Comparative analysis of the International Society of Lymphology and Taiwan Lymphoscintigraphy Staging systems: correlation, reliability, and a quantitative severity index in extremity lymphedema.

Abstract

Background: The accurate assessment and staging of lymphedema are critical for effective management. This study sought to compare the International Society of Lymphology (ISL) staging system with the Taiwan Lymphoscintigraphy Staging (TLS) system, and to evaluate the reliability of both lymphedema staging systems.

Methods: A retrospective study of patients with primary or secondary extremity lymphedema was conducted. Lymphedema was staged using both the ISL staging system and the TLS system. The correlation between the systems was analyzed using the Spearman's rank correlation coefficient, and the inter- and intra-observer reliability of the TLS system was assessed using the intraclass correlation coefficient (ICC). A severity index based on limb circumference differences adjusted for body mass index (BMI) was also developed, and its correlation with both staging systems was verified by a one-way analysis of variance (ANOVA) analysis.

Results: In total, 50 patients (mean age: 56.1±12.9 years, BMI: 24.7±3.6 kg/m²) were included in the study. A statistically significant correlation was found between the ISL staging system and the TLS system (r=0.49, P<0.05). The severity index was also significantly correlated with the ISL staging system (r=0.56, P<0.05) and the TLS system (r=0.37, P<0.05). Additionally, both systems showed high inter- and intra-observer reliability (ICC >0.90). The ANOVA results revealed significant differences in the severity index among the different ISL staging system stages and TLS system grades (P<0.05), highlighting the utility of the severity index in distinguishing varying levels of lymphedema severity.

Conclusions: The ISL staging system and the TLS system showed strong agreement and reliability. The TLS system, with its quantitative imaging approach, is particularly suited for research, while the ISL staging system remains useful for routine clinical practice. The severity index offers an effective quantitative measure for assessing lymphedema severity.