Table 2 Diagnostic test performance of the CAM-IMC for diagnosis of postoperative delirium (POD) with different cut-off points across all patients, those with cognitive impairment, and patients aged ≥ 65 years

All patients

(n = 624)

3

0.96

(0.87-1.00)

0.94

(0.92–0.96)

0.62

(0.51–0.72)

1.00

(0.90-1.00)

17.15

(12.20-24.11)

0.04

(0.01–0.15)

0.95

(0.93–0.98)

4

0.89

(0.77–0.96)

0.98

(0.96–0.99)

0.77

(0.65–0.87)

0.99

(0.98-1.00)

36.19

(21.39–61.23)

0.11

(0.05–0.24)

0.93

(0.89–0.97)

5

0.83

(0.71-0.9075)

0.99

(0.97-1.00)

0.87

(0.74–0.94)

0.98

(0.97–0.99)

67.86

(32.19-143.06)

0.17

(0.09–0.31)

0.91

(0.86–0.96)

Cognitive impairment

(n = 133)

3

1.00

(0.85-1.00)

0.93

(0.86–0.97)

0.73

(0.54–0.88)

1.00

(0.96-1.00)

13.87

(7.12–27.05)

0.00

(0.00-NaN)

0.96

(0.94–0.99)

4

0.91

(0.71–0.99)

0.97

(0.92–0.99)

0.87

(0.66–0.97)

0.98

(0.94-1.00)

33.64

(10.93–103.50)

0.09

(0.02–0.35)

0.94

(0.88-1.00)

5

0.91

(0.71–0.99)

1.00

(0.97-1.00)

1.00

(0.83-1.00)

0.98

(0.94-1.00)

Inf

(NaNInf)

0.09

(0.02–0.34)

0.95

(0.89-1.00)

Age ≥ 

65 years

(n = 398)

3

0.96

(0.86–0.99)

0.91

(0.88–0.94)

0.61

(0.49–0.72)

0.99

(0.98-1.00)

11.18

(7.90-15.82)

0.05

(0.01–0.18)

0.94

(0.90–0.97)

4

0.92

(0.80–0.98)

0.96

(0.94–0.98)

0.77

(0.64–0.87)

0.99

(0.97-1.00)

24.68

(14.38–42.36)

0.09

(0.03–0.22)

0.94

(0.90–0.98)

5

0.90

(0.77–0.97)

0.99

(0.97-1.00)

0.86

(0.73–0.94)

0.99

(0.97-1.00)

44.79

(21.38–93.85)

0.11

(0.05–0.24)

0.94

(0.89–0.98)