A comparison of frailty indexes for the prediction of falls, disability, fractures, and mortality in older men

Abstract

Objectives: To compare the validity of a parsimonious frailty index (components: weight loss, inability to rise from a chair, and poor energy (Study of Osteoporotic Fractures (SOF) index)) with that of the more complex Cardiovascular Health Study (CHS) index (components: unintentional weight loss, low grip strength, poor energy, slowness, and low physical activity) for prediction of adverse outcomes in older men.

Design: Prospective cohort study.

Setting: Six U.S. centers.

Participants: Three thousand one hundred thirty-two men aged 67 and older.

Measurements: Frailty status categorized as robust, intermediate stage, or frail using the SOF index and criteria similar to those used in CHS index. Falls were reported three times for 1 year. Disability (>or=1 new impairments in performing instrumental activities of daily living) ascertained at 1 year. Fractures and deaths ascertained during 3 years of follow-up. Analysis of area under the receiver operating characteristic curve (AUC) statistics compared for models containing the SOF index versus those containing the CHS index.

Results: Greater evidence of frailty as defined by either index was associated with greater risk of adverse outcomes. Frail men had a higher age-adjusted risk of recurrent falls (odds ratio (OR)=3.0-3.6), disability (OR=5.3-7.5), nonspine fracture (hazard ratio (HR)=2.2-2.3), and death (HR=2.5-3.5) (P<.001 for all models). AUC comparisons revealed no differences between models with the SOF index and models with the CHS index in discriminating falls (AUC=0.63, P=.97), disability (AUC=0.68, P=.86), nonspine fracture (AUC=0.63, P=.90), or death (AUC=0.71 for model with SOF index and 0.72 for model with CHS index, P=.19).

Conclusion: The simple SOF index predicts risk of falls, disability, fracture, and mortality in men as well as the more-complex CHS index.

Figure 1. Age-Adjusted Receiver Operating Characteristic (ROC) Curves for Prediction of (A) Recurrent Falls, (B) Disability, (C) Nonspine Fracture, and (D) Mortality with SOF and CHS Frailty Indices*

*The black diagonal line indicates a reference AUC of 0.50 (no better than chance alone)