Assessing global frailty scores: Development of a global burden of disease‐frailty index (gbd‐fi)

Frailty is an independent age‐associated predictor of morbidity and mortality. Despite this, many countries lack population estimates with large heterogeneity between studies. No population‐based standardised metric for frailty is available. We applied the deficit accumulation model of frailty to create a frailty index (FI) using population‐level estimates from the Global Burden of Disease (GBD) 2017 study across 195 countries to create a novel GBD frailty index (GBD‐FI). Standard FI criteria were applied to all GBD categories to select GBD‐FI items. Content validity was assessed by comparing the GBD‐FI with a selection of established FIs. Properties including the rate of deficit accumulation with age were examined to assess construct validity. Linear regression models were created to assess if mean GBD‐FI scores predicted one‐year incident mortality. From all 554 GBD items, 36 were selected for the GBD‐FI. Face validity against established FIs was variable. Characteristic properties of a FI—higher mean score for females and a deficit accumulation rate of approximately 0.03 per year, were observed. GBD‐FI items were responsible for 19% of total Disability‐Adjusted Life Years for those aged ≥70 years in 2017. Country‐specific mean GBD‐FI scores ranged from 0.14 (China) to 0.19 (Hungary) and were a better predictor of mortality from non‐communicable diseases than age, gender, Healthcare Access and Quality Index or Socio‐ Demographic Index scores. The GBD‐FI is a valid measure of frailty at population‐level but further external validation is required.