Table 4.
Incidence rate and hazard ratio of breast cancer by the episode of non-lactational mastitis.
| Non-lactational mastitis episode (mean per year) | Event | PY | IR | Crude HR (95% CI) | p-value | Adjusted HR (95% CI) | p-value |
|---|---|---|---|---|---|---|---|
| Comparison group (0) | 74 | 97722 | 7.57 | Ref. | Ref. | ||
| First tertile (<0.14) | 6 | 10732 | 5.59 | 0.68 (0.30–1.56) | 0.36 | 0.69 (0.30–1.58) | 0.38 |
| Second tertile (0.14–0.27) | 11 | 8805 | 12.49 | 1.61 (0.86–3.04) | 0.14 | 1.68 (0.89–3.19) | 0.11 |
| Third tertile (>0.27) | 20 | 5473 | 36.54 | 5.77 (3.50–9.53) | <0.001 | 5.50 (3.31–9.13) | <0.001 |
*Abbreviation: PY, person-years; IR, incidence rate, per 100,000 person-years; HR, hazard ratio; CI, confidence interval.
*Adjusted HR: adjusted for age, income, comorbidities and medication in Cox proportional hazards regression.