The higher the body mass index, the higher the level of fatigue a lupus patient is likely to experience, Illinois researchers report.
They also linked obesity to fatigue levels.
Another finding was that reducing fatigue through exercise did not lead to lower levels of adipokines, chemical messengers generated by fat tissue known as adiposes.
The study, “Serum adipokine levels and associations with patient-reported fatigue in systemic lupus erythematosus,” appeared in the journal Rheumatology International.
Up to 90 percent of lupus patients experience fatigue, adding to the disease’s healthcare costs. Previous reports have shown an association between moderate to vigorous exercise and reductions in patient-reported fatigue. Scientists were unable to identify a mechanism for this association, however.
Other research has shown that adipokines, including leptin, adiponectin, and resistin, are involved in immune-regulated lupus processes.
The Illinois researchers wanted to know if changes in adipokine levels could explain the link between exercise and reduced lupus patient fatigue.
The study involved 129 patients, 93 percent of whom were women.
Researchers assessed physical activity with an electronic device known as an accelerometer that patients wore during waking hours in the seven days of the study. They assessed fatigue with the questionnaire-based FSS and PROMIS scales and by measuring their levels of leptin, adiponectin and resistin.
One correlation with fatigue that they discovered was body mass index, a measure of body fat based on height and weight. Another was obesity.
After the team adjusted for body mass index, they found no significant correlation between levels of leptin, adiponectin, or resistin and patient-reported fatigue. They concluded that body mass index “more strongly influences patient-reported fatigue than leptin, adiponectin, or resistin.”
They came up with several possibilities for lack of a correlation between levels of fat-tissue-produced chemical messengers and fatigue. One was that all patients had relatively low levels of fatigue when the study started. They speculated that adipokine levels may account for reduced fatigue only in lupus patients with higher fatigue scores than seen in their study.
In addition, the study did not evaluate changes in adipokine levels at several points in time, the researchers pointed out. They took only one snapshot of those levels. The single reading might not have reflected an association with fatigue, if a link did exist, they said.
“Leptin, adiponectin, [the leptin/adiponectin] ratio, and resistin were not independently associated with patient-reported fatigue in this pilot study” of lupus patients, the researchers wrote. “Obesity was associated with both FSS and PROMIS fatigue scores.”
“Future studies should evaluate adipokines and fatigue in a larger” patient sample, and look at relationships between adipokine levels and fatigue over time, the team wrote.