Table 4.

POP risk score: distribution of patients and rates of POP by intervals.

	Derivation set (n = 1926)			Validation set (n = 1927)
Characteristics	Low risk (0–6 points)	Medium risk (7–9 points)	High risk (≥10 points)	Low risk (0–6 points)	Medium risk (7–9 points)	High risk (≥10 points)
Patients, n (%)	1278 (66.4)	439 (22.8)	209 (10.8)	1280 (66.4)	428 (22.2)	219 (11.4)
Predicted rate of POP, % (95% CI)	3.2 (3.1–3.3)	11.7 (11.3–12.0)	33.6 (31.8–35.5)	2.9 (2.8–3.0)	11.6 (11.1–12.2)	30.3 (28.4–32.2)
Observed rate of POP, % (95% CI)	2.4 (1.6–3.3)	14.8 (11.5–18.1)	32.1 (25.7–38.4)	2.3 (1.5–3.1)	12.6 (9.5–15.8)	32.0 (25.7–38.2)

CI: Confidence interval; POP: Postoperative pneumonia.