Measures of physical functioning after hip fracture: construct validity and responsiveness of performance-based and self-reported measures.
OBJECTIVE
this study aimed to investigate the construct validity and responsiveness of performance-based and self-reported measures of strength, mobility and balance after hip fracture.


METHODS
secondary analysis of clinical trial data.


METHODS
a total of 148 older people undergoing hip fracture rehabilitation.


METHODS
correlation coefficients assessed construct validity. Internal responsiveness was assessed by calculating effect sizes (ES) I and II. Area under the receiver operating characteristic curve (AUC) assessed external responsiveness with change in EuroQol as the reference.


RESULTS
correlations between performance-based and self-reported measures were small to medium (strength r = 0.17, mobility r = 0.45 and balance r = 0.37). The most responsive performance-based measures included walking speed (ESI 1.7, ESII 1.2), Physical Performance and Mobility Examination (ESI 1.3, ESII 1.0) and chair-rise test (ESI 1.1, ESII 0.8). Self-reported mobility (ESI 0.8, ESII 0.6) and strength (ESI 0.8, ESII 0.6) were more responsive than self-reported balance (ESI 0.3, ESII 0.2). External responsiveness (AUC) was greatest for walking speed (0.72) and lowest for the measures of body sway (0.53).


CONCLUSIONS
self-reported and performance-based indices appear to assess different constructs and may provide complementary information about physical functioning in people after hip fracture. Measures of strength and mobility showed greater ability to detect change than measures of balance.
George Institute for Global Health, University of Sydney, Sydney, Australia. ifarag@georgeinstitute.org.au
I
I
Farag
C
C
Sherrington
S J
SJ
Kamper
M
M
Ferreira
A M
AM
Moseley
S R
SR
Lord
I D
ID
Cameron
D000368:Aged; D000369:Aged, 80 and over; D004185:Disability Evaluation; D005260:Female; D006620:Hip Fractures / Q000534:rehabilitation*; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D008297:Male; D051346:Mobility Limitation; D053580:Muscle Strength / Q000502:physiology; D017063:Outcome Assessment, Health Care; D004856:Postural Balance / Q000502:physiology; D011594:Psychometrics; D020127:Recovery of Function; D057566:Self Report; D011795:Surveys and Questionnaires; D013647:Task Performance and Analysis