The team recruited patients from the UCSF Lupus Outcomes Study, an ongoing, longitudinal panel study. Body composition and regional body fat distribution were measured with a lunar prodigy, dual-energy X-ray absorptiometry system (DEXA). This analysis yielded measures of total, as well as regional, body fat and lean mass, each of which was adjusted for height to create a fat mass index (FMI) and a lean mass index (LMI). Lower extremity strength and lower right knee flexion and extension were measured. Fatigue was measured with the severity subscale of the Multidimensional Assessment of Fatigue.
The analysis focused on the 115 women for whom all data were available. Mean total-percent body fat was 41%, and the mean fatigue rating was 5.9 on the fatigue scale. Controlling for age, disease duration, and disease activity, neither total fat mass index nor lean mass index were significantly associated with fatigue severity. However, when appendicular and trunk FMI were examined separately, greater trunk FMI was significantly associated with greater fatigue. Muscle weakness also was significantly and independently associated with greater fatigue. High doses of prednisone were associated both with fatigue and abdominal obesity. Dr. Hassett also noted that fatigue could have other causes not accounted for in the study, such as physical inactivity, sleep problems, or inflammation.
[The study] was the first to demonstrate that supervised physical exercise can improve endothelial function in SLE patients.
Heart-Rate Variability
Premature coronary disease is known to be a major cause of morbidity and mortality in lupus, noted Danilo M.L. Prado, PhD, in the rheumatology division of the University of São Paulo Medical School in Brazil. This is mediated not only by traditional risk factors (e.g., diabetes and hypertension), but also by risk factors associated with the disease itself (e.g., disease activity and drugs). And another risk factor is starting to emerge: Patients with SLE are known to have lower heart-rate variability, suggesting impaired autonomic modulation.
“Attenuated heart-rate response to exercise, also known as chronotropic incompetence, has been shown to be predictive of mortality in heart disease even after adjustment for age, physical fitness, and standard cardiovascular risk factors,” Dr. Prado said. Studies associate low heart-rate recovery with attenuated parasympathetic reactivation and sympathetic overactivity following the termination of exercise.
Dr. Prado hypothesized that SLE patients would present an atypical chronotropic response. Eighteen women with SLE, but without other cardiopulmonary issues, were compared to 17 healthy controls. All subjects performed a progressive treadmill cardiopulmonary test until exhaustion in order to determine their maximal aerobic capacity. The women with SLE had significantly greater resting heart-rate levels, lower peak workload levels, and lower aerobic fitness (as measured by peak VO2) when compared with the controls.
