Reproducibility and responsiveness of the Frailty Index and Frailty Phenotype in older hospitalized patients

Marlies Feenstra*, Frederike Oud, Carolien J. Jansen, Nynke Smidt, B.C. van Munster, Sophia E. de Rooij

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Background: There is growing interest for interventions aiming at preventing frailty progression or even to reverse
frailty in older people, yet it is still unclear which frailty instrument is most appropriate for measuring change scores
over time to determine the effectiveness of interventions. The aim of this prospective cohort study was to
determine reproducibility and responsiveness properties of the Frailty Index (FI) and Frailty Phenotype (FP) in
acutely hospitalized medical patients aged 70 years and older.
Methods: Reproducibility was assessed by Intra-Class Correlation Coefficients (ICC), standard error of measurement
(SEM) and smallest detectable change (SDC); Responsiveness was assessed by the standardized response mean
(SRM), and area under the receiver operating characteristic curve (AUC).
Results: At baseline, 243 patients were included with a median age of 76 years (range 70–98). The analytic samples
included 192 and 187 patients in the three and twelve months follow-up analyses, respectively. ICC of the FI were
0.85 (95 % confidence interval [CI]: 0.76; 0.91) and 0.84 (95% CI: 0.77; 0.90), and 0.65 (95% CI: 0.49; 0.77) and 0.77
(95% CI: 0.65; 0.84) for the FP. SEM ranged from 5 to 13 %; SDC from 13 to 37 %. SRMs were good in patients with
unchanged frailty status (< 0.50), and doubtful to good for deteriorated and improved patients (0.43–1.00). AUC’s
over three months were 0.77 (95% CI: 0.69; 0.86) and 0.71 (95% CI: 0.62; 0.79) for the FI, and 0.68 (95% CI: 0.58; 0.77)
and 0.65 (95% CI: 0.55; 0.74) for the FP. Over twelve months, AUCs were 0.78 (95% CI: 0.69; 0.87) and 0.82 (95% CI:
0.73; 0.90) for the FI, and 0.78 (95% CI: 0.69; 0.87) and 0.75 (95% CI: 0.67; 0.84) for the FP.
Conclusions: The Frailty Index showed better reproducibility and responsiveness properties compared to the Frailty
Phenotype among acutely hospitalized older patients.
Keywords: Frail, Psychometric properties, Measurement properties, Reliability, Internal Medicine, Geriatric care
Original languageEnglish
Article number499
Number of pages10
JournalBMC Geriatrics
Issue number1
Early online date17-Sep-2021
Publication statusPublished - Dec-2021

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