Gait speed independently predicts both major morbidity and mortality in elderly patients who are about to undergo cardiac surgery, according to a prospective, blinded study reported in the Nov. 9 issue of the Journal of the American College of Cardiology.
"This simple, rapid, and inexpensive test effectively stratifies patients beyond traditional estimates of risk, which tend to be inaccurate in the elderly," said Dr. Jonathan Afilalo of McGill University, Montreal, and his associates.
Half the cardiac surgeries done in North America involve elderly patients (aged at least 70 years), but scoring systems for estimating operative risk perform poorly in this age group, "overestimating mortality by as much as 250%," they noted.
Dr. Afilalo and his colleagues performed what they described as the first study to test the value of gait speed as a predictor of poor outcomes in elderly cardiac surgery patients. The prospective, blinded study involved 131 patients (mean age, 76 years) who were scheduled to undergo elective coronary artery bypass and/or valve replacement or repair via standard sternotomy at four university-affiliated medical centers across Canada and the United States.
Before surgery, the study subjects were timed as they walked a distance of 5 meters in a well-lit hallway; subjects were permitted to use an aid such as a cane or walker if needed. A time of 6 seconds or longer was classified as a slow gait speed, whereas any time under 6 seconds was classified as a normal gait speed.
The primary composite end point was in-hospital mortality or any of five major complications (stroke, renal failure, prolonged ventilation, deep sternal wound infection, and need for reoperation).
In all, 60 patients (46%) were judged to have slow gait speed before surgery. Interestingly, gait speed did not correlate with the Society of Thoracic Surgeons’ risk score, "suggesting that these were representing distinct domains," the investigators said.
After surgery, 30 patients (23%) experienced the primary composite end point.
Slow gait speed was a strong and independent predictor, associated with a 3.17-fold increase in risk of the primary end point. Moreover, adding gait speed to existing risk prediction models improved their performance in predicting which patients would experience an adverse event and which patients would need "to be discharged to a health care facility for ongoing medical care or rehabilitation."
Women with slow gait speed appeared to be at particularly high risk for adverse outcomes.
The study findings have three clinical implications.
"First, by refining risk predictions in this challenging group, clinicians can have a more comprehensive assessment of their patient and provide a more accurate estimate of risk to the patient," Dr. Afilalo and his associates said (J. Am. Coll. Cardiol. 2010;56:1668-76).
Second, clinicians can better assess which elderly patients might have better success with less-invasive techniques such as transcatheter valve implantation.
And third, patients who were found to have slow gait speed might benefit from extra interventions in the perioperative period, such as more intensive monitoring, early mobilization, low-intensity exercise training, or planned discharge to a specialized rehabilitation facility, they said.
The investigators reported no financial conflicts of interest.