Abstract: Objective To study the relationship of sunlight exposure and photoprotection with clinical activity in systemic lupus erythematosus.Methods A structured questionaire was administered to 107 SLE patients,to assess their attitudes and behavior regarding sunlight exposure and photoprotection.The clinical manifestations,laboratory findings and treatment were evaluated.Results All patients were classified into two groups based on the duration of exposure to sunlight per day.Fourty-eight (44.86%) patients were exposed to direct sunlight for an average of less than one hour per day in one group and 59 (55.14%) for one hour or more in the other group.Twenty-four (22.43%) patients reported use of photoprotective measures in spring and summer.The patients in the former group had significantly lower incidences of photosensitivity,arthritis,alopecia,exacerbations,presence of anti-dsDNA antibody,decrease of complement C3,C4 and CH50 than those in the latter group(P<0.05).The incidence of renal involvement was not different between the two groups.But the severity of renal involvement was lower in the former group than that in the latter (P<0.01).The former group required hydroxychloroquine,middle to high dose of corticosteroid and CTX pulse treatment less frequently than the latter group to control the disease.After the treatment there was no significant difference in the improvement of malar rash,fever,arthralgia and ANA between the two groups.But it took significantly shorter time for the urine protein test to turn negative in the former group than that in the latter group(P<0.05).Conclusions SLE patients should reduce the duration of exposure to sunlight and take effective photoprotective measures.

Key words: Sunlight exposure, Photoprotection, Lupus erythematosus,systemic