Researchers have found that waist circumference independently predicts the risk for Barrett's esophagus, leading them to dismiss a previously reported association between body mass index (BMI) and the disease.
"Previous studies that reported associations between BMI alone and Barrett's oesophagus were likely to have been confounded by unmeasured abdominal obesity," say Ai Kubo (Northern California Kaiser Permanente, Oakland, USA) and colleagues.
The findings, published in Gut, suggest physicians should target at-risk patients with weight-loss interventions, and may also help explain why men, who carry more abdominal fat than women, experience twice the rate of the disease.
The analysis comprised results from four cohort studies in the USA, Ireland, and Australia, all of which followed the same protocol. In all, there were 1102 Barrett's esophagus patients and 1400 population-based control participants, of whom 70% were men.
Contrary to previous reports, the authors found no consistent association between BMI and risk for Barrett's esophagus. Furthermore, when they adjusted for waist circumference, there was no association among any BMI category and Barrett's esophagus in men, women, or the entire study population.
Conversely, when the authors adjusted the association between Barrett's esophagus and waist circumference to account for BMI, there was a significant relationship such that for each 5-cm increase in waist circumference, there was a 14% increase in risk for the disease.
This association was true for both men and women, with men in the upper quartile having a 2.2-fold increase in the odds of Barrett's esophagus compared with men in the lower quartile, with the comparable value for women being a 3.8-fold increased risk.
Importantly, these associations remained when the authors adjusted for gastroesophageal reflux disease (GERD), a known risk factor for Barrett's. Although abdominal obesity may contribute to GERD, the authors say this finding suggests that the relationship between waist circumference and the disease must be mediated by other factors too and may be complex.
"Further studies examining the biological mechanisms of this association will extend our knowledge regarding the pathogenesis of Barrett's oesophagus," Kubo and colleagues conclude.
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