The Piper Fatigue Scale-12 (PFS-12): psychometric findings and item reduction in a cohort of breast cancer survivors

Abstract

Purpose Brief, valid measures of fatigue, a prevalent and distressing cancer symptom, are needed for use in research. This study’s primary aim was to create a shortened version of the revised Piper Fatigue Scale (PFS-R) based on data from a diverse cohort of breast cancer survivors. A secondary aim was to determine whether the PFS captured multiple distinct aspects of fatigue (a multidimensional model) or a single overall fatigue factor (a unidimensional model). Methods Breast cancer survivors (n=799; stages in situ through IIIa; ages 29–86 yrs) were recruited through 3 SEER registries (New Mexico, Western Washington, and Los Angeles, CA) as part of the Health, Eating, Activity, and Lifestyle (HEAL) study. Fatigue was measured approximately 3 years post-diagnosis using the 22-item PFS-R that has 4 subscales (Behavior, Affect, Sensory, and Cognition). Confirmatory factor analysis was used to compare unidimensional and multidimensional models. Six criteria were used to make item selections to shorten the PFS-R: scale’s content validity, items’ relationship with fatigue, content redundancy, differential item functioning by race and/or education, scale reliability, and literacy demand. Results Factor analyses supported the original 4-factor structure. There was also evidence from the bi-factor model for a dominant underlying fatigue factor. Six items tested positive for differential item functioning between African-American and Caucasian survivors. Four additional items either showed poor association, local dependence, or content validity concerns. After removing these 10 items, the reliability of the PFS-12 subscales ranged from 0.87–0.89, compared to 0.90–0.94 prior to item removal. Conclusion The newly developed PFS-12 can be used to assess fatigue in African-American and Caucasian breast cancer survivors and reduces response burden without compromising reliability or validity. This is the first study to determine PFS literacy demand and to compare PFS-R responses in African-Americans and Caucasian breast cancer survivors. Further testing in diverse populations is warranted.

Association of Fatigue Intensification with Cognitive Impairment during Radiation Therapy for Prostate Cancer

“…When tested in our patient population, rPFS has excellent internal consistency reliability with Cronbach’s α = 0.97; each item is coded on a 0–10 numeric scale and each subscale is scored individually [35, 36]. In particular, the rPFS cognitive/mood subscale has been used in studies to quantify perceived cognitive impairment/mood change in various patient populations [34, 37, 38].…”

The role of TRAIL in fatigue induced by repeated stress from radiotherapy

“…The rPFS has a standardized α of 0.97 and an inter-item correlation between 0.30–0.70 (Piper et al, 1998). Each item is coded on a 0–10 numeric scale and each subscale is scored individually (Piper and Cella, 2010; Piper et al, 1998; Reeve et al, 2012). …”

Deriving clinically meaningful cut-scores for fatigue in a cohort of breast cancer survivors: a Health, Eating, Activity, and Lifestyle (HEAL) Study

“…The 22-item PFS-R, and its shorter version, the 12-item PFS-12, have 4 subscales: Behavioral, Affective, Sensory, and Cognitive [37–38]. Subscale scores are added together and divided by 4 to obtain a total fatigue score bound between 0 and 10 where higher scores reflect more fatigue [37–38].…”

“…With these considerations in mind, the aim of our study was to empirically determine clinically meaningful fatigue severity thresholds (cut-scores within a 0–10 scale metric) for the 22-item Piper Fatigue Scale-revised (PFS-R) [37] and its shortened 12-item version (PFS-12) [38] in a cohort of breast cancer survivors. The PFS-R and PFS-12 are multidimensional and include key dimensions of the fatigue experience including cognition, behaviors, affect, and sensory symptoms [37–38].…”

“…The PFS-R and PFS-12 are multidimensional and include key dimensions of the fatigue experience including cognition, behaviors, affect, and sensory symptoms [37–38]. We examined five candidate models of fatigue severity thresholds where breast cancer survivors could be classified on the PFS-R or PFS-12 as none, mildly, moderately, or severely fatigued on a 0–10 metric.…”