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Comparison of 2 Frailty Indexes for Prediction of Falls, Disability, Fractures, and Death in Older Women
Kristine E. Ensrud, MD, MPH;
Susan K. Ewing, MS;
Brent C. Taylor, PhD;
Howard A. Fink, MD, MPH;
Peggy M. Cawthon, PhD;
Katie L. Stone, PhD;
Teresa A. Hillier, MD, MS;
Jane A. Cauley, DrPH;
Marc C. Hochberg, MD;
Nicolas Rodondi, MD, MAS;
J. Kathleen Tracy, PhD;
Steven R. Cummings, MD; for the Study of Osteoporotic Fractures Research Group
Arch Intern Med. 2008;168(4):382-389.
Background Frailty, as defined by the index derived from the Cardiovascular Health Study (CHS index), predicts risk of adverse outcomes in older adults. Use of this index, however, is impractical in clinical practice.
Methods We conducted a prospective cohort study in 6701 women 69 years or older to compare the predictive validity of a simple frailty index with the components of weight loss, inability to rise from a chair 5 times without using arms, and reduced energy level (Study of Osteoporotic Fractures [SOF index]) with that of the CHS index with the components of unintentional weight loss, poor grip strength, reduced energy level, slow walking speed, and low level of physical activity. Women were classified as robust, of intermediate status, or frail using each index. Falls were reported every 4 months for 1 year. Disability ( 1 new impairment in performing instrumental activities of daily living) was ascertained at 4 years, and fractures and deaths were ascertained during 9 years of follow-up. Area under the curve (AUC) statistics from receiver operating characteristic curve analysis and –2 log likelihood statistics were compared for models containing the CHS index vs the SOF index.
Results Increasing evidence of frailty as defined by either the CHS index or the SOF index was similarly associated with an increased risk of adverse outcomes. Frail women had a higher age-adjusted risk of recurrent falls (odds ratio, 2.4), disability (odds ratio, 2.2-2.8), nonspine fracture (hazard ratio, 1.4-1.5), hip fracture (hazard ratio, 1.7-1.8), and death (hazard ratio, 2.4-2.7) (P < .001 for all models). The AUC comparisons revealed no differences between models with the CHS index vs the SOF index in discriminating falls (AUC = 0.61 for both models; P = .66), disability (AUC = 0.64; P = .23), nonspine fracture (AUC = 0.55; P = .80), hip fracture (AUC = 0.63; P = .64), or death (AUC = 0.72; P = .10). Results were similar when –2 log likelihood statistics were compared.
Conclusion The simple SOF index predicts risk of falls, disability, fracture, and death as well as the more complex CHS index and may provide a useful definition of frailty to identify older women at risk of adverse health outcomes in clinical practice.
Author Affiliations: Center for Chronic Disease Outcomes Research, Veterans Affairs Medical Center, and Department of Medicine and Division of Epidemiology and Community Health, University of Minnesota, Minneapolis (Drs Ensrud, Taylor, and Fink); Department of Epidemiology and Biostatistics, University of California, San Francisco (Ms Ewing), and Research Institute, California Pacific Medical Center (Drs Cawthon, Stone, and Cummings), San Francisco; Center for Health Research, Kaiser Permanente Northwest/Hawaii, Portland, Oregon (Dr Hillier); Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania (Dr Cauley); Departments of Medicine (Dr Hochberg) and Epidemiology (Dr Tracy), University of Maryland, Baltimore; and University Outpatient Clinic, Department of Community Medicine and Public Health, University of Lausanne, Lausanne, Switzerland (Dr Rodondi).
Group Information: A list of the Study of Osteoporotic Fractures Research Group was published in Arch Intern Med. 2007;167(2):138.
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