A DeMeester score is a composite number that measures how much stomach acid flows back into your esophagus over a 24-hour period. A score below 14.72 is considered normal, while anything above that threshold indicates abnormal acid reflux. The score is widely used to confirm a diagnosis of gastroesophageal reflux disease (GERD) and to help determine whether surgery might be the right next step.
What the Score Actually Measures
The DeMeester score isn’t based on a single measurement. It combines six different variables captured during a 24-hour pH monitoring test, giving a more complete picture of your reflux than any one number could. Those six variables are:
- Total acid exposure time: the percentage of the full 24-hour period your esophageal pH drops below 4 (the point at which acid causes tissue damage)
- Upright acid exposure: the percentage of time pH is below 4 while you’re standing or sitting
- Supine acid exposure: the percentage of time pH is below 4 while you’re lying down
- Number of reflux episodes: how many individual times acid reaches the sensor
- Number of prolonged episodes: how many of those episodes last longer than 5 minutes
- Longest reflux episode: the duration of the single longest acid exposure event
Each variable is compared against values from healthy people without reflux. The formula calculates how far each of your measurements deviates from those normal reference values, starting from a point set at two standard deviations below the average in healthy controls. Those deviations are then combined into one composite number. A higher score means more acid is reaching your esophagus, for longer periods, more frequently.
How the Test Works
To generate a DeMeester score, you undergo ambulatory pH monitoring. In the traditional version, a thin tube with a pH sensor at its tip is passed through your nose and positioned about 5 centimeters above the valve between your esophagus and stomach. You wear the device for 24 hours while going about your normal routine. During that time, you record when you eat, when you sleep, and when you experience symptoms like heartburn or chest pain. These logs help your doctor match acid events to what you were doing and feeling.
A wireless alternative uses a small capsule (often called a Bravo capsule) that attaches directly to the lining of your esophagus, eliminating the tube through the nose. This version can record for 48 to 96 hours, which some clinicians prefer because it captures more data and reduces the chance that a single unusual day skews the results. Both methods measure the same core variables used to calculate the DeMeester score.
What Your Score Means
The traditional cutoff is 14.72. Below that, your acid exposure is within the range seen in people without reflux disease. Above it, you have objectively abnormal acid reflux. The further above 14.72 your score lands, the more severe the reflux burden.
Some research has explored a lower threshold of 11.5 for identifying patients with symptomatic reflux, particularly after certain surgeries like sleeve gastrectomy. At that cutoff, the score catches about 84% of people with symptomatic reflux (sensitivity) and correctly identifies about 68% of those without it (specificity). But 14.72 remains the standard benchmark used in most clinical settings.
It’s worth noting that a normal DeMeester score doesn’t necessarily mean your symptoms aren’t real. Some people have a hypersensitive esophagus that reacts to even small amounts of acid that fall within the “normal” range. Your doctor will interpret the score alongside your symptoms, endoscopy findings, and other test results.
Why It Matters for Surgery Decisions
The DeMeester score plays a central role when doctors evaluate whether anti-reflux surgery is a good option. An abnormal score is the strongest predictor of a favorable surgical outcome. In other words, patients whose reflux is objectively confirmed by pH testing tend to respond best to procedures like fundoplication, where the top of the stomach is wrapped around the lower esophagus to reinforce the valve.
This holds true even for patients who have already had one anti-reflux surgery that failed. In a study of 278 patients with structural failure of a prior fundoplication, those with abnormal DeMeester scores were more than twice as likely to undergo revision surgery. After reoperation, 83% of those patients reported satisfaction with the outcome compared to 66% of patients whose scores had been normal. They were also significantly more likely to stop needing daily acid-suppressing medication, with about 78% achieving freedom from those drugs versus 60% in the normal-score group.
The takeaway: the score helps predict who will actually benefit from surgery, which is why surgeons rely on it heavily before recommending an operation.
How It Compares to Newer Metrics
The DeMeester score has been used since the 1970s, and gastroenterology has developed additional tools since then. The most prominent is acid exposure time (AET), which isolates just the total percentage of time your esophageal pH stays below 4. The Lyon Consensus 2.0, an international set of diagnostic guidelines updated in 2024, centers its diagnostic criteria around AET rather than the full DeMeester composite.
Under the Lyon Consensus, an AET above 6% is considered diagnostic of GERD, while an AET below 4% with no correlation between acid events and symptoms effectively rules it out. Values between 4% and 6% fall into an inconclusive zone where additional evidence, like the total number of reflux episodes per day, helps tip the diagnosis one way or another. More than 80 reflux episodes per day is considered adjunctive evidence for GERD, while fewer than 40 is adjunctive evidence against it.
Despite this shift in consensus guidelines, the DeMeester score remains widely used in surgical practice. Many surgeons still consider it the most reliable single number for confirming reflux severity and predicting surgical outcomes. You may see both metrics mentioned in your test results, and they often point in the same direction since total acid exposure is the most heavily weighted component of the DeMeester score anyway.