Background
There is an emerging role for radiological evaluation of psoas muscle as a marker of sarcopenia in trauma patients. Older trauma patients are more likely to undergo cranial than abdomino-pelvic imaging. Identifying sarcopenia using masseter cross-sectional area (M-CSA) has shown correlation with mortality. We sought to determine the correlation between psoas: lumbar vertebral index (PLVI) and the M-CSA, and their association with health outcomes.

Methods
Patients aged 65 or above, who presented as a trauma call over a 1-year period were included if they underwent cranial or abdominal CT imaging. Images were retrospectively analysed to obtain PLVI and mean M-CSA measurements. Electronic records were abstracted for outcomes. Logistic regression methods, log scale analyses, Cox regression model and Kaplan–Meier plots were used to determine association of sarcopenia with outcomes.

Results
There were 155 eligible patients in the M-CSA group and 204 patients in the PLVI group. Sarcopenia was defined as the lowest quartile in each group. Pearson’s correlation indicated a weakly positive linear relationship (r = 0.35, p < 0.001) between these. There was no statistical association between M-CSA sarcopenia status and any measured outcomes. Those with PLVI sarcopenia were more likely to die in hospital (adjusted OR 3.38, 95% CI 1.47–9.73, p = 0.006) and at 2 years (adjusted HR 1.90, 95% CI 1.11–3.25, p = 0.02). Only 29% patients with PLVI sarcopenia were discharged home, compared with 58% without sarcopenia (p = 0.001).

Conclusion
Sarcopenia, defined by PLVI, is predictive of increased in-patient and 2-year mortality. Our study did not support prognostic relevance of M-CSA.