When treating choledocholithiasis, a shorter duration of endoscopic papillary balloon dilation increases, rather than decreases, the risk of postprocedure pancreatitis, reported Dr. Wei-Chih Liao and his colleagues in Clinical Gastroenterology and Hepatology.
"This meta-analysis contradicts the common belief that pancreatitis results from direct pancreatic duct compression during balloon dilation, and thus dilation duration should be short," he and his colleagues wrote. On the contrary, "[endoscopic papillary balloon dilation] with an adequate duration (around 5 minutes) has lower complication rates than the current standard of endoscopic sphincterotomy, and may be used as the first-line treatment for bile duct stones."
Dr. Liao, of the National Taiwan University College of Medicine, Taipei, conducted a systematic review of Medline, the Cochrane databases, and clinicaltrials.gov to identify randomized controlled trials of endoscopic papillary balloon dilation (EPBD), endoscopic sphincteroplasty, endoscopic balloon sphincter dilation, and endoscopic balloon dilation. Studies were excluded if dilation duration was not clearly reported.
Overall, 12 studies were included in the analysis: 11 compared EPBD with endoscopic sphincterotomy (EST); 4 compared short-duration EPBD (1 minute or less) with EST; and 7 looked at long-duration EPBD (more than 1 minute) versus EST.
Only one study compared long-duration EPBD with short-duration EPBD, they wrote (Clin. Gastroenterol. Hepatol. 2012 [doi: 10.1016/j.cgh.2012.05.017]).
First, the authors looked at the risk of pancreatitis when comparing EST to short-duration EPBD. They found that the latter had a significantly higher pancreatitis risk, with a pooled odds ratio of 3.87 for developing pancreatitis post procedure, compared with EST (95% confidence interval, 1.08-13.84).
However, long-duration EPBD did not pose a significantly higher risk compared with EST (OR, 1.14; 95% CI, 0.56-2.35).
Similarly, looking at overall complications, the researchers noted a trend toward a higher overall complication rate in short-duration EPBD compared with EST (OR, 1.71; 95% CI, 0.67-4.35). "By contrast, long EPBD seemed to have a lower overall complication rate (pooled OR, 0.61; 95% CI, 0.36-1.04)," wrote the authors.
The researchers also calculated the regression coefficient of dilation duration, and found it to be –0.69, "meaning that every 1-minute increase in dilation duration up to 3 minutes was associated with a 49.8% (95% CI, –9.4% –77.0%) reduction in OR," they wrote.
The finding was similar for overall complications, with every 1-minute increase in dilation duration up to 5 minutes associated with a 45.1% reduction in OR.
In an attempt to explain the findings, Dr. Liao noted that recent evidence suggests that EPBD with dilation duration of 1 minute or less "carries a higher risk of inadequate sphincter loosening, which increases the risks of pancreatitis and failed stone extraction."
"An inadequately loosened sphincter from short-duration EPBD may limit volume expansion of its encircled contents as in a compartment syndrome, thus [worsening] compression of the pancreatic duct from post-EPBD edema and [increasing] pancreatitis risk."
The researchers added that the longest reported EPBD duration is 5 minutes.
"It is unknown whether dilation duration longer than 5 minutes may further reduce pancreatitis risk, but the degree of sphincter loosening can only increase to a certain point. ... Further studies on EPBD with different durations will be helpful to corroborate our findings and determine the optimal duration."
The study was funded by grants from the Royal Society, London; the National Science Council, Taiwan; and the National Taiwan University Hospital, Taipei. The authors stated that they had no individual conflicts to disclose.