(1127) Reduced Vertebral Bone Density Predicts Inpatient Mortality After Severe COVID-19 Infection

Introduction: Osteoporosis is associated with several comorbid conditions, including chronic lung disease, tobacco use, and increasing age, all of which are associated with worse outcomes in covid-19 infection. There are few methods to assess for bone health in patients admitted for critical illness. We hypothesized that reduced vertebral bone density assessed with admission chest computed tomography (CT) is associated with worse outcome in patients requiring intensive care unit (ICU) admission for covid-19 infection.

Methods: After obtaining institutional review board approval, all patients admitted to the medical intensive care unit (ICU) between March 2020 and December 2020, with laboratory confirmed COVID-19 and chest CT imaging were retrospectively identified. Exclusion criteria included outside hospital transfers and patients that were pregnant or < 18 years of age. Bone density was assessed by quantifying the radiographic Hounsfield units (HU) of the cancellous bone at the 5th thoracic vertebral level using Slice-O-Matic® software. Primary outcome was inpatient mortality. Univariate testing included Wilcoxon-Ranked Sum for non-parametric continuous variables and Chi-square tests or Fisher’s Exact test for dichotomous and categorical variables, respectively. Multivariate logistic regression was performed, and the outcome variable was inpatient mortality.

Results: 97 patients met inclusion criteria with a median BMI of 30.0 kg/m2 (IQR 25.4-34.6), age of 64 years (IQR 51-74), admission sequential organ failure assessment (SOFA) score of 3 (IQR 1-4), and 67% (65/97) were male. Overall, 43% (42/97) required invasive mechanical ventilation and 30% (29/97) expired. 12 patients (12%) had chronic lung disease. Median bone density HU was 186.7 (IQR 161.6 – 232.1). On univariate analysis reduced bone density HU (p < 0.001) and reduced admission platelet count (p= 0.005) were associated with inpatient mortality. On multivariate logistic regression, reduced bone density HU was associated with inpatient mortality when adjusting for admission platelet count, age, and admission SOFA score (β -0.03, 95% CI 0.96 to 0.99, p=0.001).

Conclusions: Reduced thoracic vertebral bone density measured with CT imaging is associated with inpatient mortality in patients admitted with severe COVID-19 infection.