THE SYMPTOM-ASSOCIATION PROBABILITY - AN IMPROVED METHOD FOR SYMPTOM ANALYSIS OF 24-HOUR ESOPHAGEAL PH DATA

Background/Aims: All methods currently used to quantify the temporal r elationships between symptoms and episodes of gastroesophageal reflux, as assessed by 24-hour pH monitoring, have major shortcomings. The ai m of this study was to develop and validate a simple, all-comprising s tatistical method to calculate the probability that gastroesophageal r eflux episodes and symptoms are associated. Methods: The 24-hour pH si gnal was divided into consecutive 2-minute periods. These periods and the 2-minute periods preceding the onset of symptoms were evaluated fo r the occurrence of reflux. Fisher's Exact Test was then applied to ca lculate the probability (P value) that reflux and symptom episodes wer e unrelated. Finally, the symptom-association probability (SAP) was ca lculated as (1.0 - P) x 100%. The SAP values found in 184 24-hour esop hageal pH tests were compared with the symptom index and the symptom s ensitivity index. Results: Discordance between the SAP and the symptom index was found in 21 patients (11%) and discordance between the SAP and the symptom-sensitivity index in 28 (15%). False-positive and fals e-negative symptom index values occurred preferentially in patients wi th small and large numbers of symptom episodes during the test, respec tively (P < 0.05). Conclusions: The SAP is a single, simple, quantitat ive measure of the strength of the association between symptoms and re flux episodes that is devoid of the disadvantages inherent to previous ly used methods.