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Table 3 Explanatory factors significantly related to antibiotic use (number of bed days as denominator) in Norwegian Health Enterprises, 2006–2011, derived from six multiple linear regression models

From: Hospital- and patient-related factors associated with differences in hospital antibiotic use: analysis of national surveillance results

Independent variables

WHO DDDs/100 bed days

Hospital-adjusted DDDs/100 bed days

All antibiotics

Broad-spectruma

All penicillinsb

All antibiotics

Broad-spectruma

All penicillinsb

Overall model, R 2 (adjusted R 2 )

0.49 (0.43)

0.40 (0.33)

0.55 (0.50)

0.43 (0.37)

0.36 (0.30)

0.59 (0.54)

Infect. disease ICD-10 main diag. (%)

Regression coeff. (95% C.I.)

5.35*** (2.33; 8.38)

 

3.83*** (1.34; 6.33)

2.86** (1.00; 4.71)

 

1.56** (0.59; 2.54)

Beta weight

0.47

 

0.45

0.41

 

0.44

Increment in R2

0.0690

 

0.0633

0.0509

 

0.0606

Registered nurses per 100 beds

Regression coeff. (95% C.I.)

0.17*** (0.08; 0.26)

 

0.10*** (0.04; 0.15)

0.10** (0.04; 0.17)

0.02* (0.001; 0.04)

0.04** (0.02; 0.06)

Beta weight

0.56

 

0.44

0.57

0.28

0.39

Increment in R2

0.1141

 

0.0706

0.1163

0.0293

0.0548

Hospital stay < 2 days (%)

Regression coeff. (95% confidence interval (C.I.))

0.81* (0.04; 1.57)

0.31* (0.05; 0.58)

  

0.29* (0.04; 0.53)

 

Beta weight

0.29

0.38

  

0.40

 

Increment in R2

0.0422

0.0718

  

0.0829

 

University hospital (binary)

Regression coeff. (95% C.I.)

−11.82** (−20.5; −3.2)

−2.65*** (−4.01; −1.29)

 

−8.22*** (−12.3; −4.1)

−2.72*** (−3.53; −1.91)

 

Beta weight

−0.55

−0.41

 

−0.62

−0.49

 

Increment in R2

0.1078

0.0607

 

0.1354

0.0868

 

Surgical DRG scper 100 beds

Regression coeff. (95% C.I.)

 

0.15* (0.01; 0.30)

 

0.52* (0.06; 0.97)

  

Beta weight

 

0.29

 

0.48

  

Increment in R2

 

0.0222

 

0.0589

  
  1. Significance levels: *P < 0.05, **P < 0.01, ***P < 0.001.
  2. aBroad-spectrum antibiotics: second- and third-generation cephalosporins, fluoroquinolones, carbapenems, and penicillins with enzyme inhibitors.
  3. bAll penicillins: penicillinase sensitive, penicillinase resistant and extended-spectrum penicillins.
  4. cDRG: Diagnosis-related groups.