ORIGINAL ARTICLE Impedance pH Confirms the Relationship Between GERD and BMI Nasser Hajar • Donald O. Castell • Hassan Ghomrawi • Richard Rackett • Amine Hila Received: 19 October 2011 / Accepted: 2 March 2012 / Published online: 27 March 2012 Ó Springer Science+Business Media, LLC 2012 Abstract Background During the last 20 years the prevalence of both gastroesophageal reflux disease (GERD) and obesity has been increasing in the United States. The pathophysi- ology of GERD is multifactorial and its relationship with obesity is still not well understood. Aim To evaluate the association between BMI and GERD as detected by multichannel intraluminal impedance-pH (MII-pH) monitoring. Methods Retrospective review of 122 consecutive MII-pH studies of adult patients while on PPI therapy. Patients were divided into normal (BMI \ 25), overweight (BMI C 25 and \ 30) and obese (BMI C 30). Reflux episodes were classified as acid reflux (AR), nonacid reflux (NAR), and total number of reflux episodes, as detected by MII-pH. We evaluated the symptoms associated with reflux by using the symptom index (SI). We also assessed the number of reflux episodes during recumbency and compared them in the dif- ferent BMI groups. Results The total number of reflux episodes and NAR episodes increased significantly as BMI increased. There was no significant difference between groups in AR. Similarly, during recumbency, total number of reflux episodes increased significantly when BMI increased. For symptoms associated with reflux, SI was more likely to be positive in the obese group. Conclusions This study shows a clear association between increased reflux as detected by MII-pH and higher BMI. Obesity not only increases the likelihood of reflux events, as shown in previous studies, but also makes it more likely that symptoms reported during MII-pH studies are actually due to MII detected reflux. Keywords MII-pH Á GERD Á Obesity Á Body mass index Á Esophageal motility Á Symptom index Á Reflux during recumbency Introduction During the last 20 years there has been a dramatic increase in obesity in the United States. In 2008, only the state of Colorado had a prevalence of obesity less than 20 %; in 32 states the prevalence was equal to or greater than 25 % [1–4]. Similarly, the prevalence of GERD has been rising in the United States. It was found to be 17.8 % in Olmsted County population by Locke in 1999. In another study, the prevalence was 23 % in the white population of Houston [5]. Additionally, the prevalence of obesity in young peo- ple (6–19 years) has tripled since 1980, and has now reached 18 % [1–4]. Previous studies have examined the association between obesity and GERD and have shown a strong association with increased body mass index (BMI) [6–9]. In two of these studies, GERD was defined by its typical symptoms (heartburn and regurgitation) [6, 7]. In the other three studies, pH monitoring criteria were used [8, 9]. However, the definition of GERD in these studies may have N. Hajar (&) Upstate Medical University, 750 E Adams Street, Syracuse, NY 13210, USA e-mail: dr-hajar@hotmail.com D. O. Castell Medical University of South Carolina, Charleston, SC, USA H. Ghomrawi Cornell University, New York, NY, USA R. Rackett Á A. Hila Binghamton Gastroenterology, Binghamton, NY, USA 123 Dig Dis Sci (2012) 57:1875–1879 DOI 10.1007/s10620-012-2131-6