TABLE 2.
UNIVARIATE AND MULTIVARIATE RELATIVE RISKS FOR ASPIRIN USE AND LYMPH NODE-POSITIVE BREAST CANCER AT DIAGNOSIS
| Risk-ratios for node-positive (N+ve) versus node-negative (N-ve) |
||||
|---|---|---|---|---|
| Aspirin Use | N+ve (%) | N-ve (%) | Univariate RR (95%CI) | Multivariate RR (95%CI) A |
| Non-user in year prior to diagnosis | 1,036 (50.4) | 1,020 (49.6) | Ref - | Ref - |
| Aspirin user in year prior to diagnosis | 336 (45.4) | 404 (54.6) | 0.90 (0.82, 0.99) | 0.89 (0.81, 0.97) |
| Aspirin dosing intensity | ||||
| Dosing intensity 1% - 37% B,C | 100 (53.8) | 86 (46.2) | 1.07 (0.93, 1.23) | 0.98 (0.87, 1.10) |
| Dosing intensity 38% - 79% | 85 (46.2) | 99 (53.8) | 0.92 (0.92, 0.78) | 0.96 (0.83, 1.11) |
| Dosing intensity 80% - 97% | 73 (39.5) | 112 (60.5) | 0.78 (0.78, 0.65) | 0.77 (0.65, 0.91) |
| Dosing intensity 98% - 100% | 78 (42.2) | 107 (57.8) | 0.84 (0.70, 0.99) | 0.81 (0.68, 0.96)** |
| Aspirin dose | ||||
| Low Dose < 150mg E | 288 (45.6) | 344 (54.4) | 0.90 (0.82, 0.99) | 0.90 (0.82, 0.98) |
| High Dose ≥ 150mg F | 48 (44.4) | 60 (55.6) | 0.88 (0.71, 1.09) | 0.82 (0.67, 1.00)* |
| Aspirin dosing intensity & dose | ||||
| Low dosing intensity 1% - 79% B,D | ||||
| Low dose < 150mg E | 152 (49.8) | 153 (50.2) | 0.99 (0.88, 1.12) | 0.99 (0.90, 1.10) |
| High dose ≥ 150mg F | 33 (50.8) | 32 (49.2) | 1.01 (0.79, 1.28) | 0.90 (0.72, 1.12) |
| High dosing intensity 80% - 100% | ||||
| Low dose < 150mg | 136 (41.6) | 191 (58.4) | 0.83 (0.72, 0.95) | 0.80 (0.71, 0.92) |
| High dose ≥ 150mg | 15 (34.9) | 28 (65.1) | 0.69 (0.46, 1.04) | 0.67 (0.45, 0.99)** |
| Aspirin duration G | ||||
| Non-user in 3 years prior to diagnosis | 543 (49.5) | 554 (50.5) | Ref - | Ref - |
| Aspirin user in 3 years prior to diagnosis | ||||
| Start aspirin <1.5 years prior to diagnosis | 61 (50.8) | 59 (49.2) | 1.03 (0.85, 1.24) | 1.01 (0.86, 1.18) |
| Start aspirin 1.5-3.0 years prior to diagnosis | 89 (47.1) | 100 (52.9) | 0.95 (0.81, 1.12) | 0.96 (0.83, 1.11) |
| Start aspirin ≥3.0 years prior to diagnosis | 100 (46.1) | 117 (53.9) | 0.93 (0.80, 1.09) | 0.89 (0.77, 1.03) |
| Aspirin dosing intensity & duration G | ||||
| Low dosing intensity 1%-82% D,H | ||||
| Start aspirin <1.5 years prior to diagnosis | 28 (47.6) | 31 (52.5) | 0.96 (0.73, 1.26) | 1.01 (0.80, 1.28) |
| Start aspirin 1.5-3.0 years prior to diagnosis | 60 (50.4) | 59 (48.2) | 1.02 (0.84, 1.23) | 1.08 (0.91, 1.29) |
| Start aspirin ≥3.0 years prior to diagnosis | 44 (51.8) | 41 (48.2) | 1.05 (0.84, 1.30) | 0.97 (0.80, 1.16) |
| High dosing intensity 83%-100% | ||||
| Start aspirin <1.5 years prior to diagnosis | 33 (54.1) | 28 (45.9) | 1.09 (0.86, 1.39) | 1.01 (0.83, 1.22) |
| Start aspirin 1.5-3.0 years prior to diagnosis | 29 (41.4) | 41 (58.6) | 0.84 (0.63, 1.11) | 0.82 (0.64, 1.06) |
| Start aspirin ≥3.0 years prior to diagnosis | 56 (42.4) | 76 (57.6) | 0.86 (0.70, 1.05) | 0.83 (0.68, 1.01) |
P-trend <0.01
P-trend <0.001; Ref: Referent Group. RR: Relative Risk. CI: Confidence Interval. N+ve: Node-Positive. N-ve: Node-Negative.
Adjusted for age (years, continuous), tumor size (T1, T2, T3, T4), tumor grade (low, intermediate, high, unspecified), comorbidity score (number of medication classes, continuous) and screen-detected tumor (organized screening, opportunistic screening, not screen detected).
Dosing intensity calculated as the number of days with supply of aspirin available in the year prior to diagnosis, divided by 365.
Dosing intensity by quartiles.
Dosing intensity by median.
All prescriptions in the year prior to diagnosis were for doses of < 150mg. The 150mg cutpoint represents twice the standard low-dose aspirin strength (75mg) used in Ireland.
At least one prescription in the year prior to diagnosis was for a dose of ≥ 150mg.
Women with at least three years of continuous GMS eligibility prior to diagnosis were included in this exposure response analysis.
Dosing intensity calculated as number of days with supply of aspirin available from the first aspirin exposure in the three years prior to diagnosis up to diagnosis, divided by the number of days from the first aspirin exposure in the three years prior to diagnosis up to diagnosis.