The antimalarial drug hydroxychloroquine is thought to be effective in controlling some of the manifestations of systemic lupus erythematosus, but its effectiveness has not been demonstrated conclusively. Methods. We conducted a six-month, randomized,

placebo-controlled study of the effect of discontinuing hydroxychloroquine sulfate treatment in 47 patients with clinically stable systemic lupus erythematosus. The patients were randomly assigned to continue their same dose of hydroxychloroquine (n = 25) or to receive placebo (n = 22) for 24 weeks. Ten patients in each group were also taking prednisone.

The relative risk of a clinical flare-up, defined as the development of specific clinical manifestations of systemic lupus erythematosus or an increase in their severity, was 2.5 times higher (95 percent confidence interval, 1.08 to 5.58) in the patients taking placebo than in those continuing to take hydroxychloroquine (16 of 22 patients vs. 9 of 25 had flare-ups), and the time to a flare-up was shorter (P = 0.02). The relative risk of a severe exacerbation of disease that required withdrawal from the study was 6.1 times higher (95 percent confidence interval, 0.72 to 52.44) for the patients taking placebo (5 of 22 patients vs. 1 of 25 had severe exacerbations of disease). Changes in the dose of prednisone were not different in the two groups.

Patients with quiescent systemic lupus erythematosus who are taking hydroxychloroquine are less likely to have a clinical flare-up if they are maintained on the drug. (N Engl J Med 1991; 324:150–4.)