Development and psychometric properties of the Functional Assessment of Cancer Therapy-Cutaneous T-Cell Lymphoma (FACT-CTCL) instrument.

Background: Patients with mycosis fungoides (MF)/Sézary Syndrome (SS) can experience impacted health-related quality of life (HRQoL).

Objectives: To validate the CTCL-S, a novel subscale of the Functional Assessment of Cancer Therapy-General (FACT-G), in patients with MF/SS.

Methods: Qualitative interviews were conducted with expert clinicians and patients with MF/SS. Thematic analysis identified the most common concerns, and 19 items were selected. Patients with MF/SS were recruited from a single centre. FACT-G, CTCL-S (collectively 'FACT-CTCL'), Skindex-29 and Visual Analogue Scale-Pruritis (VAS-itch) were administered. A subset repeated FACT-CTCL and VAS-itch after ≈2 weeks. Patient demographics and clinical characteristics were obtained via review of the electronic medical records. Psychometric properties were assessed. Internal consistency was estimated using Cronbach's α. Convergent and discriminant validity were assessed by comparing CTCL-S with disease stage, age, VAS-itch, FACT-G and Skindex-29. Exploratory factor analysis (EFA) was used to preliminarily assess CTCL-S dimensionality. Test-retest repeatability was summarized using intraclass correlation coefficient (ICC), within-subject standard deviation and within-subject coefficient of variation.

Results: Seventy-two patients completed the initial survey, and 35 repeated the FACT-CTCL and VAS-itch after ≈2 weeks. Two-thirds were men; most were White (78%). The majority (85%) had MF, 15% had SS and 75% early (stage IA-IIA) and 25% advanced (≥ stage IIB) disease. Preliminary EFA found a single predominant factor, supporting a hypothesis of unidimensionality of the CTCL-S. Internal consistency of the CTCL-S was high, with α = 0.95 [95% confidence interval (CI) 0.93-0.96]. There was no significant change in CTCL-S average test-retest scores [ICC 0.93 (P = 0.63)]. CTCL-S was significantly lower in advanced vs. early-stage disease [median (interquartile range) 34 (26-48) vs. 59 (44-68), P < 0.001] and strongly correlated with VAS-itch [Spearman's r (rs) -0.70, 95% CI -0.81 to -0.55], FACT-G (rs 0.77, 95% CI 0.65-0.85) and Skindex-29 (rs -0.90, 95% CI -0.94 to -0.84), supporting convergent validity. CTCL-S scores had little correlation with age (rs 0.19, 95% CI -0.05 to 0.41, P = 0.12), supporting discriminant validity.

Conclusions: The FACT-CTCL is a disease-specific instrument for assessing HRQoL with high reproducibility and good performance in a cohort of patients with MF/SS.