ABSTRACT
Prospective observational studies have shown previously that study participants have lower morbidity and mortality than non-participants. The aim of the current study was to determine whether participants in a prospective cohort study on melanoma have a different incidence and mortality of melanoma compared with non-participants and the background population. Information was collected from Swedish National Registers on participants (n = 30,501) and non-participants (n = 10,499) in the "Melanoma In Southern Sweden" (MISS) study and the background population (n = 243,032). Hazard ratios were calculated for overall incidence of cancer and melanoma, and all-cause and melanoma-specific mortality, using Cox regression. Participants had a lower overall incidence of cancer and all-cause mortality than non-participants and the background population. There was no difference in incidence of melanoma or melanoma-specific characteristics between participants and the background population. In conclusion, participants in the MISS study have a slightly better general health, but are a representative sample of the population with regard to studies of melanoma risk factors.