Uncovered, Partially Covered Double Bare Metal Stents Similar in Patency, Survival

Illustration of the human pancreas.
Researchers compared the clinical outcomes of uncovered and partially covered double bare metal stents for distal malignant biliary obstruction.

Partially covered and uncovered double bare metal stents have comparable stent patency and mortality rates for distal malignant biliary obstruction, but partially covered double bare metal stents have a lower tumor ingrowth rate, according to study findings published in Gastrointestinal Endoscopy.

The multicenter, prospective, randomized controlled trial (ClinicalTrials.gov Identifier: NCT02937246) was conducted between 2016 and 2019 in South Korea. Patients (N=258) with malignant biliary obstruction located below 1 cm of the hilum were randomly assigned to receive an uncovered double bare metal stent (n=128) or partially covered double bare metal stent  (n=130) during endoscopic retrograde cholangiopancreatography. The primary endpoint was the duration of stent patency, defined as the time to biliary reintervention due to stent dysfunction, defined as stent ingrowth, overgrowth, occlusion, or migration.

The uncovered and partially covered double bare metal stent cohorts included 46.1% and 49.2% men; had a mean age of 70.8±12.8 and 71.6±10.9 years; the cause of obstruction was pancreatic cancer among 57.0% and 61.5%; 58.6% and 63.1% had stage IV disease; and 57.0% and 51.5% had not undergone a previous drainage procedure, respectively.

Clinical success occurred among 96.1% of the uncovered double bare metal stent and 96.9% of the partially covered double bare metal stent groups. The mean durations of stent patency were 377.4 and 421.2 days (hazard ratio [HR], 1.194; 95% CI, 0.797-1.787; P =.390), respectively.

Early stent dysfunction within 2 weeks of placement occurred in 2 uncovered double bare metal stent recipients due to tumor ingrowth and 3 partially covered double bare metal stent recipients due to sludge. Late dysfunction, after 2 weeks, occurred among 36.2% and 33.9% of the uncovered double bare metal stent and partially covered double bare metal stent cohorts (P =.793), respectively. The most common causes of late dysfunction were tumor ingrowth and sludge or food debris, respectively.

No group differences were observed for the rate of any adverse events or clinical outcomes among patients who had technical success, except that more patients who received uncovered double bare metal stents had tumor ingrowth (24.4%) compared with the partially covered double bare metal stent recipients (13.4%; P =.037).

In the univariate and multivariate analyses, no predictors for stent dysfunction were observed among patients who had technical success.

As of July 2021, the mortality rate was 82.7% in the uncovered double bare metal stent and 87.5% in the partially covered double bare metal stent groups. Mortality risk was associated with chemotherapy after stent placement compared with no chemotherapy (HR, 0.572; 95% CI, 0.409-0.799; P =.001) and nonmetastatic cancer compared with metastatic cancer (HR, 0.575; 95% CI, 0.428-0.772; P <.001).

Study limitations include an inability to generalize the findings, as double bare metal stents are not available in all countries; no comparison between the stent patency of double bare stents with single layer self-expandable metal stents of other manufacturers; and the insufficient statistical power of the study.

“The current study demonstrated no significant differences in the 6-month stent patency rates and mortality between PCDBS [partially covered double bare metal stents] and UCDBS [uncovered double bare metal stents] for distal MBO [malignant biliary obstruction],” the study authors wrote. “However, PCDBS [partially covered double bare metal stents] resulted in decreased stent ingrowth rates.”

Reference

Park SW, Lee KJ, Chung MJ, et al. Covered versus uncovered double bare self-expandable metal stent for palliation of unresectable. Gastrointest Endosc. Published online September 6, 2022. doi:10.1016/j.gie.2022.08.041