RT Journal
A1 Stamos MJ, Nguyen N
T1 SUrveillance bias and postoperative complication rates—reply
JF Archives of Surgery
JO Archives of Surgery
YR 2012
FD February 1
VO 147
IS 2
SP 199
OP 200
DO 10.1001/archsurg.2011.1492
UL http://dx.doi.org/10.1001/archsurg.2011.1492
AB 
We appreciate the comments of Ms Rosenberg and Dr Haut regarding possible selection bias. We acknowledge that this is an inherent limitation of an analysis of any population-based database. We do not have specific data related to the number of duplex ultrasonography tests or computed tomographic scans performed for the 2 groups because this level of information is lacking in the Nationwide Inpatient Sample database; however, we believe that the discovery of deep vein thrombosis and/or a pulmonary embolism, as an incidental finding, as Ms Rosenberg and Dr Haut hypothesize, is not common enough to bias the overall findings to a significant degree. In terms of their comment that “the mean length of hospital stay was significantly longer after open surgery than after laparoscopic surgery (9.5 vs 6.5 days; P < .001), these patients may have been at higher risk of having additional diagnostic testing performed,” although we agree that this is likely a minor variance biasing our findings, it is more likely that this longer length of stay and the decreased ambulation inherent in the recovery after open surgery is in fact a major factor influencing the increased risk of venous thromboembolism.