Frailty in kidney transplant candidates: a comparison between physical frailty phenotype and FRAIL scales.

BACKGROUND: Frailty is common among advanced chronic kidney disease (CKD) patients who are kidney transplant (KT) candidates, and predisposes to poor outcomes after transplantation. However, frailty is not routinely measured during pretransplant work-up and it is unknown which metric should be used in this specific population. Our aim was to establish frailty prevalence in KT candidates according to different frailty scales. METHODS: Prospective longitudinal study of 451 KT candidates evaluated for frailty by both Physical Frailty Phenotype (PFP) and FRAIL scale at the time of inclusion on the KT waiting list. Clinical and functional characteristics including sociodemographics, comorbidities, disability and nutritional status were recorded. Agreement between PFP and FRAIL scales as well as dissonant patients were analyzed. RESULTS: Mean age was 60.9 years and 31.7% were female. Comorbidity burden among patients was high, with 36.9% and 16.2% presenting with diabetes and ischemic coronary disease, respectively. Disabilities were also frequent. More than 70% of patients presented with ≥ 1 PFP criteria while this percentage for ≥ 1 FRAIL criteria was 45.4%. Agreement between PFP and FRAIL was not good (kappa index 0.317). There were 132 patients who were pre-frail or frail according to PFP but non-frail according to the FRAIL scale and they presented with fewer comorbidities and less disability. CONCLUSIONS: Frailty is frequent in advanced CKD patients, although its prevalence may vary according to different scales. Agreement between PFP and FRAIL scale is not good, and FRAIL scale might misclassify as robust patients those frail/prefrail patients who are in better health conditions.