Invitation to a population-based cohort study: differences between subjects recruited using various strategies

Area of Science:

• Epidemiology
• Public Health
• Biostatistics

Background:

• Population-based prospective cohort studies are crucial for understanding disease etiology and mortality.
• Recruitment strategies can influence the representativeness of study cohorts.
• Differences in participant characteristics may arise from varying invitation methods.

Purpose of the Study:

• To compare sociodemographic, lifestyle, cancer incidence, and mortality differences between subjects recruited via community versus personal invitations.
• To analyze variations between early and late responders to personal invitations in a cohort study.

Main Methods:

• The Malmö Diet and Cancer Study (MDCS) recruited 28,098 subjects (born 1923-1950) between 1991-1996.
• Recruitment utilized community-directed (passive) and personal letter (active) invitations.
• Data collected via questionnaires, physical examinations, and national registry linkage for cancer and mortality.

Main Results:

• Community-invited subjects were older, more often female, and had more favorable sociodemographic/lifestyle factors, lower disease prevalence, cancer incidence, and mortality compared to personally invited subjects.
• Late responders to personal invitations were more likely to be male, older, have poorer socioeconomic status, higher smoking prevalence, obesity, and prevalent disease.

Conclusions:

• Recruitment strategies significantly influence the characteristics of participants in population-based cohort studies.
• Different invitation methods (community vs. personal) and response times (early vs. late) lead to distinct participant profiles.
• These variations can impact findings related to disease incidence and mortality within cohort studies.