Dr. Zubair Kabir, Senior Lecturer, Department of Epidemiology & Public Health, University College Cork, Ireland is in the burden-eu spotlight to discuss the development of a Global Burden of Disease-Frailty Index (GBD-FI).
Why is frailty important and how can it be measure?
Frailty is an age-associated risk state that independently predicts morbidity and mortality, making it an important consideration in current geriatric medicine and public health. However, despite a surge in frailty-related research, many countries still lack reliable population estimates with large heterogeneity between existing data sources and frailty measures. While no standardised metric for frailty is available, the accumulation of deficits approach is one common operational definition, and is easily applied in large variable datasets. This approach measures frailty as a state of vulnerability to stressors characterized by a cumulative burden of health-related problems (deficits) and it is measured on a continuous scale using a frailty index (FI). The FI is scored as the proportion of deficits present from any pre-selected list, considering the number of deficits rather than the nature of these problems.
How can frailty be assessed using burden of disease metrics?
The GBD-FI illustrates potential as an approach to measuring frailty in the GBD but would likely benefit from the inclusion of more disability and functional deficits. Further external validation is required. Using population estimates from the Global Burden of Disease (GBD) study 2017, standard criteria for generating a FI were applied to generate a novel "GBD-FI". The GBD-FI deficits had to be: associated with health status, increase in prevalence with age (Spearman's coefficient ≥0.7 for adult age groups 25–29 to ≥95 years), sufficiently prevalent with a prevalence between ≥1% and ≤80% for global ≥70 years, able to cover a range of systems (included GBD 'causes', 'risk factors' and 'impairments'), low in redundancy and implausibility. From all 554 GBD items a total of 36 items were selected for the GBD-FI. The index had a distinct lack of functional impairments and disabilities resulting in variable face validity compared with established FIs. It did, however, display characteristic properties of a FI including higher mean scores for females and an estimated rate of deficit accumulation of approximately 0.03 per year.
What were the main findings of our work?
For those aged ≥70 years in 2017 the GBD-FI score was 0.16 and ranged from 0.14 in China to 0.19 in Hungary. Using linear regression the mean GBD-FI scores (adjusted R-squared=14.3%) predicted one-year incident mortality rates from non-communicable diseases more effectively than other population-level measures assessed, including the proportion aged ≥85 years (adjusted R-squared=14.1%), the proportion of females (adjusted R-squared=6.8%), the Healthcare Access and Quality Index (adjusted R-squared=11.1%) and the Socio-Demographic Index score (adjusted R-squared=5.6%). Including all these variables the addition of the GBD-FI increased the adjusted R-squared value from 27.0% to 39.6%. In terms of GBD summary measures of health the GBD-FI items were responsible for 19% of the total DALY for those aged ≥70 years in 2017 (13% for YLD and 22% for YLL).
Further information on the development of the GBD-FI can be found in the journal publication below.