Participation in a Prospective Cohort Study on Melanoma did not Affect the Incidence and Mortality of the Studied Disease
Åsa M. C. Ingvar, Håkan Olsson, Per Broberg, Karolin Isaksson, Christian Ingvar, Kari Nielsen
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.
People who agree to participate in research studies have been shown to have a lower incidence of cancer and lower mortality compared with people who are non-participants. It is not clear whether the incidence of the disease that is being studied is different in participants. We wanted to find out if this was the case in our melanoma cohort study, which was initiated in 1990. The results showed that there was no difference in melanoma incidence or mortality between participants, non-participants and the background population. In conclusion, our study sample is a representative sample of the background population with regard to studies on risk factors for melanoma.