Daily Physical Activity Predicts Postdialysis Fatigue

Hemodialysis patients who were more physically active had less postdialysis fatigue (PDF) compared with less active patients in a study of patients undergoing maintenance hemodialysis thrice weekly. The amount of physical activity on the day after dialysis was most predictive of PDF, whereas the level of activity on the day of dialysis was not.

The fatigue following dialysis is not well understood but is one of the most debilitating of hemodialysis-related symptoms. It affects a large proportion of patients, may last as short as an hour or more than a day, and may be mild or severe. Up to now, no one has known if physical activity has any effect on PDF, said Patricia Gordon, PhD, RN, adjunct assistant professor in the department of medicine at the University of California, San Francisco. So she and her colleagues performed a retrospective study to investigate the extent to which daily physical activity may be associated with PDF in patients on conventional hemodialysis.

Patients originally participated in the Nandrolone and Exercise Trial, involving men and women undergoing maintenance hemodialysis thrice weekly. Participants were compliant with dialysis and had adequate dialysis delivery. Frequency, severity, and duration of PDF were assessed by questionnaires. Accelerometers, devices that measure motion of the body in three planes, measured physical activity.

The 25 patients (16 male) had a mean age of 54 years, were 56 percent African-American, 32 percent Asian or Pacific Islander, and the rest white. They had been on hemodialysis a mean of 21 months, and the mean hematocrit was 35.1 percent.

Sixteen percent of patients reported that they experienced PDF occasionally; 20 percent, often; and 40 percent, very often. The intensity ranged from none to very severe, with 28 percent rating the intensity as moderate; 24 percent, severe; and 8 percent, very severe. Most PDF lasted a “short” or “moderate” time (combined, 56 percent of responses), but 24 percent of patients said it lasted a “long” or “very long” time.

PDF was significantly associated with less physical activity (P=0.004), more months on dialysis (P=0.02), and lower Kt/V (P=0.03). It was not significantly associated with hematocrit (P=0.11), but there was a trend toward association with lower hematocrit.

The researchers said that 88 percent of the people in the study reported some degree of PDF. The more physically active participants reported less fatigue, and average daily physical activity correlated most strongly with PDF. The level of activity on the day after dialysis predicted PDF whereas the level on dialysis days did not. The investigators speculated that dialysis days may cause some patients to be more active and some less, which could affect their feelings of fatigue.

Gordon said other researchers have studied PDF in conjunction with variables other than exercise. “Postdialysis fatigue has been associated with ultrafiltration rates, osmolar flux, biocompatible and incompatible membranes,” she said. “But when researchers have manipulated those factors, it hasn’t really led to a complete amelioration of the symptom.”

She said her study suggests that “encouraging patients to be more physically active may decrease their postdialytic complaints because fatigue is very subjective, and it covers a wide range of not feeling well . . . . The next step would be to have an intervention to increase physical activity and see then if that ameliorated postdialysis fatigue to any extent.”

Gordon noted that some dialysis units have intradialytic exercise programs involving stationary cycling while being treated. Such programs are somewhat difficult to implement and require more staff attention, “but those that are in place, I think are successful,” she said.

Gordon presented her results at a poster session titled “Dialysis: Non-Cardiovascular Outcomes and Clinical Trials I.”