Table 6 Subgroup analyses for the association between antibiotics and breast cancer-specific mortality

From: Antibiotic use and survival from breast cancer: A population-based cohort study in England and Wales

ABs

England

Wales

P for heterob

Pooled adjusteda

HR (95% CI)

P

Unadjusted

HR (95% CI)

Adjusteda

HR (95% CI)

Unadjusted

HR (95% CI)

Adjusteda

HR (95% CI)

Oestrogen receptor positive (events = 1784, person-years = 168,722)

Any

1.38 (1.18, 1.61)

1.12 (0.95, 1.31)

1.20 (1.03, 1.40)

1.05 (0.88, 1.24)

0.596

1.08 (0.96, 1.22)

0.179

1-5

1.33 (1.13, 1.55)

1.10 (0.93, 1.29)

1.14 (0.97, 1.34)

1.04 (0.87, 1.23)

0.642

1.07 (0.95, 1.20)

0.278

6-11

1.57 (1.20, 2.04)

1.08 (0.82, 1.42)

1.36 (1.08, 1.72)

1.05 (0.82, 1.34)

0.858

1.06 (0.88, 1.28)

0.514

12+

2.37 (1.69, 3.32)

1.77 (1.26, 2.49)

1.81 (1.38, 2.38)

1.26 (0.94, 1.69)

0.135

1.48 (1.06, 2.06)

0.023

Oestrogen receptor negative (events = 719, person-years = 24,707)

Any

1.17 (0.94, 1.44)

1.00 (0.80, 1.24)

0.91 (0.71, 1.16)

0.77 (0.59, 1.00)

0.147

0.89 (0.69, 1.14)

0.338

1-5

1.12 (0.90, 1.39)

0.96 (0.77, 1.21)

0.85 (0.66, 1.10)

0.73 (0.56, 0.96)

0.121

0.85 (0.65, 1.11)

0.231

6-11

1.56 (1.01, 2.40)

1.18 (0.75, 1.86)

1.07 (0.66, 1.74)

0.93 (0.56, 1.54)

0.490

1.06 (0.76, 1.49)

0.736

12+

2.62 (1.39, 4.92)

1.94 (1.03, 3.66)

2.68 (1.54, 4.67)

1.95 (1.10, 3.46)

0.988

1.95 (1.27, 2.98)

0.002

Tamoxifen or aromatase inhibitor treatment in the first year after diagnosis (events = 3163, person-years = 261,464)

Any

1.59 (1.42, 1.79)

1.25 (1.11, 1.41)

1.19 (1.05, 1.35)

1.14 (0.99, 1.31)

0.346

1.20 (1.10, 1.32)

<0.001

1-5

1.51 (1.34, 1.71)

1.21 (1.07, 1.37)

1.13 (0.99, 1.28)

1.11 (0.96, 1.28)

0.381

1.17 (1.06, 1.28)

0.001

6-11

1.98 (1.66, 2.37)

1.39 (1.16, 1.67)

1.38 (1.15, 1.66)

1.19 (0.97, 1.46)

0.262

1.29 (1.11, 1.51)

<0.001

12+

2.52 (2.01, 3.15)

1.75 (1.39, 2.20)

1.90 (1.54, 2.36)

1.59 (1.26, 2.01)

0.571

1.67 (1.42, 1.97)

<0.001

No tamoxifen or aromatase inhibitor treatment in the first year after diagnosis (events = 1414, person-years = 62,094)

Any

1.23 (1.06, 1.44)

1.08 (0.92, 1.26)

0.74 (0.62, 0.89)

0.76 (0.63, 0.92)

0.007

0.91 (0.65, 1.27)

0.581

1-5

1.17 (1.01, 1.37)

1.04 (0.88, 1.22)

0.70 (0.59, 0.85)

0.73 (0.60, 0.89)

0.007

0.88 (0.62, 1.24)

0.451

6-11

1.64 (1.22, 2.20)

1.27 (0.94, 1.72)

0.90 (0.64, 1.25)

0.92 (0.65, 1.31)

0.177

1.10 (0.80, 1.50)

0.557

12+

2.49 (1.67, 3.71)

1.93 (1.28, 2.90)

1.44 (0.96, 2.16)

1.20 (0.77, 1.87)

0.124

1.53 (0.96, 2.44)

0.071

Under age 50 years at diagnosis (events = 997, person-years = 65,986)

Any

1.39 (1.14, 1.70)

1.09 (0.89, 1.35)

1.20 (0.95, 1.51)

1.21 (0.94, 1.56)

0.549

1.14 (0.97, 1.34)

0.114

1–5

1.32 (1.07, 1.61)

1.05 (0.85, 1.30)

1.13 (0.89, 1.43)

1.17 (0.91, 1.52)

0.523

1.10 (0.93, 1.29)

0.262

6–11

1.93 (1.40, 2.65)

1.39 (1.00, 1.93)

1.44 (1.03, 2.02)

1.30 (0.90, 1.86)

0.774

1.35 (1.06, 1.72)

0.016

12+

2.18 (1.42, 3.34)

1.46 (0.94, 2.27)

2.13 (1.43, 3.18)

1.85 (1.19, 2.87)

0.452

1.64 (1.20, 2.24)

0.002

Over age 55 years at diagnosis (events = 3033, person-years = 206,626)

Any

1.44 (1.29, 1.62)

1.18 (1.05, 1.32)

0.94 (0.83, 1.06)

0.87 (0.76, 1.00)

0.001

1.01 (0.76, 1.36)

0.924

1–5

1.38 (1.23, 1.54)

1.14 (1.01, 1.29)

0.89 (0.79, 1.01)

0.85 (0.74, 0.98)

0.002

0.99 (0.74, 1.32)

0.929

6–11

1.78 (1.48, 2.14)

1.28 (1.05, 1.55)

1.05 (0.86, 1.28)

0.90 (0.72, 1.12)

0.017

1.08 (0.76, 1.52)

0.683

12+

2.48 (1.96, 3.14)

1.81 (1.42, 2.30)

1.54 (1.22, 1.95)

1.32 (1.03, 1.69)

0.070

1.54 (1.13, 2.11)

0.006

  1. aAdjusted model contains age, year of diagnosis, deprivation, stage, grade, surgery, radiotherapy, chemotherapy, tamoxifen use (in year after diagnosis), aromatase inhibitor use (in year after diagnosis), Charlson comorbidities (before diagnosis), hormone replacement therapy (before diagnosis) and statin, aspirin, and metformin use (after diagnosis) and is based upon a complete case analysis, except where otherwise stated.
  2. bP-value for heterogeneity comparing adjusted hazard ratio for England and Wales.
Back to article page