Gait speed helps predict mortality after cardiac surgery

A prospective cohort study found that gait speed was an independent predictor of adverse outcomes among older adults who underwent cardiac surgery. For each 0.1 m/s decrease in 5-m gait speed, there was an 11 percent relative increase in operative mortality.

Lead researcher Jonathan Afilalo, MD, MSc, of Jewish General Hospital and McGill University in Montreal, and colleagues published their results online in JAMA Cardiology on May 11.

“The 5-m gait speed test can be used to refine estimates of operative risk, support decision making, and decide when a comprehensive geriatric assessment is warranted,” they wrote.

The researchers mentioned that the 5-m gait speed test is commonly used to screen for frailty and identify high-risk older adults who may need further evaluation. They added that the test examines impairments in lower-extremity muscle function as well as neurosensory and cardiopulmonary function.

This study’s cohort included 15,171 patients from 109 centers participating in the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database from July 1, 2011, to March 31, 2014.

Patients in the study were at least 60 years old; underwent CABG, aortic valve surgery, mitral valve surgery, or CABG combined with aortic or mitral valve surgery; and had at least one record of 5-m gait speed in the database. They were excluded if they were unable to safely walk or had an emergency or emergency salvage surgery, cardiogenic shock, inotropic support or an intra-aortic balloon pump before surgery. Centers were also excluded if they had recorded 5-m gait speeds for fewer than 10 patients.

The patients performed the 5-m gait speed test three times before surgery. At baseline, the median age was 71 years old, while 30.5 percent of patients were women. In addition, 59.4 percent of patients underwent isolated CABG, 24.8 percent underwent isolated aortic or mitral valve surgery and 15.8 percent underwent a combination of CABG and aortic or mitral valve surgery.

The median gait speed was 0.94 m/s in the CABG group, 1.00 m/s in the isolated valve surgery group and 0.94 m/s in the CABG plus valve surgery group. The median STS predicted risk of mortality was 1.70 percent, including 1.20 percent in the CABG group and 3.66 percent in the CABG plus valve surgery group.

The researchers defined operative mortality as death during the same hospitalization as the surgical procedure regardless of the timing or within 30 days of the surgical procedure regardless of venue.

The gait speed was less than 0.83 m/s in the slowest tertile, from 0.83 to 1.00 m/s in the middle tertile and more than 1.00 m/s in the fastest tertile. Patients in the slowest tertile were older and had a higher predicted risk of mortality and body mass index compared with patients in the fastest tertile. They also had higher rates of diabetes, chronic lung disease, peripherial arterial disease, prior stroke, prior MI, recent heart failure, New York Heart Association class III or IV heart failure and urgent surgery.

After adjusting for the STS predicted risk of mortality and the surgical procedure, the researchers said that gait speed was still an independent predictor of operative mortality as well as the composite outcome of mortality or major morbidity.

The researchers cited a few limitations of the study, including that all of the centers did not perform the 5-m gait speed test. They said that participating centers had significantly higher number of hospital beds, rates of residency training and white patients compared with nonparticipating centers. However, the participating and nonparticipating centers had a similar median age and percentage of women.

They added that centers used a written protocol and education sessions for training about the gait speed test. Further, the study included some high-risk patients between 80 and 89 years old and excluded patients undergoing transcatheter aortic valve replacement (TAVR). They said large-scales studies are currently examining the prognostic value of frailty in high-risk patients between 80 and 89 years old as well as TAVR patients.

“The adverse impact of slow gait speed in our study is comparable with that reported in community-dwelling frail older adults (11% per 0.1-m/s decrease), yet the time lag to observe fatal and nonfatal adverse events is considerably shorter (within 30 days after cardiac surgery as compared with many years),” the researchers wrote. “When used as the sole criterion for frailty, gait speed adds modestly to the STS risk model and should ideally be followed by a multidomain frailty test or a comprehensive geriatric assessment to discriminate risk (2-tiered approach). Additional research is needed to examine the effect of gait speed on long-term hazards and patient- centered outcomes, and to develop targeted interventions that can offset the negative impact of frailty.”