (Figure 2). 

Fig 2: Relationship between spleen-stomach area on tongue and GERD stage

In this analysis, the disease manifestations were examined on the tongues of GERD-diagnosed individuals utilizing an objective computerized tongue analysis system. The possible relation was assessed between GERD and the tongue condition as seen on imaging, utilizing the theory. A higher quantity of saliva and thicker tongue fur specifically the percentage of tongue fur in the spleen–stomach area was found to indicate the presence of disease.

Acid regurgitation may considerably raise the saliva quantity and thickness of the tongue’s fur in spleen-stomach area. In traditional Chinese medicine, inspecting images of the tongue is crucial. Tongue assessments are majorly carried to witness alterations in the nature and coating of the tongue. The normal tongue (majorly made of muscle) should be flexible. On imaging, the normal finding of the tongue is a light red body having a thin white coating. Abnormal findings can aid clinicians to figure out what is happening inside the body of a patient.

The tongue can be segregated into five areas that correspond to the status of the body’s system, including the kidney, heart-lung, spleen-stomach, and left/right liver-gall areas. Additionally, the traditional Chinese medicine theory advocates that the tongue’s fur, referring to a fur-like substance covering the tongue surface, is created by “stomach-qi.” Thus, the tongue, specifically the spleen-stomach area, and tongue fur may potentially reflect digestive system status.

It was noted that the tongue images of individuals suffering from GERD tend to with higher quantity of saliva and fur in the spleen-stomach area. The traditional Chinese medicine theory suggests that a thicker tongue coating with a greater amount of saliva corresponds to dampness and phlegm that is associated with obesity constitutional types. Numerous studies have demonstrated that dietary habits and obesity (one of the etiological factors of GERD) are linked to GERD.

Diet modification and weight reduction have been demonstrated to mitigate GERD symptoms. GERD is indeed one of the obesity-linked comorbidities. Thus, it might be the link between GERD and obesity through inspection of images of the tongue. The ROC curve is an effective methodology to investigate the sensitivity and specificity of the tongue’s features for GERD diagnosis and is plotted by sensitivity (the true positive rate) against 1 -specificity (the false positive rate) at various threshold settings. In addition to the endoscope, specificity and sensitivity combined ROC curve could elevate the tongue diagnosis value.

The area under the ROC curve is commonly utilized as a precision index, and a value greater than 0.5 demonstrates the accuracy of diagnosis. In this study, the specificity and sensitivity of the saliva quantity and the percentage of tongue fur in the spleen–stomach area was examined to diagnose GERD. The findings indicated that these tongue features have a promising diagnostic ability and may yield early information about GERD.

About 10-15% of individuals having GERD may advance to major benign or precancerous complications, also known as Barrett’s esophagus, due to the severity of reflux into the esophagus and chronic injury can cause malignant transformation.  The affected individuals have a poorer health-associated quality of life and greater economic burdens in comparison with the healthy people. There is a requisition of early diagnosis and therapy. It was noted that the elevated scores for the quantity of saliva and the tongue fur in the spleen–stomach area (%) illustrated an elevated risk of more serious GERD.

The tongue-based diagnosis positively correlated with the endoscopy findings. The abnormal findings of non-invasive tongue imaging, such as the amount of saliva and tongue fur in the spleen-stomach area, may aid clinicians prior to endoscopy. Some investigations have explored the association between gastrointestinal disorders and tongue features like the tongue temperature, the thickness of the tongue’s fur, or microbiota. However, other features of the tongue were not stated.

Sun et al. noted that the alterations in the metabolic components and micro-ecological indexes of the tongue’s fur were linked with chronic gastritis. However, the tongue's thickness or other features were not stated. According to Kainuma et al, the tongue body color of the middle area depicts acute alteration of the gastric mucosa. Hu et al. demonstrated that the tongue fur of individuals having gastric cancer was remarkably thicker in comparison with healthy control participants. Bacteria were related to the appearance of the tongue’s fur.

Comparable findings were witnessed on colorectal cancer. But, the investigators stated that the diagnostic sensitivity must be authenticated and assessment of more tongue features should be done. Wang et al assessed the tongue manifestations in individuals having peptic ulcer disease prior to and after therapy. The tongue’s fur was found to be markedly thinner, the color had altered to white, and the engorged sublingual veins had considerably improved after healing of the ulcer.

The gastrointestinal concerns are more or less related to alterations in the tongue’s fur or spleen-stomach area. Future research should determine the differences of gastrointestinal disorders in manifestations of the tongue. The strength of this observational analysis is that a computerized tongue analysis system was utilized for quantitatively and objectively examining the tongue. It may aid healthcare professionals to interpret medical images and capture quantitative and valuable information about the facial features. This will raise the consistency and reliability of GERD diagnosis.

Through the individual’s symptoms and the change in the shape and color of the tongue, the traditional Chinese medicine clinicians may realize GERD's probability and severity prior to the endoscope, specifically for individuals who are contraindicated of the endoscope. Additionally, even if the individuals are devoid of symptoms, the abnormal tongue findings may recall clinicians of additional assessment.

In conclusion, the quantity of saliva and the tongue fur in the spleen–stomach area demonstrates GERD. The traditional Chinese medicine tongue diagnosis has a promising potential to forecast GERD's risk and severity and may be utilized as an indicator for diagnosing GERD. These findings might aid healthcare professionals to early diagnose GERD noninvasively.