A snapshot of an eCohort: A comparison of the LifeGene population at baseline with the Swedish general population

Aims: With access to technologies and internet around the globe, opportunities have been provided to contact and recruit participants at a more rapid pace, without face-to-face contact. However, ‘eCohorts’ may yield substantial volunteer bias. Few studies have compared eCohorts to general populations or samples where traditional research methods have been applied. To our knowledge, no prior analyses have reported on Swedish-based LifeGene eCohort, in comparison with the Swedish general population. The aim of this study was to compare the LifeGene eCohort at baseline with the Swedish general population. Methods: The LifeGene eCohort (n = 39,862) was compared with the general population in Sweden represented by weighted data from the Swedish Public Health agency and Statistics Sweden. LifeGene is a nationwide project with yearly data collection. Descriptive statistics were used to compare demographic characteristics, and self-reported data on diagnosis of depression. Results: The LifeGene eCohort overrepresented younger people, females, those with a higher socio-economic status, non-smokers and people with a diagnosis of depression. Surprisingly, the eCohort included a larger percentage of people born outside of Sweden compared to the general population, which is not in line with previous studies. Conclusion: The results show that the participants in the LifeGene eCohort are different regarding demographic variables and some health indicators from the Swedish general population. Hence, if comparisons are made between the LifeGene eCohort and a general population it becomes important to be aware of the differences that might exist between the different cohort populations and how these might affect the estimates.