Comparison of documented and recalled histories of exposure to diagnostic x-rays in case-control studies of thyroid cancer

Am J Epidemiol. 2003 Apr 1;157(7):652-63. doi: 10.1093/aje/kwg026.


Most information concerning possible cancer risks attributable to lifetime exposure to diagnostic x-rays comes from studies in which x-ray history was ascertained by interview or questionnaire, but little is known about the accuracy of such information. The authors assessed agreement between medical x-ray histories obtained through interview and by review of medical records from thyroid cancer case-control studies conducted in Sweden (1985-1992; 123 cases and 123 controls) and from members of a prepaid health plan in the United States (1986-1991; 50 cases and 50 controls). In both studies, substantial disagreement was found between the numbers of x-ray examinations reported in the interview and in the medical records. There was an indication of relatively poorer reporting among controls, particularly for certain types of x-ray examinations and for large numbers of such examinations. Estimates of the risk associated with exposure to diagnostic x-rays were similar, regardless of whether interview or medical record data were used, even though ordinal dose classifications based on the two sources differed considerably. In populations with a high frequency of exposure, spurious associations with numbers of x-ray examinations or estimated thyroid dose might arise because of differences in recall. However, in the present data, reporting errors by cases and controls seemed to be largely nondifferential.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Age Distribution
  • Aged
  • Case-Control Studies
  • Documentation
  • Female
  • Humans
  • Male
  • Medical Records
  • Mental Recall
  • Middle Aged
  • Radiation Injuries / epidemiology*
  • Registries
  • Reproducibility of Results
  • Sex Distribution
  • Sweden / epidemiology
  • Thyroid Neoplasms / epidemiology
  • Thyroid Neoplasms / etiology*
  • United States / epidemiology