Table 4.
Risk factors for admission to hospital and intensive care unit, pH1N1 versus seasonal influenza A*
| Risk factor | All children admitted to hospital |
Children admitted to ICU |
||||
| pH1N1 (n=176) | Seasonal (n=200) | p Value | pH1N1 (n=32) | Seasonal (n=31) | p Value† | |
| Asthma | 26 (15)‡ | 9 (5) | <0.01 | 6 (19) | 1 (3) | 0.10 |
| Mild asthma | 16 (62) | 7 (78) | 0.38 | 4 (67) | 1 (100) | 1.00 |
| Moderate asthma | 6 (23) | 1 (11) | 0.44 | 1 (17) | 0 (0) | 1.00 |
| Severe asthma | 4 (15) | 1 (11) | 0.75 | 1 (17) | 0 (0) | 1.00 |
| Chronic lung disease | 12 (7) | 13 (7) | 0.92 | 0 (0) | 5 (16) | 0.02 |
| Obesity§ | 8 (7) | 14 (9) | 0.64 | 3 (20) | 2 (9) | 0.38 |
| Cardiac disease | 7 (4) | 21 (11) | 0.02 | 3 (9) | 4 (12) | 0.71 |
| Haemoglobinopathy | 19 (11) | 22 (11) | 0.95 | 1 (3) | 1 (3) | 0.75 |
| Immunodeficiency | 32 (18) | 42 (21) | 0.49 | 1 (3) | 2 (3) | 0.61 |
| Neurological impairment | 21 (12) | 26 (13) | 0.76 | 6 (19) | 8 (26) | 0.56 |
| Age <2 years and no other risk factors | 16 (9) | 35 (18) | 0.02 | 2 (6) | 4 (13) | 0.43 |
Bold values are significantly different as defined by a p value <0.05.
*
Any differences between the numbers presented in table 4 and those from O'Riordan et al8 are the result of a re-assessment of all pH1N1 and seasonal influenza A cases for this study.
†
Fisher's exact test used when cell size is small.
‡
Percentages in parentheses.
§
Obesity was defined according to guidelines from the Centers for Disease Control as a body mass index ≥95th percentile for age in children 2 years and older.12 Obesity could not be calculated for 45 (31%) and 68 (54%) children ≥2 years in the seasonal and pH1N1 groups, respectively.
pH1N1, pandemic H1N1.