Table 1. Patient characteristics.

Characteristics	Value
N	450
Demographics
Gender, male/female	261 [58]/189 [42]
Age (years)	56 [37–67]; range 18–92
Age categorical (years)
18–19	13 [3]
20–39	112 [25]
40–59	144 [32]
60–79	160 [35]
80–99	21 [5]
Ethnicity
Caucasian	443 [98.4]
African	4 [0.9]
Mixed	2 [0.4]
Other	1 [0.2]
BMI (kg/m2)	27 [24–31]; range 18–51
ASA classification
ASA I	203 [45]
ASA II	198 [44]
ASA III	48 [11]
ASA IV	1 [0.2]
Lifestyle factors
Smoking (n=423)
Never	262 [62]
Current	68 [16]
Former	93 [22]
Alcohol use, yes/no (n=408)	279 [68]/129 [32]
Drug use, yes/no (n=415)	15 [4]/400 [96]
Surgery type
Orthopaedic	283 [63]
Urological	93 [21]
Surgical	47 [10]
Gynaecological	27 [6]

Data are presented as mean ± SD, median [IQR] or frequency [%]. BMI, body mass index; ASA, American Society of Anesthesiologists.