Table 3. Adjusted relative riska of breast cancer in regularly, irregularly and never-screenedb New Zealand women, breast cancers diagnosed 2003–2011.
| Variable | Regression estimate (s.e.) | P-value | Relative risk (95% CI) | % Mortality difference (95% CI) |
|---|---|---|---|---|
|
Screening status | ||||
| Never screened | 1.00 | 0 | ||
| Not screened regularly | −0.8685 (0.1117) | <0.0001 | 0.42 (0.34–0.52) | −58 (−66 to −48) |
| Not screened regularly (adj.)c | — | — | 0.74 (0.65–0.83) | −26 (−35 to −17) |
| Not screened regularly (adj.)d | — | — | 0.69 (0.60–0.79) | −31 (−40 to −21) |
| Not screened regularly (adj.)e | — | — | 0.69 (0.61–0.79) | −31 (−39 to −21) |
| Screened regularlyb | 1.1231 (0.2622) | <0.0001 | 0.33 (0.19–0.54) | −67 (−81 to −46) |
| Screened regularly (adj.)c | — | — | 0.67 (0.55–0.82) | −33 (−45 to −18) |
| Screened regularly (adj.)d | — | — | 0.61 (0.48–0.78) | −39 (−52 to −22) |
| Screened regularly (adj.)e | — | — | 0.62 (0.49–0.78) | −38 (−51 to −22) |
| Screening category trend testf: |
χ2(1)=25:6 <0.0001 |
|||
|
Age at death (years) | ||||
| 60–64 (referent) | 1.00 | |||
| 45–49 | 0.1149 (0.0696) | 0.0987 | 1.12 (0.98–1.29) | |
| 50–54 | −0.2360 (0.0736) | 0.0013 | 0.79 (0.68–0.91) | |
| 55–59 | −0.1400 (0.0328) | <0.0001 | 0.87 (0.82–0.93) | |
| 65–69 | 0.0006 (0.0654) | 0.9924 | 1.00 (0.88–1.14) | |
| 70–74 | −0.1312 (0.0750) | 0.0802 | 0.88 (0.76–1.02) | |
| 75–79 | −0.2142 (0.0863) | 0.0131 | 0.81 (0.68–0.96) | |
|
Ethnicity | ||||
| Other | 1.00 | |||
| Māori | 0.5925 (0.0409) | <0.0001 | 1.81 (1.67–1.96) | |
| Pacific | 0.5550 (0.0586) | <0.0001 | 1.74 (1.55–1.95) | |
| Intercept | −8.9849 (0.0932) | <0.0001 | — | — |
Abbreviation: CI=confidence interval.
From negative binomial regression model adjusted for repeat measures.
Screened ⩾3 times, ⩽30 months mean screening interval, as screened by BreastScreen Aotearoa.
Adjusted 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.
Adjusted 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.
Adjusted for screening selection bias, assuming relative risk in non-screeners to women not offered screening=1.17 and target screening participation rate of 70%.
Trend test from regressing screening category as ordinal variable: no screening=1; irregular screening=2; regular screening=3.