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Table 5 Results of the primary and secondary outcomes and sensitivity analyses

From: Scaling up Quality Improvement for Surgical Teams (QIST)—avoiding surgical site infection and anaemia at the time of surgery: a cluster randomised controlled trial of the effectiveness of quality improvement collaboratives to introduce change in the NHS

Outcome, n (%)a

Unadjusted

Adjustedb

Anaemia (n = 6324)

Infection (n = 12,930)

OR (95% CI)

p-value

Primary outcomes

 Blood transfusion

183 (2.9)

302 (2.3)

0.83 (0.36, 1.91)

0.67

 Deep SSI (MSSA) (PHE)

8 (0.13)

18 (0.14)

1.01 (0.42, 2.46)

0.98

Secondary infection outcomes

 Deep SSI (MSSA) (CDC)

8 (0.13)

18 (0.14)

1.01 (0.42, 2.46)

0.98

 Deep SSI (MSSA) (either)

8 (0.13)

18 (0.14)

1.01 (0.42, 2.46)

0.98

 Deep SSI (any) (PHE)

23 (0.36)

48 (0.37)

0.97 (0.57, 1.64)

0.91

 Deep SSI (any) (CDC)

23 (0.36)

48 (0.37)

0.97 (0.57, 1.64)

0.91

 Deep SSI (any) (either)

23 (0.36)

48 (0.37)

0.97 (0.57, 1.64)

0.91

 Superficial SSI (MSSA) (PHE)

5 (0.08)

4 (0.03)

0.49 (0.13, 1.86)

0.29

 Superficial SSI (MSSA) (CDC)

5 (0.08)

10 (0.08)

0.93 (0.25, 3.45)

0.91

 Superficial SSI (MSSA) (either)

5 (0.08)

10 (0.08)

0.93 (0.25, 3.45)

0.91

 Superficial SSI (any) (PHE)

16 (0.25)

33 (0.26)

1.11 (0.55, 2.25)

0.77

 Superficial SSI (any) (CDC)

18 (0.28)

48 (0.37)

1.30 (0.62, 2.73)

0.49

 Superficial SSI (any) (either)

18 (0.28)

48 (0.37)

1.30 (0.62, 2.73)

0.49

Secondary outcomes

 

n= 6138

n= 9911

  

 Unplanned readmissions

390 (6.4)

464 (4.7)

1.09 (0.54, 2.19)

0.81

 

n= 6324

n= 12,693

  

 Critical care admission

182 (2.9)

465 (3.7)

1.05 (0.46, 2.43)

0.90

   

IRR(95%CI)

p-value

 Length of stay on critical carec,d

  N, mean (SD)

182, 1.7 (1.4)

465, 1.5 (1.3)

1.05 (0.79, 1.41)

0.73

  Median (min, max)

1 (0, 12)

1 (0, 17)

  

  N, mean (SD)

6324, 0.05 (0.4)

12,693, 0.06 (0.4)

0.97 (0.86, 1.09)

0.56

  Median (min, max)

0 (0, 12)

0 (0, 17)

  
 

n= 6138

n= 9911

  

 Length of hospital stayc

  Mean (SD)

183 (3.9)

184 (3.1)

1.03 (0.93, 1.14)

0.53

  Median (min, max)

3 (0, 137)

3 (0, 91)

  

Sensitivity analyses

  

OR(95%CI)

 

 Excluding contaminated sites

n=6324

n=8607

  

  Blood transfusion

138 (2.9)

230 (2.7)

0.81 (0.36, 1.84)

0.62

  Deep SSI (MSSA) (PHE)

8 (0.13)

14 (0.16)

1.28 (0.52, 3.16)

0.59

 Ischaemic heart disease as covariate

n=6138

n=12,295

  

  Blood transfusion

176 (2.9)

265 (2.2)

0.83 (0.37, 1.86)

0.65

 Excluding sites with no transfusions

n=6243

n=11,965

  

  Blood transfusion

183 (2.9)

302 (2.5)

1.03 (0.52, 2.05)

0.94

 Excluding sites with no reported infections

n=6243

n=11,712

  

  Deep SSI (MSSA) (PHE)

8 (0.13)

18 (0.15)

1.28 (0.51, 3.24)

0.60

 Excluding sites with 100% infection confirmation

n=5162

n=11,903

  

  Deep SSI (MSSA) (PHE)

6 (0.12)

14 (0.12)

0.85 (0.31, 2.37)

0.76

  1. Deep infections measured up to 90 days post-surgery; superficial infections measured up to 30 days post-surgery; unplanned readmission within 30 days of discharge; critical care admissions, and time spent on critical care, up to 30 days post-surgery
  2. SSI surgical site infection, MSSA methicillin-susceptible Staphylococcus aureus, PHE Public Health England, CDC Centre for Disease Control, OR odds ratio, IRR incidence rate ratio
  3. aUnless mean (SD), median, minimum, maximum as stated
  4. bTreatment effects associated with infection arm presented
  5. cMidnights in hospital
  6. dFirst analysis includes only those admitted to critical care, second also includes those not admitted to critical care imputing 0 midnights in critical care and using a zero-inflated model
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Implementation Science

ISSN: 1748-5908