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To the Editor,
We read with great interest the recent publication by Prager et al in BMJ Evidence-Based Medicine (1) and commend the authors on their important work. The authors characterize blinding practices in point-of-care ultrasound (POCUS) diagnostic accuracy clinical research. The authors evaluated whether the interpreter was blinded to patient clinical information in articles published in Emergency Medicine, Anesthesia, and Critical Care journals from January 2016 to 2020. Among 97 studies, the authors found that the POCUS interpreter was blinded to clinical information in 38.1% of studies, not blinded in 35.1%, and that the blinding practice was not reported in 26.8%. They additionally report that the same person obtained and interpreted images in 74.2% of studies, was different in 14.4%, and was not reported in 11.3%. These results demonstrate significant variability in POCUS research, leading the authors to conclude that to ensure generalizability of future research, the same person should perform and interpret the POCUS scan and not be blinded to clinical information.
The authors are firm in their recommendation and its perceived benefit. We believe, however, that it is short-sighted to uniformly recommend a study design in this rapidly evolving field. The authors (and importantly, future researchers) should carefully weigh the advantages and disadvantages of differing study designs. Both blinding and not blinding to clinical information allow co...
The authors are firm in their recommendation and its perceived benefit. We believe, however, that it is short-sighted to uniformly recommend a study design in this rapidly evolving field. The authors (and importantly, future researchers) should carefully weigh the advantages and disadvantages of differing study designs. Both blinding and not blinding to clinical information allow comprehensive evaluation of POCUS for educational uses, quality improvement, and accurate integration into clinical care. The translational science research spectrum provides a framework, from proof of concept to population level outcomes research (2), among which POCUS research undoubtedly falls. Bias, validity, reliability, reproducibility, and the research question are all important considerations researchers need to consider in developing their study design (3, 4).
We disagree with the author’s assertion that research biases are an intrinsic limitation to POCUS research methodology. Importantly, these biases should not be disregarded by unifying research methodology. As an example, researchers evaluating unstudied POCUS techniques will require a different study design than research evaluating a well-established technique, due to differing research questions; even if the final research outcome is the same.
While Prager et al have highlighted differences in study design and limitations to the performance of meta-analyzes because of significant heterogeneity, we would highly encourage prospective researchers to carefully determine the purpose of their project and to design studies to best answer their question while maximizing scientific rigor. We agree with the author’s that applicability of POCUS research to a generalized clinical setting is optimized by tailoring the study design to real-world application but this is not the sole purpose of ultrasound research which also includes education, monitoring, and quality improvement. Each researcher needs to consider his or her study purpose, and design a study to meet that purpose.
1. Prager R, Wu K, Bachar R, et al. Blinding practices during acute point-of-care ultrasound research: the BLIND-US meta-research study. BMJ Evid Based Med. 2020 Nov 11: bmjebm-2020-111577. doi: 10.1136/bmjebm-2020-111577. Epub ahead of print. PMID: 33177166.
2. Westfall JM, Mold J, Fagnan L. Practice-Based Research— “Blue Highways” on the NIH Roadmap. JAMA. 2007; 297(4): 403–406. doi:10.1001/jama.297.4.403.
3. Stone JC, Glass K, Clark J, et al. A unified framework for bias assessment in clinical research. Int J Evid Based Healthc. 2019 Jun;17(2):106-120. doi: 10.1097/XEB.0000000000000165. PMID: 31094882.
4. Simundić AM. Bias in research. Biochem Med (Zagreb). 2013; 23(1):12-5. doi: 10.11613/bm.2013.003. PMID: 23457761; PMCID: PMC3900086.