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Original Investigation
May 8, 2019

Association of Brain Atrophy and Masseter Sarcopenia With 1-Year Mortality in Older Trauma Patients

Author Affiliations
  • 1John A. Burns School of Medicine, University of Hawaiʻi at Mānoa, Honolulu
  • 2Division of Geriatrics and Gerontology, Department of Medicine, University of Washington, Harborview Medical Center, Seattle
  • 3Division of Trauma, Burn, and Critical Care Surgery, Department of Surgery, University of Washington, Harborview Medical Center, Seattle
  • 4Department of Anesthesiology & Pain Medicine, University of Washington, Harborview Medical Center, Seattle
  • 5Section of General, Thoracic, and Vascular Surgery, Department of Surgery, Virginia Mason Medical Center, Seattle, Washington
JAMA Surg. 2019;154(8):716-723. doi:10.1001/jamasurg.2019.0988
Key Points

Question  Are brain atrophy and/or masseter sarcopenia associated with mortality after traumatic injury in adults older than 65 years?

Findings  In this retrospective cohort study of 327 adults 65 years and older, both brain atrophy and masseter sarcopenia conferred independent increased hazards of death within 1 year of traumatic injury, after adjustment for age, comorbidity, clinical course, and injury characteristics.

Meaning  Brain atrophy and masseter sarcopenia may be prognostic indicators in older adults affected by trauma, which could be used to guide targeted interventions.


Importance  Older adults are disproportionately affected by trauma and accounted for 47% of trauma fatalities in 2016. In many populations and disease processes, described risk factors for poor clinical outcomes include sarcopenia and brain atrophy, but these remain to be fully characterized in older trauma patients. Sarcopenia and brain atrophy may be opportunistically evaluated via head computed tomography, which is often performed during the initial trauma evaluation.

Objective  To investigate the association of masseter sarcopenia and brain atrophy with 1-year mortality among trauma patients older than 65 years by using opportunistic computed tomography imaging.

Design, Setting, and Participants  This retrospective cohort study was conducted in a level 1 trauma center from January 1, 2011, to December 31, 2014, with a 1-year follow-up to assess mortality. Washington state residents 65 years or older who were admitted to the trauma intensive care unit with a head Abbreviated Injury Scale score of less than 3 were eligible. Patients with incomplete data and death within 1 day of admission were excluded. Data analysis was completed from June 2017 to October 2018.

Exposures  Masseter muscle cross-sectional area and brain atrophy index were measured using a standard clinical Picture Archiving and Communication System application to assess for sarcopenia and brain atrophy, respectively.

Main Outcomes and Measures  Primary outcome was 1-year mortality. Secondary outcomes were discharge disposition and 30-day mortality.

Results  The study cohort included 327 patients; 72 (22.0%) had sarcopenia only, 71 (21.7%) had brain atrophy only, 92 (28.1%) had both, and 92 (28.1%) had neither. The mean (SD) age was 77.8 (8.6) years, and 159 patients (48.6%) were women. After adjustment for age, comorbidity, complications, and injury characteristics, masseter sarcopenia and brain atrophy were both independently and cumulatively associated with mortality (masseter muscle cross-sectional area per SD less than the mean: hazard ratio, 2.0 [95% CI, 1.2-3.1]; P = .005; brain atrophy index per SD greater than the mean: hazard ratio, 2.0 [95% CI, 1.1-3.5]; P = .02).

Conclusions and Relevance  Masseter muscle sarcopenia and brain atrophy were independently and cumulatively associated with 1-year mortality in older trauma patients after adjustment for other clinical factors. These radiologic indicators are easily measured opportunistically through standard imaging software. The results can potentially guide conversations regarding prognosis and interventions with patients and their families.

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