Development and validation of a frailty index compatible with three interRAI assessment instruments

Rebecca Abey-Nesbit, Ulrich Bergler, John W Pickering, Prasad S Nishtala, Hamish Jamieson

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BACKGROUND: a Frailty Index (FI) calculated by the accumulation of deficits is often used to quantify the extent of frailty in individuals in specific settings. This study aimed to derive a FI that can be applied across three standardised international Residential Assessment Instrument assessments (interRAI), used at different stages of ageing and the corresponding increase in support needs. METHODS: deficit items common to the interRAI Contact Assessment (CA), Home Care (HC) or Long-Term Care Facilities assessment (LTCF) were identified and recoded to form a cumulative deficit FI. The index was validated using a large dataset of needs assessments of older people in New Zealand against mortality prediction using Kaplan Meier curves and logistic regression models. The index was further validated by comparing its performance with a previously validated index in the HC cohort. RESULTS: the index comprised 15 questions across seven domains. The assessment cohort and their mean frailty (SD) were: 89,506 CA with 0.26 (0.15), 151,270 HC with 0.36 (0.15) and 83,473 LTCF with 0.41 (0.17). The index predicted 1-year mortality for each of the CA, HC and LTCF, cohorts with area under the receiver operating characteristic curves (AUCs) of 0.741 (95% confidence interval, CI: 0.718-0.762), 0.687 (95%CI: 0.684-0.690) and 0.674 (95%CI: 0.670-0.678), respectively. CONCLUSIONS: the results for this multi-instrument FI are congruent with the differences in frailty expected for people in the target settings for these instruments and appropriately associated with mortality at each stage of the journey of progressive ageing.

Original languageEnglish
Article numberafac178
JournalAge and Ageing
Issue number8
Publication statusPublished - 2 Aug 2022

Bibliographical note

Funding Information:
This study was funded by the Health Research Council of New Zealand (grant no .17/363). The funder had no direct involvement in conducting the study.


  • aged care
  • frailty
  • frailty index
  • geriatric assessment
  • international Residential Assessment Instrument assessments (interRAI)
  • older people

ASJC Scopus subject areas

  • Ageing
  • Geriatrics and Gerontology


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