Intra-rater reliability of lower leg subcutaneous skin fold thickness derived from hand-held a-mode ultrasound

TLDR: Despite the relatively long period between measurements, the hand-held ultrasound device exhibited a high degree of intra-rater reliability, and ultrasound measurements may be a useful tool to quantify skin fold thickness.

Abstract: BACKGROUND: Ultrasound is an important tool to diagnose many clinical conditions. Yet hand-held devices may be prone to more data variability in part from the greater likelihood of human error. OBJECTIVE: Quantify intra-rater reliability of subcutaneous skin fold thickness from a hand-held ultrasound device. PARTICIPANTS: College-age subjects (18 men, 14 women) submitted to two sets of ultrasound subcutaneous skin fold measurements spaced (mean + sem) 10.6 + 2.2 days apart. Per measurement, they stood relaxed as ultrasound measured the subcutaneous skin fold thickness that covered their left leg’s calf muscle group. Measurements occurred with a hand-held device (BodyMetrix Pro System BX2000; Livermore, CA) used in accordance with the manufacturer’s guidelines. Four subcutaneous measurements were made 90∘ apart (anterior, medial, posterior, lateral) at the portion of the left calf with the largest circumference. To assess intra-rater reliability, we used intraclass correlation coefficients, limits of agreement, coefficient of variation and the smallest real difference. RESULTS: Intra-rater reliability was high for most of our statistical tests. CONCLUSION: Despite the relatively long period between measurements, our hand-held ultrasound device exhibited a high degree of intra-rater reliability. Given our results, ultrasound measurements may be a useful tool to quantify skin fold thickness.