title: Design and respondent selection of a population-based study on associations between breast cancer screening, lifestyle and quality of life.
abstract: BACKGROUND
  Only few studies have integrated breast cancer screening, lifestyle, and quality of life. Potential bias due to selective non-response may disrupt associations being investigated. We describe the design of a Finnish population-based study on associations between breast cancer screening and various indicators for lifestyle and quality of life, and evaluate the level of bias among the respondents from the first study rounds over 2 years.
  
  
  METHODS
  The study target population of 10,000, 49-year-old women was randomly drawn from the Finnish National Population Registry. The data included birth year, marital status, municipality, and primary language. Data on education were retrieved from Statistics Finland. Questionnaires focusing on lifestyle-related risk factors and quality of life were sent to the target population in 2012-13, 1 year before the first invitation to organized breast cancer screening. We evaluated associations between willingness to respond and demographic characteristics in the eligible study population. Additionally, we examined associations between the demographic characteristics and the Satisfaction With Life Scale (SWLS), and evaluated the impact of non-response using inverse probability weighting and multiple imputation.
  
  
  RESULTS
  The questionnaire response proportion was 52.4%. Compared to non-respondents, respondents were more often married, academically educated, and native speakers of Finnish or Swedish. Nevertheless, the estimates of the SWLS among the respondents were in line with those corrected by non-response in the eligible study population.
  
  
  CONCLUSIONS
  Based on the SWLS, the respondents are representative of women in the entire eligible study population.
authors.affiliation: Finnish Cancer Registry, Unioninkatu 20-22, 00130, Helsinki, Finland. tytti.sarkeala@cancer.fi.
authors.forename: Tytti
authors.initials: T
authors.lastname: Sarkeala
authors.affiliation: Finnish Cancer Registry, Unioninkatu 20-22, 00130, Helsinki, Finland. sirpa.heinavaara@cancer.fi.
authors.forename: Sirpa
authors.initials: S
authors.lastname: Heinävaara
authors.affiliation: Finnish Cancer Registry, Unioninkatu 20-22, 00130, Helsinki, Finland. jonna.fredman@gmail.com.
authors.forename: Jonna
authors.initials: J
authors.lastname: Fredman
authors.affiliation: National Institute for Health and Welfare, Mannerheimintie 170, 00217, Helsinki, Finland. satu.mannisto@thl.fi.
authors.forename: Satu
authors.initials: S
authors.lastname: Männistö
authors.affiliation: UKK Institute, Kaupinpuistonkatu 1, 33500, Tampere, Finland. riitta.luoto@uta.fi.
authors.forename: Riitta
authors.initials: R
authors.lastname: Luoto
authors.affiliation: Finnish Cancer Registry, Unioninkatu 20-22, 00130, Helsinki, Finland. maija.jantti@cancer.fi.
authors.forename: Maija
authors.initials: M
authors.lastname: Jäntti
authors.affiliation: Finnish Cancer Registry, Unioninkatu 20-22, 00130, Helsinki, Finland. nea.malila@cancer.fi.
authors.forename: Nea
authors.initials: N
authors.lastname: Malila
mesh_terms: D001294:Attitude to Health; D001943:Breast Neoplasms / Q000453:epidemiology / Q000523:psychology*; D005260:Female; D005387:Finland / Q000453:epidemiology; D006304:Health Status; D006801:Humans; D008019:Life Style; D017533:Marital Status; D008403:Mass Screening / Q000706:statistics & numerical data; D008875:Middle Aged; D011788:Quality of Life / Q000523:psychology; D012107:Research Design; D012307:Risk Factors