Purpose: To empirically determine clinically meaningful cut-scores on the 0-10 response scale of the revised Piper Fatigue Scale (PFS-R) and its shorter version (PFS-12). Breast cancer survivors were classified (i.e., none, mild, moderate, or severe fatigue) based on the cut-scores, and relationships between these cut-scores and decrements in health-related quality of life (HRQOL) were examined.
Methods: A total of 857 breast cancer survivors, stages in situ-IIIa, from the Health, Eating, Activity, and Lifestyle (HEAL) Study were eligible. Survivors completed the PFS-R, SF-36, and a sexual health scale approximately 3 years after diagnosis. Multivariate analysis of covariance was used to examine five fatigue severity cut-score models, controlling for demographics, clinical characteristics, comorbidity, and antidepressant use. Multivariate regression was used to examine HRQOL decrements by cut-score category.
Results: Analyses supported two similar fatigue severity cut-score models for the PFS-R and PFS-12: Model A.) none (0), mild (1-3), moderate (4-6), and severe (7-10); and Model D.) none (0), mild (1-2), moderate (3-5), and severe (6-10). For every threshold increase in fatigue severity, clinically meaningful decrements in physical, mental, and sexual health scores were observed, supporting construct validity of the fatigue cut-scores.
Conclusion: Standardized fatigue cut-scores may enhance interpretability and comparability across studies and populations and guide treating planning.