DeMeester Score for GERD

Components of esophageal pH monitoring

Esophageal pH monitoring is recorded for 24 our 48 hours at a time and the patient’s tracing is analysed under six standard components. Based on the 6 parameters, a composite pH score of DeMeester score is calculated, as a global measure of esophageal acid exposure, where a DeMeester score greater than 14.72 indicated reflux.

Prolonged monitoring became feasible in 1974 when Johnson and DeMeester developed a dependable external reference electrode technique to monitor esophageal acid exposure patients for periods up to 24 hours.

The initial 24-hour pH recordings required patient hospitalization until the 1980s when microcircuits were introduced, thus allowing esophageal pH monitoring in an outpatient setting.

The six variables involved are:

V1. Percentage of total time pH<4

V2. Percentage of upright time pH<4

V3. Percentage of supine time pH<4

V4. Number of reflux episodes

V5. Number of reflux episodes >5min

V6. Longest reflux episode

Step 1: For each of the six, a scoring value SVn = (X-A)/SD + 1 is calculated, where:

X = detection value

A = mean value

SD = standard deviation

The formula weighs each component of the 24 h record according to the dependability and reliability of the measurement.

Step 2: Then the composite DeMeester score can be obtained by adding the six sets of values obtained for each of the variables:

DeMeester Score (DMS) = SV1 + SV2 + SV3 + ... + SV6

The interpretation of the score is as follows:

■ DMS <14.72 No GERD

■ DMS 14.72 – 50 Mild GERD

■ DMS 51 – 100 Moderate GERD

■ DMS >100 Severe GERD

Use of DMS in GERD diagnosis

Gastroesophageal reflux disease (GERD) clinical presentation may consist in symptoms that are common to other esophageal and extra-esophageal diseases, so GERD cannot be diagnosed solely based on symptoms.

GERD is a common ailment of the western world, with 7% of US population being estimated to experience heartburn daily (with 44% experiencing it at least once a month). Heartburn, the most prevalent symptom of GERD occurs when acidic gastric content reaches the esophageal mucosa.

Upper digestive endoscopy or a barium esophagram may also prove to be misleading so in most cases, pH monitoring is used for definitive diagnosis. The DMS categorizes patients as GERD negative or GERD positive depending on whether the composite score is lower or greater than 14.72.

Esophageal pH monitoring provides direct physiologic measurement of acid in the esophagus and is to date, the most objective method to document reflux disease, assess its severity and monitor response to treatment.

pH monitoring followed by composite scoring is deemed a reliable method for scientific purposes as well as for clinical decision making. It can also be used in laryngopharyngeal reflux diagnosis.

About the original study

DMS was created by Johnson and DeMeester in 1974 for better discrimination of GERD, through measures of acid exposure in ambulatory pH monitoring. The mathematical calculation is based on points attributed to each standard deviation above the reference value, for 6 parameters.

In the original study, parameters with a wide range of variation in the 15 (healthy) subjects, such as the number of episodes of acid reflux, had a weak effect on the final score and those rarely found in healthy individuals, such as supine reflux, lead to increased DeMeester.

The sum of all parameters allowed the diagnosis of pathologic reflux when the threshold value (of 14.72) is exceeded.

The DeMeester score was validated by the same authors with an increase in the number of participants. Both the score and the threshold diagnosis value were validated and compared to the only other current parameter for normality with general acceptance: “the % total time esophageal pH <4 (AET)”, obtaining similar results.

DMS is now widely used especially by surgeons whilst the AET is preferred by clinicians. Please note that both parameters (DMS and AET) point to the presence of reflux and not the fact that the symptoms are caused by reflux.

DMS has valuable and undisputable GERD diagnosis capacity but should be used in tandem with another diagnostic method to establish temporal correlation between symptoms and reflux episodes.

Some DeMeester score limitations worth noting include false negative results due to causes such as:

■ pH monitoring method;

■ changes in lifestyle of patient during monitoring;

■ hypersalivation induced by the catheter;

■ gastric alkalization due to Helicobacter pylori infection.

Day-to-day variation is also a drawback of reflux testing that could be mitigated by 48 hour wireless capsule pH monitoring.

DMS also attributes different weights according to reflux pattern, with higher scores in supine position. Abnormal supine acid exposure time is observed when there is poor sleep quality, an elevated BMI, patterns of late-evening meal consumption, in Barrett’s esophagus or with severe erosive esophagitis.

Multichannel intraluminal impedance pH (MII-pH) monitoring has been found to improve the

sensitivity of the test even though the presence of isolated non-acid reflux is an uncommon finding.

New MII-pH parameters such as mean nocturnal baseline impedance (MNBI) and post-reflux swallowed induced peristaltic wave (PSPW) index may in the future (pending enough research) add to GERD diagnosis.

References

Original reference

Johnson LF, Demeester TR. Twenty-four-hour pH monitoring of the distal esophagus. A quantitative measure of gastroesophageal reflux. Am J Gastroenterol. 1974;62(4):325–332.

Other references

Neto RML, Herbella FAM, Schlottmann F, Patti MG. Does DeMeester score still define GERD? Dis Esophagus. 2019 May 1;32(5).

DeMeester TR, Peters JH, Bremner CG, Chandrasoma P. Biology of Gastroesophageal Reflux Disease: Pathophysiology Relating to Medical and Surgical Treatment 1999. Annu Rev Med, 50, 469-506