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Omeprazole test and 24-hour esophageal pH monitoring in diagnosing GERD
GASTROENTEROLOGY 1999;116:1012–1018
CORRESPONDENCE Readers are encouraged to write letters to the editor concerning articles that have been published in GASTROENTEROLOGY. Short, general comments are also considered, but use of the Correspondence section for publication of original data in preliminary form is not encouraged. Letters should be typewritten double-spaced and submitted in triplicate.
Omeprazole Test and 24-Hour Esophageal pH Monitoring in Diagnosing GERD Dear Sir: A recent article by Fass et al.1 on the efficacy of the omeprazole test in diagnosing gastroesophageal reflux disease (GERD) in patients with noncardiac chest pain shows an unusual finding. They reported that only 15 of the 23 patients with documented GERD had ambulatory 24-hour esophageal pH monitoring consistent with GERD, whereas the other 8 had only erosive esophagitis diagnosed by upper endoscopy. This is an unusually high false-negative rate for 24-hour esophageal pH monitoring in patients with GERD. Ambulatory 24-hour esophageal pH monitoring is considered the gold standard for the detection of GERD.2,3 Castell and Katz4 suggested that the high false-negative rate may be related to the use of only total percent time of acid exposure as an entry criterion for this study or to inability to utilize a strong symptom/reflux association (i.e., a positive symptom index) as an additional criterion for 24-hour esophageal pH monitoring to document GERD. Duodenogastroesophageal reflux (DGER) may be a plausible explanation for esophagitis in these 8 patients with negative findings on 24-hour pH monitoring. Although animal studies suggest that bile acids can produce pH-dependent esophageal mucosal injury,5 human evidence for the damaging effects of bile acids is controversial.6 Nevertheless, several recent reports suggest that increased DGER is more frequent and may predispose to the development of complicated GERD, including Barrett’s esophagus.7 The crucial question arising from this argument is whether DGER may have resulted in erosive esophagitis in 8 of 23 patients with GERD in this study. If this is true, then the relief of symptoms provided by omeprazole therapy in this subset of patients may be a placebo effect. The patients in this study did not undergo any diagnostic tests to rule out DGER. It is clear that endoscopic observation of bile in the esophagus or stomach is a poor indicator of its role in mucosal damage.8 A new fiberoptic system (Bilitec 2000; Synectics, Irving, TX) detects DGER spectrophotometrically, independent of pH.9 This system uses the optical property of bilirubin pigment in detecting bile. Bilirubin has a characteristic spectrophotometric absorption band at 450 nm. The basic working principle of this fiberoptic system is that an absorption near this wavelength suggests the presence of bilirubin and therefore represents DGER. Bilitec has been validated independently and successfully used in many studies as an objective tool for assessing DGER.10 In conclusion, in my judgment DGER must be excluded by using Bilitec in patients with documented esophagitis in the setting of negative ambulatory 24-hour esophageal pH monitoring for GERD. MANSOOR AHMAD, M.D. Division of Gastroenterology Department of Medicine Baqai Medical College Karachi, Pakistan 1. Fass R, Fennerty MB, Ofman JJ, et al. The clinical and economic value of a short course of omeprazole in patients with noncardiac chest pain. Gastroenterology 1998;115:42–49.
2. Euler AR, Byrne WJ. Twenty-four-hour esophageal intraluminal pH probe testing: a comparative analysis. Gastroenterology 1981;80: 957–961. 3. Jamieson JR, Sten HJ, DeMeester TR, et al. Ambulatory 24-hour esophageal pH monitoring: normal values, optimal thresholds, specificity, sensitivity and reproducibility. Am J Gastroenterol 1992;87:1102–1111. 4. Castell DO, Katz PO. The acid suppression test for unexplained chest pain. Gastroenterology 1998;115:222–224. 5. Lillemoe KD, Johnson LF, Harmon JW. Role of components of gastroduodenal contents in experimental acid esophagitis. Surgery 1982;92:276–284. 6. Vaezi MF, Singh S, Richter JE. Role of acid and duodenogastric reflux in esophageal injury: a review of animal and human studies. Gastroenterology 1995;108:1897–1907. 7. Attwood SEA, DeMeester TR, Brenner CG, et al. Alkaline gastroesophageal reflux: implications in the development of complications in Barrett’s columnar-lined lower esophagus. Surgery 1989; 106:764–776. 8. Stein HJ, Smyrk TC, DeMeester TR, et al. Clinical value of endoscopy and histology in the diagnosis of duodenogastric reflux disease. Surgery 1992;112:796–804. 9. Vaezi MF, Richter JE. Role of acid and duodenogastroesophageal reflux in gastroesophageal reflux disease. Gastroenterology 1996; 111:1192–1199. 10. Vaezi MF, LaCamera RG, Richter JE. Bilitec 2000 ambulatory duodenogastric reflux monitoring system: studies on its validation and limitations. Am J Physiol 1994;267:G1050–G1057.
Reply. As noted by Dr. Ahmad, 8 (34.8%) of the GERD-positive patients, with documented erosive esophagitis on upper endoscopy, had normal findings on 24-hour esophageal pH monitoring, which translates to a sensitivity of 65%.1 Previous studies reported sensitivity that varied from 79% to 96% and specificity from 85% to 100%.2–4 We believe that the sensitivity of 24-hour esophageal pH monitoring has been overestimated and the true rate is probably closer to the lower end of the reported sensitivity range. Schenk et al.5 recently assessed the diagnostic value of empirical treatment with omeprazole in the diagnosis of GERD and found that 26% of the patients with endoscopically proven erosive esophagitis had a normal 24-hour esophageal pH monitoring. The test has inherent limitations that have not been recognized before, resulting in the recent reports of lower sensitivity. We recently evaluated the effect of the test itself on reflux-provoking activities (unpublished data). This study was a natural extension of our clinical observation that many patients are incapacitated by the side effects that the test causes. We showed that ambulatory 24-hour esophageal pH monitoring significantly reduced the time spent being active, number of meals and cups of coffee consumed, frequency of symptoms such as acid regurgitation and chest pain, and severity of heartburn. Almost half of the patients reported having dysphagia during the test. Most patients experienced side effects and stated that the test bothered them most of the time. We concluded that the test had a significant effect on decreasing reflux-provoking activities. Patients assumed a more sedentary lifestyle during the test. This may influence the reliability of the test as a physiological measure of acid reflux. We do not suggest that negative findings on 24-hour esophageal pH monitoring in patients with documented erosive esophagitis
CORRESPONDENCE Readers are encouraged to write letters to the editor concerning articles that have been published in GASTROENTEROLOGY. Short, general comments are also considered, but use of the Correspondence section for publication of original data in preliminary form is not encouraged. Letters should be typewritten double-spaced and submitted in triplicate.
Omeprazole Test and 24-Hour Esophageal pH Monitoring in Diagnosing GERD Dear Sir: A recent article by Fass et al.1 on the efficacy of the omeprazole test in diagnosing gastroesophageal reflux disease (GERD) in patients with noncardiac chest pain shows an unusual finding. They reported that only 15 of the 23 patients with documented GERD had ambulatory 24-hour esophageal pH monitoring consistent with GERD, whereas the other 8 had only erosive esophagitis diagnosed by upper endoscopy. This is an unusually high false-negative rate for 24-hour esophageal pH monitoring in patients with GERD. Ambulatory 24-hour esophageal pH monitoring is considered the gold standard for the detection of GERD.2,3 Castell and Katz4 suggested that the high false-negative rate may be related to the use of only total percent time of acid exposure as an entry criterion for this study or to inability to utilize a strong symptom/reflux association (i.e., a positive symptom index) as an additional criterion for 24-hour esophageal pH monitoring to document GERD. Duodenogastroesophageal reflux (DGER) may be a plausible explanation for esophagitis in these 8 patients with negative findings on 24-hour pH monitoring. Although animal studies suggest that bile acids can produce pH-dependent esophageal mucosal injury,5 human evidence for the damaging effects of bile acids is controversial.6 Nevertheless, several recent reports suggest that increased DGER is more frequent and may predispose to the development of complicated GERD, including Barrett’s esophagus.7 The crucial question arising from this argument is whether DGER may have resulted in erosive esophagitis in 8 of 23 patients with GERD in this study. If this is true, then the relief of symptoms provided by omeprazole therapy in this subset of patients may be a placebo effect. The patients in this study did not undergo any diagnostic tests to rule out DGER. It is clear that endoscopic observation of bile in the esophagus or stomach is a poor indicator of its role in mucosal damage.8 A new fiberoptic system (Bilitec 2000; Synectics, Irving, TX) detects DGER spectrophotometrically, independent of pH.9 This system uses the optical property of bilirubin pigment in detecting bile. Bilirubin has a characteristic spectrophotometric absorption band at 450 nm. The basic working principle of this fiberoptic system is that an absorption near this wavelength suggests the presence of bilirubin and therefore represents DGER. Bilitec has been validated independently and successfully used in many studies as an objective tool for assessing DGER.10 In conclusion, in my judgment DGER must be excluded by using Bilitec in patients with documented esophagitis in the setting of negative ambulatory 24-hour esophageal pH monitoring for GERD. MANSOOR AHMAD, M.D. Division of Gastroenterology Department of Medicine Baqai Medical College Karachi, Pakistan 1. Fass R, Fennerty MB, Ofman JJ, et al. The clinical and economic value of a short course of omeprazole in patients with noncardiac chest pain. Gastroenterology 1998;115:42–49.
2. Euler AR, Byrne WJ. Twenty-four-hour esophageal intraluminal pH probe testing: a comparative analysis. Gastroenterology 1981;80: 957–961. 3. Jamieson JR, Sten HJ, DeMeester TR, et al. Ambulatory 24-hour esophageal pH monitoring: normal values, optimal thresholds, specificity, sensitivity and reproducibility. Am J Gastroenterol 1992;87:1102–1111. 4. Castell DO, Katz PO. The acid suppression test for unexplained chest pain. Gastroenterology 1998;115:222–224. 5. Lillemoe KD, Johnson LF, Harmon JW. Role of components of gastroduodenal contents in experimental acid esophagitis. Surgery 1982;92:276–284. 6. Vaezi MF, Singh S, Richter JE. Role of acid and duodenogastric reflux in esophageal injury: a review of animal and human studies. Gastroenterology 1995;108:1897–1907. 7. Attwood SEA, DeMeester TR, Brenner CG, et al. Alkaline gastroesophageal reflux: implications in the development of complications in Barrett’s columnar-lined lower esophagus. Surgery 1989; 106:764–776. 8. Stein HJ, Smyrk TC, DeMeester TR, et al. Clinical value of endoscopy and histology in the diagnosis of duodenogastric reflux disease. Surgery 1992;112:796–804. 9. Vaezi MF, Richter JE. Role of acid and duodenogastroesophageal reflux in gastroesophageal reflux disease. Gastroenterology 1996; 111:1192–1199. 10. Vaezi MF, LaCamera RG, Richter JE. Bilitec 2000 ambulatory duodenogastric reflux monitoring system: studies on its validation and limitations. Am J Physiol 1994;267:G1050–G1057.
Reply. As noted by Dr. Ahmad, 8 (34.8%) of the GERD-positive patients, with documented erosive esophagitis on upper endoscopy, had normal findings on 24-hour esophageal pH monitoring, which translates to a sensitivity of 65%.1 Previous studies reported sensitivity that varied from 79% to 96% and specificity from 85% to 100%.2–4 We believe that the sensitivity of 24-hour esophageal pH monitoring has been overestimated and the true rate is probably closer to the lower end of the reported sensitivity range. Schenk et al.5 recently assessed the diagnostic value of empirical treatment with omeprazole in the diagnosis of GERD and found that 26% of the patients with endoscopically proven erosive esophagitis had a normal 24-hour esophageal pH monitoring. The test has inherent limitations that have not been recognized before, resulting in the recent reports of lower sensitivity. We recently evaluated the effect of the test itself on reflux-provoking activities (unpublished data). This study was a natural extension of our clinical observation that many patients are incapacitated by the side effects that the test causes. We showed that ambulatory 24-hour esophageal pH monitoring significantly reduced the time spent being active, number of meals and cups of coffee consumed, frequency of symptoms such as acid regurgitation and chest pain, and severity of heartburn. Almost half of the patients reported having dysphagia during the test. Most patients experienced side effects and stated that the test bothered them most of the time. We concluded that the test had a significant effect on decreasing reflux-provoking activities. Patients assumed a more sedentary lifestyle during the test. This may influence the reliability of the test as a physiological measure of acid reflux. We do not suggest that negative findings on 24-hour esophageal pH monitoring in patients with documented erosive esophagitis