A Research Of The Minimal Erythema Dose In Lupus Erythematosus And Dermatomyositis

Background: Photosensitivity is one of the most common clinical phenomenon of lupus erythematosus and dermatomyositis.It is important in the judgement of the diagnosis and treatment.Minimal Erythema Dose(MED)is an accurate and objective test method to detect photosensitivity.But the MED test is not widely used frequently in LE or DM.Instead,we rely on the complaints of the patients and clinical experience.Therefore,the true prevalence of photosensitivity is still not clear.At the same time,which of the disease show more sensitive to UVR,whether the MED is related to the laboratory assay or the severity of the disease,whether the MED changes after the treatment is still unkown.Methods: We select the lupus erythematosus and dermatomyositis patients who was treated in our hospital from 10/2014 to 2/2016.We record the history of every patient,including the onset time,main symptoms(whether there is any skin purpura,fever,joint pain,mucosa bleeding,hair loss,mouth ulcers,muscle aches,vision loss,dizziness,headache,fatigue,asthma,etc.),history of medicine,whether experiencing discomfort(skin aggravating,inducing new skin,dizziness,headache,fatigue and other systemic reactions)after sun exposure.Perform the Minimal Erythema Dose test at the same time,and record the related laboratory indexes and test results(including blood routine,urine routine,24 hour protein quantitative,liver and kidney function,ANA,ENA,ds-DNA,complement,chest X-ray,electrocardiogram,echocardiogram,brain magnetic resonance,joint X-ray,etc).After finishing the collection of relevant data,the relationship between the MED index change and other factors is calculated by chi-square test,t test analysis.Results: Finally,there is 130 patients involved in this research,including 62 patients of lupus erythematosus and 68 patients of dermatomyositis.In the 62 patients of LE,47 patients were diagnosed of SLE,4 patients SCLE and 11 patients CCLE.At the mean time,In the 68 patients of DM,47 patients were diagnosed of DM and the other 21 patients ADM(Amyopathic dermatomyositis).MED drop ratio of SLE,DM,ADM were 44.7%,34.0%,61.9%.MED is not correlated to related laboratory tests.The patients who has already been treated with corticosteroids and hydroxychloroquine have a lower rate of the drop of MED.The drop of MED is related to the SLEDAI.Conclusion: 1.In the study,the prevalence of the MED drop in the lupus erythematosus and dermatomyositis is consistent with domestic and international research,where the prevalence of ADM is even higher than other diseases.2.The disease severity in patients with SLE has some degree of correlation values to MED.3.The CDASI has no correlation values to MED.4.The SLE patients treated by glucocorticoid has a lower rate of the MED drop than those who was not treated;4.The MED of lupus patients and dermatomyositis patients is not related to the laboratory parameters.