Seasonal distribution of systemic lupus erythematosus activity and its correlation with climate factors

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with a variety of clinical manifestations. Although inter-individual variations exist with respect to susceptibility to develop SLE, no study has been carried out to determine the role of different climate conditions in predisposing the susceptible individuals to SLE. The objective of this study was to investigate the role of different seasons and climate factors on SLE activity. From 2000 to 2009, the seasonal distribution of 2,802 active SLE patients recruited from Anhui Provincial Hospital and the First Affiliated Hospital of Anhui Medical University was analyzed retrospectively. The climate data were provided by the Institute of Geographical Sciences and Resources, Chinese Academy of Sciences. The correlation between climate factors and SLE activity was also analyzed. The proportion of active SLE patients in winter, spring, summer, and autumn was 10.06, 10.31, 9.74, and 8.66‰, respectively. In autumn, the proportion was much lower than that in winter and spring (P < 0.05). The proportion among winter, spring, and summer had no statistical difference (P > 0.05). The number of active SLE patients had no correlation with air temperature (r = 0.483, P > 0.05), relative humidity (r = -0.294, P > 0.05), and sunshine percentage (r = 0.503, P > 0.05), but it had positive correlation with amount of precipitation (r = 0.601, P < 0.05), wind velocity (r = 0.713, P < 0.01), and sunshine duration (r = 0.769, P < 0.01) and negative correlation with barometric pressure (r = -0.664, P < 0.05). The disease activity of patients with SLE is affected by seasons and climate factors.