Measurement of Lower Limb Volume: Agreement Between Optoelectronic Perometer and Water Volumeter method, and Test-retest Reliability of Separate Methods In Healthy Human Participants.

Abstract

Question - To investigate the test-retest reliability of separate methods and agreement between lower limb volume measurements for the optoelectronic perometer and water volumetry method. Design - A Quantitative, between methods agreement and test-retest reliability study Participants - Fifteen healthy university students (8 women and 7 men) were recruited using convenience sampling with no participant dropouts. Intervention - All participants dominant lower limb volumes were measured 3 times using water volumetry and optoelectronic perometer methods. Outcome measures - Test-retest reliability and standard error of measurement for volumetry and perometer were evaluated using the ICC (3,1) model. Between methods agreement was reported using Bland-Altman difference plot illustrated by the (± 1.96 x SD) from the mean and a one sample t Test respectively. Results - Test-retest reliability for both the perometer and water volumeter was: ICC (3,1) = 0.994 and ICC (3,1) = 0.986 respectively. The standard error of measurement for volumetry and perometer was clinically acceptable. A lack of agreement between methods was observed. The Bland-Altman difference plot showed the perometer method consistently overestimated lower limb volume by 832ml compared to the volumeter. The upper (1444.59ml) and lower (219.33ml) levels of agreement were observed. Conclusion - Both methods are suitable for the measurement of lower limb volume. There was a lack of agreement between the two methods. Therefore, suggesting water volumeter and perometer are not interchangeable. A standardised protocol was developed which facilitated the excellent test-retest reliability for both measurement methods. Further protocol development and studies conducted on a special clinical population is recommended.