Project Summary Frailty is a phenotype defined as a state of decreased physiologic reserve and resistance to stressors. The most commonly cited phenotype of frailty is Fried frailty, established in a population of community-dwelling older adults, and is related to, yet independent of comorbidity and functional disability. Fried frailty is associated with poor outcomes in older adults. The prevalence of Fried frailty in the end-stage renal disease (ESRD) population has been shown to be 5-7 times higher than community-dwelling older adults. Specifically in the ESRD population, Fried frailty has been shown to be a predictor of increased mortality, falls, and increased hospitalizations. Our research group has previously shown that Fried frailty is associated with poor outcomes in kidney transplant (KT). Frail KT patients were at increased risk of mortality, early hospital readmission and delayed graft function compared to non-frail counterparts. Use of Fried frailty for risk prediction in older ESRD patients, considering KT, may not be completely accurate. Fried frailty does not include any ESRD-specific factors. No studies have defined a specific phenotype of frailty in older adults with ESRD. Using a phenotype unique to this population is likely to improve outcomes prediction in older adults with ESRD. To improve risk prediction and clinical decision making in older patients (age ?55) with ESRD, we propose: 1) to develop an expert consensus on the definition of an ESRD-specific measure of frailty in older adults, 2) to test the predictive accuracy of ESRD-specific frailty and quantify the associations between ESRD-specific frailty and outcomes in older KT candidates 3) to quantify the prevalence of ESRD-specific frailty and association with poor transplant outcomes among older KT recipients. A better understanding of frailty in older patients with ESRD is necessary for patient selection, counseling and consideration for KT.