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Volume 17, Number 8—August 2011

Research

Case–Control Study of Risk Factors for Hospitalization Caused by Pandemic (H1N1) 2009

Kate A. Ward, Paula J. SpokesComments to Author , and Jeremy M. McAnulty
Author affiliations: Author affiliation: New South Wales Department of Health, Sydney, New South Wales, Australia

Main Article

Table 3

Risk factors for mechanical ventilation because of pandemic (H1N1) 2009 infection, Sydney, Australia, 2009*

Patient characteristic
No. (%) case-patients, n = 37
No. (%) controls, n = 603
OR (95% CI)
p value
Adjusted OR (95% CI)
p value
Sex
M 11 (30) 207 (34)
F
26 (70)
396 (66)
1.2 (0.6–2.6)
0.5674


Age, y
16–25 3 (8) 61 (10) 3.7 (0.7–19) 5.5 (0.7–42.0)
26–35 11 (30) 92 (15) 9.1 (2.5–33.3) 12.2 (2.5–58.2)
36–45 12 (32) 111 (18) 8.2 (2.3–29.7) 10.4 (2.3–48.3)
46–55 8 (22) 111 (18) 5.5 (1.4–21.0) 10.2 (2.3–45.9)
>55
3 (8)
228 (38)

0.0114

0.0176
Aboriginal status
Nonindigenous 36 (97) 596 (99)
Indigenous
1 (3)
7 (1)
2.4 (0.3–19.7)
0.426


Body mass index†
Underweight (<18.5) 3 (9) 15 (3) 8.6 (2.0–37.9) 10.6 (1.9–58.9)
Normal (18.5–24.9) 6 (17) 259 (45) 0.0004 0.0022
Overweight (25.0–29.9) 10 (29) 175 (30) 2.5 (0.9–6.9) 3.2 (1.0–10.3)
Obese 1 (30.0–34.9) 5 (14) 79 (14) 2.7 (0.8–9.2) 1.8 (0.5–7.4)
Obese 2 (35.0–39.9) 5 (14) 29 (5) 7.4 (2.1–25.9) 9.8 (2.4–40.1)
Obese 3 (>40)
6 (17)
21 (4)
12.3 (3.7–41.6)

11.6 (2.7–49.3)

Health condition‡
Asthma 13 (65) 93 (15)
No regular medication 5 (14) 48 (8) 2.2 (0.8–6.1) 0.0061
Regular medication 8 (22) 45 (7) 3.8 (1.6–8.9)
Heart disease§ 3 (9) 41 (7) 1.3 (0.4–4.3) 0.7136
Kidney disease¶ 1 (3) 8 (1) 2.1 (0.3–16.9) 0.5013
Mental health problem 6 (16) 49 (8) 2.2 (0.9–5.5) 0.0958
Neurologic problem 3 (8) 42 (7) 1.2 (0.3–4.0) 0.792
Immunosuppression 1 (3) 22 (4) 0.7 (0.1–5.6) 0.7655
Obstructive sleep apnea 2 (5) 23 (4) 1.4 (0.3–6.4) 0.6296
Lung disease 6 (16) 31 (5) 3.6 (1.4–9.2) 0.0084 8.6 (2.6–28.5) 0.0005
Diabetes 5 (14) 38 (6) 2.3 (0.9–6.3) 0.0977 4.4 (1.2–15.6) 0.0383
Liver disease 2 (5) 20 (3) 1.7 (0.4–7.4) 0.503
Pregnancy
8 (22)
7 (1)
23.4 (8.0–69.2)
<0.001
40.5 (9.7–168.1)
<0.0001
Smoking status
Nonsmoker 17 (46) 372 (62) 2.4 (1.0–5.5) 0.0325
Current or former smoker
20 (54)
231 (38)
1.9 (1.0–3.7)
0.0605


Influenza vaccine in 2009 20 (54) 202 (34) 0.3 (0.1–0.8) 0.0163

*OR, odds ratio; CI, confidence interval.
†Data missing for 2 case-patients and 25 controls.
‡Groups are not mutually exclusive.
§Date missing for 2 case-patients and 12 controls.
¶Data missing for 3 controls.

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