About

The Duke Activity Status Index (DASI) quantifies functional capacity through a 14-item questionnaire measuring ability to perform daily activities. Originally validated by Hlatky et al. in 1989, DASI correlates with peak oxygen uptake (VO₂ peak) at r = 0.80, making it a reliable non-exercise surrogate. Each activity carries a weighted metabolic cost derived from measured oxygen consumption. A score below 34 indicates inability to achieve 4 METs, the threshold associated with increased perioperative cardiac complications per ACC/AHA guidelines.

Preoperative risk stratification relies on functional capacity assessment. Patients scoring under 34 points require additional evaluation before intermediate or high-risk surgery. The tool converts raw DASI scores to estimated peak VO₂ (mL/kg/min) and metabolic equivalents (METs). Underestimating functional limitation delays necessary cardiac workup. Overestimating capacity risks intraoperative hemodynamic instability.

Formulas

The DASI score equals the sum of weights for activities the patient can perform.

DASI = 14∑i=1 w_i ⋅ a_i

Where w_i is the metabolic weight for activity i, and a_i equals 1 if the patient can perform the activity, 0 otherwise.

Estimated peak oxygen uptake derives from the regression equation:

VO₂ peak = 0.43 × DASI + 9.6

Result units are mL/kg/min. Converting to metabolic equivalents:

METs = VO₂ peak3.5

Where 3.5 mL/kg/min represents resting metabolic rate (1 MET). Clinical interpretation: METs < 4 indicates poor functional capacity requiring further cardiac evaluation before surgery.

Reference Data

Activity	Weight (Points)	MET Equivalent	Category
Self-care (eating, dressing, bathing, toilet)	2.75	1.0 - 2.0	Basic ADL
Walking indoors (around house)	1.75	2.0	Mobility
Walking 1-2 level blocks	2.75	2.5 - 3.0	Mobility
Climbing flight of stairs or hill	5.50	4.0 - 5.0	Exertion
Running short distance	8.00	8.0	Vigorous
Light housework (dusting, dishes)	2.70	2.0 - 3.0	Household
Moderate housework (vacuuming, sweeping)	3.50	3.0 - 4.0	Household
Heavy housework (scrubbing floors, moving furniture)	8.00	6.0 - 8.0	Household
Yard work (raking, weeding)	4.50	4.0 - 5.0	Outdoor
Sexual relations	5.25	3.0 - 5.0	Physical
Moderate recreation (golf, bowling, dancing)	6.00	4.0 - 6.0	Recreation
Strenuous sports (swimming, tennis, football)	7.50	7.0 - 10.0	Vigorous
MET Threshold for Low Cardiac Risk	≥34	≥4.0	Clinical Cutoff
MET Threshold for Moderate Risk Surgery	-	≥4.0	ACC/AHA
MET Threshold for High Risk Surgery	-	≥10.0	ACC/AHA
Maximum DASI Score	58.2	~9.9	Upper Limit
Minimum DASI Score	0	~2.7	Lower Limit
Correlation with Treadmill VO₂	r = 0.80		Validation
Original Validation Sample	n = 50		Hlatky 1989
Sensitivity at 4 MET Cutoff	89%		Diagnostic
Specificity at 4 MET Cutoff	82%		Diagnostic

Frequently Asked Questions

A DASI score of 34 or higher corresponds to approximately 4 METs, which ACC/AHA guidelines define as adequate functional capacity for most intermediate-risk surgeries. Patients scoring below 34 warrant additional preoperative cardiac evaluation including stress testing or imaging. The 4-MET threshold correlates with activities like climbing a flight of stairs without stopping or walking two level blocks at normal pace.

DASI correlates with treadmill-measured peak VO₂ at r = 0.80, making it a valid screening tool. However, CPET provides direct measurement of anaerobic threshold, ventilatory efficiency (VE/VCO₂), and cardiac output response. CPET remains superior for borderline cases, patients with discordant symptoms, or high-risk procedures. DASI functions as a rapid triage tool; CPET delivers definitive functional assessment.

DASI weights were empirically derived by Hlatky et al. through regression analysis correlating questionnaire responses with measured oxygen uptake. They represent weighted coefficients maximizing predictive accuracy for peak VO₂ rather than absolute metabolic costs. Standard MET values from the Compendium of Physical Activities reflect average energy expenditure during sustained activity. DASI weights optimize correlation in a clinical questionnaire context.

Musculoskeletal limitations confound DASI interpretation. A patient unable to climb stairs due to knee arthritis rather than cardiovascular limitation will score lower than their true cardiac capacity. In such cases, document the limiting factor and consider pharmacologic stress testing with imaging (dobutamine echocardiography or adenosine myocardial perfusion) which bypasses physical exercise requirements entirely.

Scores in the 30-38 range straddle the 4-MET threshold and require clinical correlation. Factor in patient age, comorbidities, surgical risk category, and symptom trajectory. A declining 65-year-old scoring 35 warrants more concern than a stable 45-year-old scoring 32. Consider supplementing with 6-minute walk distance or stair-climbing time for objective functional data before committing to additional cardiac workup.

DASI provides absolute functional capacity without age adjustment. Normal peak VO₂ declines approximately 8-10% per decade after age 30. A 75-year-old scoring 40 (approximately 4.9 METs) performs at a higher percentile for age than a 45-year-old with the same score. Reference age-stratified VO₂ norms when counseling patients. The 4-MET surgical threshold applies regardless of age.