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Table 1 Description of study population

From: Multilevel competing risk models to evaluate the risk of nosocomial infection

General Frequency  
Number of admissions 109,216  
Number of admission-days 813,739  
Number of ICUs 159  
Number of nosocomial bacteremia during ICU stay 5,498 (5.03%)  
Number of deaths without NB during ICU stay 12,678 (11.61%)  
Number of discharges without NB from ICU 90,142 (82.54%)  
Number of administrative censored admissions 898 (0.82%)  
Overall risk of nosocomial bacteremia (censored excluded) 5.08%  
Overall rate of nosocomial bacteremia 6.75 / 1,000 admission-days  
Risk factors Frequency (%) Frequency (%)
  (patient level) (ICU level)
ICU / hospital level covariates   
Number of beds in ICU:   
0 to 10 (reference) 30,389 (27.82) 61 (38.36)
11 to 20 46,524 (42.60) 71 (44.65)
21 to 30 21,668 (19.84) 19 (11.95)
31 to 40 7,673 (7.03) 5 (3.14)
> 40 2,962 (2.71) 3 (1.89)
Number of beds in hospital:   
0 to 500 (reference) 52,426 (48.00) 94 (59.12)
501 to 1,000 8,259 (7.56) 10 (6.29)
> 1,000 48,531 (44.44) 55 (34.59)
Type of hospital:   
Private 6,541 (5.99) 12 (7.55)
Public 102,675 (94.01) 147 (92.45)
Type of ICU:   
Polyvalent (reference) 96,478 (88.34) 138 (86.79)
Medical 3,895 (3.57) 5 (3.14)
Surgery 3,103 (2.84) 3 (1.89)
Coronary 525 (0.48) 2 (1.26)
Traumatology 3,273 (3.00) 6 (3.77)
Post-surgery cardiology 1,834 (1.68) 4 (2.52)
Burn 108 (0.10) 1 (0.63)
University+teaching hospital (reference) 67,917 (62.19) 86 (54.09)
Teaching hospital (no university) 30,089 (27.55) 52 (32.70)
Hospital without teaching/university 11,210 (10.26) 21 (13.21)
Calendar year of admission   
2006 (reference) 14,318 (13.11)  
2007 17,819 (16.32)  
2008 21,559 (19.74)  
2009 25,660 (23.49)  
2010+ 29,860 (27.34)  
Patient level covariates   
APACHE II score:   
0 to 10 (reference) 40,353 (36.95)  
11 to 20 44,654 (40.89)  
21 to 30 19,191 (17.57)  
> 30 5,018 (4.59)  
Age (years):   
0 to 40 54,477 (49.88)  
41 to 60 12,931 (11.84)  
61 to 80 (reference) 29,371 (26.89)  
> 80 12,437 (11.39)  
Days in hospital before ICU admission:   
0 to 3 (reference) 87,208 (79.85)  
4 to 6 5,864 (5.37)  
7 to 10 4,962 (4.54)  
> 10 11,182 (10.24)  
Type of diagnosis:   
Cardiovascular (reference) 54,374 (49.79)  
Respiratory 15,243 (13.96)  
Gastrointestinal 14,626 (13.39)  
Central nervous system 17,567 (16.08)  
Other diagnoses 7,406 (6.78)  
Antibiotic treatment 48 h before and/or after ICU admission 23,178 (21.22)  
Gender (male) 71,223 (65.21)  
Origin: community (reference) 54,996 (50.36)  
Origin: hospital/ICU 54,220 (49.64)  
Trauma 8,927 (8.17)