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. Spokes
, and Jeremy M. McAnulty
, and Jeremy M. McAnulty
Table 2
Risk factors for hospitalization caused by pandemic (H1N1) 2009 influenza for female case-patients and controls of childbearing age, Sydney, Australia, 2009*
| Patient characteristic | No. (%) case-patients, n = 99 | No. (%) controls, n = 181 | OR (95% CI) | p value | Adjusted OR (95% CI) | p value |
|---|---|---|---|---|---|---|
| Age, y | ||||||
| 16–25 | 28 (28) | 43 (24) | 1.4 (0.8–2.6) | |||
| 26–35 | 37 (37) | 64 (35) | 1.3 (0.7–2.2) | 0.5233 | ||
| 36–45 |
34 (34) |
74 (41) |
Referent |
|||
| Aboriginal status | ||||||
| Nonindigenous | 95 (98) | 177 (96) | Referent | 0.3864 | ||
| Indigenous |
4 (4) |
4 (2) |
1.9 (0.5–7.6) |
|||
| Body mass index† | ||||||
| Underweight (<18.5) | 8 (9) | 9 (5) | 2.8 (1.0–8.0) | |||
| Normal (18.5–24.9) | 31 (33) | 99 (57) | Referent | |||
| Overweight (25.0–29.9) | 15 (16) | 35 (20) | 1.4 (0.7–2.8) | 0.0003 | ||
| Obese 1 (30.0–34.9) | 17 (18) | 18 (10) | 3.0 (1.4–6.6) | |||
| Obese 2 (35.0–39.9) | 10 (11) | 4 (2) | 8.0 (2.3–27.3) | |||
| Obese 3 (>40) |
12 (13) |
8 (5) |
4.8 (1.8–12.8) |
|||
| Health condition‡ | ||||||
| Asthma | 46 (46) | 35 (19) | Referent | |||
| No regular medication | 7 (7) | 21 (12) | 0.9 (0.4–2.3) | <0.001 | 10 (4.0–21.0) | <0.0001 |
| Regular medication | 39 (39) | 14 (8) | 7.7 (3.9–15.3) | |||
| Heart disease§ | 0 | 1 (0.5) | <0.001 | 0.9871 | ||
| Kidney disease | 0 | 1 (0.5) | <0.001 | 0.987 | ||
| Mental health problem | 17 (17) | 19 (11) | 1.8 (0.9–3.6) | 0.1139 | ||
| Neurologic problem | 4 (4) | 8 (4) | 0.9 (0.3–3.1) | 0.8809 | ||
| Immunosupression | 1 (1) | 2 (1) | 0.9 (0.1–10.2) | 0.942 | ||
| Obstructive sleep apnea | 10 (10) | 4 (2) | 5.0 (1.5–16.3) | 0.0081 | ||
| Lung disease | 10 (10) | 4 (2) | 5.0 (1.5–16.3) | 0.0081 | 7 (2.0–28.0) | 0.0043 |
| Diabetes | 14 (14) | 2 (1) | 14.7 (3.3–66.3) | 0.0005 | 20 (4.0–103.0) | 0.0003 |
| Metabolic disorder | 1 (1) | 2 (1) | 0.9 (0.1–10.2) | 0.942 | ||
| Liver disease | 5 (5) | 0 | >999.9 | 0.9798 | ||
| Blood disorder | 4 (4) | 8 (4) | 0.9 (0.3–3.1) | 0.8809 | ||
| Pregnancy |
40 (40) |
7 (4) |
16.9 (7.2–39.6) |
<0.001 |
28 (11.0–70.0) |
<0.0001 |
| Smoking status | ||||||
| Nonsmoker | 53 (54) | 130 (72) | Referent | |||
| Current smoker | 24 (24) | 32 (18) | 1.8 (1.0–3.4) | 0.0057 | ||
| Former smoker |
22 (22) |
19 (11) |
2.8 (1.4–5.7) |
|||
| Influenza vaccine in 2009¶ | 20 (20) | 30 (17) | 1.3 (0.7–2.4) | 0.4262 |
*OR, odds ratio; CI, confidence interval.
†8 controls and 6 case-patients missing data.
‡Groups are not mutually exclusive.
§1 control and 3 case-patients missing data.
¶1 case-patient missing data.
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Page updated: August 15, 2011
Page reviewed: August 15, 2011
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