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Table 4 Incident rate ratios, with 95% confidence intervals (CIs) for cardiovascular events following pandemic influenza vaccination (pandemrix) among higher risk individuals, stratified by antiplatelet users versus non-users

From: Influenza vaccination and risk for cardiovascular events: a nationwide self-controlled case series study

  

AMIa

 

Strokea

 

Pulmonary embolisma

Anti-platelet users (n = 3932)

 

Antiplatelet non-users (n = 1097)

Anti-platelet users (n = 2203)

 

Antiplatelet non users (n = 923)

Anti-platelet users (n = 319)

 

Antiplatelet non users (n = 540)

N

IRR (95% CI)c

N

IRR (95% CI)c

N

IRR (95% CI)c

N

IRR (95% CI)c

N

IRR (95% CI)c

N

IRR (95% CI)c

Baseline periodb

2921

1.0 (ref.)

443

1.0 (ref.)

1561

1.00 (ref.)

500

1.0 (ref.)

194

1.00 (ref.)

370

1.0 (ref)

Pre vaccination interval

            

 1–14 days

117

0.87 (0.71–1.06)

8

0.51 (0.25–1.05)

45

0.69 (0.51–0.94)

10

0.51 (0.27–0.98)

7

0.92 (0.42–2.01)

23

1.37 (0.88–2.14)

Post vaccination interval

            

 1–14 days

55

0.41 (0.31–0.54)

50

3.28 (2.37–4.54)

39

0.60 (0.43–0.84)

25

1.29 (0.84–1.97)

10

1.30 (0.66–2.56)

8

0.48 (0.23–0.98)

 15–28 days

64

0.48 (0.37–0.62)

37

2.35 (1.64–3.38)

45

0.70 (0.52–0.96)

35

1.78 (1.24–2.57)

6

0.76 (0.33–1.77)

16

0.96 (0.57–1.61)

 29–59 days

167

0.58 (0.49–0.68)

111

3.15 (2.46–4.03)

114

0.84 (0.68–1.03)

67

1.50 (1.12–2.01)

23

1.19 (0.72–1.98)

26

0.71 (0.45–1.10)

 60–90 days

160

0.59 (0.47–0.75)

101

2.77 (2.08–3.70)

94

0.74 (0.56–0.99)

76

1.62 (1.15–2.29)

20

0.86 (0.45–1.64)

19

0.52 (0.29–0.95)

 91–120 days

169

0.65 (0.52–0.82)

124

3.34 (2.55–4.36)

98

0.79 (0.60–1.05)

70

1.53 (1.09–2.16)

25

1.10 (0.59–2.04)

24

0.69 (0.40–1.19)

 121–180 days

279

0.53 (0.46–0.61)

220

2.64 (2.22–3.13)

207

0.74 (0.64–0.87)

140

1.48 (1.21–1.81)

34

0.85 (0.56–1.28)

54

0.79 (0.58–1.09)

  1. AMI acute myocardial infarction, IRR incident rate ratio, CI confidence interval
  2. aAnalyses was restricted among higher cardiovascular-risk patients. These are results from self-controlled case series analysis using data for first-time AMI, stroke and pulmonary embolism patients who were vaccinated with Pandemrix. The start of observation period was May 1, 2009 and end of observation period was September 30, 2010 or the day of emigration or death (whichever came first). Person-time of each vaccinated individual was divided into following risk-periods: pre-vaccination interval (1–14 days prior to vaccination) and postvaccination intervals (1–14 days, 15–28 days, 29–59 days, 60–90 days, 91–120 days, 121–180 days following vaccination)
  3. bAll remaining part of the observation period was used for baseline comparison (unexposed person-time)
  4. cAdjusted for calendar period (January–March, April–August, and September–December)
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BMC Cardiovascular Disorders

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