Table 1 Preoperative and demographic data of the two study groups

Number of patients

1,279

1,775

Sex

 Female

340 (27%)

554 (31%)

0.006

 Male

939 (73%)

1,221 (69%)

Age, years

67.9 ± 0.3

67.8 ± 0.2

0.600

Body mass index, kg/m²

28.2 ± 0.2 (24.8/30.7)

25.5 ± 0.2

0.994

ASA score

 1

3 (0.2%)

2 (0.1%)

0.413

 2

31 (2%)

59 (3%)

0.147

 3

1,143 (89%)

1,548 (87%)

0.069

 4

101 (8%)

163 (9%)

0.212

 5

1 (0.1%)

3 (0.2%)

0.494

APACHE II score

17.0 ± 0.2

16.7 ± 0.1

0.151

 Missing

73 (5.7%)

101 (5.7%)

Mallampati

 1

142 (11%)

246 (14%)

0.024

 2

884 (69%)

1,139 (64%)

0.004

 3

168 (13%)

307 (17%)

0.002

 4

15 (1%)

16 (1%)

0.460

 Missing

70 (6%)

67 (4%)

0.025

Pre-operative hemoglobin

 g/dL

13,1 ± 0.6

13.0 ± 0.5

0.899

 Missing

217 (17%)

337 (19%)

Pre-operative creatinine

 mg/dL

1.15 ± 0.2

1.15 ± 0.2

0.520

 Missing

385 (30%)

365 (21%)

Pre-operative creatinine kinase

 U/L

119.1 ± 5.5

125.2 ± 5.7

0.055

 Missing

483 (38%)

487 (27%)