Response to the letter to the editor: Clarifying NSQIP follow-up and estimated perioperative outcomes in lumbar decompression with or without fusion

Dear Editor,

We thank the authors of the Letter to the Editor for their careful review of our manuscript [1] and for their thoughtful comments. We appreciate the opportunity to clarify the points raised.

First, we acknowledge a typographic error in the Materials and Methods section. The text should state that the American College of Surgeons (ACS)-National Surgical Quality Improvement Program (NSQIP) database captures outcomes up to 30 days, not 300 days. All analyses in our study were limited strictly to 30-day postoperative outcomes, and no conclusions regarding longer-term complications, such as nonunion, late instability, or revision surgery, were intended or inferred. We regret any confusion this error may have caused.

Second, with regard to the reporting of mean mortality and mean morbidity as “estimated probabilities,” these values correspond directly to definitions provided in the ACS-NSQIP user guide. Specifically, the probabilities of mortality and morbidity included in the database are derived using hierarchical regression analysis based on patient-level effects. They represent the estimated probability (ranging from 0 to 1) that a given case will experience a morbidity or mortality event based on pre-existing conditions. These probabilities are recalculated every six months using data from the preceding 12 months; accordingly, both the underlying data and the predictive algorithm evolve over time.

We hope this clarification adequately addresses the concerns raised and improves the interpretability of our findings. We thank the authors again for their constructive feedback and for the opportunity to further clarify our methodology.