Letter to the Editor: Comment on “Gastrointestinal Management Enhanced Recovery After Surgery Protocol Improves Postoperative Recovery in Patients Undergoing Posterior Lumbar Interbody Fusion”

To the Editor,

We read with interest the article by Zeng et al, ¹ “Gastrointestinal Management Enhanced Recovery After Surgery Protocol Improves Postoperative Recovery in Patients Undergoing Posterior Lumbar Interbody Fusion,” which highlights the promising role of gastrointestinal (GI)-focused ERAS protocols in spinal surgery. The results showing improved bowel function and reduced postoperative complications are encouraging. However, several methodological considerations merit further discussion to enhance the internal validity and interpretability of these findings.

First, the study does not account for baseline nutritional status or functional frailty, which are critical determinants of both gastrointestinal recovery and postoperative outcomes. While serum albumin was recorded preoperatively, more sensitive markers of malnutrition (eg, prealbumin, transferrin) or frailty indices were not evaluated. ² The omission of such variables potentially limits the comparability between the control and intervention groups, especially since nutritional reserve can substantially affect both GI function and wound healing. Stratifying or adjusting for these baseline differences would strengthen subgroup comparability and improve the diagnostic precision of the observed associations.

Second, while the authors report multiple statistically significant improvements in clinical and patient-reported outcomes, no adjustment was made for multiple comparisons across the numerous endpoints evaluated. With over a dozen outcomes—including subjective scores like PAC-SYM and GIS, complication rates, and recovery timelines—the potential for Type I error is non-negligible. Without corrections (eg, Bonferroni, Holm), some statistically significant results may represent false positives. Transparent pre-specification of primary endpoints and multiplicity adjustments would enhance the credibility and reproducibility of these findings. ³

Third, the study compares cohorts from 2 distinct time periods (2017-2018 vs 2019-2020), raising concerns about temporal confounding due to concurrent institutional improvements unrelated to the GI-ERAS protocol. Changes in surgical technique, anesthesia protocols, or perioperative staffing may have evolved over time and could independently influence outcomes such as length of stay or complication rates. While the authors acknowledged this limitation, they did not implement analytic techniques—such as interrupted time series or difference-in-differences models—that could help isolate the true effect of the intervention from background trends ⁴

In conclusion, Zeng et al. ¹ Present an important contribution to ERAS literature in spine surgery, particularly regarding gastrointestinal recovery. Addressing methodological concerns related to baseline patient status, multiplicity correction, and time-based confounding would further solidify the impact and generalizability of their findings. We commend the authors for advancing research in this area and encourage future studies to adopt prospective, multicenter designs with robust statistical controls to strengthen causal inference.