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Is It Heartburn or GERD? The Truth About Diagnosis in Low Prevalence Areas

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Soraya Malik in Health & Wellness October 2026 • 4 min read.

"Unpacking the complexities of diagnosing GERD using questionnaires in regions where the condition is less common."


Gastroesophageal reflux disease (GERD) is a widespread concern, but its diagnosis isn't always straightforward, especially in regions where it's less common. Typical symptoms like heartburn and acid regurgitation often lead to a diagnosis, and symptom-based questionnaires have become popular tools. However, these questionnaires, designed for populations with high GERD prevalence, may not perform as reliably in areas where GERD is less frequent.

One such tool is the Carlsson-Dent questionnaire (CDQ), a standardized symptom-based questionnaire for GERD. While effective in high-prevalence populations, its accuracy in low-prevalence settings is uncertain. This article explores a study assessing the CDQ's effectiveness in diagnosing GERD in Thailand, a region with a relatively low prevalence of the disease.

The goal is to determine if the CDQ can accurately identify GERD in a Thai population compared to more objective measures like endoscopy and 24-hour pH monitoring. Understanding the CDQ's performance in this context can help refine diagnostic approaches and ensure appropriate management of GERD in diverse populations.

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GERD and Acid Reflux

GERD occurs when stomach acid repeatedly flows back into the esophagus, causing irritation and symptoms such as heartburn. Mayo Clinic distinguishes occasional acid reflux from GERD, which develops when reflux happens repeatedly over time. WebMD, Cleveland Clinic, and Healthline describe GERD as involving acid reflux into the esophagus or throat and discuss symptoms, causes, and treatment options.

Navigating GERD Diagnosis: The CDQ Study in Thailand

Question mark transforming into stomach.

To evaluate the CDQ, researchers in Thailand recruited 100 patients experiencing dyspepsia (indigestion) according to Rome II criteria. All participants completed a Thai version of the CDQ and underwent an endoscopic examination. Patients without esophagitis or peptic ulcers, but with positive CDQ scores, then underwent 24-hour pH monitoring to measure the amount of acid reflux.

The study revealed some interesting findings:

  • The study group consisted of 100 patients, with 68% being female, and an average age of 45.6 years.
  • Six patients with Los Angeles grade A esophagitis (mild inflammation) had negative CDQ scores, suggesting the questionnaire missed their GERD.
  • Of the 44 patients with positive CDQ scores, only a small fraction had confirmed GERD through endoscopy or pH monitoring.
  • The CDQ identified only 11 out of the 17 GERD cases detected by endoscopy and pH monitoring, resulting in a sensitivity of 64%.
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Research in Low-Prevalence Regions

A study of i-Scan detection examined minimal-change esophagitis in dyspeptic patients with or without GERD in a region where GERD prevalence is low. The researchers noted that accompanying dyspepsia symptoms might increase the likelihood of recruiting patients with functional heartburn. Another report states that tools such as the Carlsson-Dent questionnaire may detect people with GERD more sensitively than endoscopy in a low-prevalence region.

Questionnaire Validation Limits

The Carlsson-Dent questionnaire has been evaluated as a diagnostic tool for GERD in areas with low disease prevalence. Other questionnaires, including the frequency scale for symptoms of GERD and the S scale, have been studied in Asian countries with promising results. However, the source emphasizes that further studies in different populations are needed to confirm the validity of these tools.

Symptom-Based Diagnosis

Symptom-based diagnosis is widely used in Western countries, where the source describes its sensitivity and specificity as acceptable. Structural questionnaires were developed to standardize this approach, but studies assessing their validity have produced conflicting results. Reported sensitivity for these questionnaires ranges from 60% to 92%, and the Carlsson-Dent questionnaire focuses on the sensations patients experience along with provoking, worsening, and relieving factors.

These results suggest that the CDQ may over-diagnose GERD in the Thai population compared to endoscopy and pH monitoring. The researchers propose that the CDQ might be picking up cases of functional heartburn, a condition with similar symptoms but without the objective evidence of acid reflux. Conversely, some GERD cases may have been missed by endoscopy and pH monitoring.

The Takeaway: CDQ and GERD in Low-Prevalence Areas

The study underscores the importance of considering the local prevalence of GERD when using symptom-based questionnaires. While the CDQ can be a useful tool, it may not be as accurate in low-prevalence areas like Thailand, potentially leading to over-diagnosis.

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Patient Experience and Diagnosis

A study examined the performance of the Carlsson-Dent Questionnaire in the Thai population, where GERD prevalence is low. Its diagnostic performance was assessed against endoscopy or 24-hour pH monitoring. The study reflects the practical challenge of evaluating GERD through patient-reported symptoms while comparing those reports with clinical tests.

This highlights the need for clinicians to interpret CDQ results cautiously and consider objective testing, such as endoscopy and pH monitoring, especially when symptoms don't align with typical GERD presentation or when treatment is ineffective.

Ultimately, a comprehensive approach that combines symptom assessment with objective testing is crucial for accurate GERD diagnosis and appropriate management, ensuring that patients receive the right care based on their individual needs and circumstances.

Reading the CDQ against clinical tests

The questionnaire and the clinical tests did not identify exactly the same people: some CDQ-positive results were not confirmed, while some test-detected cases had negative scores. This mismatch means the questionnaire’s result is not equivalent to confirmation by the comparison tests.[1]

Because pH monitoring was omitted for some patients with low scores, the study’s sensitivity estimate may not capture all GERD cases. The comparison therefore has an important measurement gap, rather than providing a complete count of cases missed by the questionnaire.[1] [2]

  • The sample was selected arbitrarily because the authors lacked prior performance data for the CDQ in low-prevalence populations.[2]
  • Some patients with low CDQ scores and insignificant endoscopic findings did not undergo pH monitoring, which could leave GERD cases uncounted.[2]

How the Thai study assessed the Carlsson-Dent questionnaire

PopulationPatients with dyspeptic symptoms by Rome II criteria[2]
SettingTertiary centre[2]
DurationMay 2007 to January 2008[2]
ComparisonEndoscopy and 24 hour pH monitoring[2]
Main outcomePerformance of CDQ for diagnosis of GERD[2]
Effect sizeSensitivity of CDQ was 64%[2]
Times cited13[2]

A separate report cited by the authors found that only a small share of positive CDQ scores coincided with endoscopically detected esophagitis. That comparison used endoscopy for the outcome and does not include the pH-monitoring comparison used in the Thai study.[1]

What remains uncertain about CDQ performance

  • How well would the CDQ perform in other populations, given the authors’ call to validate symptom questionnaires across different groups?[1]
  • How much of the disagreement between symptom scores and clinical tests reflects functional heartburn, and how much reflects GERD missed by the tests?[2] [3]

Sources

  1. The Value of Carlsson-Dent Questionnaire in Diagnosis of Gastroesophageal Reflux Disease in Area With Low Prevalence of Gastroesophageal Reflux Disease (Europe PMC, 2011)
  2. The Value of Carlsson-Dent Questionnaire in Diagnosis of Gastroesophageal Reflux Disease in Area With Low Prevalence of Gastroesophageal Reflux Disease (The Korean Society of Neurogastroenterology and Motility, 2011)
  3. i-Scan detection of minimal change esophagitis in dyspeptic patients with or without Gastroesophageal Reflux disease (2016)

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.5056/jnm.2011.17.2.164, Alternate LINK

Title: The Value Of Carlsson-Dent Questionnaire In Diagnosis Of Gastroesophageal Reflux Disease In Area With Low Prevalence Of Gastroesophageal Reflux Disease

Subject: Gastroenterology

Journal: Journal of Neurogastroenterology and Motility

Publisher: The Korean Society of Neurogastroenterology and Motility

Authors: Nisa Netinatsunton, Siriboon Attasaranya, Bancha Ovartlarnporn, Sulee Sangnil, Sopa Boonviriya, Teerha Piratvisuth

Published: 2011-04-30

Everything You Need To Know

1

What exactly is Gastroesophageal reflux disease (GERD), and why is it important?

Gastroesophageal reflux disease (GERD) is a digestive disorder where stomach acid frequently flows back into the esophagus, causing heartburn and potentially other complications. The significance of GERD lies in its impact on the individual's health and quality of life. Persistent acid reflux can lead to esophagitis (inflammation of the esophagus), Barrett's esophagus, and even esophageal cancer if left untreated. In the context of regions with lower prevalence, the implications are that diagnostic tools need to be carefully evaluated for accuracy to prevent misdiagnosis and ensure appropriate management of the condition.

2

What is the Carlsson-Dent questionnaire (CDQ) and why is it important?

The Carlsson-Dent questionnaire (CDQ) is a symptom-based questionnaire used to assess GERD. It helps in identifying individuals experiencing symptoms associated with acid reflux, such as heartburn and acid regurgitation. Its importance stems from its widespread use as a preliminary diagnostic tool. However, the reliability of the CDQ can vary depending on the population. In high-prevalence areas, it is generally effective. In low-prevalence areas, the CDQ may not be as accurate, potentially leading to either over-diagnosis or under-diagnosis of GERD. The implication is that when CDQ is used in low-prevalence populations, the results should be interpreted cautiously, and further investigation may be required.

3

What does 'low prevalence' mean in the context of this information, and why is it significant?

In the context of the study, 'low prevalence' refers to regions or populations where the occurrence of GERD is less frequent compared to other areas. The significance is that the accuracy of diagnostic tools, like the Carlsson-Dent questionnaire (CDQ), can be affected by prevalence. When GERD is less common, a questionnaire designed for high-prevalence settings might yield a higher rate of false positives, incorrectly identifying individuals as having GERD. The implication is that diagnostic strategies in low-prevalence areas need to be adapted, potentially incorporating more objective measures such as endoscopy and 24-hour pH monitoring to confirm the diagnosis and provide accurate diagnosis.

4

What methods were used to diagnose GERD in the Thai study, and why are they important?

The study in Thailand used a Thai version of the Carlsson-Dent questionnaire (CDQ), endoscopy, and 24-hour pH monitoring. The CDQ was used to assess symptoms of GERD, while endoscopy and pH monitoring were used to provide objective measures of acid reflux. The significance lies in the comparison of these tools to understand the CDQ's accuracy. The implications are that the CDQ can have a lower sensitivity in low-prevalence areas. This means that it may miss some cases of GERD that are detectable through endoscopy and pH monitoring, and could lead to under-diagnosis.

5

What were the key findings of the study regarding the accuracy of the Carlsson-Dent questionnaire (CDQ)?

The study's findings suggest that the Carlsson-Dent questionnaire (CDQ) may over-diagnose GERD in low-prevalence populations. The CDQ identified 44 patients with positive scores, but only a fraction of these were confirmed as having GERD through endoscopy or pH monitoring. This suggests that the questionnaire might be picking up other conditions, such as functional heartburn. It also highlights that the CDQ may have a lower sensitivity in low prevalence regions. The implication is that when the CDQ is used in low prevalence settings, doctors should consider the possibility of over-diagnosis and may need to employ additional diagnostic methods to confirm the diagnosis of GERD to ensure patients receive accurate and appropriate treatment.

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