Table 2

Factors influencing hospitalisation of individuals affected by pandemic influenza (H1N1) 2009 and risk factors for the development of pneumonia.

Independent variables

n

Individuals hospitalised/with pneumonia (%)

Univariate analysis OR (95%CI)

p-value

Multivariate analysis OR (95%CI)

p- value

Hospitalisation

Pneumonia

275

130 (47.3)

25.5 (20.0;32.5)

<0.001

18.2 (13.6;23.9)

<0.001

No pneumonia reported

40,236

1,366 (3.4)

reference

Risk factors present

2,342

284 (12.1)

4.6 (3.6;4.7)

<0.001

3.6 (3.1;4.3)

<0.001

No risk factor reported

37,187

1,215 (3.3)

Reference

Chronic disease

2,250

261 (11.6)

3.8 (3.3;4.4)

<0.001

No chronic disease reported

37,298

1,240 (3.3)

Reference

Immunosuppression

112

30 (26.8)

10.8 (7.1;16.3)

<0.001

No risk factor reported

37,187

1,215 (3.3)

reference

Respiratory disease

1,072

87 (8.1)

2,6 (2,1; 3,3)

<0.001

No risk factor reported

37,187

1,215 (3.3)

reference

Obesity*

159

19 (11.9)

4.0 (2,5; 6,5)

<0.001

No risk factor reported

37,187

1,215 (3.3)

reference

Cardio-vascular disease

260

34 (13.1)

4.5 (3.1; 6.4)

<0.001

No risk factor reported

37,187

1,215 (3.3)

reference

Diabetes

172

19 (11.0)

3.7 (2.3; 5.9)

<0.001

No risk factor reported

37,187

1,215 (3.3)

reference

Other chronic disease

70

70 (15.4)

5.4 (4.1; 7.0)

<0.001

No risk factor reported

37,187

1,215 (3.3)

reference

Pregnancy

106

25 (25.6)

9.9 (6.1;16.0)

<0.001

No pregnancy reported

16,957

527 (3.1)

reference

Age

0 - 2 years

920

107 (11.6)

3.3 (2.7;4.1)

<0.001

2.9 (2.2;3.8)

<0.001

All other age groups

51,563

1,977 (3.8)

reference

3 - 14 years

17,486

509 (2.9)

0,6 (0.5;0.7)

<0.001

0.7 (0.6;0.8)

<0.001

All other age groups

34,997

1,575 (4.5)

reference

Male

27,345

1,114 (4.1)

1.1 (0.9;1.2)

= 0.069

1.1 (0.9;1.2)

= 0.224

Female

24,628

927 (3.8)

reference

Acceleration period

28,820

967 (3.4)

0.7 (0.6; 0.8)

<0.001

0.8 (0.7;0.9)

= 0.020

Initiation period

23,663

1,117 (4.7)

reference

Pneumonia

Risk factors

2,162

76 (3.5)

7.4 (5.7;9.8)

<0.001

8.1 (6.1;10.7)

<0.001

No risk factor reported

36,305

177 (0.5)

reference

Chronic disease

2,082

75 (3.6)

7.6 (5.8;9.9)

<0.001

No chronic disease reported

36,402

179 (0.5)

reference

Immunosuppression

103

7 (6.8)

14.9 (6.9;32.7)

<0.001

No risk factor reported

36,305

177 (0.5)

reference

Respiratory disease

994

34 (3.4)

7.2 (4.9;10.5)

<0.001

No risk factor reported

36,305

177 (0.5)

reference

Obesity*

143

9 (6.3)

13.8 (6.9;27.5)

<0.001

No risk factor reported

36,305

177 (0.5)

reference

Cardio-vascular disease

243

5 (2.1)

4.3 (1.7;10.4)

= 0.002

No risk factor reported

36,305

177 (0.5)

reference

Diabetes

157

1 (0.6)

1.3 (0.2;9.4)

= 0.790

No risk factor reported

36,305

177 (0.5)

reference

Other chronic disease

425

18 (4.2)

9.1 (5.5;14.8)

<0.001

No risk factor reported

36,305

177 (0.5)

reference

Pregnancy

95

2 (2.1)

4.6 (1.1;19.0)

= 0.074

No pregnancy reported

17,194

80 (0.5)

reference

Age

0 - 2 years

712

15 (2.1)

3.3 (1.9;5.5)

<0.001

2,8 (1.5;5.2)

<0.001

All other age groups

40,019

261 (0.7)

reference

3 - 14 years

13,453

92(0.7)

1.1 (0.8;1.3)

= 0.914

All Other age groups

27,278

184 (0.7)

reference

Male

21,158

146 (0.7)

1.1 (0.7;1.4)

= 0.413

1.1 (0.8;1.4)

= 0.545

Female

19,228

120 (0.6)

reference

Acceleration period

22,640

182 (0.8)

1.6 (1.2;2.0)

= 0.001

1.3 (1.0;1.7)

= 0.038

Initiation period

18,081

94 (0.5)

reference

ILI**

4,442

39 (0.9)

1.3 (1.0;1.8)

= 0.090

1.4 (1.0;2.1)

= 0.032

No ILI

36,289

237 (0.7)

reference

Fever (>38.5°C)

34,905

258 (0.7)

1.9 (1.2;3.1)

= 0.007

2.0 (1.2;3.5)

= 0.013

No fever reported

4,826

18 (0.4)

reference

* Obesity requiring treatment or body mass index > 30

** ILI: acute onset of symptoms and fever and cough and headache or musculoskeletal pain

Poggensee et al. BMC Infectious Diseases 2010 10:155   doi:10.1186/1471-2334-10-155

Open Data