title: Validity and reproducibility of self-reported age at menopause in women participating in the DOM-project.
abstract: OBJECTIVE
  To study validity and reproducibility of self reported age at menopause.
  
  
  METHODS
  Subjects were 1003 and 4892 Dutch women respectively aged 58-73, who participated in a population-based breast cancer screening project. The median time since menopause was 7 years for the validity study. The time span between the two questionnaires in the reproducibility study was 7-9 years.
  
  
  RESULTS
  Of the women with a natural menopause, 70% recalled their age at menopause correctly to within one year. For women with a surgical menopause this percentage was 80%. The validity decreased with increasing number of years since menopause. Reproducibility to within one year was 71% for women with a natural menopause and 79% for women with a surgical menopause; 95% of the women were consistent in reporting whether they had had a natural or a surgical menopause.
  
  
  CONCLUSIONS
  As a consequence of this misclassification, the effect of age at menopause may be underestimated in studies relating self reported age at menopause to disease occurrence or mortality.
authors.affiliation: Julius Center for Patient Oriented Research, University of Utrecht, The Netherlands.
authors.forename: I
authors.initials: I
authors.lastname: den Tonkelaar
mesh_terms: D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008593:Menopause / Q000502:physiology*; D011939:Mental Recall; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D011795:Surveys and Questionnaires