Perometry as the most objective tool to measure arm swelling
Does this research and others have the evidence to indicate that it is the most objective tool to measure arm swelling?
Choice of relative arm volume increase (RAVI) >10%.
In the introduction, the authors state: “Proposed definitions for lymphoedema include:
(a) 200 ml limb volume difference
(b) 10% relative arm volume increase (RAVI)
(c) 2.0 cm circumferential difference at any point between arms and
(d) L-Dex bioimpedance increase of either 7.5 (2sd) or 10 units or greater.
They go onto state: “Arm measurements are not routine practice in Europe prior to axillary node clearance, but prospective studies have demonstrated that RAVI of ≥5% identifies increased risk of subsequent lymphoedema and is a suitable threshold for considering early intervention.”
In patients and methods, the authors state “The protocol (see supplementary data), predefined lymphoedema as a RAVI as equal to or >10% relative arm volume increase upper arm or lower arm or both from baseline (compared to the contralateral arm).” There is no rationale in the paper or the supplementary data to support this decision. Even if it was supported when the study commenced the body of evidence is that 10% is too late to stop the progression. The protocol should have been amended to reflect current evidence.
The use of L-Dex >7.5 or >10 is referenced to ImpediMed despite ImpediMed using 6.5 as the nearest to 2 SD rather than 7.5.
Figure 1 table
- The number on follow-up appears to be 1001 but 2 metrics (> 100 mL and > 200 mL) have n=1036.
- Symptoms of heaviness and swelling as well as QoL survey (FACT-B) appear to align better with BIS rather than perometry.
Discrepancies between paper and supplementary data.
Under the protocol heading in supplementary data the authors state: “Indeed, by 24 months, 25.5% of patients had a volume greater than 200ml…”. However, Figure 1 table shows 68% at 24 months. Which is correct?
The abstract states 24.5% underwent sleeve application but there are multiple numbers in the paper these include:
In the results: “Sensitivity and specificity of BIS and RAVI were compared to the 221 patients with a compression-sleeve application (a clinical surrogate for lymphoedema) between 3 and 24 months.”If the number is 221 then 24.5% means the total is 902, where does the 902 come from?
Progression of Lymphoedema: “At sleeve application 187 patients had a RAVI < 20% but despite the compression-sleeves application for 22 (IQR 11–33) months, progression to RAVI ≥ 20% occurred in 29 cases (15.7%).” The data suggests 34 patients had RAVI of >20% when the intervention was commenced.
The supplementary data table S5 shows patients who progressed but there are 3 triggers for intervention – <5%; >5<10%;>10<20% not just RAVI of 10%. The paper states that progression in lymphoedema occurred in 15% of patients despite the use of compression garments for ~22 months. Why did the researchers let the lymphoedema progress for such a long period without further intervention? It is also unclear what type of compression garment was prescribed. The only information provided is that it was a circular-knit compression- sleeve garment. What level of compression was it? Was this consistent across centres? I am a clinician, not a researcher but when I find discrepancies or don’t understand the findings in a research paper I do question the conclusions of that research. I do agree with the authors that “BIS alone for screening for lymphoedema is not recommended”. It never has been. Clinicians know that assessment must include a variety of tools and decisions should never be reliant on one tool. BIS remains a valuable part of my assessment repertoire when screening for lymphoedema. [/av_textblock] [/av_one_full]