Master of Science
Luke, Patrick P.
Introduction: Frailty and sarcopenia are related concepts that can impact outcomes after kidney transplantation. Measures of these two entities and new/emerging metrics of sarcopenia remain to be validated.
Methods: In a prospective cohort study, kidney and kidney-pancreas transplant recipients were assessed at the time of transplant with the Physical Frailty Phenotype, bioimpedance analysis, quadriceps muscle layer thickness (QMLT), and CT. The impact on length of stay (LOS), prediction of frailty/sarcopenia, and relative concordance of metrics were analyzed.
Results: Low QMLT, a putative surrogate of sarcopenia/frailty, was more frequently associated with longer LOS (>14 days) after transplant. Additionally, QMLT was predictive of low muscle mass but insufficient at discriminating true sarcopenia, while CT of the abdominal muscles at the L3 level showed good discrimination for sarcopenia.
Conclusions: Further exploration of QMLT and cut-offs for CT and functional metrics in the transplant population are required for future studies and risk stratification.
Summary for Lay Audience
Kidney failure leaves patients dependent upon either dialysis or kidney transplant to stay alive. While waiting for transplant, patients can become frail due to age, co-morbid disease, or kidney failure itself. Frailty leads to susceptibility to disease and complications from illness and surgery. Underpinning frailty is sarcopenia, or the loss of muscle characterized by both loss of muscle mass, and strength; having good strength with lower overall muscle mass does not make one sarcopenic.
The relationship between frailty, sarcopenia and the outcomes of kidney transplant, were explored. We studied the utility of using ultrasound measurement of thigh muscles to see if muscle thickness could identify frailty and sarcopenia, and if it could predict how long someone stayed in hospital after transplant. Overall, people with thicker/more muscle had shorter stays in hospital than those with less muscle in the thighs, with an average of 4 days less in hospital (8 vs. 12 days). While significant, those with thicker thigh muscles more often had someone donate a kidney to them, rather than receiving a deceased donor kidney. It is known that living donor recipients have shorter hospital stays, so the impact of thigh muscle thickness is difficult to interpret. Thigh muscle thickness was not clearly associated with frailty, but it did show correlation with low overall muscle mass. Despite this, thigh muscle thickness did not reliably predict sarcopenia, which relies on both muscle mass and function.
Valid measures for identifying sarcopenia in those undergoing transplant are evolving, so we explored how well different measures of sarcopenia compared to CT scan data. We measured the total cross sectional area of the muscles in the torso/core and compared these values to our other measures of muscle (using a body composition analyzer), and strength and walking speed as measures of muscle function. CT provided a relatively good ability to identify sarcopenia (both low muscle mass and strength), with analysis of a single CT picture. This holds promise for refining how we identify patients with sarcopenia in both research and clinical practice with the aim to provide ways of treating/preventing sarcopenia in the future.
Levine, Max A., "Quadriceps Muscle Layer Thickness in Kidney Transplant Recipients: A Potential Measure of Frailty and Sarcopenia" (2020). Electronic Thesis and Dissertation Repository. 7004.
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