Quantifying skin disease burden in mycosis fungoides-type cutaneous T-cell lymphomas - The severity-weighted assessment tool (SWAT)

Objective: To develop a quantitative tool to assess severity of mycosis fungoides. Design: Prospective analysis of a cohort. Setting: University department of dermatology-based cutaneous lymphoma clinic. Patients: From 1984 to 1995, 1186 visits from 323 referred patients seen in a multidisciplinary cutaneous lymphoma program. Main Outcome Measures: Severity-weighted assessment tool (SWAT) scores were obtained for patients at each visit. This score represents the product of the percentage total body surface area (%TBSA) involvement of each lesion type (patch, plaque, and tumor or ulceration), multiplied by a weighting factor: SWAT = (patch %TBSAX x 1)+(plaque %TBSA x 2) + (tumor or ulcer %TBSA x 3). In addition, the standard measurements of TBSA involvement and physician global assessments were recorded for comparison. Results: The SWAT score correlated well with %TBSA (r=0.95, P<.001), physician global assessment (r=0.60, P<.001), and time to complete remission during psoralen-UV-A therapy (r=0.80, P<001), therefore indicating validity against standard measures. Analysis of individual and subsets of patients demonstrated that the SWAT score more accurately quantified changes in skin disease burden, including mixed responses to treatment, than did %TBSA alone. Conclusions: The SWAT score is a useful clinical measurement for mycosis fungoides. The SWAT score captures overall physician impressions of disease status on a continuous dimensionless numerical scale, therefore providing a defined, objective, and sensitive quantitative measure. This tool is suitable for individual patient assessment, clinical trials, and outcome comparisons.