Table 2 Adjusted relative riska of breast cancer mortality in ever- and never-screenedb New Zealand women, 1999–2011

From: Mammography service screening and breast cancer mortality in New Zealand: a National Cohort Study 1999–2011

Variable Regression estimate (s.e.) P -value Relative risk (95% CI) % Mortality difference (95% CI)
Screening status
Never screened    1.00 0
Ever screened −0.9685 (0.1273) <0.0001 0.38 (0.30–0.49) −62 (−70 to −51)
Ever screened (adj.)c 0.71 (0.62–0.80) −29 (−38 to −20)
Ever screened (adj.)d 0.66 (0.57–0.75) −34 (−43 to −25)
Ever screened (adj.)e 0.66 (0.58–0.76) −34 (−42 to −24)
Age at death (years)
60–64 (referent)    1.00  
45–49 −0.0628 (0.0512) 0.2198 0.94 (0.85–1.04)  
50–54 −0.2660 (0.0742) 0.0003 0.77 (0.66–0.89)  
55–59 −0.1378 (0.0582) 0.0179 0.87 (0.78–0.98)  
65–69 −0.0608 (0.0336) 0.0704 0.94 (0.88–1.01)  
70–74 −0.1211 (0.0625) 0.0526 0.89 (0.78–1.00)  
75–79 −0.0676 (0.0846) 0.4242 0.93 (0.79–1.10)  
80–84 −0.0072 (0.1587) 0.9637 0.99 (0.73–1.36)  
85+ 0.5230 (0.1082) <0.0001 1.69 (1.36–2.09)  
Ethnicity
Other    1.00  
Māori 0.5130 (0.0475) <0.0001 1.67 (1.52–1.83)  
Pacific 0.4668 (0.0606) <0.0001 1.59 (1.42–1.80)  
Intercept −8.8737 (0.0784) <0.0001
  1. Abbreviation: CI=confidence interval.
  2. aFrom negative binomial regression model adjusted for repeat measures.
  3. bEver or never screened with BreastScreen Aotearoa.
  4. cAdjusted for screening selection bias, assuming relative risk in non-screeners to women not offered screening=1.17 and mean screening participation rate of 64% for 2001–2011.
  5. dAdjusted for screening selection bias, assuming relative risk in non-screeners to women not offered screening=1.17 and recorded screening participation rate of 71% for 2012–2013.
  6. eAdjusted for screening selection bias, assuming relative risk in non-screeners to women not offered screening=1.17 and target screening participation rate of 70%.