Table 2.

Multivariable analysis of breast cancer by location of first residence and duration of stay

Number of participantsMean duration of residency, years (SD)IR per 1,000 person yearsAge-adjusted HR (95% CI)HRa (95% CI)HRb (95% CI)
Location of first residencen = 744n = 731n = 664
 Reykjavik347444.7 (15)3.151.00 (Ref.)1.00 (Ref.)1.00 (Ref).
 Coastal village326220.6 (11)2.720.86 (0.72–1.02)0.89 (0.75–1.06)0.87 (0.72–1.04)
 Rural area260419 (8)2.850.89 (0.74–1.06)0.91 (0.75–1.09)0.88 (0.73–1.07)
Age when moving away from coastal villagea
 1–11 y5237.3 (2)3.151.00 (0.73–1.37)1.06 (0.77–1.46)1.11 (0.80–1.54)
 12–19 y125316.1 (2)2.710.86 (0.68–1–08)0.89 (0.71–1.13)0.88 (0.69–1.13)
 20 y and older148429.1 (12)2.580.81 (0.65–1.01)0.83 (0.66–1.04)0.78 (0.61–0.99)
Age when moving away from rural areab
 1–11 y4267.8 (2)3.191.01 (0.71–1.42)1.01 (0.71–1.43)1.05 0.73–1.51)
 12–19 y88116.0 (2)2.700.84 (0.65–1.10)0.88 (0.67–1.16)0.85 (0.64–1.13)
 20 y and older129324.6 (6)2.860.88 (0.70–1.10)0.89 (0.71–1.12)0.85 (0.67–1.09)
  • NOTE: HRa adjusted for age at entry, birth cohort, education, physical activity, parity, height, and BMI in midlife, and HRb additionally adjusted for age at menarche and age at first child.

  • Abbreviations: CI, confidence interval; IR, incidence rate; n, number of breast cancer diagnosis in analysis.

  • aData on duration of residency in coastal village were missing for 2 women.

  • bData on duration of residency in rural area were missing for 4 women.