We thank the author for his thoughtful comments (1) and for pointing out some inherent flaws with retrospective studies. We made every attempt to present a balanced view (2), but… Click to show full abstract
We thank the author for his thoughtful comments (1) and for pointing out some inherent flaws with retrospective studies. We made every attempt to present a balanced view (2), but there are data that are not captured in the database that we are using, including the ones that the author mentions. However, given the size of the sample, it seems likely that at least some of these variables were evenly distributed. This article is protected by copyright. All rights reserved.
               
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