Table 1. Characteristics of Study Cohort

Validated Questionnaire vs Physicians’ Judgment to Estimate Preoperative Exercise Capacity

Characteristic Demographics

Assessment of exercise capacity is critical to preoperative evaluation. Practice guidelines recommend that patients proceed to noncardiac surgery without further testing if their exercise capacity exceeds 4 metabolic equivalent tasks (METs).1 This assumption that good exercise capacity indicates low perioperative risk is largely extrapolated from studies involving objective exercise testing. Clinical practice instead involves clinicians subjectively estimating exercise capacity by questioning patients about activities of daily living. This method might not accurately predict performance on exercise testing2 or postoperative outcomes.3 Validated questionnaires correlated with objectively measured exercise capacity may help overcome this limitation. We conducted a prospective cohort study to compare physicians’ subjective assessment of preoperative exercise capacity against one such questionnaire, the Duke Activity Status Index (DASI).4

Age, median (range), y

66 (40-84)

Female, sex, No. (%)

29 (39)

Comorbid disease, No. (%) Coronary artery disease Heart failure Cerebrovascular disease Diabetes mellitus

Results | Eighty-seven individuals were approached from June to August 2012, with 74 completing the DASI questionnaire and physician subjective assessment (Table 1 and Table 2). Patients subjectively rated by physicians as “normal” or “fit” generally had higher DASI scores (Spearman ρ, 0.56; 95% CI, 0.380.70). Nonetheless, the DASI questionnaire showed only slight agreement with physicians’ subjective assessment (weighted κ, 0.11; 95% CI, 0.05-0.22) when estimating patients’ functional capacity (Figure). Physicians generally underestijamainternalmedicine.com

13 (18) 3 (4) 5 (7) 12 (16)


56 (76)

Current smoker

13 (18)

Chronic obstructive pulmonary disease Malignancy

9 (12) 54 (73)

Laboratory tests Hemoglobin, median (range), g/dL Anemia, No. (%) eGFR, median (range), mL/min/1.73 m2 Preoperative renal insufficiency, No. (%)a

Methods | Following institutional research ethics approval from the University Health Network, Toronto, Ontario, Canada, we obtained written informed consent from patients who were 40 years or older, scheduled to undergo major elective noncardiac surgery at the Toronto General Hospital, Toronto, and had 1 or more risk factors (ie, coronary artery disease, heart failure, cerebrovascular disease, diabetes, hypertension, peripheral arterial disease, age ≥70 years, renal insufficiency, smoking). Participants completed the DASI questionnaire at their preoperative assessment clinic visit. DASI scores were divided by 3.5 to estimate METS.5 The attending anesthesiologist in the clinic or operating room, while blinded to DASI scores, rated each participant’s functional capacity as “unfit” (10 METs) based on their usual preoperative examination, which typically assessed activities of daily living and exercise capacity (eg, ability to climb stairs). Each participant was evaluated by any one of 38 consultant anesthesiologists. A sample size of 74 was required to measure a Pearson correlation coefficient of 0.60, with a lower 2-sided 95% confidence limit excluding 0.30 with 90% power.

Study Cohort (N = 74)

13.6 (8.6-17.5) 23 (31) 86.5 (26.6-139.1) 11 (15)

Planned surgical procedure Surgery, No. (%) Head and neck

20 (27)


15 (20)

Intrathoracic Urologic or gynecologic Vascular

7 (9) 25 (34) 7 (9)

Preoperative functional capacity METs estimated by DASI, median (range)b

12.2 (2.9-16.6)

Abbreviations: DASI, Duke Activity Status Index; eGFR, estimated glomerular filtration rate; METs, metabolic equivalent tasks. SI conversion factor: To convert hemoglobin to grams per liter, multiply by 10. a

Dialysis-dependence or eGFR lower than 60 mL/min/1.73 m2.


Calculated by dividing DASI scores by 3.5.5

mated functional capacity compared with the questionnaire. For example, DASI scores were consistent with normal or better fitness (ie, ≥4 METs) in most patients that physicians had instead rated as “unfit” (ie,

Validated questionnaire vs physicians' judgment to estimate preoperative exercise capacity.

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