111. Can body composition measures on computed tomography predict mortality in patients with spinal metastases undergoing surgery?

Abstract

<h3>BACKGROUND CONTEXT</h3> Although survival of patients with spinal metastases has improved in recent decades due to advances in multimodal therapy, there are currently no reliable predictors of mortality. Computed tomography (CT) body composition measurements have been recently proposed as biomarkers for survival in patients with and without cancer. Patients with cancer routinely undergo CT for staging or surveillance of therapy and body composition assessed using opportunistic CTs might be used to determine survival in patients with spinal metastases. <h3>PURPOSE</h3> The purpose of our study was to determine the value of body composition measures obtained on opportunistic abdomen CTs to predict 90-day and 1-year mortality in patients with spinal metastases undergoing surgery. We hypothesized that low muscle and abdominal fat mass were predictors of mortality. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> Between 2001 and 2016, 196 patients who underwent surgery for spinal metastases at a single tertiary center underwent CT of the abdomen within three months prior to surgery. <h3>OUTCOME MEASURES</h3> Ninety-day and 1-year mortality. <h3>Methods</h3> Quantification of cross-sectional areas (CSA) and CT attenuation in Hounsfield units (HU) of abdominal subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and paraspinous skeletal muscle were performed on CT images at the level of L4 using an in-house automated algorithm under the supervision of a fellowship-trained musculoskeletal radiologist. Sarcopenia was determined by total muscle area (cm²) divided by height squared (m²) with cutoff values of <52.4 cm²/m² for men and <38.5 cm²/m² for women. Bivariate and multivariate Cox proportional-hazard analyses were used to determine the associations between body compositions and 90-day and 1-year mortality. <h3>Results</h3> The median age was 62 years (interquartile range = 53-70). Mortality rates at 90 days and 1 year were 24% and 54%, respectively. Sarcopenia and decreased muscle attenuation were associated with increased mortality for both timepoints (p=0.04 and p=0.04, respectively) after controlling for sex, age, body mass index, Charlson Comorbidity score, primary tumor type, visceral metastases, and duration between diagnosis of spinal metastases and surgery. Decreased SAT area was associated with increased 90-day mortality after controlling for the same covariates (p<0.01). <h3>Conclusions</h3> Decreased muscle attenuation and sarcopenia are independently associated with an increased risk of 90-day and 1-year mortality for patients surgically treated for spinal metastases, and low SAT CSA is independently associated with increased risk of 90-day mortality. Therefore, body composition measurements could serve as novel biomarkers for prediction of mortality in patients with spinal metastases. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.