Protein-energy malnutrition

Protein-energy malnutrition (PEM) is a common complication in patients with end-stage renal disease. PEM is known to be associated with cardiac comorbidity and inflammation and predictive of poor survival in patients being treated with dialysis. The nutritional status of patients undergoing dialysis is assessed in a number of different ways, including serum albumin, subjective global assessment (SGA), dietary protein intake, handgrip strength (HGS), and measurements of lean body mass. Serum albumin, often thought of as the most tell tale measurement, has recently proven to have many limitations. Therefore, it is essential to identify a marker that assesses nutritional status more reliably than does serum albumin and better predicts outcome in dialysis patients.

Handgrip strength is a simple, quick, easily performed and inexpensive bedside test. A previous study reported that HGS in end-stage renal disease patients close to inception of dialysis shows a strong positive correlation with LBM, suggesting that HGS may be a direct marker of body lean muscle mass. The factors that predict outcome in hemodialysis patients may not necessarily apply to peritoneal dialysis (PD) patients, it is necessary to evaluate whether HGS is a useful nutritional marker and has prognostic implication in the PD population.

Therefore, a study was designed as a prospective follow-up in a large cohort of PD patients from a single dialysis center in Hong Kong. PD accounts for nearly 80% of the dialysis modality in Hong Kong. The study aimed to evaluate clinical factors associated with HGS in patients undergoing maintenance PD and to determine whether HGS is a useful and independent prognostic indicator in the PD population.

A total of 233 prospectively enrolled (120 men and 113 women), who had been receiving continuous ambulatory PD for > 3 months, served as subjects. Nutritional status was assessed using SGA, body mass index, serum albumin, HGS, and LBM as estimated by CK. On the basis of the SGA assessment, each patient's nutritional status was scored as follows: 1 =normal nutrition, 2 =mild malnutrition, and 3=moderate and severe malnutrition. HGA was measured by using the Smedley handy dynamometer by experienced research staff. The patients were instructed to apply as much handgrip pressure as possible by using the nondominant hand. The measurements were repeated thrice, and the highest score was recorded in kilograms. The subjects were asked to bring 24-hour urine and dialysate samples on the morning of the nutritional assessment for measurement of urea and creatinine concentrations.

The patients were prospectively followed up after the assessments made at study baseline. During the follow-up period, all deaths were recorded. The clinical outcomes evaluated were all-cause and cardiovascular mortality.

Baseline HSG was significantly associated with age, sex, height, diabetes, residual glomerular filtration rate (GFR), and hemoglobin but not with C-reactive protein (CRP). After adjustment for age, sex and height, HSG was most strongly correlated with lean body mass on the basis of creatinine kinetics (r = 0.334, P < 0.001), followed by serum albumin and subjective global assessment. Both men and women who died had lower handgrip strengths than did those who remained alive (P < 0.001). Following control for age, sex, diabetes, atherosclerotic vascular disease, GFR, hemoglobin, CRP, and serum albumin, greater handgrip strength was predictive of lower all-cause [hazards ration (HR): 0.95 (95% CI:0.92, 0.99); P = 0.005] and cardiovascular [HR: 0.94 (0.90, 0.98); P = 0.004] mortality.

In this investigation, HSG was not only a marker of body lean muscle mass, but also provided important prognostic information independent of other covariates. It is suggested that handgrip strength be used in conjunction with serum albumin as a nutrition-monitoring tool in patients undergoing PD.

A. Wang, M. Sea, Z. Ho, et al. Evaluation of handgrip strength as a nutritional marker and prognostic indicator in peritoneal dialysis patients. Am J Clin Nutr;81:79-86 (January, 2005). [Correspondence: AY-M Wang, Department of Medicine and Therapeutics, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, NT, Hong Kong. E-mail: awing@cuhk.edu.hk].

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