Methodological challenges in the use of hip-specific composite outcomes: linking measurements from hip fracture trials to the International Classification of Functioning, Disability and Health Framework.

INTRODUCTION

The prevalence of hip-specific outcome measures in randomized trials reflects what directs our outcome assessment following a hip fracture. The present study provides an overview on the most commonly-used hip-specific outcome instruments used for postoperative assessment of hip fracture with respect to their covered contents. This can facilitate the selection of appropriate items for specific purposes in clinical as well as research settings.

METHODS

We used the International Classification of Functioning, Disability and Health (ICF) model to distinguish concepts within the instrument. All items from the questionnaires were categorized into one of three categories using the ICF linking rules for a standardized approach. The hip-specific composites measures were also compared to other types of prevalent measures: generic and patient-based instruments.

RESULTS

All of the items in the instruments could be mapped to the ICF. We report the highest frequency of ICF activity and participation (71%) within the Harris hip score (HHS) which is similar to the frequency of ICF content found in the generic measures (82%). Hip-specific composites focused mostly on walking and moving long and short distances, while in patient-reported measures there was a concentration on the concept of sensation of pain and pain in body parts.

DISCUSSION AND CONCLUSION

The prevalent use of the HHS, over the other hip-specific instruments, could be attributed to its likeness in concept to other generic measures. The dominance of the ICF category of activity and participation reflects what is important to clinicians treating a hip fracture. Composite scores remain problematic as they cut across different ICF concepts. As long as the popularity of composite scoring systems continues, an overall score may not represent the true patient preferences and concerns in clinical trials. Future studies could apply the results from this study for the creation of an ICF category-based item banking or investigators could operationalize the ICF categories within these candidate measures for specific interventions.