Aims. The aim of this study was to develop a Frailty Index (FI) using questions common to three different standardised international Residential Assessment Instrument assessments (interRAI) which are mandated throughout New Zealand for the needs assessments of older adults.
Methods. Anonymized data from Individuals living in New Zealand aged 55 years and older that had an assessment with either a Contact Assessment (CA), a Home Care assessment (HC) or a Long-Term Care Facility (LTCF) assessment between September 2012 and December 2018 was utilised. 15 questions common to the three interRAI instruments and related to health deficits were identified and included to build a FI utilising an accumulative deficit model.
Results.There were a total of 324,249 participants. Of these, 89,506 had a CA assessment, 151,270 had an HC assessment, and 83,473 had an LTCF assessment. The rate of mortality was 0.6% (557) within the CA cohort, 23.0% (34,861) within HC, and 31.1% (25,966) within LTCF. An increasing FI was associated with lower survival within each instrument. The FI was validated by its ability to predict mortality showed similar discrimination and good calibration across instruments.
Conclusions.This study was performed using a large dataset of older people and provides good statistical power and predictive performance across three groups of people with differing characteristics. The FI could be routinely calculated from the 80,000 New Zealanders who have an interRAI annually and the results applied across multiple healthcare settings to guide clinical decision making and improve health resource allocation.