Myosteatosis as an independent risk factor for mortality after kidney allograft transplantation: a retrospective cohort study

Abstract

Background Patients with end-stage renal disease may display both a loss of skeletal muscle mass and an increase in muscle fat deposits. We aimed to analyse the impact of low skeletal muscle mass index (SMI, surrogate marker of sarcopenia) and low muscle density (MD, surrogate marker of myosteatosis) on patient survival after kidney transplantation (KT). Methods In a retrospective cohort of 200 kidney transplant recipients (KTr), we measured on an unenhanced cross-sectional computed tomography scan taken at the level of the third lumbar vertebra within the previous year or at the time of KT, both SMI (muscle cross-sectional area normalized for height 2 , reported in cm 2 /m 2 ) and MD (mean attenuation of muscle cross-sectional area, expressed in Hounsfield units). We determined age-specific and sex-specific normality thresholds on 130 healthy subjects. The baseline factors associated with low MD were assessed by logistic regression analysis. Cox proportional hazard univariable and multivariable models were constructed to identify predictive factors of patient survival. Results Among the 200 patients of the cohort, 123 were male (62%), and mean age was 54.8 ± 13.8 years. A total of 181 KTr required renal replacement therapy before KT (91%), and 36 KTr (18%) received repeat kidney transplant after previous failed KT. Mean MD was 30.6 ± 9 HU in men and 29.7 ± 8.3 HU in women, whereas SMI was 49.7 ± 8.6 cm 2 /m 2 in men and 42.3 ± 7.3 cm 2 /m 2 in women. MD was below the 2.5th percentile for the healthy population in 49 KTr (25%), defining the myosteatosis group, while SMI was below the 2.5th percentile for the reference population in 10 KTr (5%). Independent risk factors for myosteatosis were two or more KT [adjusted odds ratio (aOR) 5.2, 95% confidence interval (95% CI): 2.22-12.4, P = 0.0001], a history of stroke (aOR 3.7, 95% CI: 1.30-10.7, P = 0.015), and body mass index > 25 kg/m 2 (aOR 2.94, 95% CI: 1.4-6.18, P = 0.004). Myosteatosis was independently associated with mortality [adjusted hazard ratio (aHR) 2.12, 95% CI: 1.06-4.24, P = 0.033], as were cardiovascular disease (HR 2.06, 95% CI: 1.02-4.15, P = 0.043) and age (aHR 1.06, 95% CI: 1.03-1.09, P = 0.0003). Low SMI was not associated with mortality. Conclusions Myosteatosis, which was more prevalent than low skeletal muscle mass, might be an important prognostic marker in patients undergoing KT.

Diagnosis, prevalence, and outcomes of sarcopenia in kidney transplantation recipients: A systematic review and meta‐analysis

“…As reported in dialysis patients and chronic obstructive pulmonary disease patients, 4,75 the combined criterion exhibited a lower positive rate than the LMM alone in the assessment of sarcopenia, but it improved the accuracy of the sarcopenia diagnosis, which is now internationally recognized as the standard assessment criterion. The prevalence of sarcopenia assessed by EWGSOP and AWGS was lower than that by other methods, which included LMM assessment by CT, may be a pre‐requisite for presurgical anatomic mapping, and can be used to assess early and late‐term post‐transplant complications for KT patients, 29,76 but the resulting prevalence varies widely, ranging from 5.0% 30 to 72.1% 6 due to the use of different cut‐off thresholds. It is recommended that future studies should use uniform CT cut‐off thresholds to assess the LMM.…”

“…Out of these, 20 studies were excluded for reasons detailed in Table S2 . Finally, 23 6 , 7 , 8 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 studies were included, involving 2535 KTRs with 59.7% of male subjects. Of these, nine studies were from Europe, seven were from Asia, five were from South America, one was from North America, and one was from Oceania.…”

“…35 Wong et al found that after adjusting for the age, sex, dialysis vintage, type of transplant, length of hospital stay for KT admission, delayed graft function, diabetes, and rejection within the first month of KT, the risk of readmission within 30 days after KT in sarcopenia patients was 7.22 times higher than in patients without sarcopenia (95% CI: 1.87-27.91). 29 Included studies showed mortality rates of 20%, 30 10.2%, 35 and 10% 44 in sarcopenia patients after KT. Chan et al reported that after adjustment for age, sex, ethnicity, smoking habit, and alcohol consumption, post-KT sarcopenia patients had a 1.94-fold (95% CI: 1.10-3.42) higher risk of death and acute hospitalization than those without sarcopenia.…”

“…found that after adjusting for the age, sex, dialysis vintage, type of transplant, length of hospital stay for KT admission, delayed graft function, diabetes, and rejection within the first month of KT, the risk of readmission within 30 days after KT in sarcopenia patients was 7.22 times higher than in patients without sarcopenia (95% CI: 1.87–27.91) 29 . Included studies showed mortality rates of 20%, 30 10.2%, 35 and 10% 44 in sarcopenia patients after KT. Chan et al .…”

Defining sarcopenia and myosteatosis: the necessity for consensus on a technical standard and standardized cut‐off values

“…With great interest we read the paper by Morel et al . 1 in the Journal of Cachexia, Sarcopenia and Muscle . The authors presented an interesting study on the impact of low skeletal muscle mass index (as a surrogate marker for sarcopenia) and low muscle density (as a surrogate marker for myosteatosis) on patient survival after kidney transplantation.…”