A comparison of fatigue scales in postpoliomyelitis syndrome.

Abstract

To examine the applicability and validity of traditional fatigue questionnaires in postpoliomyelitis syndrome (PPS) patients with disabling fatigue. Cross-sectional study. PPS and disabling fatigue were ascertained according to published criteria. Descriptiveness was determined using the McNemar test, and interscale z-score agreement was estimated with Pearson's coefficients. PPS clinic. Fifty-six survivors of poliomyelitis: 39 met criteria for PPS, 25 of whom met criteria for disabling fatigue. Not applicable. The Fatigue Severity Scale (FSS), visual analog scale (VAS) for fatigue, and Fatigue Impact Scale (FIS). Twenty-four patients scored 50% or higher on the scale range for FSS, compared with 19 patients for VAS for fatigue (P=.042), and 7 patients for FIS (P<.001). Scores for patients with disabling fatigue averaged 81.5%, 62%, and 40.9% of the scale range for FSS, VAS for fatigue, and FIS, respectively. Agreement was moderate between the FSS and VAS for fatigue (r=.45, P=.02), but low between FSS and FIS (r=.29, P=.15), and FIS and VAS for fatigue (r=.20, P=.33). Two sample t tests showed significant differences between those with disabling fatigue and those without, based on FSS scores (t=3.8, P<.001), but not for VAS for fatigue or FIS scores. FSS was the most descriptive of the instruments tested. Scores generated by the scales were not interchangeable. Of the 3 scales, FFS seemed to be the most informative for the clinical assessment of fatigue in patients with PPS.