Response to Letter by Shiue
We appreciate the comments of Shiue on the potential role of cigarette smoking in confounding the association between reflux esophagitis (RE) and subsequent stroke.
Our study was motivated by the lack of empirical epidemiologic documentation on a potential association between RE and cardiovascular diseases hypothesized in the literature. Our study did not attempt to establish a direct cause-effect relation between RE and subsequent stroke, given that it was a retrospective observational study from claims data that lack key variables, including smoking habit. Our purpose was to explore the potential association of these 2 conditions from population-based data to provide pointers for in-depth, conclusive studies. As mentioned in the Discussion section of the article, several shared risk factors could explain the association between RE and stroke. In addition to cigarette smoking, several unfavorable lifestyle factors, including obesity, alcohol consumption, and dietary habits, are recognized to be associated with stroke1 and with RE.2 Notably, several poorly-understood factors, such as genetic background, psychological distress, environmental factors, and autonomic dysregulation, may contribute to this association and need to be studied in future research. Consistent with our discussion of the findings in the original article, we submit that our data provide evidence for a clinically important association between RE and stroke that needs clinician alertness as well as further research. The data are inadequate to examine causality.
Another issue raised regarding the epidemiologic findings on the risk of stroke among cigarette smokers in Taiwan is interesting, further highlighting the need for a purposive epidemiologic survey to clarify this issue, as suggested by Shiue.