Heterogeneity in hip fracture patients: age, functional status, and comorbidity.

OBJECTIVES: To examine unidentified heterogeneity in hip fracture patients that may predict variation in functional outcomes.
DESIGN: Observational, longitudinal, multisite cohort study.
SETTING: Three separate cohorts from five hospitals in the metropolitan New York area and eight hospitals in Baltimore. PARTICIPANTS: Two thousand six hundred ninety-two hip fracture patients treated at one of 13 hospitals and followed for 6 months postfracture. MEASUREMENTS: A mobility measure with three categories (independent (walks independently or with a device), limited independence (needs human assistance or supervision to walk 150 feet or one block or able only to walk indoors), and unable to walk) was developed for use with all three cohorts. A similar measure was developed for the other activities of daily living (ADLs): bathing, dressing, feeding, and using the toilet. Cluster analysis was used to form homogenous groups of patients based on baseline demographic characteristics, comorbid conditions, and baseline mobility and ADL independence.
RESULTS: Seven homogeneous subgroups were identified based on prefracture age, health, and functional status, with measurably different 6-month functional outcomes. At least 90% of patients could be correctly classified into the seven groups using simple decision rules about age, ADLs, and dementia status at baseline. Dementia was the only comorbid condition that segmented the groups.
CONCLUSION: The heterogeneous hip fracture population can be grouped into homogenous patient clusters based on prefracture characteristics. Differentially targeting services and interventions to these subgroups may improve functional status outcomes.