Comparison of estimates of resting energy expenditure equations in haemodialysis patients

Purpose: Waste products of metabolism accumulate in patients with chronic kidney disease, and require clearance by haemodialysis (HD). We wished to determine whether there was an association between resting energy expenditure (REE) and total energy expenditure (TEE) in HD patients and body composition. Subjects/methods: We determined REE by recently validated equations (CKD equation) and compared REE with that estimated by standard equations for REE, and TEE calculated from patient reported physical activity, in HD patients with corresponding body composition measured by dual energy X-ray absorptiometry (DEXA) scanning. Results: We studied 107 patients, 69 male (64.5%), mean age 62.7 +/- 15.1 years. The CKD equation REE was 72.5 +/- 13.3 watts (W) and TEE 83.2 +/- 9.7 W. There was a strong association between REE with body surface area (BSA) (r(2) = 0.80), total soft lean and fat lean tissue mass (r(2) = 0.69), body mass index (BMI) (r(2) = 0.34), all p<0.001. REE estimated using the modified Harris Benedict, Mifflin St. Jeor, Katch McArdle, Bernstein and Robertson equations underestimated REE compared to the CKD equation. TEE was more strongly associated with BSA (r(2) = 0.51), appendicular muscle mass (r(2) = 0.42), than BMI (r(2) = 0.15) all p<0.001. TEE was greater for those employed (104.9 +/- 10.7 vs. 83.1 +/- 12.3 W, p<0.001), and with no co-morbidity (88.7 +/- 14.8 vs. 82.7 +/- 12.3 W, p<0.05). Conclusions: Standard equations underestimate REE in HD patients compared to the CKD equation. TEE was greater in those with more skeletal muscle mass, in those who were employed and in those with the least comorbidity. More metabolically active patients may well require greater dialytic clearances.