Systemic lupus erythematosus in Iceland 1975 through 1984. A nationwide epidemiological study in an unselected population.

This unselected group of patients included all cases diagnosed and managed in hospitals, as well as outside hospitals in Iceland over the 10-year period from 1975 to 1984. Seventy-six new cases were found, with an incidence of 5.9 and 0.8/100,000 for females and males at risk, respectively. The mean age at diagnosis was 46.6 years. Twenty-five percent of the patients would have been missed had the study included hospital patients only. A clinical pattern different from previous studies was found as illustrated by a low incidence of kidney disease; nephritis was found in 20% of patients