Safety on stairs: influence of a tread edge highlighter and its position.
BACKGROUND
Falls sustained when descending stairs are the leading cause of accidental death in older adults. Highly visible edge highlighters/friction strips (often set back from the tread edge) are sometimes used to improve stair safety, but there is no evidence for the usefulness of either.


OBJECTIVE
To determine whether an edge highlighter and its location relative to the tread edge affect foot placement/clearance and accidental foot contacts when descending stairs.


METHODS
Sixteen older adults (mean±1SD age; 71±7years) with normal vision (experiment 1) and eight young adults (mean±1SD age; 24±4years) with visual impairment due to simulated age-related cataract (experiment 2) completed step descent trials during which a high contrast edge highlighter was either not present, placed flush with the tread edge, or set back from the edge by 10mm or 30mm. Foot placement/clearance and the number of accidental foot contacts were compared across conditions.


RESULTS
In experiment 1, a highlighter set back by 30mm led to a reduction in final foot placement (p<0.001) and foot clearance (p<0.001) compared to a highlighter placed flush with the tread edge, and the percentage of foot clearances that were less than 5mm increased from 2% (abutting) to 17% (away30). In experiment 2, a highlighter placed flush with the tread edge led to a decrease in within-subject variability in final foot placement (p=0.004) and horizontal foot clearance (p=0.022), a decrease in descent duration (p=0.009), and a decrease in the number of low clearances (<5mm, from 8% to 0%) and the number of accidental foot contacts (15% to 3%) when compared to a tread edge with no highlighter present.


CONCLUSIONS
Changes to foot clearance parameters as a result of highlighter presence and position suggest that stairs with high-contrast edge highlighters positioned flush with the tread edge will improve safety on stairs, particularly for those with age-related visual impairment.
Bradford School of Optometry and Vision Science, University of Bradford, Bradford, West Yorkshire, BD7 1DP, UK. Electronic address: R.Foster2@bradford.ac.uk.
Richard J
RJ
Foster
Division of Medical Engineering, School of Engineering, University of Bradford, Bradford, West Yorkshire, BD7 1DP, UK.
John
J
Hotchkiss
Division of Medical Engineering, School of Engineering, University of Bradford, Bradford, West Yorkshire, BD7 1DP, UK.
John G
JG
Buckley
Bradford School of Optometry and Vision Science, University of Bradford, Bradford, West Yorkshire, BD7 1DP, UK.
David B
DB
Elliott
D000056:Accident Prevention / Q000379:methods*; D000058:Accidental Falls / Q000517:prevention & control*; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology; D002386:Cataract / Q000150:complications; D005260:Female; D005528:Foot / Q000502:physiology; D005684:Gait / Q000502:physiology; D006801:Humans; D008297:Male; D011434:Proprioception / Q000502:physiology; D012449:Safety; D015354:Vision, Low / Q000209:etiology / Q000503:physiopathology*; D055815:Young Adult
Falls; Stair descent; Stair safety; Tread edge highlighter; Trip risk; Visual impairment