Obesity and Gastroesophageal Reflux: Quantifying the Association Between Body Mass Index, Esophageal Acid Exposure, and Lower Esophageal Sphincter Status in a Large Series of Patients with Reflux Symptoms

Obesity and gastroesophageal reflux disease (GERD) are increasingly important health problems. Previous studies of the relationship between obesity and GERD focus on indirect manifestations of GERD. Little is known about the association between obesity and objectively measured esophageal acid exposure. The aim of this study is to quantify the relationship between body mass index (BMI) and 24-h esophageal pH measurements and the status of the lower esophageal sphincter (LES) in patients with reflux symptoms. Data of 1,659 patients (50% male, mean age 51 ± 14) referred for assessment of GERD symptoms between 1998 and 2008 were analyzed. These subjects underwent 24-h pH monitoring off medication and esophageal manometry. The relationship of BMI to 24-h esophageal pH measurements and LES status was studied using linear regression and multiple regression analysis. The difference of each acid exposure component was also assessed among four BMI subgroups (underweight, normal weight, overweight, and obese) using analysis of variance and covariance. Increasing BMI was positively correlated with increasing esophageal acid exposure (adjusted R 2 = 0.13 for the composite pH score). The prevalence of a defective LES was higher in patients with higher BMI (p < 0.0001). Compared to patients with normal weight, obese patients are more than twice as likely to have a mechanically defective LES [OR = 2.12(1.63–2.75)]. An increase in body mass index is associated with an increase in esophageal acid exposure, whether BMI was examined as a continuous or as a categorical variable; 13% of the variation in esophageal acid exposure may be attributable to variation in BMI

Prospective assessment of axial back pain symptoms before and after bariatric weight reduction surgery

The prevalence of obesity in developed countries has reached alarming levels, doubling in the United States since 1980. Although obese patients with chronic low back pain are frequently advised to lose weight, the association between these medical conditions remains unproven. This study prospectively assessed clinically reported changes in chronic axial low back pain symptoms after weight reduction from bariatric surgery for morbid obesity. Prospective longitudinal study. Fifty-eight consecutive patients with morbid obesity and chronic axial low back pain undergoing bariatric surgery over a period of 6 months. Patients were considered morbidly obese if they were 50% to 100% above their ideal body weight or having a body mass index (BMI) greater than 40. Visual Analog Scale (VAS) for axial low back pain, Short Form-36 (SF-36) Health Survey, and Oswestry Disability Index (ODI) Patients undergoing weight reduction surgery were assessed preoperatively and postoperatively at 12 months with validated clinical measures for axial back pain and disability (VAS, SF-36, and ODI). Bariatric surgery parameters included demographic data, weight, and BMI. Statistical analysis included paired t tests and multiple regression techniques. Of the initial 58 patients, 38 (65%) completed both preoperative (Pre-Op) and postoperative (Post-Op) questionnaires at 12 months. These 38 subjects included 30 women and 8 men, with an age range of 20 to 68 years (mean 48.4±10.1). Overall, these patients showed a decrease in mean weight from 144.52±41.21 kg Pre-Op to 105.59±29.24 Post-Op (p<.0001) and BMI from 52.25±12.61 kg/m 2 Pre-Op to 38.32±9.66 Post-Op (p<.0001). Patients demonstrated a statistically significant mean 44% decrease in axial back pain on the VAS scale (p=.006; 5.2±3.35 Pre-Op, to 2.9±3.1 Post-Op). Analysis of the SF-36 major components revealed that patients experienced significant increases in mean physical health by 58% (p<.0001; 44.5±20.09 to 70.24±26.84) and in median mental health by 6% (p=.03; 70±7.14 to 73.39±11.78). Patients also showed statistically significant 24% decrease in Post-Op ODI score for physical disability (p=.05) from 26.75±16.56 Pre-Op to 20.35±18.71 Post-Op (p=.05). This study suggests that the substantial weight reduction after bariatric surgery may be associated with moderate reductions in preexisting back pain at early-follow-up. This effect did not appear to be the result only of an overall improvement in well-being associated with weight loss. However, larger randomized controlled clinical studies with longer-term follow-up are needed to definitively determine a causal relationship