Performance of the Swedish version of the Revised Piper Fatigue Scale

Abstract

PurposeThe Revised Piper Fatigue scale is one of the most widely used instruments internationally to assess cancer-related fatigue. The aim of the present study was to evaluate selected psychometric properties of a Swedish version of the RPFS (SPFS). MethodsAn earlier translation of the SPFS was further evaluated and developed. The new version was mailed to 300 patients undergoing curative radiotherapy. The internal validity was assessed using Principal Axis Factor Analysis with oblimin rotation and multitrait analysis. External validity was examined in relation to the Multidimensional Fatigue Inventory-20 (MFI-20) and in known-groups analyses. ResultsTotally 196 patients (response rate = 65%) returned evaluable questionnaires. Principal axis factoring analysis yielded three factors (74% of the variance) rather than four as in the original RPFS. Multitrait analyses confirmed the adequacy of scaling assumptions. Known-groups analyses failed to support the discriminative validity. Concurrent validity was satisfactory. ConclusionThe new Swedish version of the RPFS showed good acceptability, reliability and convergent and- discriminant item-scale validity. Our results converge with other international versions of the RPFS in failing to support the four-dimension conceptual model of the instrument. Hence, RPFS suitability for use in international comparisons may be limited which also may have implications for cross-cultural validity of the newly released 12-item version of the RPFS. Further research on the Swedish version should address reasons for high missing rates for certain items in the subscale of affective meaning, further evaluation of the discriminative validity and assessment of its sensitivity in detecting changes over time.