Validity of the Foot and Ankle Ability Measure (FAAM) in Diabetes Mellitus

The Foot and Ankle Ability Measure (FAAM) has been shown to be reliable, valid, and responsive in a general orthopaedic population. The purpose of this study was to evaluate validity for the FAAM in individuals with diabetes. It was hypothesized that FAAM scores would relate to measures of physical function while not correspond to measures of mental health. It was also hypothesized that FAAM scores would be different based on reported general health.

Eighty-three subjects with diabetes and foot and ankle related complaints completed intake information during a routine clinical visit. Subjects had an average age of 60.3 (range, 21 to 93; SD 13.7) years. Subjects were grouped based on their reported general health with 55 (64.7%) and 28 (32.9%), reporting excellent-good and fair-poor general health, respectively. Pearson correlation coefficients were used to assess the relationship between the FAAM and SF-36. As evidence for discriminative validity, one-way ANOVA was used to determine if FAAM scores could distinguish between individuals that reported excellent-good from those that reported fair-poor levels of general health.

The FAAM had high correlation to the SF-36 physical function subscale (r > 0.60) and physical component summary score (r > 0.70) and significantly (p < 0.005) lower correlation to the mental health subscale (r < 0.33) and mental component summary score (r < 0.30). One-way ANOVA found those that reported excellent-good general health scored significantly higher on the ADL subscale (57 vs 44 [F(1,82) = 4.6, p = 0.035]) but did score differently on the Sports subscales (32 vs 22 [F(1,70)=1.7, p = 0.20]).

This study offers evidence of validity for the FAAM ADL subscale as an outcome instrument to measure physical function in individuals with diabetes and foot and/or ankle related disorders. Further research is needed for the Sports subscale in individuals with diabetes who are functioning at a higher level.