[Influence of seasons on risk of flare-up of systemic lupus: retrospective study of 66 patients].

Purpose: To establish the possible connection between visceral, arthro-cutaneous and biological spreading of systemic lupus (SL) and hours of sunlight.

Material And Methods: Retrospective study of 66 SL patients, consisting of 52 visceral and 14 arthro-cutaneous cases taking into account the chronological pattern of each new aggravation, based on 480 clinical records.

Results: Increased frequency in visceral aggravation was observed in the post-summer period (August-January) (n = 57), as compared with the pre-summer period (February-July) (n = 25) (RR = 1.75, P = 0.006). This post-summer visceral aggravation was correlated with cutaneous affection (RR = 4.18) and absence of previous corticotherapy (RR = 3.97). Visceral and arthro-cutaneous aggravations taken together revealed a more disturbed immune balance pattern in the post-summer period (anti-dsDNA: 30 versus 25.1 IU/L [P = 0.07]; C3: 0.83 vs 0.921 IU/L [P = 0.05]; C4: 0.146 vs 0.183 [P = 0.05]), providing evidence of greater severity. Moderate thrombopenia (50-120 10(9)/L) accompanying visceral SL with antiphospholipids (n = 33) was more frequent during the post-summer period, even in the absence of aggravation (P = 0.03). The quarterly distribution of visceral aggravations was correlated with average hours of sunlight in the preceding quarter (P = 0.01).

Conclusion: There is a post-summer increase in the frequency and severity of visceral SL spreading correlated to cutaneous exacerbation and sunlight.