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Reproducibility and day time bias correction of optoelectronic leg volumetry: a prospective cohort study.

Engelberger RP, Blazek C, Amsler F, Keo HH, Baumann F, Blättler W, Baumgartner I, Willenberg T - BMC Med Res Methodol (2011)

Bottom Line: Reproducibility was expressed as analytical and within-individual coefficients of variance (CVA, CVW), and as intra-class correlation coefficients (ICC).A total of 492 leg volume measurements were analysed.A therefore determined time-correction formula permitted further improvement of CVW.

View Article: PubMed Central - HTML - PubMed

Affiliation: Swiss Cardiovascular Center, Division of Clinical and Interventional Angiology Inselspital, University Hospital and University of Bern, Switzerland.

ABSTRACT

Background: Leg edema is a common manifestation of various underlying pathologies. Reliable measurement tools are required to quantify edema and monitor therapeutic interventions. Aim of the present work was to investigate the reproducibility of optoelectronic leg volumetry over 3 weeks' time period and to eliminate daytime related within-individual variability.

Methods: Optoelectronic leg volumetry was performed in 63 hairdressers (mean age 45 ± 16 years, 85.7% female) in standing position twice within a minute for each leg and repeated after 3 weeks. Both lower leg (legBD) and whole limb (limbBF) volumetry were analysed. Reproducibility was expressed as analytical and within-individual coefficients of variance (CVA, CVW), and as intra-class correlation coefficients (ICC).

Results: A total of 492 leg volume measurements were analysed. Both legBD and limbBF volumetry were highly reproducible with CVA of 0.5% and 0.7%, respectively. Within-individual reproducibility of legBD and limbBF volumetry over a three weeks' period was high (CVW 1.3% for both; ICC 0.99 for both). At both visits, the second measurement revealed a significantly higher volume compared to the first measurement with a mean increase of 7.3 ml ± 14.1 (0.33% ± 0.58%) for legBD and 30.1 ml ± 48.5 ml (0.52% ± 0.79%) for limbBF volume. A significant linear correlation between absolute and relative leg volume differences and the difference of exact day time of measurement between the two study visits was found (P < .001). A therefore determined time-correction formula permitted further improvement of CVW.

Conclusions: Leg volume changes can be reliably assessed by optoelectronic leg volumetry at a single time point and over a 3 weeks' time period. However, volumetry results are biased by orthostatic and daytime-related volume changes. The bias for day-time related volume changes can be minimized by a time-correction formula.

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Related in: MedlinePlus

Absolute legBD difference between visit 1 and 2 (calculated by subtracting the legBD from visit 2 minus legBD from visit 1) plotted against the time difference of measurement (calculated by: exact daytime of measurement at visit 2 - the exact daytime of measurmeent at visit 1) . legBD, lower leg without the foot (from B-measure to D-measure)
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Figure 2: Absolute legBD difference between visit 1 and 2 (calculated by subtracting the legBD from visit 2 minus legBD from visit 1) plotted against the time difference of measurement (calculated by: exact daytime of measurement at visit 2 - the exact daytime of measurmeent at visit 1) . legBD, lower leg without the foot (from B-measure to D-measure)

Mentions: We found a significant linear correlation between the exact daytime and leg volume measurements for both legBD (r2 = 0.05, P = .01) and limbBF (r2 = 0.08, P = .001). After statistical adjustment for body mass index (BMI), this correlation was no longer significant. Furthermore, a significant linear correlation was found for the leg volume change (absolute and relative) between the two visits and the difference of exact time of leg volume measurement between the two visits, as illustrated in Figure 1 and 2. Adjustment for BMI, age, sex, and severity of venous disease according to the CEAP classification did not alter this correlation. For each hour of difference between the exact measurement time points at each visit, a mean absolute legBD difference of 6.2 ml (95% CI: 3.5 - 9.0 ml) was observed (r2 = 0.14, P < .001), corresponding to a mean relative legBD difference of 0.29% (95% CI: 0.16 - 0.41%, r2 = 0.15, P < .001) per hour of difference. This resulted in a time-correction formula for the legBD:


Reproducibility and day time bias correction of optoelectronic leg volumetry: a prospective cohort study.

Engelberger RP, Blazek C, Amsler F, Keo HH, Baumann F, Blättler W, Baumgartner I, Willenberg T - BMC Med Res Methodol (2011)

Absolute legBD difference between visit 1 and 2 (calculated by subtracting the legBD from visit 2 minus legBD from visit 1) plotted against the time difference of measurement (calculated by: exact daytime of measurement at visit 2 - the exact daytime of measurmeent at visit 1) . legBD, lower leg without the foot (from B-measure to D-measure)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3198754&req=5

Figure 2: Absolute legBD difference between visit 1 and 2 (calculated by subtracting the legBD from visit 2 minus legBD from visit 1) plotted against the time difference of measurement (calculated by: exact daytime of measurement at visit 2 - the exact daytime of measurmeent at visit 1) . legBD, lower leg without the foot (from B-measure to D-measure)
Mentions: We found a significant linear correlation between the exact daytime and leg volume measurements for both legBD (r2 = 0.05, P = .01) and limbBF (r2 = 0.08, P = .001). After statistical adjustment for body mass index (BMI), this correlation was no longer significant. Furthermore, a significant linear correlation was found for the leg volume change (absolute and relative) between the two visits and the difference of exact time of leg volume measurement between the two visits, as illustrated in Figure 1 and 2. Adjustment for BMI, age, sex, and severity of venous disease according to the CEAP classification did not alter this correlation. For each hour of difference between the exact measurement time points at each visit, a mean absolute legBD difference of 6.2 ml (95% CI: 3.5 - 9.0 ml) was observed (r2 = 0.14, P < .001), corresponding to a mean relative legBD difference of 0.29% (95% CI: 0.16 - 0.41%, r2 = 0.15, P < .001) per hour of difference. This resulted in a time-correction formula for the legBD:

Bottom Line: Reproducibility was expressed as analytical and within-individual coefficients of variance (CVA, CVW), and as intra-class correlation coefficients (ICC).A total of 492 leg volume measurements were analysed.A therefore determined time-correction formula permitted further improvement of CVW.

View Article: PubMed Central - HTML - PubMed

Affiliation: Swiss Cardiovascular Center, Division of Clinical and Interventional Angiology Inselspital, University Hospital and University of Bern, Switzerland.

ABSTRACT

Background: Leg edema is a common manifestation of various underlying pathologies. Reliable measurement tools are required to quantify edema and monitor therapeutic interventions. Aim of the present work was to investigate the reproducibility of optoelectronic leg volumetry over 3 weeks' time period and to eliminate daytime related within-individual variability.

Methods: Optoelectronic leg volumetry was performed in 63 hairdressers (mean age 45 ± 16 years, 85.7% female) in standing position twice within a minute for each leg and repeated after 3 weeks. Both lower leg (legBD) and whole limb (limbBF) volumetry were analysed. Reproducibility was expressed as analytical and within-individual coefficients of variance (CVA, CVW), and as intra-class correlation coefficients (ICC).

Results: A total of 492 leg volume measurements were analysed. Both legBD and limbBF volumetry were highly reproducible with CVA of 0.5% and 0.7%, respectively. Within-individual reproducibility of legBD and limbBF volumetry over a three weeks' period was high (CVW 1.3% for both; ICC 0.99 for both). At both visits, the second measurement revealed a significantly higher volume compared to the first measurement with a mean increase of 7.3 ml ± 14.1 (0.33% ± 0.58%) for legBD and 30.1 ml ± 48.5 ml (0.52% ± 0.79%) for limbBF volume. A significant linear correlation between absolute and relative leg volume differences and the difference of exact day time of measurement between the two study visits was found (P < .001). A therefore determined time-correction formula permitted further improvement of CVW.

Conclusions: Leg volume changes can be reliably assessed by optoelectronic leg volumetry at a single time point and over a 3 weeks' time period. However, volumetry results are biased by orthostatic and daytime-related volume changes. The bias for day-time related volume changes can be minimized by a time-correction formula.

Show MeSH
Related in: MedlinePlus