Table 2.

Age-standardized incidence rates and incidence rate ratios by case volume

	Age standardized Incidence (95% CI)
Age group	High-volume	Medium-volume	Low-volume
All	3.5 (3.3–3.8)	3.3 (3.1–3.6)	2.3 (2.2–2.5)
≤ 70 years	2.7 (2.5–2.9)	2.8 (2.5–3.0)	2.0 (1.8–2.2)
> 70 years	9.1 (7.9–10.4)	7.1 (6.0–8.4)	4.6 (4.0–5.4)

Age standardization according to the European Standard Population 2013 per 100,000 people

High-volume hospital used as reference for the incidence rate ratio comparisons. An incidence rate ratio over 1 indicates a higher incidence than the reference