Introduction Conventional catheter-based systems used for ambulatory oesophageal pH monitoring have been reported to affect patient behaviour. As physical activity has been associated with gastro-oesophageal reflux disease (GORD), there is a risk that abnormal behaviour will degrade the value of this diagnostic investigation and consequent management strategies. Our aim was to provide the reporting physician with objective peri-investigational changes in activity, and the means to assess the association between activity and pH during the test, using a wearable activity monitor.

Methods Trial registered at clinicaltrials.gov (NCT01507298) and ethics approved (11/LO/1981). Twenty patients listed for 24h pH monitoring underwent activity monitoring using a lightweight ear-worn accelerometer (e-AR sensor, Imperial College London) 2 days prior to, and during their investigation. PH was measured and recorded using a conventional naso-gastric catheter and waist worn receiver. Objectively measured activity levels, including subject-specific activity intensity quartiles, were calculated and compared over the 3 days. Physical activity was added to standard test outputs to supplement interpretation and diagnosis.

Results Average patient activity levels decreased by 26.5% during pH monitoring (Range -4.5–51.0%, p = 0.036). The amount of high intensity activities decreased by 24.4% (Range –4.0–75.6%, p = 0.036), and restful activity increased on average by 34% although this failed to reach statistical significance (-24.0–289.2%, p = 0.161). Some patients exhibited consistent associations between bouts of activity and acidic episodes (Figure 1).

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Abstract PTU-176 Figure 1

Conclusion The results of this study support the previously reported reduction in activity during ambulatory oesophageal pH monitoring,^1,2 with the added reliability of objective activity data. In the absence of more pervasive pH monitoring systems (e.g. wireless), quantifying activity changes in the setting of activity-induced reflux might facilitate recalibration of patient DeMeester scores and therefore more appropriate management of GORD.

Reference

1. Fass R, et al. Effect of ambulatory pH monitoring on reflux-provoking activities. Dig Dis Sci 1999;44:2263–9

2. Mearin F, et al. How standard is a standard day during a standard ambulatory 24-hour esophageal pH monitoring? Scand J Gastroenterol 1998;33:583–5

Disclosure of Interest None Declared.