The contribution of resting heart rate and routine blood tests to the clinical assessment of disease activity in systemic lupus erythematosus.

OBJECTIVE: To contrast the contribution of simple clinical tests, such as resting heart rate (HR), complete blood count (CBC), and erythrocyte sedimentation rate (ESR), versus immunological tests in the assessment of disease activity in systemic lupus erythematosus (SLE).

METHODS: During an evaluation of disease activity indices in SLE, 39 patients had a full clinical evaluation in 99 visits including a disease activity index (MEX-SLEDAI), and serial measurements of HR, ESR, CBC, complement (C3, C4) and anti-dsDNA antibody levels (Farr).

RESULTS: Resting HR exhibited the highest correlation with MEX-SLEDAI scores (rs = 0.62). Thus, the disease was active (MEX-SLEDAI score of 2 or more) in all but one of 15 patients (93.3%) that had an HR > 90/min during the study. Hemoglobin levels (Hb) and ESR showed the second highest correlation (rs = -0.51, and 0.50, respectively). Seventeen patients had an Hb < 13 g/dl at least once; 14 (82.4%) had active disease during the study. Lymphocyte count, C3 levels, and anti-dsDNA levels correlated less strongly with disease activity (rs = -0.27, -0.29, and 0.30 respectively). Forward stepwise multiple regression analysis showed that HR, Ht, and C3 were independent markers of disease activity in this population (R2 = 0.51, p < 0.0001).

CONCLUSION: Closer attention to resting HR and CBC results may improve the assessment of disease activity in SLE.