Association of Multiple Melanocytic Naevi with Education, Sex and Skin Type. A Northern Finland Birth Cohort 1966 Study with 46 Years Follow-up.

Having multiple melanocytic naevi (< 50 naevi) is one of the strongest risk factors for melanoma. However, the epidemiology in adults is unclear. This comprehensive dermatological status investigation of 1,932 birth-cohort study cases aged 46 years analysed the prevalence of multiple melanocytic naevi and their association with sex, socioeconomic status (education) in childhood and adulthood, skin type and sunbathing habits. The prevalence of multiple melanocytic naevi was 11.6% (223/1,930). Higher education (odds ratio (OR) 2.11, 95% confidence interval (95% CI) 1.51-2.96), male sex (OR 1.48, 95% CI 1.07-2.06), sun-sensitive skin type (OR 2.09, 95% CI 1.34-3.27) and regular use of sunscreen (OR 2.03, 95% CI 1.23-3.37) were associated with increased risk of multiple naevi. Inflammatory skin diseases decreased (OR 0.49, 95 CI% 0.33-0.72) the risk of multiple naevi. In conclusion, several risk factors were found for multiple naevi among adults living in high latitudes, in Northern Finland.