Factores de riesgo para el melasma. Medellín-2005

Melasma is a hiperpigmentation of unknown cause primarily of the face. Is common in women of the tropics. Pregancy, UV light and oral contraceptives have been implicated, but the level of association is unknown. This study pretends to find the degree association between the ethilogical factors of melasma with the development of the disease in women older then 18 years, in Medellín. Methods: A case and control study was carried out, including 101 adulta women; 67 of them had a diagnosis of melasma, and the other 34 were healthy controls. The size of the sample was calculated based on solar exposure as main risk factor with a theoretical frequency of 99% for cases and 88% for controls, by clinical experience with a confiability of 95%. The case control ratio was 2 to 1. The instrument for collecting of information was a questionaire designed for the study. The data was obtained by telefom. A bivariated analysis was performed done, calculating the differences of proportions and the OR value, with confiability intervals and p value, with a confiability of 95%. Results: Median age was 38.3 years with a range between 21 and 57. Cases: Duration of disorder varied from 1 to 20 years, 32 had an homogeneous pattern (47.7%) 35 reticular (52.2%); centrofacial distribution was the most common (52.2%) followed by malar (35.8%) and in third place, mandibular (11.9%). Eigthy for cent 80.5% were more visible with Wood's light, 16.4% didn't show any difference and 3% were less visible. Risk factors: Risk factors, didn't show significant association with melasma: skin phototype, number of pregnancies, actual use of contraceptives or other non hormonal drugs, hormonal therapy different from femenine hormones, history of thyroid disease and history of sola rexposure. A bigger disparity reason for suffering the disease was confirmed for those with first degree relatives with melasma, with an OR 2.58 (1.08-6.73 intervals) and p = 0.029 and use of cosmetic makeup (powder or foundation) OR 3.69 (1.36-10.12) p = 0.0036. The intake of cola drinks was a protective factor OR 0.021 (0.06-0.07) and p = 0.0026. Conclusions: We can conclude that of the many implicated factors for the development of melasma, by scientific studies of popular belief, only the family history of disease and the use of makeup were risks in women older then 18 years in the city of Medellin. The fact that colas intake acted as a protective factor requires further studies.