Between January 1997 and December 2006, there were 640 patients who conformed to the diagnostic criteria for SLE and had a SLEDAI score of $10. Results indicated that the number of patients with active SLE was highest in winter (December, January and February) and lowest at the junction between summer and autumn (July, August and September). Distribution of the 640 patients over 12 months is shown in Figure 1 and Table 1 .