Dyspnea in ambulatory patients with SLE: prevalence, severity, and correlation with incremental exercise testing.

Objective: We sought to determine the prevalence and severity of dyspnea, and to correlate dyspnea with clinical features and exercise limitation in ambulatory patients with systemic lupus erythematosus (SLE).

Methods: Twenty-five consecutive patients were evaluated with a validated pulmonary questionnaire, chest radiograph, 2-dimensional echocardiography, resting pulmonary function tests, and incremental exercise testing.

Results: Dyspnea was reported by 60% (95% CI 39-79) of patients; 20% (95% CI 7-40) had severe dyspnea (inability to dress without dyspnea) and 12% (95% CI 3-31) had moderate dyspnea (dyspnea after walking 100 yards). Compared to patients without dyspnea, patients with dyspnea were more likely to have had a history of clinical lupus involving the lung (80 vs 40%, p = 0.05), a lower total lung capacity (77.5 vs 94.8%, p = 0.002), and a reduced maximum oxygen consumption (VO2max of 53.4 vs 67.7%, p = 0.01). Patients with severe dyspnea and patients without dyspnea did not differ in duration of prednisone use, activity of disease, weight, or in frequency of Raynaud's phenomenon (p > 0.05). Only 4% of all patients had abnormal left ventricular motion on 2-dimensional echo; patients with moderate or severe dyspnea had normal left ventricular motion. Of the 5 patients with severe dyspnea, 4 (80%) had restrictive lung disease and 1 (20%) had an isolated diffusion defect. All patients with dyspnea had an abnormal exercise test, but so did 9/10 without dyspnea (p > 0.05). Severity of dyspnea correlated highly with maximum exercise tolerance measured by VO2max (R2 = 0.51, p = 0.0001).

Conclusion: In ambulatory patients with SLE, dyspnea is common, frequently disabling, associated with a history of lupus involvement of the lung, and correlates highly with objective measures of exercise limitation.