Sarvottam, Kumar

AbstractBackgroundFrailty, including low muscle mass, is an emerging risk factor for poor outcomes after lung transplant. The sarcopenia index (SI)—(serum creatinine value/cystatin C value) × 100—is a novel blood test to approximate muscle mass. We sought to validate SI among lung transplant patients.MethodsWe retrospectively identified adult lung transplant recipients from 2000 through 2012 at our institution who underwent computed tomography within 1 year before transplant and had preserved blood samples. Creatinine and cystatin C values were measured using the samples and used to calculate SI. Muscle mass was estimated by computed tomographic measurement of skeletal muscle cross‐sectional surface area (SA) at the L1 to L3 vertebral levels. Correlation between SI and SA was evaluated.ResultsOf 28 patients meeting eligibility criteria, most were white (96%) and men (54%). Median (interquartile range) body mass index, SI, and SA were 25.9 (22‐30) kg/m2, 106 (91‐119), and 157 (113‐195) cm2, respectively. The Pearson correlation coefficient between SI and SA was significant at L2 (0.43; P = .02) and L3 (0.41; P = .03).ConclusionSarcopenia index is a potentially objective measure for estimating muscle mass that is noninvasive and less expensive. Sarcopenia index could be considered in lung transplant candidate selection following prospective validation in larger cohorts.

Objectives: Sarcopenia is associated with a poor prognosis in the ICU. The purpose of this study was to describe a simple sarcopenia index using routinely available renal biomarkers and evaluate its association with muscle mass and patient outcomes. Design: A retrospective cohort study. Setting: A tertiary-care medical center. Patients: High-risk adult ICU patients from October 2008 to December 2010. Interventions: The gold standard for muscle mass was quantified with the paraspinal muscle surface area at the L4 vertebrae in the subset of individuals with an abdominal CT scan. Using Pearson’s correlation coefficient, serum creatinine-to-serum cystatin C ratio was found to be the best performer in the estimation of muscle mass. The relationship between sarcopenia index and hospital and 90-day mortality, and the length of mechanical ventilation was evaluated. Measurements and Main Results: Out of 226 enrolled patients, 123 (54%) were female, and 198 (87%) were white. Median (interquartile range) age, body mass index, and body surface area were 68 (57–77) years, 28 (24–34) kg/m2, and 1.9 (1.7–2.2) m2, respectively. The mean (± sd) Acute Physiology and Chronic Health Evaluation III was 70 (± 22). ICU, hospital, and 90-day mortality rates were 5%, 12%, and 20%, respectively. The correlation (r) between sarcopenia index and muscle mass was 0.62 and coefficient of determination (r 2) was 0.27 (p < 0.0001). After adjustment for Acute Physiology and Chronic Health Evaluation III, body surface area, and age, sarcopenia index was independently predictive of both hospital (p = 0.001) and 90-day mortality (p < 0.0001). Among the 131 patients on mechanical ventilator, the duration of mechanical ventilation was significantly lower on those with higher sarcopenia index (–1 d for each 10 unit of sarcopenia index [95% CI, –1.4 to –0.2; p = 0.006]). Conclusions: The sarcopenia index is a fair measure for muscle mass estimation among ICU patients and can modestly predict hospital and 90-day mortality among patients who do not have acute kidney injury at the time of measurement.