Response to Re: Systematic review and meta‐analysis of narrow band imaging for non‐muscle‐invasive bladder cancer

Abstract

We read with interest the recent article by Gravestock et al. 1 about the effect of narrowband imaging-guided transurethral resection of bladder tumor compared with white light on recurrence rates in non-muscle-invasive bladder cancer. The authors performed a systematic review and meta-analysis on this topic, including only randomized controlled trials (RCTs) to utilize the highest possible level of evidence. However, previous systematic reviews included observational studies that showed different results. Those previous studies represent real-world data (RWD) as they correspond to clinical information that produced new knowledge. 2 In this setting, where RCTs are scarce or difficult to reproduce, the inclusion of observational studies could provide greater applicability to clinical practice instead of leading to decisions based on results from a limited number of studies or patients.In addition to the comment above, we would like to point out four further considerations concerning the information sources and search strategy used. First, no information was provided about the review protocol or the existence of a registration number. Second, the search strategy for each database was not described, which is mandatory for all systematic reviews. Third, the authors limited their search to studies published in the English language, which is not acceptable since there might be many other relevant studies published in different languages. Finally, the authors did not look for unpublished literature. These aspects are included in the criteria set out by the Cochrane handbook for systematic reviews, which require authors to reproduce their search strategies and to limit publication and selection bias. 3,4 In conclusion, although this is an interesting systematic review and meta-analysis, we highlight some methodological aspects that should not be overlooked. Furthermore, despite the importance of evidence synthesis with the highest possible level of evidence, it is essential not to lose sight of the value of RWD and real-world evidence.