Table 3.
Year periods | Time intervalsb | Obs | Exp | Adjusted RRc | 95% confidence interval |
---|---|---|---|---|---|
1963–1978 | All (2059) | 422 | 211.4 | 2.2 | 2.0–2.4 |
1979–1988 | All (1604) | 296 | 151.5 | 2.1 | 1.9–2.4 |
1989–1999 | All (779) | 132 | 37.8 | 3.9 | 3.2–4.7 |
1963–1978 | 1st month | 32 | 4.6 | 12.2 | 7.4–20.2 |
1979–1988 | 1st month | 41 | 4.2 | 20.3 | 12.5–32.9 |
1989–1999 | 1st month | 40 | 3.8 | 26.0 | 15.4–44.7 |
1963–1978 | 1–11 months | 21 | 5.8 | 4.4 | 2.6–7.2 |
1979–1988 | 1–11 months | 17 | 7.5 | 2.5 | 1.4–4.1 |
1989–1999 | 1–11 months | 32 | 5.2 | 7.5 | 4.9–11.2 |
1963–1978 | 1–4 years | 75 | 31.4 | 2.7 | 2.1–3.5 |
1979–1988 | 1–4 years | 64 | 30.5 | 2.3 | 1.7–3.0 |
1989–1999 | 1–4 years | 34 | 16.1 | 2.2 | 1.5–3.1 |
1963–1978 | 5–9 years | 72 | 36.5 | 2.2 | 1.7–2.8 |
1979–1988 | 5–9 years | 83 | 47.8 | 1.9 | 1.5–2.3 |
1989–1999 | 5–9 years | 25 | 11.9 | 2.2 | 1.4–3.4 |
1963–1978 | 10–19 years | 149 | 83.3 | 1.9 | 1.6–2.3 |
1979–1988 | 10–19 years | 91 | 60.9 | 1.6 | 1.3–2.0 |
1963–1978 | 20+ years | 73 | 49.9 | 1.5 | 1.2–2.0 |
aThe number of women admitted with BBD from 1963 to 1978 was 8350, from 1979 to 1988 was 9988 and from 1989 to 1999 was 5134.
bNumber of women with breast cancer in the reference cohort in parentheses.
cAdjusted for age in 5-year age bands, time period in single calendar years and district of residence; comparing Obs/Exp in the BBD cohort (data in table) with Obs/Exp in the reference cohort (data not shown separately).