Background

[In additional to accepted 24-hour ambulatory pH studies, multichannel intraluminal impedance testing is thought to improve pre-operative assessment and aid diagnosis of atypical reflux-related symptoms. While a measure of concordance between the results of these two tests is expected, as both aim to detect the same phenomenon of reflux, the actual concordance between pH study results and impedance values in typical reflux-related symptoms is unknown.]

 Aims

To assess the correlation between pH studies and impedance testing in patients with typical reflux symptoms.

 Methods

100 consecutive patients undergoing oesophageal physiology testing for typical reflux symptoms of heartburn or regurgitation were reviewed. All patients were required to cease acid suppressant and promotility agents at least 7 days prior. Pre-study localisation of the lower oesophageal sphincter was made manometrically. All patients were encouraged to ingest a refluxogenic challenge meal during the study period. Reflux episodes noted during meal times were excluded. Pearson’s correlation co-efficient was calculated for catheter-based 24-hour pH results compared to 8-channel intraluminal oesophageal impedance values. Common descriptors of association between the two tests’ results were calculated.

Results

Correlation between Demeester composite score and total number of impedance detected reflux events was r = 0.4015.  The positive predictive value of impedance for Demeester score > 14.72 was 83%. The sensitivity of abnormal impedance testing for detecting abnormal Demeester score was 15.63% and the specificity was 94.4%.

 Conclusion

There is poo­­­r correlation between 24-hour pH results and impedance scores. Therefore, the utility of impedance assessment for typical reflux symptoms is poor.