Page 122 - REV T-I JOURNAL INTERIOR ISSUU 18 2-3

198 HIGHSMITH ET AL.

Table 3. Mean/Median Stair Performance
Table 3. Mean/Median Stair Performance
Instrument HAI SAI

Condition Uphill Downhill Ascent Descent
Time (sec) mean SD mean SD mean SD mean SD

Trial 1 4.71 0.86 4.80 1.14 4.95 1.01 3.82 0.97
Trial 2 4.71 0.99 4.74 1.19 5.15 1.62 3.72 0.80

Trial 3 4.72 1.03 4.78 1.40 4.68 1.33 3.61 0.80
% diff 0.11% -- 1.07% -- 6.72% -- 2.76% --

Score mean median mean median mean median mean median
Trial 1 10.8 11.0 10.9 11.0 9.7 11.0 12.0 11.0

Trial 2 10.8 11.0 10.9 11.0 9.9 11.0 11.7 11.0
Trial 3 10.8 11.0 10.9 11.0 10.1 11.0 11.8 11.0

The specificity of the HAI was determined to be Assessment of intra-rater reliability for the HAI

good for uphill and adequate for downhill assessment. was found to be good for uphill but adequate for
The lower specificity on ramp descent was a result of downhill gait in this sample based on the strength

some subjects being scored by the raters as having of correlation (Spearman’s Rho). These results were
asymmetrical step length although they actually had identical to the inter-rater reliability in this sample,
symmetrical step lengths based on having step length with uphill being found as good and downhill being
DoA below 0.1. This could mean that identifying step found as adequate. The downhill inter-rater reliability
length symmetry during ramp descent may be more assessment was adequate. These results differ slightly
difficult and there is the potential for an increased from the results of previous work, which found excel-
rate of false positives (i.e., giving a lower HAI score lent inter-rater reliability in a more heterogeneous
for step symmetry). The negative likelihood ratios sample of TFA subjects utilizing C-Leg MPKs (2).
confirm that the HAI is a “sometimes useful” test for The modest differences could be multi-factorial and
both uphill and downhill assessments of hill gait. In potentially include sample heterogeneity, rater expe-
summary, the HAI was found to be an adequate to rience and background, a lack of scoring instructions
excellent assessment tool of step length symmetry for the instrument, slight performance interpretation
during uphill and downhill gait of subjects in this differences, and other factors.
sample. The assessment was found to be more sen- The consistency of HAI times, with a percent
sitive for downhill assessment and more specific for change in time of 0.1% and 1.1% for ascent and
uphill in high-functioning persons with unilateral descent, respectively, and the reliability of uphill HAI
TFA. Due to the lower specificity in ramp descent, scores among trials provide some evidence of the
low scores may be vulnerable to false results in this instrument’s stability on repeat testing within a single
population. However, due to the good and excellent visit. Based on the negligible differences in time to
sensitivity of the HAI, lower scores should truly iden- ambulate on the ramp and HAI scores, no learning or
tify those with less symmetrical step length during fatigue effects were noted in this sample. This internal
ramp gait. consistency commonly suggests no benefit between