# Lower Hemoglobin Following Adult Spine Deformity Surgery Leads to Longer Hospital Length of Stay

## TL;DR

After spine surgery, lower hemoglobin levels are linked to longer hospital stays, but strict transfusion rules didn't change outcomes.

## Contribution

The study evaluates the impact of rigid transfusion thresholds on postoperative hemoglobin and hospital length of stay following adult spine deformity surgery.

## Key findings

- Rigid transfusion thresholds did not significantly affect nadir hemoglobin values or hospital length of stay.
- Lower nadir hemoglobin levels were associated with longer hospital stays, with LOS decreasing as hemoglobin levels increased.
- No significant differences were found in estimated blood loss, operative time, or demographic factors between the two groups.

## Abstract

Background

Patients commonly require blood transfusion for adult spinal deformity (ASD) surgery. Following the COVID-19 pandemic, the American Red Cross experienced the worst blood bank shortage in history, resulting in more rigid transfusion thresholds (RTT) across hospitals within the United States. This laboratory-driven threshold offers insight into the value of rigid criteria for transfusion utilization following ASD surgery.

Purpose

To evaluate the impact of RTT (Hemoglobin of 7.5g/dl) following ASD surgery on hospital length of stay (LOS) and to explore the relationship between nadir hemoglobin (Hgb) and LOS.

Methods

ASD patients from January 1, 2021 to June 30, 2021 (RTT) and from March 1, 2022 to August 31, 2022 Unrestricted Transfusion Threshold (UTT) were identified and compared with respect to demographic, operative, and postoperative outcomes including LOS.

Results

Fifty-one ASD patients were in the RTT group versus 43 in the UTT group. The two groups were similar in the number of females (61% vs 53%, p=0.533) and age (60.1 years vs 56.6 years, p=0.317). There was no difference in mean estimated blood loss (583.2ml vs 517.4ml, p=0.394) or operative time (291.9min vs 266.8min, p=0.187). Mean postoperative nadir (lowest) Hgb was similar between the cohorts as well (9.0 g/dl vs 9.3 g/dl, p=0.730). There was a higher percentage of RTT patients (8, 19%) with a nadir Hgb below 7.5 g/dl vs UTT patients (17, 33%), but there was no difference in the total number of patients reaching nadir values below 9.5, 8.5, or 7.5 g/dl. Across 94 patients, LOS was significantly longer at lower nadir hemoglobin, declining from 8.2 days (<7.5 g/dL) to 3.6 days (>9.5 g/dL) across ordered categories.

Conclusions

Rigid transfusion thresholds following ASD surgery did not impact nadir Hgb values nor LOS. Lower nadir postoperative Hgb values were associated with a longer LOS. Further investigation to understand this association could be beneficial for more objective transfusion recommendations with the potential to reduce LOS.