Assessment of functional capacity before major non-cardiac surgery: an international, prospective cohort study.

Wijeysundera DN; Pearse RM; Shulman MA; Abbott TEF; Torres E; Ambosta A;
Croal BL; Granton JT; Thorpe KE; Grocott MPW; Farrington C; Myles PS;
Cuthbertson BH; METS study investigators.

Lancet. 391(10140):2631-2640, 2018 06 30.
VI 1

BACKGROUND: Functional capacity is an important component of risk
assessment for major surgery. Doctors’ clinical subjective assessment of
patients’ functional capacity has uncertain accuracy. We did a study to
compare preoperative subjective assessment with alternative markers of
fitness (cardiopulmonary exercise testing [CPET], scores on the Duke
Activity Status Index [DASI] questionnaire, and serum N-terminal
pro-B-type natriuretic peptide [NT pro-BNP] concentrations) for predicting
death or complications after major elective non-cardiac surgery.

METHODS: We did a multicentre, international, prospective cohort study at
25 hospitals: five in Canada, seven in the UK, ten in Australia, and three
in New Zealand. We recruited adults aged at least 40 years who were
scheduled for major non-cardiac surgery and deemed to have one or more
risk factors for cardiac complications (eg, a history of heart failure,
stroke, or diabetes) or coronary artery disease. Functional capacity was
subjectively assessed in units of metabolic equivalents of tasks by the
responsible anaesthesiologists in the preoperative assessment clinic,
graded as poor (<4), moderate (4-10), or good (>10). All participants also
completed the DASI questionnaire, underwent CPET to measure peak oxygen
consumption, and had blood tests for measurement of NT pro-BNP
concentrations. After surgery, patients had daily electrocardiograms and
blood tests to measure troponin and creatinine concentrations until the
third postoperative day or hospital discharge. The primary outcome was
death or myocardial infarction within 30 days after surgery, assessed in
all participants who underwent both CPET and surgery. Prognostic accuracy
was assessed using logistic regression, receiver-operating-characteristic
curves, and net risk reclassification.

FINDINGS: Between March 1, 2013, and March 25, 2016, we included 1401
patients in the study. 28 (2%) of 1401 patients died or had a myocardial
infarction within 30 days of surgery. Subjective assessment had 19.2%
sensitivity (95% CI 14.2-25) and 94.7% specificity (93.2-95.9) for
identifying the inability to attain four metabolic equivalents during
CPET. Only DASI scores were associated with predicting the primary outcome
(adjusted odds ratio 0.96, 95% CI 0.83-0.99; p=0.03).

INTERPRETATION: Subjectively assessed functional capacity should not be
used for preoperative risk evaluation. Clinicians could instead consider a
measure such as DASI for cardiac risk assessment.