Adductor pollicis muscle thickness: a promising anthropometric parameter for patients with chronic renal failure

Protein-calorie malnutrition is a prevalent disorder in chronic renal failure (CRF) and a major risk factor for increased mortality in hemodialysis (HD) patients. Although many methods have been used to assess malnutrition in CRF, the role of adductor pollicis muscle thickness (APMt) is not established yet.

This study aimed to analyze the APMt in HD patients and to investigate the correlation between APMt and conventional anthropometric, laboratory, and bioelectrical impedance markers, as well as its association with mortality/morbidity in a period of 12 months of follow-up.

The study included 143 HD patients from a single facility. After dialysis, the dry weight, height, mid-arm circumference, triceps skinfold thickness, and APMt were measured. Subsequently, the body mass index, percentage of standard body weight, the mid-arm muscle circumference, and the mid-arm muscle area were calculated. Blood counts were performed for hemoglobin, creatinine, and albumin. Patients were also submitted to a single-frequency tetrapolar bioimpedance test for measuring resistance, reactance, phase angle, and percentage of body cell mass. The correlation between APMt and anthropometric, laboratory, and bioelectrical impedance parameters was calculated using Pearson's linear correlation. Multiple linear regression analysis was used to select independent risk factors to death and hospitalizations in 6 and 12 months of follow-up, among parameters selected by univariate analysis.

Patients were aged 52.2 ± 16.6 years (20 to 83 years) on average, 58% were men, and mean dialysis vintage was 5.27 ± 5.12 years. APMt was 11.85 ± 1.63 mm (men, 12.34 ± 1.53; women, 11.19 ± 1.51; P < .0001). APMt was positively correlated with body mass index (r = 0.37; P < .0001), mid-arm circumference (r = 0.437; P < .0001), mid-arm muscle circumference (r = 0.494; P < .0001), mid-arm muscle area (r = 0.449; P < .0001), percentage of standard body weight (r = 0.355; P = .000), creatinine (r = 0.230; P = .006), albumin (r = 0.207; P = .013), percentage of body cell mass (r = 0.293; P = .000), and phase angle (r = 0.402; P < .0001), and negatively correlated with resistance (r = -0.403; P < .0001). The APMt ≤10.6 mm was associated with a 3.3 times greater risk of hospitalization within 6 months of follow-up (OR = 3.3, 95% CI: 1.13 to 9.66; P = .029) compared with patients with an APMt >10.6 mm. The APMt was not associated with risk of death at 6 and 12 months or hospitalization within 12 months of follow-up.

This is the first study testing APMt as an anthropometric marker in HD patients. The parameter is easy to measure and does not seem to be significantly affected by variations in hydration status. The parameter was significantly correlated with markers reflecting the condition of the muscle compartment, but not with parameters estimating the fat mass. The determination of an APMt cutoff point for malnutrition in patients with CRF and its correlation with morbidity and mortality will require further investigation in clinical studies.