Table 1

Characteristics of ever-smokers and never-smokers before propensity score matching

Ever-smokersNever-smokersStandardised difference
N190 686370 912
Index date (days from the origination date)1685.0±631.81662.8±644.20.035
Male gender154 436 (81.0)125 704 (33.9)1.083
Age65.1±13.866.4±15.3−0.086
Patients in hospitals with <500 beds113 571 (59.6)234 007 (63.1)
Brinkman Index687.1±552.60
Target organ of the elective surgery
 Skin or subcutaneous tissues27 030 (14.2)51 387 (13.9)
 Muscle, bone, limb or trunk28 735 (15.1)77 715 (21.0)
 Nervous system, head or CNS3837 (2.0)8630 (2.3)
 Eyes5737 (3.0)16 015 (4.3)
 Ear, nose or throat9136 (4.8)12 631 (3.4)
Face, mouth or neck4214 (2.2)8558 (2.3)
 Chest16 803 (8.8)32 501 (8.8)
 Cardiovascular29 145 (15.3)41 977 (11.3)
 Abdomen61 430 (32.2)99 277 (26.8)
 Urological system or adrenal gland15 084 (7.9)21 407 (5.8)
 Genital18 383 (9.6)53 640 (14.5)
Comorbidity
 Heart failure26 194 (13.7)43 000 (11.6)−0.064
 Coronary artery disease33 742 (17.7)48 221 (13.0)−0.131
 Peripheral artery disease14 275 (7.5)19 396 (5.2)
 Myocardial infarction5864 (3.1)6620 (1.8)
Stroke/TIA/SE15 536 (8.1)24 967 (6.7)
 Renal dysfunction13 197 (6.9)20 416 (5.5)−0.059
 Hepatic dysfunction32 266 (16.9)51 509 (13.9)
 Hypertension76 458 (40.1)134 012 (36.1)−0.082
 Diabetes mellitus60 156 (31.5)95 561 (25.8)−0.128
 Cancer105 626 (55.4)191 698 (51.7)−0.074
 Infectious disease29 603 (15.5)48 032 (12.9)
 COPD16 370 (8.6)14 580 (3.9)−0.193
  • N (per cent) or mean±SD. Standardised difference was calculated only for variables used for the calculation of propensity score.

  • CNS, central nervous system; COPD, chronic obstructive pulmonary disease; SE, systemic embolism; TIA, transient ischaemic attack.