Protocol - Frailty

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Study of Osteoporotic Fractures (SOF) Frailty Index


Publicly available


The SOF Frailty Index is an assessment of frailty based on an individual's weight change over the past three years, physical ability to perform five chair stands without using arms for support, and energy level. If the individual meets two of the three criteria (weight loss of 5% or more, inability to do chair stands, low/lack of energy), the individual is considered frail.


Weight loss

  1. What was your weight 3 years ago? __ __ __ lbs
  2. What is your weight today? __ __ __ lbs
  3. [Interviewer/computer: calculate weight loss percentage] Change in weight (Q1-Q2)/weight 3 years ago (Q1)

           = ___ __ % loss

Ability to do 5 chair stands

     4. [Interviewer: Ask respondent to sit in chair, then rise up without using arms, repeat 4 more times.] Was respondent able to do chair stands without assistance? Yes or No

Energy level

    5. Do you feel full of energy? Yes or No


Q1. Score = 1 if weight loss ? 5%, otherwise, score = 0

Q2. Score = 1 if unable to do chair stands without assistance (No), otherwise, score = 0

Q3. Score = 1, if No, otherwise, score = 0

If summed score is 2 or 3, respondent is frail;

if score is 1 respondent is pre-frail;

if score is 0, respondent is robust.

Personnel and Training Required

The interviewer must be trained to conduct personal interviews with individuals from the general population. The interviewer must be trained and found to be competent (i.e., tested by an expert) at the completion of personal interviews. The interviewer should be trained to prompt respondents further if a "don't know" response is provided.

Equipment Needs

The PhenX Working Group acknowledges that these questions can be administered in a computerized or noncomputerized format (i.e., paper-and-pencil instrument). Computer software is necessary to develop computer-assisted instruments. The interviewer will require a laptop computer/handheld computer to administer a computer-assisted questionnaire. Chair for chair stands


Requirement CategoryRequired
Average time of greater than 15 minutes in an unaffected individualNo
Major equipmentNo
Specialized requirements for biospecimen collectionNo
Specialized trainingNo

Mode of Administration

Life Stage:


Specific Instructions:

Frailty can occur at younger ages than the traditional 65-year cutpoint for "older" and certainly does not need to be restricted to the SOF age (69 years of age and older).

Research Domain Information

Release Date:

July 2, 2018


Declines in physiologic complexity or reserve in body systems, leading to loss of homeostatic capability to withstand stressors and resulting vulnerabilities.


Frailty is associated with weakness and the inability to perform normal daily activities, particularly in older adults. Frailty leads to increased morbidity and mortality.

Selection Rationale

This well-established protocol has been used on a large prospective cohort study of older adults.





Process and Review

The Expert Review Panel has yet to review this measure.


National Institute on Aging, Study of Osteoporotic Fractures (SOF) Frailty Index

General References

Ensrud, K. E., Ewing, S. K., Taylor, B. C., Fink, H. A., Cawthon, P. M., Stone, K. L., ... Cummings, S. R. (2008). Comparison of 2 frailty indexes for prediction of falls, disability, fractures, and death in older women. Archives of Internal Medicine,168(4), 382-9

Ensrud, K. E., Ewing, S. K., Cawthon, P. M., Fink, H. A., Taylor, B. C., Cauley, J. A., ... Osteoporotic Fractures in Men Research Group. (2009). A comparison of frailty indexes for the prediction of falls, disability, fractures, and mortality in older men. Journal of the American Geriatric Society, 57(3), 492-498.

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