 In a first step, a descriptive analysis will be carried out in order to describe the characteristics of the sample. Basic summary statistics, such as proportions, means and standard deviations, will be used to characterize the population. In order to identify the factors associated with the severity of the disease on the one hand and the phototype on the other, comparisons between groups severe versus non-severe and light phototype versus dark phototype will be carried out by unconditional logistic regression. All potential predictors of severity will first be assessed individually, and Odds Ratio OR, corresponding 95 CIs and P values will be calculated. The significance of the OR will be determined by the Wald test χ2, and the predictors with P .20 will then be evaluated using a multivariate analysis with a pre-selection procedure. Possible interactions and multi-colinearity will be examined. Finally, the quality of fit of the final model will be evaluated using the logistic regression diagnostic procedure. P 0.05 will be considered as statistically significant. The Hosmer-Lemeshow test will be carried out to test the suitability of the model. 