Reply to Dr. Mosca

We read Dr. Mosca’s comments with interest, and would reply as follows. We agree that there may have been a selection bias due to the prospective nature of data collection in the Diamond stent group, compared with the retrospective review in the Wallstent group. This limitation of the study was detailed in the text.

The difference in the number of patients with a prior plastic stent between the two groups was not significant, so it is unclear whether the Diamond stent group may have had disease more likely to lead to metal stent occlusion. In addition, there was no significant difference between the two groups in the choice of a metal stent at the index endoscopic retrograde cholangiopancreatography; hence, no reliable conclusions can be drawn as to whether the Wallstent cohort had a longer stent patency as a result.

In case of stent occlusion, our policy was either to place another metal stent through the first, place a plastic stent, or send the patient for percutaneous drainage. This did not differ in relation to the type of metal stent used.

There was no significant duodenal stenosis in either group, so locally advanced disease precluding stent placement was not an issue. The difference in the follow-up time is a reflection of the non-concurrent nature of the study, as the Wallstent patients were treated 1-2 years before the Diamond stent group. We agree that there was a selection bias in the Diamond stent group with regard to the age of the patients, and this is stated in the paper. We cannot comment on the reasons for the withdrawal of the Diamond stent in the United States, as these are not in the public domain.

In summary, we echo Dr. Mosca’s comments that the occlusion rate and patency of metal stents is dependent on multiple factors. Which type of metal stent should be placed for palliation of malignant biliary obstruction has still to be determined, but the efficacy of newer stents should be investigated in prospective, randomized studies.