Participation in a Prospective Cohort Study on Melanoma did not Affect the Incidence and Mortality of the Studied Disease.

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.