Table 1.

Commonly used functional assessment tools in clinical practice: benefits and limitations when used in older renal transplant candidates

Functional assessment tools	Methods	Benefits	Limitations
Physical assessment questionnaires	Self-reported ability to perform varied tasks using SF36, IADL, PASE	•Easy to administer	•Subjective •Inaccurate reporting •Cannot be used as a longitudinal measure
Karnofsky Performance Status Scale	Assigned score of 0%–100% based on reported functional abilities	•Easy to administer •Quickly identifies sickest group	•Subjective •Variability in reporting
Fried’s Frailty Phenotype Score	Score of 0–5 on domains, namely: (1) weight loss (2)exhaustion (3)physical activity (4)grip strength (5)walking speed Scoring interpretation: 0 = nonfrail 1–2 = prefrail ≥3 = frail	•Widely used in research •Well validated	•Has subjective and objective components •In clinical practice not accurately performed, leading to errors
Frailty Index	Index of cumulative deficits (functional impairments, cognitive impairments, laboratory findings, disabilities); scored 0–1 Scoring interpretation: 0 = good health status 0.5 = fair health status 1 = poor health status	•Comprehensive •Sensitive •Precise •Well validated in the older and surgical populations	•Has subjective and objective components •Time consuming •Does not differentiate frailty from comorbidity or disability •Not validated in the transplant population
Physical performance capacity measures	Walking speed, grip strength, repeat chair stands, 6-min walk test, timed up-and-go tests	•Easy to administer •Low/no cost •Not time consuming	•Assesses specific functions and muscle groups •Not great stand-alone test
SPPB	Measures lower-extremity strength Score from 0–4 on: (1) standing balance (2)walking speed (3)chair stand tests Score of <10 = SPPB impaired	•Completely objective •Well validated in older, chronic kidney disease, and transplant populations •Easy to administer •Not time-consuming	•Assesses lower extremity only and cannot be used in those with lower-extremity amputations or impairments
Morphometric measurements	(i)Sarcopenia diagnosed by muscle mass, measured by anthropometry, bioelectrical impedance analysis, dual energy X-ray absorptiometry scan, computed tomography, or magnetic resonance imaging (ii)Morphometric age calculation: using psoas muscle area, psoas muscle density, and percentage of aortic wall calcification measured on abdominal computed tomography imaging	•Objective •No additional studies necessary for transplant population as imaging studies are done frequently •Objective •No additional studies necessary for transplant population as imaging studies are done frequently	•Expensive •Requires trained personnel •No clear diagnosing criteria leads to underdiagnosis •Expensive •Requires trained personnel •Needs special software
Cardiopulmonary fitness test	Tests exercise tolerance by measuring peak oxygen uptake using incremental treadmill or stationary bike	•Well validated •Effective predictor of cardiac mortality	•Not well validated in kidney transplant •Inadequate results in advanced renal patients due to early discontinuation of testing or inability to achieve maximal exercise capacity •Expensive •Needs trained professionals to perform •Time consuming

IADL, instrumental activities of daily living; PASE, Physical Activity Scale for the Elderly; SF36, Short Form-36 Physical Function Scale; SPPB, Short Physical Performance Battery.