Agreement Between 35 Published Frailty Scores in the General Population

Abstract

In elderly populations, frailty is associated with higher mortality risk. Although many frailty scores (FS) have been proposed, no single score is considered the gold standard. We aimed to evaluate the agreement between a wide range of FS in the English Longitudinal Study of Ageing (ELSA). Through a literature search, we identified 35 FS that could be calculated in ELSA wave 2 (2004-2005). We examined agreement between each frailty score and the mean of 35 FS, using a modified Bland-Altman model and Cohen's kappa (κ). Missing data were imputed. Data from 5,377 participants (ages ≥60 years) were analyzed (44.7% men, 55.3% women). FS showed widely differing degrees of agreement with the mean of all scores and between each pair of scores. Frailty classification also showed a very wide range of agreement (Cohen's κ = 0.10-0.83). Agreement was highest among "accumulation of deficits"-type FS, while accuracy was highest for multidimensional FS. There is marked heterogeneity in the degree to which various FS estimate frailty and in the identification of particular individuals as frail. Different FS are based on different concepts of frailty, and most pairs cannot be assumed to be interchangeable. Research results based on different FS cannot be compared or pooled.

Keywords: Bland-Altman model; Cohen's kappa coefficient; accuracy; agreement; disability; elderly population; frailty scores; reliability.

Figure 1.

Agreement (calculated with Cohen's κ) between pairs of frailty scores (595 combined pairs of scores) among participants in wave 2 of the English Longitudinal Study of Ageing, 2004–2005. The plot is sorted by frailty model and then from highest (red) to lowest (blue) median value of Cohen's κ coefficient. BDE, Beaver Dam Eye Study Index; BFI, Brief Frailty Index; BMI, body mass index; MFS, Modified Frailty Score; CGA, Comprehensive Geriatric Assessment; CGAST, Comprehensive Geriatric Assessment Screening Tests; CSBA, Conselice Study of Brain Aging Score; EFIP, Evaluative Frailty Index for Physical Activity; EFS, Edmonton Frail Scale; FI40, 40-item Frailty Index; FI70, 70-item Frailty Index; FIBLSA, Frailty Index Beijing Longitudinal Study of Ageing; PFI, Physical Frailty Index; FiND, Frail Non-Disabled (FiND) Questionnaire; FS, Frail Scale; FSS, Frailty Staging System; G8, G-8 geriatric screening tool; GFI, Groningen Frailty Indicator; HRCA, Hebrew Rehabilitation Center for Aged Vulnerability Index; HSF, Health Status Form; NLTCS, National Long Term Care Survey Frailty Index; PHF, Phenotype of Frailty; MPHF, Modified Phenotype of Frailty; SDFI, Static/Dynamic Frailty Index; SHCFS, Canadian Study of Health and Aging Clinical Frailty Scale; SI, Screening Instrument; SOF, Study of Osteoporotic Fractures; SPPB, Short Physical Performance Battery; SPQ, Sherbrooke Postal Questionnaire; IFQ, Inter-Frail Questionnaire; TFI, Tilburg Frailty Indicator; VES13, Vulnerable Elders Survey; WHOAFC, World Health Organization Assessment of Functional Capacity; WHRH, WHOAFC and self-reported health; ZED1, Zutphen Elderly Study (Physical Activity and Low Energy); ZED2, Zutphen Elderly Study (Physical Activity and Weight Loss); ZED3, Zutphen Elderly Study (Physical Activity and Low BMI).

Figure 2.

Prediction interval widths obtained with Bland-Altman models for all 595 combined pairs of frailty scores, English Longitudinal Study of Ageing, wave 2 (2004–2005). The narrowest prediction interval widths are shown in red, and the widest are shown in blue. The plot is sorted by frailty model and then by the narrowest prediction interval. BDE, Beaver Dam Eye Study Index; BFI, Brief Frailty Index; BMI, body mass index; MFS, Modified Frailty Score; CGA, Comprehensive Geriatric Assessment; CGAST, Comprehensive Geriatric Assessment Screening Tests; CSBA, Conselice Study of Brain Aging Score; EFIP, Evaluative Frailty Index for Physical Activity; EFS, Edmonton Frail Scale; FI40, 40-item Frailty Index; FI70, 70-item Frailty Index; FIBLSA, Frailty Index Beijing Longitudinal Study of Ageing; PFI, Physical Frailty Index; FiND, Frail Non-Disabled (FiND) Questionnaire; FS, Frail Scale; FSS, Frailty Staging System; G8, G-8 geriatric screening tool; GFI, Groningen Frailty Indicator; HRCA, Hebrew Rehabilitation Center for Aged Vulnerability Index; HSF, Health Status Form; NLTCS, National Long Term Care Survey Frailty Index; PHF, Phenotype of Frailty; MPHF, Modified Phenotype of Frailty; SDFI, Static/Dynamic Frailty Index; SHCFS, Canadian Study of Health and Aging Clinical Frailty Scale; SI, Screening Instrument; SOF, Study of Osteoporotic Fractures; SPPB, Short Physical Performance Battery; SPQ, Sherbrooke Postal Questionnaire; IFQ, Inter-Frail Questionnaire; TFI, Tilburg Frailty Indicator; VES13, Vulnerable Elders Survey; WHOAFC, World Health Organization Assessment of Functional Capacity; WHRH, WHOAFC and self-reported health; ZED1, Zutphen Elderly Study (Physical Activity and Low Energy); ZED2, Zutphen Elderly Study (Physical Activity and Weight Loss); ZED3, Zutphen Elderly Study (Physical Activity and Low BMI).

Figure 3.

Absolute error (over-/underestimation) of frailty in the median frailty value from the modified Bland-Altman model obtained with all 595 combined pairs of frailty scores, English Longitudinal Study of Ageing, wave 2 (2004–2005). The over-/underestimation is the absolute value of the intercept plus the product of the slope and the median. The intercept and slope are obtained from the Bland-Altman model. The median is calculated as the median value of the mean of 2 frailty scores for each pair. The lowest absolute errors are shown in red, and the highest are shown in blue. The plot is sorted by frailty model and then by the lowest absolute error. BDE, Beaver Dam Eye Study Index; BFI, Brief Frailty Index; BMI, body mass index; MFS, Modified Frailty Score; CGA, Comprehensive Geriatric Assessment; CGAST, Comprehensive Geriatric Assessment Screening Tests; CSBA, Conselice Study of Brain Aging Score; EFIP, Evaluative Frailty Index for Physical Activity; EFS, Edmonton Frail Scale; FI40, 40-item Frailty Index; FI70, 70-item Frailty Index; FIBLSA, Frailty Index Beijing Longitudinal Study of Ageing; PFI, Physical Frailty Index; FiND, Frail Non-Disabled (FiND) Questionnaire; FS, Frail Scale; FSS, Frailty Staging System; G8, G-8 geriatric screening tool; GFI, Groningen Frailty Indicator; HRCA, Hebrew Rehabilitation Center for Aged Vulnerability Index; HSF, Health Status Form; NLTCS, National Long Term Care Survey Frailty Index; PHF, Phenotype of Frailty; MPHF, Modified Phenotype of Frailty; SDFI, Static/Dynamic Frailty Index; SHCFS, Canadian Study of Health and Aging Clinical Frailty Scale; SI, Screening Instrument; SOF, Study of Osteoporotic Fractures; SPPB, Short Physical Performance Battery; SPQ, Sherbrooke Postal Questionnaire; IFQ, Inter-Frail Questionnaire; TFI, Tilburg Frailty Indicator; VES13, Vulnerable Elders Survey; WHOAFC, World Health Organization Assessment of Functional Capacity; WHRH, WHOAFC and self-reported health; ZED1, Zutphen Elderly Study (Physical Activity and Low Energy); ZED2, Zutphen Elderly Study (Physical Activity and Weight Loss); ZED3, Zutphen Elderly Study (Physical Activity and Low BMI).