Computed tomography‐determined skeletal muscle density predicts 3‐year mortality in initial‐dialysis patients in China

Abstract

BackgroundSkeletal muscle mass and quality assessed by computed tomography (CT) images of the third lumbar vertebra (L3) level have been established as risk factors for poor clinical outcomes in several illnesses, but the relevance for dialysis patients is unclear. A few studies have suggested a correlation between CT‐determined skeletal muscle mass and quality at the first lumbar vertebra (L1) level and adverse outcomes. Generally, chest CT does not reach beyond L1. We aimed to determine whether opportunistic CT scan (chest CT)‐determined skeletal muscle mass and quality at L1 are associated with mortality in initial‐dialysis patients.MethodsThis 3‐year multicentric retrospective study included initial‐dialysis patients from four centres between 2014 and 2017 in China. Unenhanced CT images of the L1 and L3 levels were obtained to assess skeletal muscle mass [by skeletal muscle index, (SMI), cm2/m2] and quality [by skeletal muscle density (SMD), HU]. Skeletal muscle measures at L1 were compared with those at L3. The sex‐specific optimal cutoff values of L1 SMI and L1 SMD were determined in relation to all‐cause mortality. The outcomes were all‐cause death and cardiac death. Cox regression models were applied to investigate the risk factors for death.ResultsA total of 485 patients were enrolled, of whom 257 had both L1 and L3 images. Pearson's correlation coefficient between L1 and L3 SMI was 0.84 (P < 0.001), and that between L1 and L3 SMD was 0.90 (P < 0.001). No significant association between L1 SMI and mortality was observed (P > 0.05). Low L1 SMD (n = 280, 57.73%) was diagnosed based on the optimal cutoff value (<39.56 HU for males and <33.06 HU for females). Multivariate regression analysis revealed that the low L1 SMD group had higher risks of all‐cause death (hazard ratio 1.80; 95% confidence interval 1.05–3.11, P = 0.034) and cardiac death (hazard ratio 3.74; 95% confidence interval 1.43–9.79, P = 0.007).ConclusionsIn initial‐dialysis patients, there is high agreement between the L1 and L3 measures for SMI and SMD. Low SMD measured at L1, but not low SMI, is an independent predictor of both all‐cause death and cardiac death.

Prediction of hematologic toxicity in luminal type breast cancer patients receiving neoadjuvant chemotherapy using CT L1 level skeletal muscle index

“…CT technology is the primary modality for quantifying body composition. Research suggests that body composition data can be derived from three distinct CT scan regions: chest (encompassing T1 to L1), abdomen (spanning T10 to L4), and pelvis (covering L4 to L5) 14 , with abdominal L3 being the most widely utilized 15 . However, only the chest CT data is available for most BC patients and there is a lack of supplementary abdominal CT information.…”