Pancreatic stents (PS) should not be left in situ for more than 7 to 10 days during endoscopic retrograde cholangiopancreatography

Reference: Hill, S.K., C. Bhalla, and A. Thomson, Risk of bacterial colonization of pancreatic stents used in endoscopic retrograde cholangiopancreatography. J Clin Gastroenterol, 2012. 46(4): p. 324-7.

Brief Summary: Pancreatic stents (PS) are often used during endoscopic retrograde choloangiopancreatography to reduce the risk of pancreatitis.  However, if left in situ for more than 2 weeks, there is evidence that they may lead to pancreatic duct injury via micro-organism colonization.  The main objective of this study was to investigate the incidence of pancreatic stent colonization and study the relationship between the pancreatic stent colonization with type, length, duration and time the PS remained situ.   The authors were able to obtain 47 pancreatic stents in situ, and these stents were then sent away for microbial culture where the pancreatic stents were then classified as being either significant or insignificant based on their microscopic colonization.  The cultures were classified as being insignificant if there was no growth of pathological organisms with clinical significance. 

Results: Pancreatic stents left in situ for more than 10 days were found to have a 3.3 times greater risk of harmful microscopic colonization compared to just 2 days.  There was no significant relationship found based on type or length of pancreatic stent. 

Implications for Practice: Current recommendations suggest that pancreatic stents remain in place for no more than 14 days. However, this study shows that the Pancreatic Stents should not remain in place for more than 10 days.  More generally, the Pancreatic Stents should be removed as soon as their preventive value for post-ERCP pancreatitis is exhausted. 

Discussion: Studies like this which detail and optimize best practices are important and more should be done.  It would be interesting to find out why 10 days seemed to be the cutoff point.  This probably has to do with the rate of colonization of the bacteria, and there are probably some interesting follow up studies to elucidate this.

Brief Commentary on Statistics and Study Design:  The overall study design and statistical approach seemed to be good.  A multi-variate logistic regression model was fitted which is the correct statistical model to use for this.  It would appear as if the predictor variables in the model were duration and length of the Pancreatic Stent, and all other variables were thrown out of the logistic regression model due to their non-significance with the outcome variable.  The authors did say that the other variables (age, gender, indication, or diagnosis) had no significant correlation with bacterial colonization, and this was harmful.

I am curious as to why there were no power calculations done.  I assume that 47 samples would be ample though.