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Climatic Influence on the Prevalence of Noncutaneous Disease Flare in Systemic Lupus Erythematosus in Hong Kong CHEUK-CHUN SZETO, HING-YIM MOK, KAI-MING CHOW, TSZ-CHEUNG LEE, JOHN YIN-KONG LEUNG, EDMUND KWOK-MING LI, THOMAS KAI-CHEUNG TSUI, SAMUEL YU, and LAI-SHAN TAM
ABSTRACT. Methods. We reviewed all noncutaneous lupus flare in 222 consecutive patients with SLE followed in our clinic from 1995 to 2005. Specific organ involvement of each flare was reviewed. The variation in the prevalence of lupus flare by calendar month and the relation with climatic factors were determined. Results. The total followup was 18,412 patient-months. In total, there were 313 episodes of noncutaneous flare recorded in 129 patients. There were more lupus flares in December and January [2.31 episodes, vs 1.58 episodes per 100 patient-months for other calendar months; relative risk (RR) 1.46, 95% CI 1.12-1.90, p = 0.004], and more flares of lupus nephritis in December and January (1.14 episodes, vs 0.60 episodes per 100 patient-months for other calendar months; RR 1.90, 95% CI 1.29-2.80, p = 0.001). There were more cases of membranous nephropathy in December and January (0.46 episode, vs 0.18 episode per 100 patient-months for other calendar months; RR 2.59, 95% CI 1.36-4.93, p = 0.0027), while the variation in prevalence of proliferative lupus nephritis was not statistically significant. There was also a significant U-shape correlation between the rate of lupus flare and the monthly average environmental temperature (r = 0.802, p = 0.0096), with higher flare rate at extremes of temperature. Conclusion. We found substantial seasonal variation in the incidence of noncutaneous flare in our SLE patients, with peak incidence in December and January. There was a U-shaped relation between environmental temperature and the prevalence of noncutaneous flare. Keeping a warm living environment and avoiding exposure to extremes of temperature may help to reduce flare for SLE patients in subtropical countries. (J Rheumatol First Release April 1 2008) Key Indexing Terms:
SYSTEMIC LUPUS ERYTHEMATOSUS
From the Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, and Hong Kong Observatory, Kowloon, Hong Kong, China. Supported in part by Chinese University of Hong Kong research accounts 7101215 and 6901031. C-C. Szeto, MD, FRCP(Edin), Senior Lecturer, Department of Medicine and Therapeutics, Prince of Wales Hospital; H-Y. Mok, PhD, Senior Scientific Officer, Hong Kong Observatory; K-M. Chow, MBChB, MRCP(UK), Associate Consultant, Department of Medicine and Therapeutics, Prince of Wales Hospital; T-C. Lee, PhD, Scientific Officer; J.Y-K. Leung, MSc, Scientific Officer, Hong Kong Observatory; E.K-M. Li, MD, FRCPC, Professor, Department of Medicine and Therapeutics, Prince of Wales Hospital; T.K-C. Tsui, BSc, Programmer, Hong Kong Observatory; S. Yu, BSc, Research Assistant; L-S. Tam, MD, MRCP(UK), Associate Professor, Department of Medicine and Therapeutics, Prince of Wales Hospital. Address reprint requests to Dr. C.C. Szeto, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China. E-mail: ccszeto@cuhk.edu.hk Accepted for publication January 10, 2008. |
