MAGENT

DASI: how the Duke Activity Status Index score is calculated

The Duke Activity Status Index (DASI) adds a fixed weight for each of 12 everyday activities a person says they can do. The total runs from 0 to 58.2. An estimate of peak oxygen uptake follows from it: VO2peak = 0.43 × DASI + 9.6 mL/kg/min. Magent's calculator uses the weights from Hlatky and colleagues, 1989.

Not a medical device. Not a diagnosis or dosing recommendation.

Use this calculator via API

What is the DASI?

The DASI is a short questionnaire about physical activity. Each of its 12 questions asks whether the person can do a particular activity, from looking after themselves to strenuous sport. A yes adds that activity's weight. A no adds nothing. Harder activities carry larger weights.

Hlatky and colleagues published the questionnaire in the American Journal of Cardiology in 1989 as a brief way to estimate functional capacity. Their Table I gives the weights, and a regression line turns the total into an estimated peak VO2.

Magent's calculator takes the 12 yes/no answers and returns the DASI total, the maximum of 58.2 and the estimated VO2peak.

This page explains the arithmetic. It doesn't say what a score means for a particular person.

The DASI formula

activity (yes = weight, no = 0)                      weight
self-care                                             2.75
walk indoors                                          1.75
walk a block or two on level ground                   2.75
climb a flight of stairs or walk up a hill            5.50
run a short distance                                  8.00
light housework                                       2.70
moderate housework                                    3.50
heavy housework                                       8.00
yardwork                                              4.50
sexual relations                                      5.25
moderate recreational activities                      6.00
strenuous sports                                      7.50

DASI    = sum of the weights answered yes            (0 to 58.2)
VO2peak = 0.43 × DASI + 9.6                           mL/kg/min

Exact expression the calculator uses:

DASI = 2.75*self_care + 1.75*walk_indoors + 2.75*walk_blocks + 5.50*climb_stairs + 8.00*run_short + 2.70*light_housework + 3.50*moderate_housework + 8.00*heavy_housework + 4.50*yardwork + 5.25*sexual_relations + 6.00*moderate_recreation + 7.50*strenuous_sports (Yes = weight, No = 0); VO2peak_mL/kg/min = 0.43*DASI + 9.6 (Hlatky 1989 Table I)

Inputs

InputActivityWeight if yes
self_careSelf-care, such as eating, dressing, bathing or using the toilet2.75
walk_indoorsWalk indoors, such as around the house1.75
walk_blocksWalk a block or two on level ground2.75
climb_stairsClimb a flight of stairs or walk up a hill5.50
run_shortRun a short distance8.00
light_houseworkLight work around the house2.70
moderate_houseworkModerate work around the house3.50
heavy_houseworkHeavy work around the house8.00
yardworkYardwork4.50
sexual_relationsSexual relations5.25
moderate_recreationModerate recreational activities6.00
strenuous_sportsStrenuous sports7.50

Each input is true or false, and all 12 are required. Anything else returns an invalid_flag error.

How the calculation works

  1. Record a yes or no for each activity.
  2. Add the weights of the activities answered yes. The total is the DASI, from 0 to 58.2.
  3. Estimate peak VO2. Multiply the DASI by 0.43 and add 9.6.
  4. Round the VO2peak estimate to 1 decimal place.

Even with every answer no, the VO2peak estimate is 9.6, because that is where the regression line starts.

Units

The DASI total has no units. The VO2peak estimate is in millilitres of oxygen per kilogram of body weight per minute (mL/kg/min). The calculator doesn't convert it to any other unit.

Worked examples

These use Magent's own expected values for the calculator.

Example 1: no activities

  1. All 12 answers no.
  2. DASI 0.0.
  3. VO2peak 9.6 mL/kg/min.

Example 2: stairs or a hill, nothing else

  1. Yes to climbing a flight of stairs or walking up a hill. No to all the others.
  2. DASI 5.5.
  3. VO2peak 12.0 mL/kg/min.

Example 3: light housework, nothing else

  1. Yes to light housework. No to all the others.
  2. DASI 2.7.
  3. VO2peak 10.8 mL/kg/min.

Example 4: running a short distance, nothing else

  1. Yes to running a short distance. No to all the others.
  2. DASI 8.0.
  3. VO2peak 13.0 mL/kg/min.

Example 5: all twelve activities

  1. All 12 answers yes.
  2. DASI 58.2, the maximum.
  3. VO2peak 34.6 mL/kg/min.

History of the DASI

The calculator cites Hlatky and colleagues, American Journal of Cardiology, 1989, which presented "a brief self-administered questionnaire to determine functional capacity". The 12 activity weights and the VO2peak line (0.43 × DASI + 9.6) used by the calculator are from that paper's Table I. The light housework weight is 2.70 in that table, which is why it differs slightly from the 2.75 used for self-care and walking a block or two.

When it's used

The DASI is used when a quick, questionnaire-based estimate of a person's activity level is wanted instead of, or before, a measured exercise test.

Where it's used

Because it is a set of questions, the DASI can be completed in a clinic, on a ward or by the person on paper.

Who uses it

The answers come from the person, or from whoever asks them the questions. The calculator adds the weights and works out the VO2peak estimate.

Limits of the calculation

  • The answers are self-reported. The calculator doesn't interview anyone or check the answers.
  • The VO2peak figure is an estimate from a regression line, not a measurement. It isn't an exercise test.
  • The calculator doesn't convert VO2peak to METs.
  • It doesn't apply any cut-off from later studies, and this page doesn't say what to do with a result.

Clinical decisions belong to a qualified clinician who knows the patient.

  • H2FPEF score is a separate points score with six components. The DASI is built from activity answers.
  • Duke criteria and the Duke treadmill score share the Duke name but are separate tools. The DASI is a questionnaire.

Glossary

  • Functional capacity: how much physical activity a person can manage.
  • VO2peak: peak oxygen uptake, the highest rate of oxygen use during exercise.
  • mL/kg/min: millilitres of oxygen per kilogram of body weight per minute.
  • Regression line: an equation fitted to data to estimate one value from another.

Common mistakes

  • Using 2.75 for light housework. Hlatky 1989 Table I gives 2.70.
  • Reading VO2peak as measured. It is estimated from the DASI.
  • Expecting a VO2peak of 0 when every answer is no. The line starts at 9.6.
  • Leaving questions blank. All 12 answers are required.

Source

Hlatky MA, et al. A brief self-administered questionnaire to determine functional capacity (the Duke Activity Status Index). Am J Cardiol. 1989;64(10):651-654. DOI: 10.1016/0002-9149(89)90496-7. PMID: 2782256

Frequently asked questions

What is the maximum DASI score?

58.2, when all 12 activities are answered yes.

How is VO2peak worked out from the DASI?

VO2peak = 0.43 × DASI + 9.6, in mL/kg/min, from Hlatky 1989.

Why is light housework 2.70 and not 2.75?

That is the weight in Hlatky 1989 Table I. The calculator uses it as published.

Does the calculator give METs?

No. It returns the DASI total and the VO2peak estimate.

Is the DASI the same as the Duke treadmill score?

No. The DASI is a questionnaire. The treadmill score comes from an exercise test.