Table 1 Comparison of variables between patients with and without difficult airways (n = 2068)

Sex, n

0.185

0.001

 Male/

32

969

78

923

 Female

24

1043

45

1022

Age, yr, median (IQR)

62 (52–69)

50 (41–62)

< 0.001

61 (50–67)

50 (40–61)

< 0.001

Body mass index, kg/m²

23.4 (3.6)

22.9 (3.5)

0.260

23.3 (3.4)

22.8 (3.5)

0.134

Thyromental distance, cm

6.7 (0.8)

7.7 (0.9)

< 0.001

7.0 (0.9)

7.7 (0.9)

< 0.001

Modified Mallampati test > 2, n (%)

34 (60.7)

537 (26.7)

< 0.001

61 (49.6)

510 (26.2)

< 0.001

Mouth opening, cm

3.4 (0.5)

4.1 (0.6)

< 0.001

3.6 (0.6)

4.1 (0.6)

< 0.001

Hyomental distance, cm

4.6 (0.4)

5.3 (0.5)

< 0.001

4.7 (0.5)

5.3 (0.5)

< 0.001

Tongue thickness, cm

6.3 (0.5)

5.9 (0.5)

< 0.001

6.3 (0.5)

5.9 (0.5)

< 0.001

Grade of head-up angle, 1/2/3/4, n

30/26/0/0

2006/6/0/0

< 0.001

94/29/0/0

1942/3/0/0

< 0.001

Small mandible, yes, n (%)

15 (26.8)

51 (2.5)

< 0.001

23 (18.7)

43 (2.2)

< 0.001

TMJ range of motion, mm

9.5 (2.5)

14.0 (2.3)

< 0.001

10.7 (2.7)

14.1 (2.2)

< 0.001

Expected glottal visibility, mm

-11.0 (8.1)

9.6 (8.3)

< 0.001

-5.3 (9.8)

9.9 (8.1)

< 0.001