Evaluation of symptom index in identifying gastroesophageal reflux disease-related noncardiac chest pain

Background: Symptom index (SI), which represents the percentage of perceived gastroesophageal reflux-related symptoms that correlate with esophageal acid reflux events (pH <4), has been suggested as a measure to improve diagnosis of gastroesophageal reflux (GER)-related noncardiac chest pain (NCCP). Because no study has evaluated the value of the symptom index in NCCP patients, data to support this claim have yet to be elucidated. Aim: To evaluate the value of SI in identifying gastroesophageal reflux disease (GERD)-related NCCP patients. Methods: Patients enrolled in this study were referred by a cardiologist after a comprehensive work-up excluded a cardiac cause for their chest pain. All patients underwent upper endoscopy to determine esophageal inflammation and 24-hour esophageal pH monitoring to assess esophageal acid exposure. Patients were instructed to record all chest pain episodes during the pH test. Patients with a positive SI (≥50%) underwent the proton pump inhibitors (PPI) test, which is a therapeutic trial using a short course of high dose PPI. Results: A total of 94 patients with NCCP were included in this study. Forty-seven (50%) had either a positive upper endoscopy or an abnormal pH test and were considered GERD-Positive. Forty-seven patients (50%) had both tests negative and were considered GERD-Negative. Total number of reflux episodes and percent total, supine and upright time pH less than 4, were significantly higher in the GERD-Positive group as compared with the GERD-Negative group (P < 0.0001, P < 0.0001, P = 0.0045, and P < 0.0001 respectively). Only 9 (19.1%) patients in the GERD-Positive group and 5 (10.6%) patients in the GERD-Negative group had a positive SI (p = ns). Eight (89%) out of the 9 patients who had a positive SI in the GERD-Positive group and 2 (40%) out of 5 patients in the GERD-Negative group responded to the PPI test. Conclusion: Positive SI is relatively uncommon in NCCP patients, regardless if GERD is present or absent. Hence, symptom index provides very little improvement in diagnosing GERD-related NCCP.