The electronic frailty index (eFI) was developed and validated using primary care data of over 900,000 people aged $\geq$65 years in England (Clegg et el, 2016). It cosiders 36 deficits (comorbidities, symptoms, disabilities, abnormal lab values, and polupharmacy), calculcuted directly from EHRs. NHS England anticipate eFI “being used frequently as it: (1) has been externally validated using routine primary care data and its use is recommended in NICE Guideline 56 on Multimorbidity; (2) is available in all GP practices and therefore promotes consistency; (3) uses existing GP data and therefore requires no additional resource” (link).

eFI seems a valuable feature in studies concerning the elderly, alongside the hospital frailty risk score (HFRS), which Seng Chan You implemented back in 2018 (OHDSI Forum post).

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