CT of Patients With Hip Fracture: Muscle Size and Attenuation Help Predict Mortality

OBJECTIVE. Our objective was to determine the association between muscle cross-sectional area and attenuation, as measured on routine CT scans, and mortality in older patients with hip fracture. MATERIALS AND METHODS. A retrospective 10-year study of patients with hip fracture was conducted with the following inclusion criteria: age 65 years or older, first-time hip fracture treated with surgery, and CT of the chest, abdomen, or pelvis. This yielded 274 patients (70.4% women; mean [+/- SD] age, 81.3 +/- 8.3 years). On each CT scan, two readers independently measured the size (cross-sectional area, indexed for patient height) and attenuation of the paravertebral muscle at T12 and the psoas muscle at L4. We then determined the association between overall mortality and the muscle size and muscle attenuation, while adjusting for demographic variables (age, sex, ethnicity, and body mass index), American Society of Anesthesiologists (ASA) classification, and Charlson comorbidity index (CCI). RESULTS. The overall mortality rate increased from 28.3% at 1 year to 79.5% at 5 years. Mortality was associated with decreased thoracic muscle size (odds ratio [OR], 0.66; 95% CI, 0.49-0.87). This association persisted after adjusting for demographic variables (OR, 0.69; 95% CI, 0.50-0.95), the ASA classification (OR, 0.70; CI, 0.51-0.97), and the CCI (OR, 0.72; 95% CI, 0.52-1.00). Similarly, decreased survival was associated with decreased thoracic muscle attenuation after adjusting for all of these combinations of covariates (OR, 0.67-0.72; 95% CI, 0.49-0.99). Decreased lumbar muscle size and attenuation trended with decreased survival but did not reach statistical significance. CONCLUSION. In older adults with hip fractures, CT findings of decreased thoracic paravertebral muscle size and attenuation are associated with decreased overall survival.