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Table 4 Sensitivity analysis for association between low dose aspirin exposure and breast cancer-specific death

From: Post-diagnostic prescriptions for low-dose aspirin and breast cancer-specific survival: a nested case-control study in a breast cancer cohort from the UK Clinical Practice Research Datalink

Comparisona Cancer-specific deaths Controls OR (95% CI) low dose aspirin exposed vs. non-exposed P OR (95% CI) 1 to 11 low dose aspirin prescriptions vs. none P OR (95% CI) 12 or more low dose aspirin prescriptions vs. none P
Main analysis: Diagnosis to six months prior to death 1,435 5,697 0.98 (0.83, 1.15) 0.77 0.88 (0.71, 1.09) 0.25 1.08 (0.87, 1.33) 0.48
Post diagnostic aspirin in patients with no pre-diagnostic aspirin prescriptionsb 1,125 4,457 0.82 (0.64, 1.04) 0.10 0.81 (0.59, 1.10) 0.17 0.84 (0.59, 1.18) 0.31
Post diagnostic aspirin in patients with pre-diagnostic aspirin prescriptionsb 142 515 0.95 (0.52, 1.71) 0.86 0.82 (0.43, 1.56) 0.55 1.08 (0.57, 2.03) 0.81
Pre-diagnostic low dose aspirin prescriptionsc 1,559 6,186 0.99 (0.83, 1.18) 0.93 1.01 (0.83, 1.22) 0.93 0.94 (0.67, 1.32) 0.71
Diagnosis to one year prior to deathd 1,272 5,048 1.06 (0.89, 1.26) 0.51 1.01 (0.80, 1.27) 0.95 1.11 (0.89, 1.40) 0.36
Diagnosis to two years prior to deathe 959 3,797 0.89 (0.72, 1.10) 0.28 0.62 (0.46, 0.85) 0.003 1.22 (0.93, 1.60) 0.15
One year after diagnosis to six months prior to deathf 1,099 4,356 0.93 (0.77, 1.12) 0.43 0.84 (0.65, 1.09) 0.20 1.01 (0.79, 1.29) 0.94
Stage 1 and 2 breast cancer patients only 469 1,856 1.09 (0.82, 1.46) 0.54 0.83 (0.55, 1.24) 0.36 1.41 (0.98, 2.04) 0.07
Stage 3 and 4 breast cancer patients only 161 478 1.13 (0.68, 1.86) 0.64 1.24 (0.66, 2.33) 0.50 0.98 (0.45, 2.12) 0.96
Restricted to patients receiving prescriptions for hormone therapy (in first six months) 875 3,466 1.08 (0.90, 1.30) 0.43 0.93 (0.72, 1.20) 0.55 1.23 (0.97, 1.56) 0.08
Patients with a recorded stage from cancer registries with high rates of stage recording (adjusted for stage)g 487 1,911 0.92 (0.67, 1.27) 0.62 0.95 (0.62, 1.45) 0.81 0.90 (0.59, 1.37) 0.62
Including breast cancer-specific deaths where breast cancer is recorded as any cause of death 1,786 7,090 1.05 (0.91, 1.20) 0.53 1.01 (0.84, 1.21) 0.95 1.09 (0.91, 1.30) 0.37
Time varying covariate analysish 1,440 8,374 1.06 (0.92, 1.22) 0.45 0.98 (0.81, 1.20) 0.88 1.13 (0.94, 1.35) 0.20
Time varying covariate analysisi 1,440 8,374 1.04 (0.90, 1.20) 0.60 0.96 (0.79, 1.67) 0.67 1.12 (0.93, 1.35) 0.22
  1. aAll sensitivity analyses refer to low dose aspirin prescriptions in the time period from breast cancer diagnosis to six months before death, and are adjusted for matching criteria only, unless otherwise stated.
  2. bPre-diagnostic low dose aspirin prescriptions in one year prior to breast cancer diagnosis, restricted to individuals with one year of medication records prior to diagnosis.
  3. cPre-diagnostic low dose aspirin prescriptions in one year prior to breast cancer diagnosis.
  4. dRestricted to individuals with at least 1.5 years of follow-up so relevant exposure period is at least a duration of six months.
  5. eRestricted to individuals with at least 2.5 years of follow-up so relevant exposure period is at least a duration of six months.
  6. fRestricted to individuals with at least two years of follow-up so relevant exposure period is at least a duration of six months.
  7. gStage missing for 15% of individuals and breast cancer patients included from the Northern and Yorkshire Cancer Registry and Information Service, the Trent Cancer Registry, the Eastern Cancer Registration and Information Centre, the Oxford Cancer Intelligence Unit and the West Midlands Cancer Intelligence.
  8. hReported estimates are hazard ratios and 95% confidence intervals (CIs), adjusted for age and year of breast cancer diagnosis.
  9. iReported estimates are sub-distribution hazards ratios and 95% CIs, adjusted for competing risks of death, age and year of breast cancer diagnosis.
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