Original article Normal values of 24-hour ambulatory esophageal impedance-pH monitoring in a rural South African cohort of healthy participants E. J. Ndebia, A. M. Sammon, E. Umapathy, J. E. Iputo Department of Physiology, Faculty of Health Sciences, Walter Sisulu University, Mthatha, South Africa SUMMARY. There are no data on 24-hour multichannel intraluminal impedance and pH monitoring in African populations. The purpose of this study was to provide the normal values of esophageal impedance and pH monitoring in a rural African populations. South African healthy rural participants were recruited and underwent 24 hours of esophageal impedance and pH monitoring. The median and the 95th percentiles of the total reflux episodes were 49 and 97, respectively, of which the corresponding number of acidic, weakly acidic, and weakly alkaline reflux were 15 and 55, 17 and 51, and 8 and 36, respectively. The compositions of the total reflux were 5 and 21 for liquid, 27 and 72 for mixed, and 10 and 39 for gas reflux, respectively. The median bolus clearance was 18 seconds and the median bolus exposure was 14 minutes/24 hours. The proximal extent was 6%. The 95th percent time of esophageal exposure to acid was 8.6 in 24 hours. Female and overweight participants were associated with an increased number of reflux events. There were more reflux episodes, and of which, more were weakly alkaline compared with previous similar studies. The findings provide reference values of gastroesophageal reflux for a South African rural population. KEY WORDS: esophagus, reference value, reflux, South Africa. INTRODUCTION The prevalence of gastroesophageal reflux disease (GERD) appears to be highest in North America and Europe, whereas epidemiologic data from the Indian subcontinent, Africa, South America, and the Middle East are sparse. 1 According to Segal, 2 few studies have reported on gastroesophageal reflux (GER) and its complications in African countries. More pre- cisely, Somefun et al. 3 reported that GERD was uncommon in Nigeria and almost non-existent in other Sub-Saharan countries. Dent et al. 4 believe that GERD is more common among western individuals compared with Asian and Afro-Caribbean subjects. The data suggest that GERD is rare in Sub-Saharan African countries probably because there are too few reports for evaluation. There are no population- based studies describing the prevalence of GERD in African countries, and only a few studies reported on GER and its complications. 2 According to Kang, 5 more data are required, especially from Africa and some Asian countries. It is possible that population differences in GER symptoms may exist, and it is important that standard reference ranges are estab- lished for African countries. The newer technique involving the recording of esophageal intraluminal impedance and pH simultaneously is a most valuable tool for assessing the relation between the different parameters involved in the normal pattern of GER. The technique gives quantitative data on the fre- quency, nature, type, and duration, and correlates them to the pH of the reflux; it also helps to distin- guish between pathological and physiological reflux. Many studies have already been done in western populations using the multichannel intraluminal impedance and pH technique (MII-pH). Normal values were established in Europe, 6 China, 7 and USA, 8 but this has not been done in Africa. There- fore, the aim of this study was to define the normal values of oesophageal reflux parameters during 24 hours of MII-pH in a rural South African cohort of healthy participants. Address correspondence to: Mr Eugene Jamot Ndebia, MSc, Department of Physiology, Faculty of Health Sciences, Walter Sisulu University, Private bag X1, Nelson Mandela Drive, Mthatha, Eastern Cape 5117, South Africa. Email: endebia@wsu.ac.za Financial support: Medical Research Council (MRC) of South Africa awarded to Professor Jehu Iputo. Jennie Marsh Trust of United Kingdom awarded to Dr Alastair M Sammon. Conflicts of interest: None. Diseases of the Esophagus (2015) ••, ••–•• DOI: 10.1111/dote.12333 © 2015 International Society for Diseases of the Esophagus 1 V C 2015 International Society for Diseases of the Esophagus 385 Diseases of the Esophagus (2016) 29, 385–391 DOI: 10.1111/dote.12333 Downloaded from https://academic.oup.com/dote/article/29/4/385/2328756 by guest on 25 June 2022