Comparative analysis of the association between 35 frailty scores and cardiovascular events, cancer, and total mortality in an elderly general population in England: An observational study

Abstract

Background

Frail elderly people experience elevated mortality. However, no consensus exists on the definition of frailty, and many frailty scores have been developed. The main aim of this study was to compare the association between 35 frailty scores and incident cardiovascular disease (CVD), incident cancer, and all-cause mortality. Also, we aimed to assess whether frailty scores added predictive value to basic and adjusted models for these outcomes.

Methods and findings

Through a structured literature search, we identified 35 frailty scores that could be calculated at wave 2 of the English Longitudinal Study of Ageing (ELSA), an observational cohort study. We analysed data from 5,294 participants, 44.9% men, aged 60 years and over. We studied the association between each of the scores and the incidence of CVD, cancer, and all-cause mortality during a 7-year follow-up using Cox proportional hazard models at progressive levels of adjustment. We also examined the added predictive performance of each score on top of basic models using Harrell’s C statistic. Using age of the participant as a timescale, in sex-adjusted models, hazard ratios (HRs) (95% confidence intervals) for all-cause mortality ranged from 2.4 (95% CI: 1.7–3.3) to 26.2 (95% CI: 15.4–44.5). In further adjusted models including smoking status and alcohol consumption, HR ranged from 2.3 (95% CI: 1.6–3.1) to 20.2 (95% CI: 11.8–34.5). In fully adjusted models including lifestyle and comorbidity, HR ranged from 0.9 (95% CI: 0.5–1.7) to 8.4 (95% CI: 4.9–14.4). HRs for CVD and cancer incidence in sex-adjusted models ranged from 1.2 (95% CI: 0.5–3.2) to 16.5 (95% CI: 7.8–35.0) and from 0.7 (95% CI: 0.4–1.2) to 2.4 (95% CI: 1.0–5.7), respectively. In sex- and age-adjusted models, all frailty scores showed significant added predictive performance for all-cause mortality, increasing the C statistic by up to 3%. None of the scores significantly improved basic prediction models for CVD or cancer. A source of bias could be the differences in mortality follow-up time compared to CVD/cancer, because the existence of informative censoring cannot be excluded.

Conclusion

There is high variability in the strength of the association between frailty scores and 7-year all-cause mortality, incident CVD, and cancer. With regard to all-cause mortality, some scores give a modest improvement to the predictive ability. Our results show that certain scores clearly outperform others with regard to three important health outcomes in later life. Finally, we think that despite their limitations, the use of frailty scores to identify the elderly population at risk is still a useful measure, and the choice of a frailty score should balance feasibility with performance.

Abstract

Using data from the English Longitudinal Study of Ageing, Gloria Aguayo and colleagues compare the association between 35 frailty scores and cardiovascular events, cancer, and total mortality.

Author summary

Why was this study done?

• Frailty has been associated with poor outcomes in the elderly, and the need for valid instruments for its assessment is generally recognised.

• Many frailty scores have been developed based on different theoretical concepts; however, none of them can be considered the gold standard.

• The predictive capacity of frailty scores has mainly been studied for mortality, and evidence on their ability to predict other important outcomes in the elderly population, such as cardiovascular or cancer events, is limited (cardiovascular) or nonexistent (cancer) at the present time.

What did the researchers do and find?

• We performed secondary analyses of the most comprehensive list of frailty scores in 5,294 participants of the English Longitudinal Study of Ageing, and we demonstrated that all frailty scores were associated with future mortality and that some of them were also associated with later cardiovascular events. However, no relationship with cancer was observed.

• In addition, the results of this study showed that multidimensional frailty scores may have a stronger and more stable association with mortality and incidence of cardiovascular events.

• Beside the results evidenced that despite significant associations of frailty scores with mortality, the added discriminative ability of frailty scores to chronological age may be limited.

What do these findings mean?

• The comparative evaluation of the strength of associations between different frailty scores and major health outcomes in older adults provides a solid evidence base for researchers, clinicians, and health professionals working with elderly populations to choose the most appropriate instrument for their needs.

• Furthermore, the findings highlight the vast heterogeneity in composition and performance of existing frailty scores.