Achieving an exercise capacity of more than 6.5 metabolic equivalents - such as daily brisk walking for 30-40 minutes -- might be protective, according to researchers.

As aerobic fitness increases, the risk of chronic kidney disease (CKD) progressively decreases suggesting a protective role for exercise, according to a new study of male veterans.

“The findings of the present study demonstrate that health benefits associated with higher exercise capacity also extend to lowering the risk of developing CKD,” stated Peter Kokkinos, PhD, of Veterans Affairs Medical Center in Washington DC, and colleagues.

The investigators prospectively assessed peak exercise capacity for 5,812 male veterans at the center using a standard treadmill test. The men were referred for exercise testing for clinical reasons.

All participants were free of CKD stage 3 and above at baseline with an estimated glomerular filtration rate of 60 mL/min per 1.73 m² or higher. CKD developed in 1,010 men (17%) during follow-up.

According to results published in Mayo Clinic Proceedings, the risk of CKD declined by 22% with every 1 metabolic equivalent (MET) increase in exercise capacity. Compared to the least fit individuals, the odds of CKD were 13%, 45%, and 58% lower in the low-, moderately-, and high-fit groups, respectively.

Researchers adjusted the fitness groupings for age. They also adjusted their models for CKD predictors, such as race, diabetes, hypertension, dyslipidemia, alcoholism, glucose-lowering medication, and lipid-lowering medication.

Men with lower GFR may be deficient in vascular density and recruitment, the researchers suggested.  Also, a significant number of the veterans had a high body mass index and diabetes. Insulin resistance, dyslipidemia, and hypertension may contribute to vascular stiffness and systemic inflammation, setting the stage for CKD.

By contrast, physically active men have greater capillary recruitment during exercise, which likely corresponds to a greater renal reserve and a lower likelihood of CKD.

Starting an aerobic exercise routine is reasonable for many men with their doctors' permission, the investigators noted: “The average exercise capacity of approximately more than 6.5 METs necessary to realize these health benefits is achievable by many middle-aged and older men by daily exercises, such as brisk walking.”

Source

1. Kokkinos, P, et al. MayoClinic Proceedings, April 2015; doi: 10.1016/j.mayocp.2015.01.013.

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The Prostate Health Index (phi), a blood test that combines 3 PSA measurements into a single score, improves detection of clinically significant prostate cancer (PCa) and could help decrease the number of unnecessary prostate biopsies, researchers reported.

In a study of 658 men aged 50 years and older with PSA levels of 4–10 ng/mL, Stacy Loeb, MD, of New York University, and colleagues investigated whether phi can improve specificity for detecting clinical significant PCa and reduce PCa over diagnosis. The researchers used the Epstein definition of clinically significant PCa (Gleason score 7 or higher, 3 or more positive cores, and more than 50% involvement of any core).

The test measures total, free, and [-2]proPSA (p2PSA), the latter being an isoform of free PSA identified as the most PCa-specific form found in tumor extracts.

Phi outperformed its individual components in detecting clinically significant PCa, the researchers reported in The Journal of Urology (2015;193:1163-1169). Using a 90% sensitivity cutoff for significant versus insignificant PCa (a phi threshold of 28.6) could potentially avoid 30% of biopsies with indolent or no PCa compared with 21.7% using free PSA alone, the investigators reported.

The new study builds on previous research showing that phi improves specificity and provides a greater net benefit for PCa detection compared with total and percent free PSA, the researchers pointed out.

“Phi is a simple blood test that we recommend for use as part of a multivariable approach to reduce unnecessary biopsies and over diagnosis,” the authors concluded.

Dr. Loeb's group acknowledged some study limitations, including the use of biopsy criteria to define clinical significance. “Although biopsy criteria are frequently used, these end points are not perfect and other factors such as life expectancy also have a key role in defining over diagnosis,” they wrote.

With regard to study strengths, the researchers noted that their study used a prospectively enrolled source population, including a large number of men from multiple centers across the United States.

The study population had a median age of 63 years. Of the 658 men, 324 (49.2%) had PCa detected on biopsy. Among the men with PCa, 52.5% had clinically significant disease and 33.7% had Gleason 7 or higher tumors.

The study was funded by Beckman Counter Inc., of Carlsbad, Calif., which markets the phi test. The test received FDA premarket approved in June 2012 and the company announced the test's availability in the United States in May 2014.

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