Musculus psoas major morphology - a novel predictor of mortality in elderly polytraumatized patients

Abstract

Introduction: Numerous papers in different fields have already shown that CT imaging of the Musculus Psoas Major (MPM) can be used to predict patient outcome. Unfortunately, most of the methods presented in the literature are very complex and not easy to perform in the clinic. Therefore, the objectives of the study were to introduce a novel and convenient method for measuring the MPM to trauma surgeons and to prove the association between MPM morphology and mortality in elderly polytraumatized patients.

Material and methods: The retrospective outcome study was conducted at our level I trauma center. All patients admitted from 2006 to 2020 were included if they (1) presented with multiple injuries (≥2 body regions) and an Injury Severity Score (ISS) ≥16, (2) were at least 65 years of age, and (3) were diagnosed using a whole-body computed tomography. Subsequently, the ratios of short-axis to long-axis of both MPM were measured, and their mean value was evaluated as a candidate predictor of 31-day mortality.

Results: Our study group consisted of 158 patients (63.3% male; median age, 76 years; median ISS, 25). In the survivors (55.7%), the mean MPM score was significantly higher compared to the fatalities (0.57 versus 0.48; p < 0.0001). Multivariate binary logistic regression analysis identified the MPM score as a protective predictor of 31 day-mortality (OR = 0.92, p < 0.001), whereas age (OR 1.08, p = 0.002 and ISS (OR 1.06, p = 0.006) revealed as significant risk factors for mortality. ROC statistics provided an AUC = 0.724 (p < 0.0001) and a cut-off level of 0,48 (sensitivity, 80.7%; specificity, 54.3%).

Conclusion: The present study demonstrated that MPM score levels lower than 0.48 might be considered an additional tool to identify elderly patients at high risk of death following major trauma. In our opinion, the assessment of the MPM score is an easy, convenient, and intuitive method to gain additional information quickly after admission to the hospital that could be implemented without great effort into daily clinical practice.

Keywords: CT-imaging; Elderly patients; Mortality; Musculus psoas major; Polytrauma.

Fig. 1

Flow chart of the study sample

Fig. 2

Measuring MPM in CT-images of axial views at the level of the L3 vertebra of a soft tissue window (Lx:Long axis, Sx: short axis; A = stadium 0, B = stadium 1, C = stadium 2, D = stadium 3)

Fig. 3

Mean MPM scores in survivors and fatalities

Fig. 4

Survivors and fatalities in the four patient groups according to the MPM stadium

Fig. 5

ROC curve of 31-day mortality and MPM score

Fig. 6

Mean MPM scores in survivors and fatalities separated by gender