The prevalence of multiple sclerosis (MS) varies with latitude: it increases with distance from the equator in both hemispheres. To seek evidence on whether solar radiation is a protective factor for MS, this study investigated whether skin cancer, as an indicator of solar radiation, is less common in people with MS than in others.
Unit of Health-Care Epidemiology, Department of Public Health, Institute of Health Sciences, Oxford University, Oxford, UK. michael.goldacre@dphpc.ac.uk
