To the Editor:
The recent narrative review by Tran et al.1 comprehensively outlining the transversus abdominis plane block is a welcome addition to the literature. Surprisingly, however, the review identified very few indications where the transversus abdominis plane block may actually have any potential clinical benefit. Indeed, Tran et al. suggest that open appendectomy (as relatively uncommon as those are), Cesarean delivery in the absence of any intrathecal opiates (also uncommon), and potentially open colorectal operations when contraindications preclude the use of the clearly superior thoracic epidural option, represent very few firm indications for its use. That said, the block appears to have considerable potential, and Tran et al. also outline a wide-ranging number of areas that warrant further investigation. In doing so, they emphasize that adequately powered and well-designed clinical trials are needed to compare the transversus abdominis plane block with a number of potentially important comparators, including the newer proximal interfacial plane blocks (e.g., erector spinae plane block).
However, an important consideration that was missing from the article was the lack of any specific mention of the end points that should be included in potential future trials. That is, for these trials to be adequately powered, there needs to be careful consideration as to what end points should be measured and compared. Indeed, Myles et al.2 recently reported in their systematic review and consensus analysis of what the important patient comfort outcomes should be. Whereas Tran et al. do state that “hard outcomes” such as length of stay—which is unlikely to be affected after appendectomy—should be reported in transversus abdominis plane bock studies, there are likely many more relevant outcomes that should be considered. Even if they are well-designed, conducting trials that simply investigate short-term (less than 24-h) pain assessments and/or opiate requirements, which arguably are rather poor patient-centered outcomes, will likely not further advance this important field.
So although I commend Tran et al. on a comprehensive and excellent dissertation on the transversus abdominis plane block, I suggest that they also push the field forward not just by suggesting that additional trials should be undertaken, but by highlighting the end points that should form the basis for these important trials. There are clearly transversus abdominis plane block–related areas that need further investigation, but they must be done through the right kind of trials.
The author declares no competing interests.