Protein-Energy Wasting More Prevalent in Women and Increases with Age

Approximately one-third of older adults in Europe are classified as malnourished upon admission to the hospital. Many patients also have chronic kidney disease (CKD), making nutritional problems more complex compared with those without CKD. Protein-energy easting (PEW) is defined as inadequate nutrient intake, in combination with other factors including inflammation, acidosis, and endocrine disorders that lead to increased net breakdown of protein or fat.

The prevalence of PEW is well described in patients initiating or receiving maintenance dialysis; however, there are few data available on the prevalence and risk factors for PEW among non­dialysis-dependent patients with CKD. Further, existing studies do not focus on the most vulnerable elderly patients and the majority were single-center studies.

Karin Windahl, RD, MSc, and colleagues recently conducted a large prospective observational cohort study designed to examine the prevalence and risk factors for PEW determined by the seven-point Subjective Global Assessment (SGA) tool. In addition, the researchers sought to describe the association between PEW and obesity in relation to patients’ baseline characteristics. Study results were reported in the Journal of Renal Nutrition [2018; 28(3):165-174].

The analysis included a total of 1334 patients. Median age was 76 years, and 65.5% were male. Median estimated glomerular filtration rate was 18.2 mL/min/1.73 m2 (interquartile range, 14.8-21.4). Most of the patients had normal nutritional status by SGA score (SGA 6-7), 26% were moderately malnourished (SGA 3-5), and <1% had severe malnutrition (SGA 1-2). In SGA subscales, 20.8% (n=278) of the patients had experienced recent weight loss, 23.4% (n=312) had inadequate food intake and/or gastrointestinal symptoms, 28.1% (n=375) had signs of subcutaneous fat loss, and 33.8% (n=451) had signs of muscle wasting.

In general, a muscle wasting score ≤5 on a SGA subscale was more prevalent than an overall SGA score ≤5. The prevalence of both PEW and muscle wasting was greater in the oldest patients (36% in those ≥80 years of age). Nearly 60% of patients with a diagnosis of depression or dementia were diagnosed with PEW.

Patients who were diagnosed with PEW indicated by an overall SGA score ≤5 had significantly lower body mass index (BMI), waist circumference, plasma albumin, plasma sodium, hemoglobin, 24-hour creatinine, and urea clearance. Normalized protein catabolic rate was also lower in patients with PEW compared with those without PEW. Overall, the correlation coefficients between seven-point SGA and the biochemical markers for PEW were low but statistically significant. The strongest correlations with seven-point SGA were with creatinine and urea clearance, BMI, waist circumference, and protein intake.

The risk of PEW increased with age, starting with >70 years; the risk was most prominent among the oldest (>80 years of age) (odds ratio, 1.87; 95% confidence interval [CI], 1.33-2.63). There was a significant association between female sex and an increased risk of PEW (OR, 1.32; 95% CI, 1.03-1.69).

In analyses of subscale scores, muscle wasting and loss of fat tissue had the largest changes, and the ORs increased with age. In patients >80 years of age, the OR for muscle wasting was 2.13 (95% CI, 1.53-2.97) and for subcutaneous fat loss, the OR was 2.53 (95% CI, 1.77-3.61), compared with patients 65 to 69.9 years of age.

There was no influence of the comorbidity burden based on the Charlson comorbidity index on the risk of PEW; however, late referral, defined as <1 year prior to inclusion, had a borderline statistically significant association with PEW. The strongest association with PEW was seen in a history of psychiatric disease such as depression or dementia: OR, 3.72; 95% CI, 2.33-5.95. The risk of PEW also increased with the presence of other comorbid conditions such as chronic pulmonary disease, cerebrovascular disease, heart failure, peripheral artery disease, and cancer; these associations did not reach statistical significance, however. BMI confounded the relationship between diabetes and PEW and had no association in the adjusted model.

Overall, the study cohort was overweight, with a mean BMI of 28.4 kg/m2 and mean waist circumference of 105.8 cm in men and 100.3 cm in women. Based on World Health Organization standards, 34% of patients (n=435) were obese, 37% (n=469) were overweight, and 9% (n=110) were underweight (BMI <22 kg/m2, according to European Society of Clinical Nutrition and Metabolism recommendations). Women were more often obese and underweight than men, and patients >80 years of age were more often underweight and less often obese.

Limitations to the study cited by the authors included the possibility that the generalizability of results may be limited by the manner in which patients were recruited.

In summary, the researchers said, “This European, multicenter study reports that the prevalence of PEW is 26% in older adults with CKD (stage 4-5) not on dialysis. Patients especially at risk are elderly (>80 years), women, and those with psychiatric disease. Protein wasting was common (25%) among the obese; I.e., obese sarcopenia. We conclude that it is very important to detect early signs of PEW in older adults with CKD, and further research is needed to study interventions directed specifically toward the elderly.”

Takeaway Points

  1. Researchers in Sweden conducted a prospective observational study to examine risk factors of protein-energy wasting (PEW) patients with non–dialysis-dependent CKD stage 4-5 >65 years of age.
  2. Muscle wasting and loss of subcutaneous fat were the most frequent alterations according to the Subjective Global Assessment 7-point scale, particularly in patients >80 years of age.
  3. The prevalence of PEW was higher in women, increased with age, and was higher in patients with depression/dementia.