This article is linked to Schumann et al and Enck papers. To view
these articles visit https://doi.org/10.1111/apt.14400 and https://
Department of Internal and Integrative Medicine, Faculty of Medicine,
Kliniken Essen-Mitte, University of Duisburg-Essen, Essen, Germany
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Letter: it is time to adopt new objective parameters to
accurately identify patients with functional heartburn
We read with great interest the study by Choksi et al
symptom-association probability (SAP) is not a useful parameter to
distinguish functional heartburn (FH) from reflux hypersensitivity
(RH), when analysing acid measurements from 48-hour wireless pH
monitoring. In particular, this traditional index of symptom-reflux
association was highly variable between day 1 and day 2 of pH test-
ing, thus leading to different diagnosis of hypersensitivity or func-
tional heartburn for each monitored day. Furthermore, pre-operative
SAP values did not predict surgical outcome. This study is a further
confirmation of the well-known limited diagnostic accuracy of this
particularly when measurement of all types of reflux is
not performed (ie, pH-metry instead of impedance-pH), and high-
lights the need for new and more objective features to improve our
ability to identify patients with RH and FH.
In keeping with this requirement, some recent investigations have
highlighted the relevance of some innovative, objective and reliable
parameters that can be adopted when applied to tracings achieved
from impedance-pH monitoring, which is presently recognised as the
best technique to detect gastro-oesophageal reflux episodes.
are represented by the baseline impedance, especially when measured
at night when swallow or reflux-related artefacts are minimal (mean
nocturnal baseline impedance; MNBI), which has been shown to be a
marker of impaired mucosal integrity, and the post-reflux swallow-
induced peristaltic wave (PSPW), defined by an antegrade impedance-
detected bolus propagation reaching all distal impedance monitoring
sites within 30 seconds of a reflux episode, which has been high-
lighted as a marker of chemical clearance and a hallmark of GERD
The PSPW index and MNBI provide significant diag-
nostic yield in distinguishing RH from FH, even when SAP is nega-
More importantly, ROC analysis has demonstrated
combined assessment of PSPW and MNBI allowed excellent separa-
tion of RH and FH (AUC 0.957). SAP positivity was only found in 62%
of hypersensitive patients, whereas PSPW/MNBI positivity was
detected in 92% (P < 0.0001). Therefore, the calculation of PSPW
index and MNBI affords the diagnosis of RH independently of—and
significantly better than—SAP index. Impairment of chemical clear-
ance, expressed by a low PSPW index, and loss of mucosal integrity,
expressed by a low MNBI, provide a potential explanation of the
increased perception of reflux episodes in patients with RH. In addi-
tion, it is worth noting that these 2 new measures have the great
advantage of providing an objective measurement and, therefore, do
not suffer from patients’ symptom reporting or from the lack of reflux
episodes occurrence during the monitoring day.
LETTERS TO THE EDITORS
© 2018 John Wiley & Sons Ltd