The Schwartz Cancer Fatigue Scale: testing reliability and validity.

PURPOSE/OBJECTIVES: To describe the psychometric development of the Schwartz Cancer Fatigue Scale (SCFS). DESIGN: A multiphase instrumentation study describing construct and operational definitions, informal and formal content validity, reliability, and validity analysis. SAMPLE: Content validity established with 20 subjects. Reliability and validity evaluated with 166 subjects residing in diverse parts of the United States. FINDINGS: Eleven items that failed to show variance, had high interitem correlations, or failed to discriminate were eliminated. Factor analysis resulted in a four-factor solution that accounted for 70% of the variance. Cronbach's alpha for the total scale was estimated to be 0.96 and to be between 0.82 and 0.93 for the subscales. CONCLUSIONS: The 28-item SCFS has demonstrated reliability and content and construct validity. Factor analysis supports the four subscales (physical, emotional, cognitive, and temporal). Preliminary construct validity has been demonstrated by differences in fatigue between those people who are currently receiving treatment and those who have completed treatment and by scores on a visual analogue scale of fatigue. IMPLICATIONS FOR NURSING PRACTICE: The SCFS may prove to be clinically relevant in assessing the effect of interventions to treat and manage cancer-related fatigue.