Reply to Tamhane and McGwin

We thank Drs Tamhane and McGwin for their interest in our paper on argon plasma coagulation (APC) of small-bowel lesions during double-balloon enteroscopy [1] and for their points of criticism [2]. They state that there was no information on patients lost to follow-up, but in the paper it is mentioned at the beginning of the Results section that only 50 out of 63 patients could be enrolled into the analysis for several reasons including loss to follow-up. This means that patients for whom follow-up information was poor were excluded from the analysis.

Additionally, they have doubts about the average follow-up of 55 months. These data are correct, because for all 50 patients the follow-up was done within a defined period of 3 months in 2009. But we agree that it would have been interesting for readers to know how many re-bleedings occurred because only a few patients, especially among those with Osler disease, suffered from two or more re-bleedings. The number of blood transfusions was documented for the whole follow-up period including all re-bleeding episodes.

Third, they point out that, for comparison of pre-APC and post-APC findings, the paired t test rather than the two-sample test and McNemar’s rather than Fisher’s test should have been used. They further point out that the follow-up with respect to mortality, bleeding, and blood transfusion should be analyzed using methods for time-to-event methods, such as Kaplan – Meier estimates. We did the correct analyses, but we failed to report them correctly. Therefore we would like to add an erratum to our paper. This will note that we did actually use the paired t and the McNemar tests and calculated mortality using Kaplan – Meier estimates, and a corrected Table 4 shows, for comparison of before and after APC, P values of 0.25 for the Osler group and 0.001 for the non-Osler group. Regarding re-bleeding and transfusion, the time interval data were inhomogeneous so that we could not carry out a formal Kaplan – Meier analysis; however we summarized the available information in the Outcome subsection of the Results.

• References

• 1 May A, Friesing-Sosnik T, Manner H et al. Long-term outcome after argon plasma coagulation of small-bowel lesions using double-balloon enteroscopy in patients with mid-gastrointestinal bleeding. Endoscopy 2011; 43: 759-765
• 2 Tamhane A, McGwin G. Paired-data analysis is required in the study by May et al. Endoscopy 2012; 44: 220