Fatigue can be an important predictor for cardiovascular (CV) events in patients with end-stage renal disease (ESRD), according to Japanese researchers.

Fatigue is among the most frequent symptoms in maintenance dialysis patients. The prevalence ranges from 60% to 97% in ESRD patients on long-term dialysis treatment, the investigators noted.

Investigators led by Hidenori Koyama, MD, of Osaka City University Graduate School of Medicine in Osaka, surveyed the prevalence and severity of fatigue in 788 hemodialysis (HD) patients by using a recently established fatigue scale, which consists of 64 items (i.e., symptoms), such as “feeling shaky on my feet,” “feeling restless due to anxiety,” “getting a low back ache,” “dosing off frequently.”

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Researchers asked subjects to rate how often in a recent week they experienced the symptoms on a 0-4 scale. classified the 64 items into eight fatigue-related factors (fatigue itself, anxiety and depression, loss of attention and memory, pain, overwork, autonomic imbalance, sleep problems, and infection).

The researchers obtained reference values by administered the questionnaire to healthy volunteers. They used data from questionnaires completed by 171 volunteers to calculate the means and standard deviations (SDs) for the eight factors. HD patients whose scores on the questionnaire were higher than twice the SD of the mean of healthy subjects were considered a highly scored group.

Highly scored patients made up 14.7% of the HD cohort, the investigators reported in the Clinical Journal of the American Society of Nephrology (2010; published online ahead of print). After a median follow-up of 26 months, 82 CV events occurred (15 fatal, 67 nonfatal). Highly scored patients had had a twofold increased risk of CV events compared with HD patients who were not highly scored, independent of age, diabetes, CV disease (CVD) history, and markers of inflammation and malnutrition.

In addition, 14.7%, 12.5%, 8.4%, 26.9%, 8%, 26.1%, 8.3%, and 17.5% of HD patients were high scorers with respect to fatigue itself, anxiety and depression, loss attention and memory, pain, overwork, autonomic imbalance, sleep problems, and infection, respectively.

A high score for fatigue itself was independently associated with a twofold increased risk of CV events, after adjusting for potential confounders. The presence of diabetes and a CVD history were associated with a 2.6 and 2.5 times increased risk.

In a subgroup of patients without a CVD history, overwork was associated with a 2.5 times increased risk of CV events and autonomic imbalance was associated with a significant twofold increased risk, according to the investigators.

“Our results clearly show that fatigue is an important predictor for CV events in a high-risk population, namely, ESRD patients under hemodialysis treatment,” the authors wrote.