Temporal muscle thickness as a new indicator of nutritional status in older individuals

Aim: Temporal muscle wasting is subjectively evaluated during nutritional assessment of protein–energy malnutrition. However, a quantitative evaluation method has not been established. The aim was to verify the validity and reliability of temporal muscle thickness measurement in comparison with established indicators of nutritional status, such as body mass index. Methods: A cross-sectional study was carried out from September 2016 through June 2017. A total of 73 individuals aged ≥65 years were recruited from two facilities and one community walking group. Temporal muscle thickness was measured using ultrasonography. Nutritional status was assessed with anthropometric measurements and laboratory examinations. Results: For validity, the temporal muscle thickness showed strong correlations with muscle mass, including calf circumference (r = 0.608, P < 0.001) and arm muscle circumference (r = 0.433, P < 0.001). In contrast, no strong correlations were observed with serum protein levels, such as albumin (r = 0.324, P = 0.005), or fat mass evaluated as triceps skinfold thickness (r = 0.216, P = 0.067). Temporal muscle thickness was significantly related to body mass index after adjusting for possible confounding factors of masticatory status, age and sex (β = 0.335, P = 0.007). As for reliability, the intrarater reliability of the temporal muscle measurement was 0.99 (95% confidence interval 0.98–1.00). Bland–Altman plot analysis showed no systematic errors, and the coefficient of variation of temporal muscle thickness measurements was 2.3%. Conclusions: The present study suggests that measuring a temporal muscle thickness using ultrasonography is a valid and reliable method for evaluating nutritional status. Geriatr Gerontol Int 2019; 19: 135–140.