October 19, 2018
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Better cardiorespiratory fitness reduces all-cause mortality risk

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Wael Jaber
Wael Jaber

Cardiorespiratory fitness was inversely associated with long-term mortality, according to a study published in JAMA Network Open.

The greatest survival was associated with extremely high aerobic fitness, especially in older patients and those with hypertension, according to the study.

“Patients should be encouraged to ask their health care providers for an exercise prescription if they are planning on starting and exercise program,” Wael Jaber, MD, cardiologist at Cleveland Clinic, told Cardiology Today. “A prescription can be ‘filled’ in any cardiac rehab centers where patients can be guided and coached with individual recommendations.”

Stress testing

Kyle Mandsager, MD, of the Cleveland Clinic Foundation, and colleagues analyzed data from 122,007 patients (mean age, 53 years; 59% men) who underwent stress testing from 1991 to 2014.

Exercise treadmill testing was performed according to standardized protocols. Cardiorespiratory fitness was quantified as peak estimated metabolic equivalents, which was determined by speed and treadmill grade at peak exercise.

Patients were categorized by performance: low (< 25th percentile), below average (25th-49th percentile), above average (50th-74th percentile), high (75th-97.6th percentile) and elite ( 97.7th percentile).

The primary outcome was all-cause mortality.

During a median follow-up of 8.4 years and 1.1 million person-years of observation, all-cause mortality occurred in 13,637 patients.

When adjusted by risk, all-cause mortality was inversely proportional to cardiorespiratory fitness, with the lowest risk seen in patients in the elite group compared with the low group (adjusted HR = 0.2; 95% CI, 0.16-0.24). Those in the elite group even had improved survival compared with those in the high-performance group (aHR = 0.77; 95% CI, 0.63-0.95).

Running on treadmill 
Cardiorespiratory fitness was inversely associated with long-term mortality.
Source: Adobe Stock

An increase in all-cause mortality was linked to reduced cardiorespiratory fitness when the low-performance group was compared with the elite group (aHR = 5.04; 95% CI, 4.1-6.2). This also occurred when the below-average group was compared with the above-average group (aHR = 1.41; 95% CI, 1.34-1.49). The association between increased all-cause mortality and reduced cardiorespiratory fitness was comparable to or greater than traditional risk factors, including smoking (aHR = 1.41; 95% CI, 1.36-1.46), CAD (aHR = 1.29; 95% CI, 1.24-1.35) and diabetes (aHR = 1.4; 95% CI, 1.34-1.46).

Reduction in mortality

Patients aged at least 70 years in the elite- or high-performing groups had a statistically significant reduction in mortality (aHR = 0.71; 95% CI, 0.52-0.98). Among patients with hypertension, a significant reduction in risk-adjusted all-cause mortality was also seen in the elite-performing group vs. the high-performing group (aHR = 0.7; 95% CI, 0.5-0.99).

Compared with other performance groups, patients with cardiorespiratory fitness greater than 2 standard deviations above the mean for sex and age had an incremental reduction in all-cause mortality.

“Maintaining a high aerobic functional class is associated with greater risk reduction than treating many known traditional risk factors such as hypertension, diabetes and prior history of CAD,” Jaber said in an interview. “The risk reduction appears to follow a dose-response pattern with no upper limits of benefits; patients with highest functional class benefits most. We need to test whether an improvement in functional class over time with training can move individual patients from one mortality curve to a better one.” – by Darlene Dobkowski

For more information:

Wael Jaber, MD, can be reached at Cleveland Clinic Main Campus, 9500 Euclid Ave., Mail Code J1-5, Cleveland, OH 44195.

Disclosures: The authors report no relevant financial disclosures.