title: Non-response to baseline, non-response to follow-up and mortality in the Whitehall II cohort.
abstract: BACKGROUND
  Little is known about the associations between non-response to follow-up surveys and mortality, or differences in these associations by socioeconomic position in studies with repeat data collections.
  
  
  METHODS
  The Whitehall II study of socioeconomic inequalities in health provided response status from five data collection surveys; Phase 1 (1985-88, n = 10 308), Phase 5 (1997-99, n = 6533), and all-cause mortality to 2006. Odd-numbered phases included a medical examination in addition to a questionnaire.
  
  
  RESULTS
  Non-response to baseline and to follow-up phases that included a medical examination was associated with a doubling of the mortality hazard in analyses adjusted for age and sex. Compared with complete responders, responders who missed one or more phases, but completed the last possible phase before they died, had a 38% excess risk of mortality. However, those who missed one or more phases including the last possible phase before death had an excess risk of 127%. There was no evidence that these associations differed by socioeconomic position.
  
  
  CONCLUSIONS
  In studies with repeat data collections, non-response to follow-up is associated with the same doubling of the mortality risk as non-response to baseline; an association that is not modified by socioeconomic position.
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, UK. j.ferrie@public-health.ucl.ac.uk
authors.forename: Jane E
authors.initials: JE
authors.lastname: Ferrie
authors.forename: Mika
authors.initials: M
authors.lastname: Kivimäki
authors.forename: Archana
authors.initials: A
authors.lastname: Singh-Manoux
authors.forename: Alison
authors.initials: A
authors.lastname: Shortt
authors.forename: Pekka
authors.initials: P
authors.lastname: Martikainen
authors.forename: Jenny
authors.initials: J
authors.lastname: Head
authors.forename: Michael
authors.initials: M
authors.lastname: Marmot
authors.forename: David
authors.initials: D
authors.lastname: Gimeno
authors.forename: Roberto
authors.initials: R
authors.lastname: De Vogli
authors.forename: Marko
authors.initials: M
authors.lastname: Elovainio
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Shipley
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002423:Cause of Death; D015331:Cohort Studies; D005260:Female; D015438:Health Behavior; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires