The diagnostic accuracy of soft tissue oedema measurements: a systematic review and best-evidence synthesis

PURPOSE: Effective lymphoedema management relies on early detection and treatment during its reversible phase, underlining the importance of accurate measurement tools. This systematic review aims to identify measurement instruments for quantitatively diagnosing lymphoedema and their diagnostic accuracy. METHODS: Literature was systematically searched on the diagnostic accuracy of instruments for assessing soft tissue oedema across body parts in adults. Inclusion criteria encompassed studies establishing diagnostic accuracy (sensitivity and/or specificity) of instruments for quantifying oedema through volume changes, tissue characteristics, or lymphatic system function. Searches included Embase, Medline, Web of Science, and CINAHL databases from inception to March 18, 2024. Methodological quality was assessed using the COSMIN checklist for criterion validity and QUADAS-2. Diagnostic value was evaluated through the Youden index, and the level of evidence was established using a new best-evidence synthesis approach. RESULTS: A total of 44 studies were included, identifying 14 index measurement instruments. The most frequently studied instruments were tape measurements, ultrasound, and multi-frequency bio-impedance analysis (MF-BIA). Instruments with very high diagnostic value (Youden index ≥ 0.90) included MF-BIA, perometry, and MRI. However, the quality of evidence supporting these instruments was lacking. Nine different instruments served as references, with tape measurements, consensus criteria, and water volumetry being the most applied. CONCLUSION: This review underscores the complexity of accurately diagnosing lymphoedema, with no single instrument emerging as a definitive gold standard. Clinicians must weigh the available evidence and consider the clinical context, such as early detection, when selecting measurement instruments for diagnosing lymphoedema.