Letter to the Editor on “Psoas Muscle Index as a Predictor of Perioperative Outcomes in Geriatric Patients Undergoing Spine Surgery” by Pernik et al

To the Editor,

I read with great interest the article by Pernik, et al titled “Psoas Muscle Index as a Predictor of Perioperative Outcomes in Geriatric Patients undergoing Spine Surgery. ¹ ” The research conducted is commendable and provides crucial insights into the use of the psoas muscle index as a predictor of perioperative outcomes in geriatric patients undergoing spinal surgery. While I appreciate the utility of the psoas muscle index as presented in the study, I write this letter to bring attention to several important points that warrant further consideration and discussion:

1. The statistical method used to identify cut-off point for Psoas Muscle Index is not mentioned in the study.

2. The usual method described in the literature for calculating the Psoas Muscle Index (PMI) is by normalizing the total psoas area to the height of the patient. ² The method used in the current study is not validated. It is crucial for any diagnostic or predictive tool to undergo rigorous validation to ensure its accuracy and reliability in clinical settings.

3. The imaging modality used for PMI includes both CT and MRI. The reliability of CT-MRI comparisons in the study appears uncertain. Furthermore, the MRI sequence used is also not clearly defined. Standardization of imaging protocols is essential for ensuring consistency and comparability in research studies. It is vital to establish the reliability and validity of these imaging modalities when used interchangeably.

4. The inclusion of a broad range of patients in the study, in terms of surgical intervention, including all thoracolumbar spine surgeries involving both degenerative and spinal deformity, is noted. The quantitative value of instrumentation can affect the parameters taken for outcome measurement (Total intraoperative transfusion volume and total postoperative transfusion volume).

Addressing these points will not only enhance the robustness of the study's findings but also contribute to a more comprehensive understanding of the Psoas Muscle Index as a predictor of perioperative outcomes in geriatric patients undergoing spinal surgery. Further research and validation are essential to establish its clinical significance.