MO591THE EVALUATION OF SARCOPENIA IN NON-DIALYSIS CHRONIC KIDNEY DISEASE STAGES BY COMPUTED TOMOGRAPHY
Authors: Donato Beatriz , Fernandes Adriana Paixão , Raimundo Mário , Falcao Luis , Velho Sónia , Primitivo Ana , Fernandes Sara , Teixeira Catarina , Costa Ana Cortesão , Silva Sónia , Almeida Edgar 
Published: May 2021

Abstract

Background and Aims
Sarcopenia is common in chronic kidney disease (CKD) and it has been reported a correlation between the increased prevalence of sarcopenia and worsening kidney function. Computed tomography (CT) is the gold standard for studying sarcopenia because of its capacity to identify quantitative and qualitative changes in muscle mass. Our major aim was to evaluate the prevalence of sarcopenia ant its association with renal function, in non-dialysis CKD patients, using a diagnostic criterion that has not been applied before in this population.

Method
We conducted a longitudinal retrospective analysis on a cohort of non-dialysis CKD patients who visited an outpatient Nephrology clinic between January 2012 and December 2012 and continued follow-up until December 2018. We selected those who underwent a CT scan as part of their clinical workup and simultaneously had a serum creatinine determination within 90 days of the scan. CT images were obtained and evaluated for body composition analysis by one investigator blinded to clinical data. Images were selected by radiologists at the third lumbar vertebra (L3). Segmentation of tissue cross-sectional areas was conducted according to the following Hounsfield unit thresholds: -29 to 150 for skeletal muscle, -190 to -30 for subcutaneous and intramuscular adipose tissue and -50 to -150 for visceral adipose tissue. Skeletal muscle area (SMA) was normalized for stature to calculate the skeletal muscle index (SMI). Sarcopenia was defined as SMI lower than 41 cm2/m2 in women and 43 cm2/m2 in men with body mass index (BMI) &lt; 25 kg/m2 and &lt; 53 in men with BMI &gt; 25 kg/m2, as described by Martin et al, based on the International Consensus of Sarcopenia. Visceral obesity was defined as visceral fat area &gt; 130 cm2. Diagnosis and classification of CKD were based on the Kidney Disease Improving Global Outcomes criteria and the glomerular filtration rate was estimated from the serum creatinine levels using the CKD Epidemiology Collaboration equation.

Results
Out of the 521 non-dialysis CKD patients referred to the nephrology clinic, 43 patients met the inclusion criteria. Mean age was 71.0 ± 14.6 years, 55.8% were male and 97.7% were caucasian. The mean follow-up time was 4.3 ± 2.3 years. Most patients had CKD stages 3 to 5 (67.4%) and the mean GFR was 45.4 ± 32.6 ml/min/1.73m2. In our entire cohort, 16 patients were sarcopenic (37.3%; median age: 77.5 years; 9 female and 7 male) and a high prevalence of sarcopenia was observed in stages 3 and 4 of CKD (54,5% and 50%, respectively). There was a non-significant difference in age (77.5 vs. 68, p=0.068), comparing with patients without sarcopenia. The group of the sarcopenic patients had lower BMI (24.4 vs. 28.4 Kg/m2, p=0.008) and height (65.9 vs. 77.6, p=0.01), although BMI &gt; 30 Kg/m2 (1 vs. 9, p=0.052) and visceral obesity (7 vs. 19, p=0.084) were not significantly different between the two groups. Moreover, we observed that patients with sarcopenia tended to have lower albumin levels (2.9 vs. 3.7, p=0.034) and higher LDL levels (135 vs. 67.5, p=0.04). Regarding mortality, 18 patients (41,9%) died during follow-up and the frequency of sarcopenia was significantly higher among non-survivors (68.8% vs. 25.9%, p=0.006). In the univariate logistic regression, for every decrease of one unit in the SMI, mortality increased by 10% (p=0.012).

Conclusion
Sarcopenia is common in patients with non-dialysis dependent CKD, particularly in advanced stages, and is strongly associated with mortality in this population. Our study highlights the importance of early diagnosis and implementation of therapeutic strategies to minimize the adverse outcomes in CKD patients.