A simple medical device development according to normative values of calf circumference across ages: results from the Italian Longevity Check-up 7+ (Lookup 7+) project

Background: Wide consensus exists on the notion that low muscle mass is a predictor of negative health-related events, such as disability, morbidity, and mortality. Indeed, the European Working Group on Sarcopenia in Older People 2 had identified muscle mass as the key component to confirm the diagnosis of sarcopenia. However, the lack of normative values for muscle mass across ages hampers the practical assessment of this important parameter. The aim of the present study was to produce cross-sectional centile and normative values for calf circumference (a surrogate estimation of muscle mass) across a wide spectrum of ages using a large and unselected sample of community-dwellers enrolled in the Longevity Check-up 7+ (Lookup 7+) project. Methods: This is a cross-sectional study using the data of Lookup 7+ project, an ongoing study started in June 2015 and conducted in unconventional settings (i.e., exhibitions, malls, and health promotion campaigns). Candidate participants were considered eligible for enrolment if they were at least 45 years of age and provided written informed consent. Calf circumference was measured using an inextensible but flexible plastic tape in a sitting position with the knee and ankle at a right angle and the feet resting on the floor. Normative values for calf circumference from ages 45 to 80 + years were generated. Results: A total of 11 814 participants were enrolled from 1 June 2015 to 30 September 2022. The mean age of participants included in the analyses was 61.8 years (standard deviation; 10.2 years; range: 45-98 years), and 6686 (57%) were women. Normative values for calf circumference were obtained for men and women, stratified by age groups. Accordingly, a calf circumference tape, with colour bands that demarcate the centiles range into which the patient falls, was created and validated. Conclusions: Our study established age- and gender-specific centile reference values for calf circumference. The calf circumference tape can be used to easily interpret the assessment in every-day practice for the early detection of individuals with or at risk of sarcopenia and malnutrition.