Plastic or metal stents for malignant stricture of the common bile duct? Results of a randomized prospective study. A randomized trial of endoscopic drainage methods for inoperable malignant strictures of the common bile duct. Endoscopic biliary endoprosthesis in the palliation of malignant obstruction of the distal common bile duct: a randomized trial. Hydrophilic hydromer-coated polyurethane stents versus uncoated stents in malignant biliary obstruction: a randomized trial. A prospective randomised multicentre trial comparing 10 Fr Teflon Tannenbaum stents with 10 Fr polyethylene Cotton-Leung stents in patients with malignant common duct strictures. A prospective, randomized, controlled trial of metal stents for malignant obstruction of the common bile duct. A prospective randomized study of hydrophilic polymer-coated polyurethane versus polyethylene stents in distal malignant biliary obstruction. A prospective randomized trial of Teflon versus polyethylene stents for distal malignant biliary obstruction. Prospective, randomized, single-center trial comparing 3 different 10F plastic stents in malignant mid and distal bile duct strictures. [Randomized prospective study to compare the efficiency between standard plastic and polyurethane stents in biliary tract malignant obstruction]. Covered metal versus plastic stents for malignant common bile duct stenosis: a prospective, randomized, controlled trial. Randomised trial of self-expanding metal stents versus polyethylene stents for distal malignant biliary obstruction. "Tannenbaum" Teflon stents versus traditional polyethylene stents for treatment of malignant biliary stricture. Randomised trial of endoscopic stenting versus surgical bypass in malignant low bileduct obstruction. A prospective, randomized multicenter trial comparing DoubleLayer and polyethylene stents for malignant distal common bile duct strictures. Randomised trial of endoscopic endoprosthesis versus operative bypass in malignant obstructive jaundice. Uncovered Hanaro Versus Luminex metal stents for palliation of malignant biliary strictures. Multicenter randomized trial of the spiral Z-stent compared with the Wallstent for malignant biliary obstruction. A prospective randomised study of "covered" versus "uncovered" diamond stents for the management of distal malignant biliary obstruction. Tannenbaum and metal stents in the palliative treatment of malignant distal bile duct obstruction: a comparative study of patency and cost effectiveness. Prospective randomized trial comparing Tannenbaum Teflon and standard polyethylene stents in distal malignant biliary stenosis.
The systematic use of metal stents to treat biliary obstruction is restricted by high cost compared with plastic stents. The aims of this study were to compare cost and efficacy of plastic stents and metal stents in the treatment of patients with malignant common bile duct strictures and to define factors that predict survival of these patients.
                One hundred eighteen patients (mean age 75 years) with malignant strictures of the common bile duct were randomized to placement of a plastic stent or metal stent. Comparisons were made with the Mann-Whitney or chi-square test as indicated; survival rates were compared with a Cox proportional hazards model.
                There was no significant difference in survival between the two groups. Time to first obstruction was longer for patients in the metal stent group (metal stent, median not reached vs. plastic stent, 5 months; p = 0.007). The number of additional days of hospitalization, days of antibiotic therapy, and the numbers of ERCPs and transabdominal US procedures was significantly higher in the plastic stent group. After multivariate analysis, only the presence of liver metastases was independently related to survival (p < 0.0005; OR = 2.25). This variable defined a group with a shorter survival. Median survival of patients with hepatic metastasis at diagnosis was 2.7 months compared with 5.3 months for patients without liver metastasis; in the latter group, the overall cost associated with metal stents was lower than for plastic stents.
                Metal stent placement is the most effective treatment of inoperable malignant common bile duct stricture. Placement of a metal stent is cost effective in patients without hepatic metastases, whereas a plastic stent should be placed in patients with spread of the tumor to the liver. Although metallic stents remain patent longer than plastic stents, the optimal palliation of inoperable malignant biliary strictures remains controversial because of the high cost of metallic stents and short patient survival.
                A total of 101 patients (mean age 72.5+/-12.9 years) with malignant strictures of the common bile duct were included in this study, after three exclusions for technical failure (n = 3) and one for noncompliance with study design. The etiology of the strictures included pancreatic cancer (65), cholangiocarcinoma (21), ampullary tumor (3), and metastatic lymph nodes (12). Patients were randomized to receive either an 11.5F polyethylene stent to be exchanged in case of dysfunction (group 1, n = 33), an 11.5F stent to be exchanged every 3 months (group 2, n = 34), or a self-expanding metallic Wallstent (group 3, n = 34).
                Endoscopic procedures were successful (including complete relief of jaundice) in 97.1 % of cases. Procedure-related morbidity was 11.9%, and mortality was 2.9%. Bilirubinemia after 48 hours (37.2%+/-21.7% decrease from the preoperative level) did not differ between groups. Patients were followed for a mean of 166 days (median 143, range 0 to 596 days). Overall survivals were not different between groups, but complication-free survival for groups 2 and 3 was longer than that of group 1 (p < 0.05). Cumulated hospital days were 7.4+/-1.5, 10.6+/-1.7, and 5.5+/-1.4 (groups 1, 2, and 3, respectively) (p < 0.05; analysis of variance). Cost analysis showed that metallic stents were advantageous in patients surviving more than 6 months, whereas a plastic stent was advantageous in patients surviving 6 months or less.
                Metallic stents and plastic stents exchanged every 3 months are valuable alternatives for increasing complication-free survival in patients with malignant strictures of the common bile duct. Metal stents are advantageous in patients with the longest life expectancy. A total of 52 jaundiced elderly patients who had malignant obstruction of the distal common bile duct and who required palliative biliary decompression were randomized to receive either an endoscopically placed biliary endoprosthesis (10 French gauge) or conventional surgical bypass. Patients within the two treatment groups were well matched and 51 were followed until their death. Patients treated with endoprosthesis had a significantly shorter initial hospital stay than those treated surgically. In the long term, overall survival in the two groups was similar and jaundice was relieved in over 90 per cent of patients. Despite more re-admissions to hospital for those patients treated endoscopically, the total time spent in hospital still remained significantly shorter in this treatment group compared with those subjected to surgery. The endoscopically placed biliary endoprosthesis is a valuable alternative to conventional surgical bypass in the palliation of extrahepatic biliary obstruction. Hydromer-coated polyurethane stents (HCPS) have a low coefficient of friction that may reduce sludge formation and potentially increase stent longevity.
                Eighty-three patients (39 men, mean age 69.3 years) with malignant mid or distal bile duct strictures were prospectively randomized to receive either 10F HCPS (n = 40) or standard polyethylene stents (n = 43).
                Fifteen patients (18.1%) underwent surgery after stent insertion. Six patients were lost to follow-up (7.2%), whereas 34 died of the underlying disease without evidence of stent occlusion (15 HCPS group and 19 polyethylene group). Median survival was 75 days (range 15 to 372 days) and 108 days (range 25 to 325 days) in the HCPS and polyethylene stent groups, respectively (p = not significant). Stent occlusion was observed in 25 patients (42%), 16 with HCPS stents and 9 with polyethylene stents, with a median patency of 103 days (range 40 to 280 days) and 68 days (range 32 to 175 days), respectively (p = not significant).
                HCPS do not appear to provide significant clinical advantages in terms of stent longevity over standard plastic prostheses. Stent blockage is a multifactorial process in which stent design and materials, bacteria, proteins, and bile viscosity play a role.
                To compare the patency of the 10 Fr Teflon Tannenbaum (TT) stent to that of the 10 Fr Cotton-Leung (CL) polyethylene stent with sideholes, in patients with malignant obstructive jaundice.
                Patients were recruited to this prospective multicentre randomised study if they had a newly diagnosed malignant bile duct stricture below the hilum of the liver suitable for stenting with a 10 Fr stent. Data were collected and monitored by a professional monitoring company. Primary patency was the interval between stent placement and first exchange or death without recurrent jaundice.
                134 consecutive patients were recruited between November 1994 and June 1997; 65 were randomised to the TT stent and 69 to the CL stent. Median patency and 95% confidence intervals were 181 (59, 303) days for the TT stent and 133 (92, 174) days for the CL stent, with no significant difference between the two stents (p=0.49). Median survival and 95% confidence intervals were 115 (71, 159) days for the TT stent and 151 (112, 190) days for the CL stent, with no significant difference between the two stents (p=0.765).
                Neither Teflon as a stent material nor the Tannenbaum design prolong the patency of plastic stents. Endoscopic insertion of biliary stents is the preferred method of palliation for inoperable malignant biliary obstruction; however, migration and clogging are frequent problems with conventional endoprostheses. We sought to determine if expandable metal stents offer improved palliation compared to conventional stents. Sixty-two patients with common bile duct lesions were randomized to receive polyethylene or metal stents. Stents were placed endoscopically or by the combined percutaneous-endoscopic route. Early results (< 1 month) were similar in both groups. Long-term follow-up (n = 28 polyethylene, median: 5 months; n = 27 metal, median: 5 months) showed a higher stent failure rate in the polyethylene (n = 12; 43%) compared to the metal group (n = 6; 22%). The incidence of cholangitis was significantly higher (p < 0.05) in the polyethylene (n = 10; 36%) compared to the metal group (n = 4; 15%). Life-table analysis showed a significantly reduced incidence of stent failure (p = 0.0035) in the metal stent compared to the polyethylene group. The total duration of hospital stay for treatment of stent related problems was significantly higher in the polyethylene (11.8 +/- 3 days) compared to the metal group (4 +/- 1.9 days; p = 0.02). The costs for retreatment because of stent failure were significantly higher in the plastic (DM 5900 +/- 1516) compared to the metal group (DM 2070 +/- 977). As a result, the overall costs (treatment of stent related complications & stents) were higher in the polyethylene group (DM 6000 +/- 1500).(ABSTRACT TRUNCATED AT 250 WORDS) Hydrophilic polymer-coated polyurethane (HPCP) stents have a low friction coefficient and a hydrophilic layer, which may reduce biofilm formation and increase the period of stent patency. We compared the patency rates with this new stent with the standard Amsterdam-type polyethylene (PE) stent in a prospective randomized trial.
                One hundred patients with an unresectable distal malignant bile duct stricture without a previous drainage procedure were randomly assigned to receive either a HPCP stent or a PE stent. The diameter (10 Fr), length (9 cm) and stent design (Amsterdam type) were similar in both stents. Nine patients were excluded. Forty-four patients received an HPCP stent and 47 patients a PE stent. The diagnoses included carcinoma of the pancreas (n = 78), papilla (n = 1), bile duct (n = 10), and metastases (n = 2).
                Stent insertion was successful in all patients. Stent dysfunction occurred in 27 of the HPCP stents and 20 of the PE stents, with median stent patency periods of 77 days (95 % CI, 53-101 days) for HPCP stents and 105 days (95 % CI, 42-168 days) for PE stents. The patency period was significantly longer for the PE stent (P = 0.04). Early complications occurred in four patients (4%), one in the HPCP group and three in the PE group.
                Hydrophilic polymer-coated polyurethane stents do not prolong the patency period of biliary stents. In fact, the current standard treatment using polyethylene stents in patients with distal malignant biliary obstruction showed a significantly longer patency period. Clogging of biliary stents continues to be a major clinical problem. Different polymer materials may have different effects on clogging. In vitro studies have shown a direct relation between the frictional coefficient of a polymer and the amount of encrusted material. Teflon appeared to be the best polymer for biliary stents. Two different types of stents made of Teflon have been tested in clinical practice and showed favourable patency rates. However, a randomized trial has never been performed. We compared the patency of an Amsterdam-type polyethylene stent with a Teflon stent in a prospective randomized trial.
                Between September 1995 and November 1996, 42 patients received a Teflon stent and 42 patients a polyethylene stent. All patients had a distal malignant biliary stricture without a previous drainage procedure. Diagnoses included carcinoma of the pancreas (n = 76), papilla (n = 1), bile duct (n = 5) and metastases (n = 2). The internal and external diameter (10 Fr), length (9 cm) and stent design (a straight stent with two side flaps and one side hole at each end) were similar for both stents.
                A reduction in bilirubin of more than 20% within one week was seen in 91% of the patients. Early complication rates were similar in both groups (10%). The median follow-up was 142 days. Stent dysfunction occurred in 28 Teflon and 29 polyethylene stents. The thirty-day mortality was 14% in both groups. Patient survival did not differ significantly between the groups (median survival: Teflon 165 days, polyethylene 140 days). The median stent patency was 83 days for Teflon and 80 days for polyethylene stents, and was not significantly different either.
                Teflon material did not improve patency in biliary stents with an Amsterdam-type design. The aim of this study was to determine whether patency rates differ with respect to the material, design, and surface texture of 3 different plastic stents.
                A total of 120 patients (median age 70.5 years; interquartile range 62-78 years) with malignant mid or distal bile duct strictures, seen between March 1996 and May 1999, were prospectively randomized to receive a 10F polyurethane stent, a Teflon Tannenbaum stent, or a hydrophilic hydromer-coated polyurethane stent. The primary study outcome measure was the interval between stent insertion and the first episode of clogging (or the presence of jaundice at death without stent exchange). All 3 types of stent were studied by scanning electron microscopy before insertion.
                A total of 19 patients were excluded from long-term follow-up. Median duration of stent patency was 76 days overall (interquartile range 29-150 days) and 76 (interquartile range 30-110) days for hydrophilic hydromer-coated polyurethane, 108 (interquartile range 33-186) days for 10F polyurethane, and 58 (interquartile range 21-188) days for Teflon Tannenbaum stents. There were no statistically significant differences among stent types. The hydrophilic hydromer-coated stent had the smoothest surface, as visualized by scanning electron microscopy.
                No significant differences in the patency of 3 types of stents were detected in this randomized trial. In particular, the hydrophilic hydromer-coated plastic stent did not provide clinical advantages despite its smooth surface. The aim of this paper is to compare the efficiency between standard plastic stents and polyurethane stents used in biliary tract malignant obstruction. The main problem of the plastic prosthesis is their early occlusion. On the other hand there is the hypothesis that due to the less porousness of the polyurethane surface, there might be lesser adherence and consequently a late occlusion. Thirty-eight patients in two groups of 19 were evaluated prospectively and at random in the Jerusalem Hadassah Hospital and the HIGA San Martín La Plata. They had biliary tract obstruction due to inoperable tumors. Biliary endoprosthesis (plastic standard or polyurethane 10 French diameter) were placed, according to the randomization, after a previous staging with clinical examination, laboratory analysis and images. The follow-up with the same parameters was monthly done. Twelve of the 38 patients were female and 26 male; age average 62.73 (range 81-49). The stents were placed in 17 patients with biliary cancer, 14 pancreatic cancer, 2 papila cancer, 2 gallbladder cancer with bile duct invasion and 3 liver metastasis with biliary tract compression. The clinical and laboratory parameters in 36 patients at 30 days improved. On the contrary, 2 (1 plastic standard and 1 polyurethane stent) did not improve. There were 29 deaths due to the basic illness and not related to the endoscopic method. The mean obstruction occurred at 12.76 weeks (range 32-4) in the standard stents and 12.05 (range 24-2) in the polyurethane ones.
                There were no significant differences in the two groups patients. Most patients with malignant common bile duct strictures are suited only for palliation of jaundice by placement of a polyethylene (PE) stent using an endoscopic retrograde cholangiographic technique. Occlusion of these stents occurs after 3 to 4 months, whereas uncovered self-expanding metal stents (SEMS) remain open twice as long. The initial higher cost of the latter might be balanced by a decreased need for repeat intervention.
                To compare the patency of 10F PE stents and covered 30F steel SEMS (Wallstent; Boston Scientific Nordic AB, Helsingborg, Sweden).
                Single-center, prospective, randomized, controlled trial.
                General hospital in Stockholm, Sweden, which has a catchment area of 0.6 million people.
                Non-referred, unresectable malignant common bile duct strictures.
                Endoscopic retrograde cholangiography with plastic stents or covered SEMS.
                Time to stent failure, requiring a new stent.
                Similar setting and patients, and costs in Scandinavia.
                Fifty-one and 49 patients were allocated to the PE stent and SEMS groups, respectively. Fifty-six patients died without stent failure within 10 months (median, 2.6 months). Twenty-two PE stent and 9 SEMS patients (P = .009) developed failure after a median of 1.1 and 3.5 months, respectively (P = .007). Median patency times were 1.8 and 3.6 months in the PE and SEMS groups, respectively (P = .002). Median survival was 4.5 months; in 35 patients with distant metastases, the median survival was 2.5 months (P = .002)(PE group, 1.9 months).
                The more-effective SEMS are recommended in unresectable patients with malignant common bile duct strictures, who survive a median of 4.5 months. Less costly plastic stents are preferable in the one third of patients who have distant metastases. In our study, the cost was equal. Self-expanding metal stents are claimed to prolong biliary-stent patency, although no formal comparative trial between plastic and expandable stents has been done. In a prospective randomised trial, we assigned 105 patients with irresectable distal bile-duct malignancy to receive either a metal stent (49) or a straight polyethylene stent (56). Median patency of the first stent was significantly prolonged in patients with a metal stent compared with those with a polyethylene stent (273 vs 126 days; p = 0.006). The major cause of stent dysfunction was tumour ingrowth in the metal-stent group and sludge deposition in the polyethylene-stent group. Treatment after any occlusion included placement of a polyethylene stent. In the metal-stent group none of 14 second stents occluded, whereas 11 of 23 (48%) second stents clogged in the polyethylene-stent group (p = 0.002). Overall median survival was 149 days and did not differ significantly between treatment groups. Incremental cost-effectiveness analysis showed that initial placement of a metal stent results in a 28% decrease of endoscopic procedures. Self-expanding metal stents have a longer patency than polyethylene stents and offer adequate palliation in patients with irresectable malignant distal bile-duct obstruction. Premature stent clogging is the major limitation with plastic stents used in the treatment of malignant biliary structures. A pilot study suggested improved duration of patency of the Tannenbaum stent compared with polyethylene stents. The aim of this prospective, multicenter randomized trial was to compare the Tannenbaum Teflon stent with a conventional polyethylene endoprosthesis (Cotton-Leung biliary stent set) for the treatment of malignant biliary strictures.
                Patients over age 18 years with symptoms caused by nonhilar malignant biliary strictures were enrolled. Patients were randomized to receive a 10F Tannenbaum or polyethylene stent after a guidewire was passed beyond the stricture. One hundred six patients (mean age 72 years and 71 years, respectively) were enrolled (54 Tannenbaum, mean age 72 years; 52 polyethylene, mean age 71 years).
                Tannenbaum and polyethylene stent placement was successful in, respectively, 100% and 96% of procedures without complications. The mean (SD) 90-day stent patency of the Tannenbaum stent was 67% (7%) compared with 73% (7%) for the polyethylene stents.
                The present study demonstrated no difference in ease of implantation or stent patency between Tannenbaum and polyethylene stents. The development of non-surgical techniques for the relief of malignant low bileduct obstruction has cast doubt on the best way of relieving jaundice, particularly in patients fit for surgery whose life expectancy is more than a few weeks. We did a randomised prospective controlled trial comparing endoscopic stent insertion and surgical biliary bypass in patients with malignant low bileduct obstruction. 204 patients were randomised (surgery 103, stent 101); 3 subsequently proved to have benign disease and were excluded, leaving 101 surgical and 100 stented patients for assessment. Technical success was achieved in 94 surgical and 95 stented patients, with functional biliary decompression obtained in 92 patients in both groups. In stented patients, there was a lower procedure-related mortality (3% vs 14%, p = 0.01), major complication rate (11% vs 29%, p = 0.02), and median total hospital stay (20 vs 26 days, p = 0.001). Recurrent jaundice occurred in 36 stented patients and 2 surgical patients. Late gastric outlet obstruction occurred in 17% of stented patients and 7% of the surgical group. Despite the early benefits of stenting there was no significant difference in overall survival between the two groups (median survival: surgical 26 weeks; stented 21 weeks; p = 0.065). Endoscopic stenting and surgery are effective palliative treatments with the former having fewer early treatment-related complications and the latter fewer late complications. Endoscopic biliary stenting is an established treatment for malignant obstructive jaundice. Stent clogging continues to be a major problem with plastic stents. The aim of this study was to carry out a prospective comparison of two stents with different materials and shapes: the Olympus DoubleLayer stent (DLS; perfluoro alkoxy, without sideholes) and the standard polyethylene (PE) stent (with sideholes).
                A total of 120 patients (70 women; mean age 71, range 36 - 91) with jaundice due to malignant strictures of the middle to distal third of the common bile duct were randomly assigned to receive either DLS (n = 60) or PE (n = 60) biliary stents. Patients with cholangitis, hemobilia, previous biliary drainage, hilar stricture, or ampullary cancer were excluded.
                In all, 28 DLS patients (47 %) and 17 PE stent patients (29 %) died without clinical evidence of stent occlusion after a mean of 114 and 105 days, respectively ( P < 0.05). Twenty-six DLS patients (43 %) and 38 PE stent patients (63 %) had symptoms of stent clogging after a mean of 144 and 99 days, respectively ( P < 0.05). Stent dysfunction (stent orifice impacted on the bile duct or duodenal wall, stent migration) was recorded in six DLS patients (10 %) and five PE patients (8 %) (n. s.). Kaplan-Meier analysis of DLS and PE stent clogging-free survival showed a significantly longer patency period with the DLS stents (P = 0.0005).
                These results show that DoubleLayer stents have a longer patency period than PE stents. Patients who received PE stents had a higher risk of stent occlusion (relative risk 3.05; 95 % CI, 1.57 - 5.89) before death than DLS patients. In patients with obstructive jaundice caused by malignant stricture of the extrahepatic bile duct we compared survival time, complication rates, hospitalisation requirements, and quality of life after palliation by endoscopic endoprosthesis or bypass surgery. During diagnostic endoscopic cholangiography 50 patients were randomised to the two treatment alternatives. All 25 patients randomised to endoprosthesis were treated by this procedure, whereas only 19 of 25 patients randomised to bypass surgery underwent operative biliary-digestive anastomosis. Life table analysis revealed no difference in survival between treatment groups or randomisation groups. No differences were found when other variables were compared. We conclude, that palliation of obstructive jaundice in malignant bile duct obstruction with endoscopically introduced endoprosthesis is as effective as operative bypass. Endoscopic stent insertion is the optimum method of palliation for malignant biliary obstruction. Various types of self-expanding metal stents have been introduced in the market. Whether one type of stents is superior to the others in terms of stent patency remains undefined.
                This randomized trial compared 2 uncovered metal stents with similar technical characteristics, but significant cost difference, in the palliation of inoperable malignant biliary strictures.
                Ninety-two patients with inoperable biliary obstruction were randomized to receive either a 10-mm diameter Hanaro or Luminex uncovered metal stent. The duration of stent patency, the overall patient survival, the mechanism of stent occlusion, and the adverse events were analyzed.
                Eighty-nine patients were included in the analysis; 44 received Hanaro stents and 45 Luminex stents. The overall median patency rates between the 2 stents did not differ (328 d for the Hanaro vs. 289 d for the Luminex stent; P=0.815). Similarly, no difference was found between the overall median survival rates by the 2 stents (347 d for the Hanaro vs. 307 d for the Luminex stent; P=0.654). Two major procedure-related complications occurred, perforation (Hanaro stent) and proximal stent migration (Luminex stent). Stent occlusion requiring reintervention occurred in 25 patients (11 with the Hanaro vs. 14 with the Luminex stent; P=0.521).
                The 2 uncovered metal stents are comparable in terms of placement, occlusion rates, overall stent patency, and patient survival; Hanaro stent insertion, however, seems to be a cost-saving strategy at least in Greece. The industry standard since 1990 for self-expanding biliary metallic stents has been the Wallstent. In 1998 the Spiral Z-stent was released. This randomized trial compared the Z-stent with the Wallstent in the treatment of malignant biliary obstruction.
                Patients with unresectable malignant biliary obstruction distal to the bile duct bifurcation were randomized to receive a 10-mm diameter Wallstent or a 10-mm diameter Z-stent.
                A total of 145 patients were randomized; 13 were excluded. Sixty-four patients who received a Z-stent and 68 who had a Wallstent are included in the analysis. Tumors responsible for bile duct obstruction were pancreatic cancer (108), cholangiocarcinoma (15), metastatic cancer (6), and papillary cancer (3). Metallic stents were successfully placed in all patients. Seven technical problems were encountered during placement of the Z-stent and 5 with the Wallstent. There were 21 occlusions requiring reintervention (8 Z-stent, 13 Wallstent; p = 0.30). Median time to reintervention was the following: Z-stent, 162 days; Wallstent, 150 days (p = 0.22). A total of 104 patients died of progressive disease or other cause; 7 patients remain alive with patent stents. The overall calculated median patency rates were: Z-stent, 152 days; Wallstent, 154 days (p = 0.90).
                The Spiral Z-stent is comparable with the Wallstent in terms of placement, occlusion rates, and overall patency. Occasional early occlusion of both stents suggests tumor characteristics instead of the size of the mesh openings in the stents as important factors. Covered self-expandable metal stents (EMS) were recently developed to overcome tumour ingrowth in conventional EMS. However, supporting evidence for the efficacy of covered EMS is lacking.
                We enrolled 112 patients with unresectable distal biliary malignancies. They were randomly assigned to polyurethane covered (n = 57) or original diamond stent (n = 55).
                Stent occlusion occurred in eight patients (14%) after a mean of 304 days in the covered group, and in 21 patients (38%) after a mean of 166 days in the uncovered group. The incidence of covered EMS occlusion was significantly lower than that of uncovered EMS (p = 0.0032). The cumulative stent patency of covered stents was significantly higher than that of uncovered stents (p = 0.0066). No tumour ingrowth occurred in the covered group while it was observed in 15 patients in the uncovered group. In subgroup analysis, the cumulative patency of the covered EMS was significantly higher in pancreatic cancer (p = 0.0363) and metastatic lymph nodes (p = 0.0354). There was no significant difference in survival between the two groups. Acute cholecystitis was observed in two of the covered group and in none of the uncovered group. Mild pancreatitis occurred in five of the covered group and in one of the uncovered group.
                Covered diamond stents successfully prevented tumour ingrowth and were significantly superior to uncovered stents for the treatment of patients with distal malignant biliary obstruction. However, careful attention must be paid to complications specific to covered self-expandable metal stents, such as acute cholecystitis and pancreatitis. Stent clogging is the major limitation of palliative treatment for malignant biliary obstruction. Metal stents have much better patency than plastic stents, but are more expensive. Preliminary data suggest that the recently designed plastic (Tannenbaum) stent has better duration of patency than the polyethylene stent. This study aimed to compare the efficacy and cost effectiveness between the Tannenbaum stent without side holes and the uncovered metal stent for patients with malignant distal common bile duct obstruction.
                In this study, 47 patients (median age, 73 years, range, 56-86 years) with inoperable malignant distal common bile duct strictures were prospectively randomized to receive either a Tannenbaum stent (n = 24) or an uncovered self-expandable metal stent (n = 23). The patients were clinically evaluated, and biochemical tests were analyzed if necessary until their death or surgery for gastric outlet obstruction. Cumulative first stent patency and patient survival were compared between the two groups. Cost-effectiveness analysis also was performed for the two study groups.
                The two groups were comparable in terms of age, gender, and diagnosis. The median first stent patency was longer in the metal group than in the Tannenbaum stent group (255 vs 123.5 days; p = 0.002). There was no significant difference in survival between the two groups. The total cost associated with the Tannenbaum stents was lower than for the metal stents (17,700 vs 30,100 euros; p = 0.001), especially for patients with liver metastases (3,000 vs 6,900 euros; p < 0.001).
                Metal stent placement is an effective treatment for inoperable malignant distal common bile duct obstruction, but Tannenbaum stent placement is a cost-saving strategy, as compared with metal stent placement, especially for patients with liver metastases and expected short survival time. Our aim was to compare the clinical efficacy of the Tannenbaum (TB) biliary prostheses, a recently designed Teflon stent without side holes, with the Cotton-Huibregtse (CH) polyethylene stent.
                Fifty-seven patients (26 men, mean age 75.5 years) with unresectable malignant tumors and distal biliary stenosis were included (38 pancreatic head cancer, 17 cholangiocarcinoma, 2 ampullary cancer). Patients were prospectively randomized to have a 10F, 7 cm long TB (29 patients) or CH (28 patients) stent inserted endoscopically. Four patients (2 TB and 2 CH) were excluded: 3 because of the failure of stent insertion and 1 because of a protocol violation. The patients were evaluated clinically and, if necessary, with biochemical tests every month until death or until they needed surgery for symptoms of gastric outlet obstruction. When occlusion or dislocation occurred, the stent was replaced with one of the same type. Cumulative stent patency and patient survival were estimated with the Kaplan-Meier life-table analysis and compared by log-rank chi-square test.
                The two groups were comparable in mean age, gender, and diagnosis. The patients were followed for a mean of 145.5 days (range 24 to 613); by the end of the study 47 patients (81%) had died or developed symptoms of gastric outlet obstruction. Median survival was 88 days (range 24 to 613) in the TB group and 75.6 days (23 to 486) in the CH group. Stent exchange (occlusion 16, dislocation 3) was necessary for 5 patients in the TB group and 7 in the CH group. No statistical difference was found on comparing the mean duration of function of the first, second, and third stents (analysis of variance, p = 0.80). The median duration of stent function was 96 days (range 11 to 613) in the TB group and 75.5 days (range 23 to 323) in the CH group. No significant difference was found in either survival time (p = 0.48) or stent patency (p = 0.12).
                This study found no significant advantage of the Tannenbaum prostheses over the standard polyethylene stent in the palliation for patients with distal malignant biliary stenosis with regard to survival or length of stent patency.
Endoscopic metal stents are the intervention of choice at present in patients with malignant distal obstructive jaundice due to pancreatic carcinoma. In patients with short predicted survival, their patency benefits over plastic stents may not be realised. Further RCTs are needed to determine the optimal stent type for these patients.