Hong Life CalculatorsUnderstanding the DASI calculator — concept and principle
This calculator scores the Duke Activity Status Index (DASI), a 12-question self-report of everyday activities, and turns it into an estimated peak oxygen uptake (VO₂) and a capacity in METs. Doctors use it before surgery and in heart and lung clinics as a quick estimate of functional capacity; patients use it to understand what the questionnaire measures.
How it is calculated
- Each "yes" adds a fixed weight: self-care 2.75, walking indoors 1.75, walking a block or two 2.75, stairs or a hill 5.50, running a short distance 8.00
- Light housework 2.70, moderate housework 3.50, heavy housework 8.00, yard work 4.50, sexual relations 5.25, moderate recreation 6.00, strenuous sports 7.50
- DASI = sum of weights, 0–58.2
- Peak VO₂ (mL/kg/min) = 0.43 × DASI + 9.6
- METs = VO₂ ÷ 3.5
The principle
Hlatky and colleagues (1989) asked patients about their daily activities and then measured their peak oxygen uptake on a treadmill. Activities that need more energy got larger weights, and the total correlated well with measured VO₂. One MET is the oxygen used at rest, about 3.5 mL per kg per minute, so METs express capacity as a multiple of resting energy use. Before non-cardiac surgery, the ability to manage about 4 METs, such as climbing a flight of stairs, is a common marker of adequate capacity.
Worked example
Defaults: yes to self-care, walking indoors, walking a block, stairs, light and moderate housework, yard work and sexual relations; no to running, heavy housework, moderate recreation and strenuous sports.
- DASI = 2.75 + 1.75 + 2.75 + 5.50 + 2.70 + 3.50 + 4.50 + 5.25 = 28.7.
- Peak VO₂ = 0.43 × 28.7 + 9.6 = 21.9 mL/kg/min.
- Capacity = 21.9 ÷ 3.5 = 6.3 METs.
How to read the result
About 6 METs means this person can likely manage moderate activity such as brisk walking or yard work. Higher scores mean greater capacity. The answers are self-reported, so the estimate may differ from a measured exercise test, especially in people who over- or underrate their abilities.
Common mistakes
- Answering for what you used to do rather than what you can do now.
- Treating the estimate as a measured exercise test.
- Answering "no" because you choose not to do something, rather than because you cannot.
- Comparing METs across different questionnaires.
Frequently asked questions
What is a good DASI score?
Higher is better; scores above about 34 have been linked with lower risk before surgery in some studies.
What does 1 MET mean?
The energy used at rest, about 3.5 mL of oxygen per kg per minute.
Why is DASI used before surgery?
It is a quick, standardised way to estimate functional capacity.
Sources: Hlatky MA, Boineau RE, Higginbotham MB, et al., "A brief self-administered questionnaire to determine functional capacity (the Duke Activity Status Index)", Am J Cardiol 1989;64(10):651–654