Longitudinal construct validity of the Health Utilities Indices Mark 2 and Mark 3 in hip fracture

Abstract

The objective of this study is to evaluate the longitudinal construct validity of the Health Utilities Index Mark 2 (HUI2) and Health Utilities Index Mark 3 (HUI3) using a convergent/divergent validity approach in patients recovering from hip fracture, with the Functional Independence Measure (FIM) as the comparator. A total of 278 patients with a primary diagnosis of hip fracture were interviewed 3-5days after surgery and then at 1 and 6months using the HUI2, HUI3 and the FIM and a Likert-type rating of hip pain. A priori hypotheses were formulated. Convergent and divergent correlations between HUI2, HUI3 and FIM change scores for the baseline to 1-month and baseline to 6-month intervals were examined. Overall HUI2 detected continued gain in health-related quality of life between 1 and 6months after fracture, as the change increased from 0.20 to 0.29 units. The correlation between change in the overall HUI2 score and total FIM score was moderate (r=0.50) over the 6-month interval, but larger than the observed correlation over the 1-month interval (r=0.36). The correlation between change in overall HUI3 score and total FIM over the 1-month interval was small (r=0.32), and the correlation between change in overall HUI3 score and total FIM was moderate (r=0.37) over the 6-month interval. All hypotheses for the divergent correlations were supported. Weaker correlations were reported for change over 1month as compared to change over the 6months after fracture. Findings supported the longitudinal construct validity of the overall HUI2 and HUI3 for the assessment of recovery following hip fracture, particularly for change over the 6months following fracture.