title: Lessons Learned From Methodological Validation Research in E-Epidemiology.
abstract: Traditional epidemiological research methods exhibit limitations leading to high logistics, human, and financial burden. The continued development of innovative digital tools has the potential to overcome many of the existing methodological issues. Nonetheless, Web-based studies remain relatively uncommon, partly due to persistent concerns about validity and generalizability.
  
  
  
  The objective of this viewpoint is to summarize findings from methodological studies carried out in the NutriNet-Santé study, a French Web-based cohort study.
  
  
  
  On the basis of the previous findings from the NutriNet-Santé e-cohort (>150,000 participants are currently included), we synthesized e-epidemiological knowledge on sample representativeness, advantageous recruitment strategies, and data quality.
  
  
  
  Overall, the reported findings support the usefulness of Web-based studies in overcoming common methodological deficiencies in epidemiological research, in particular with regard to data quality (eg, the concordance for body mass index [BMI] classification was 93%), reduced social desirability bias, and access to a wide range of participant profiles, including the hard-to-reach subgroups such as young (12.30% [15,118/122,912], <25 years) and old people (6.60% [8112/122,912], ≥65 years), unemployed or homemaker (12.60% [15,487/122,912]), and low educated (38.50% [47,312/122,912]) people. However, some selection bias remained (78.00% (95,871/122,912) of the participants were women, and 61.50% (75,590/122,912) had postsecondary education), which is an inherent aspect of cohort study inclusion; other specific types of bias may also have occurred.
  
  
  
  Given the rapidly growing access to the Internet across social strata, the recruitment of participants with diverse socioeconomic profiles and health risk exposures was highly feasible. Continued efforts concerning the identification of specific biases in e-cohorts and the collection of comprehensive and valid data are still needed. This summary of methodological findings from the NutriNet-Santé cohort may help researchers in the development of the next generation of high-quality Web-based epidemiological studies.
authors.affiliation: Équipe de Recherche en Epidémiologie Nutritionnelle (EREN), Centre de Recherche en Epidémiologie et Statistiques, COMUE Sorbonne Paris Cité, Inserm (U1153), Inra (U1125), Cnam, Université Paris 13, Bobigny, France. e.kesse@eren.smbh.univ-paris13.fr.
authors.forename: Emmanuelle
authors.identifier: 0000-0002-9715-3534
authors.initials: E
authors.lastname: Kesse-Guyot
authors.forename: Karen
authors.identifier: 0000-0003-3618-9573
authors.initials: K
authors.lastname: Assmann
authors.forename: Valentina
authors.identifier: 0000-0001-9480-5210
authors.initials: V
authors.lastname: Andreeva
authors.forename: Katia
authors.identifier: 0000-0002-1207-6729
authors.initials: K
authors.lastname: Castetbon
authors.forename: Caroline
authors.identifier: 0000-0001-6467-5056
authors.initials: C
authors.lastname: Méjean
authors.forename: Mathilde
authors.identifier: 0000-0002-8322-8857
authors.initials: M
authors.lastname: Touvier
authors.forename: Benoît
authors.identifier: 0000-0002-4573-3166
authors.initials: B
authors.lastname: Salanave
authors.forename: Valérie
authors.identifier: 0000-0002-9000-0180
authors.initials: V
authors.lastname: Deschamps
authors.forename: Sandrine
authors.identifier: 0000-0002-3463-0989
authors.initials: S
authors.lastname: Péneau
authors.forename: Léopold
authors.identifier: 0000-0002-7589-3179
authors.initials: L
authors.lastname: Fezeu
authors.forename: Chantal
authors.identifier: 0000-0003-2006-5269
authors.initials: C
authors.lastname: Julia
authors.forename: Benjamin
authors.identifier: 0000-0002-7970-171X
authors.initials: B
authors.lastname: Allès
authors.forename: Pilar
authors.identifier: 0000-0003-1706-3107
authors.initials: P
authors.lastname: Galan
authors.forename: Serge
authors.identifier: 0000-0002-3168-1350
authors.initials: S
authors.lastname: Hercberg
keywords: bias, epidemiology; cohort studies