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.