There is no consensus regarding the most reliable and valid measures of cognitive dysfunction in adolescents and adults with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The Wood Mental Fatigue Inventory (WMFI) is commonly used in adults while the Pediatric Quality of Life Multidimensional Fatigue Scale (PedsQL MFS) is commonly used in adolescents. This study examined whether the WMFI was valid in adolescents. Over a two-year period, participants in a cohort study completed four questionnaires: PedsQL, PedsQL MFS, Functional Disability Inventory (FDI), and WMFI. We examined the validity of the WMFI in 55 healthy adolescents and 55 with ME/CFS, determined how well the WMFI and PedsQL MFS cognitive fatigue subscale correlated with one another and with general quality of life surveys, and examined each questionnaire’s responsiveness to change over time. The PedsQL MFS cognitive fatigue subscale and the WMFI had a strong negative correlation for both healthy controls and ME/CFS patients at baseline with R 2 values of .3915 and .8049 respectively. There was a similar strong negative correlation (R 2 = .7739) between the two questionnaires in ME/CFS participants at the 24 month point of follow-up after multi-modal treatment. Each questionnaire was found to be similarly responsive to change. The WMFI had a high correlation with the PedsQL MFS cognitive fatigue subscale . The WMFI has the advantage of ease of scoring. Both measures were responsive to changes in mental fatigue among those with ME/CFS over time.
Welch et al. (Wed,) studied this question.