Table 2.

Alternative to BMI: Metrics that Might Augment Kidney Transplant Candidacy Assessments

Metric	Definition	Healthy Definition	Associated Outcomes in ESKD	Pros/Cons
Waist circumference (WC)	Waist measured horizontally, just above the hip bone	<80 cm in women, <94 cm in men [58]	Significant association between larger WC and post-transplant mortality [22]	Pros: Direct assessment of abdominal obesity, low cost, rapid Cons: Operator dependent; requires training to ensure reliability
Waist-to-hip ratio (WHR)	Waist circumference / hip circumference	>0.85 in women, >0.97 in men [59]	Associated with all-cause mortality in ESKD [59]	Pros: Measure of fat distribution, low cost, rapid Cons: Operator dependent; requires training to ensure reliability
Mid-arm muscle circumference (MAMC)	Mid-arm circumference (cm) – 3.142 × TSF (cm). TSF measured with skinfold caliper; surrogate for lean body mass (LBM) [60]	Normal ≥ 90%, Depleted < 90%	Larger MAMC is an independent predictor of survival in hemodialysis patients [60]	Pro: Estimate of nutritional stores and protein reserves Cons: Operator dependent; requires training to ensure reliability
Serum creatinine	Marker measured via standard blood test; surrogate for muscle mass	Higher levels might indicate higher muscle mass for patients with ESKD.	Higher pre-KT serum creatinine levels associated with better graft and patient survival post-transplant [52]	Pro: Assessed routinely; inexpensive Cons: potentially confounded by kidney function and dialysis adequacy
CT and MRI	Laser-based 3D body imaging of visceral adipose tissue (VAT)	Morphometric features of lean abdominal mass	Low psoas mucle cross-sectional area and density on CT associated with waitlist mortality[61]	Pro: Often used in transplant evaluation Cons: Cost, radiation (CT), convenience
Dual-energy X-ray absorptiometry (DEXA)	Whole body fan beam method to determine lean body mass [52]	Normal ≥ −1 Osteopenia < −1.1	Bone mineral density associated with post-transplant fracture risk [62]	Pro: Can directly measure lean muscle mass and fat and bone density Cons: Cost, convenience
Bioelectrical impedance spectroscopy (BIS)	Measures body impedance to an applied alternating electric current; allows for calculation of total muscle mass	Normal BCM cell percentage of lean body mass: For men: 53% – 59% For women: 50% – 56%	Sarcopenia measured by BIS associated with 2–3 fold higher mortality in elderly HD patients after adjustment for covariates[24]	Pro: Can directly measure lean muscle mass, more cost-effective and portable than other imaging modalities Cons: Sensitive to changes in total body water/volume status

Abbreviations: WC – waist circumference; WHR – waist-to-hip ratio; ESKD – end-stage kidney disease; MAMC – mid-arm muscle circumference; TSF – triceps skinfold thickness; KT – kidney transplant; CT – computed tomography; MRI – magnetic resonance imaging; DEXA – dual-energy X-ray absorptiometry; BIS – bioelectrical impedance spectroscopy; BCM – body cell mass