Frailty Index Calculator
Calculate the frailty index from present and measured health deficits to assess geriatric frailty severity.
What Is the Frailty Index?
The frailty index (FI) measures how many health deficits a person has relative to the total deficits assessed. It is calculated as present deficits divided by measured deficits. Typical frailty assessments evaluate 30 to 40 variables covering comorbidities, function, cognition, and laboratory abnormalities.
How the Score Is Calculated
Enter the number of deficits present and the total number of deficits measured in your assessment. The index ranges from 0 to 1. A higher value means greater accumulation of age-related health problems and increased vulnerability to stressors such as illness or hospitalization.
Interpretation Categories
An index below 0.10 is generally classified as robust. Scores from 0.10 to 0.24 suggest pre-frailty with moderate deficit burden. An index of 0.25 or higher indicates frailty and is linked to higher risk of adverse outcomes. Like other composite clinical scores such as the Child-Pugh Calculator, the frailty index summarizes multiple domains into one actionable measure. In older adults, mood screening with tools like the PHQ-2 Depression Screening Calculator can complement frailty assessment when depression may affect function.
Frequently Asked Questions
What deficits are included in a frailty index?
Deficits vary by study protocol but often include chronic diseases, symptoms, disabilities, cognitive impairment, and abnormal lab values. The measured total should match the checklist used in your assessment.
Can present deficits exceed measured deficits?
No. Present deficits must be less than or equal to the total number of deficits measured. The calculator returns an error if present exceeds measured.
What is the difference between pre-frail and frail?
Pre-frail (0.10 to 0.24) indicates intermediate deficit accumulation and may benefit from closer monitoring. Frail (0.25 or higher) reflects substantial vulnerability to clinical decline.
Is the frailty index the same as the Clinical Frailty Scale?
No. The frailty index is a deficit accumulation ratio. The Clinical Frailty Scale is a pictorial ordinal scale. Both assess frailty but use different methods.
Does a low frailty index rule out clinical risk?
A robust index does not exclude serious individual conditions. Use frailty scoring alongside diagnosis-specific tools and clinical judgment.
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