Skeletal Muscle Area Is an Independent Predictor for Mortality in Elderly Patients With ANCA Associated Vasculitis

Abstract

Objectives This study aims to investigate the relationship between baseline skeletal muscle area and infections or death in elderly AAV patients with renal involvement.Results A total of 57 AAV patients with renal involvement older than 65 years from a single center in China were enrolled. The mean age was 72.4 ±5.6 years. The baseline BVAS score was 17.04 ±4.40, and eGFR was 18.64 (7.63, 33.79) ml/min×1.73m2. Skeletal muscle area was calculated on CT at the third lumbar vertebra level. The mean muscle area was 102.68 ±24.41 cm2. After a median follow-up of 555 days, 29 patients experienced 36 episodes of severe infections. The median time to infection was 30 (15, 63) days. Ten patients died of infection, and two of fatal bleeding. The median time to death was 59 (26, 77) days. The muscle area correlates with age and BMI. Univariate Logistic regression showed that age (OR 1.11, P=0.044), muscle area (OR 0.97, P=0.008) and hsCRP (OR 1.01, P=0.017) were predictors of severe infection. In the multivariate Cox regression, muscle area (HR 0.97, P=0.022) independently predicted one-year mortality. Conclusion Elderly AAV patients have a high rate of infection and death during the first year following induction. Muscle area measured at L3 vertebrae level on non-contrast-enhanced CT is an independent predictor of 1-year infection and mortality.