TABLE 1.
Relationship between age, specimen type, and ICT positivity in children with proven influenza A virus H1N1 09 infection who had the ICT performeda
| Specimen type and patient age group | No. of patients with ICT performed | No. of patients with positive ICT result for influenza A virus | ICT sensitivity (%) (95% CI) |
|---|---|---|---|
| Respiratory swabs | |||
| All ages | 71 | 47 | 66.2 (54.0-77.0) |
| 1st age quartile (0-4.0 yr) | 17 | 10 | 58.8 (32.9-81.6) |
| 2nd age quartile (4.1-6.7 yr) | 18 | 11 | 61.1 (35.7-82.7) |
| 3rd age quartile (6.8-11.1 yr) | 18 | 13 | 72.2 (46.5-90.3) |
| 4th age quartile (11.2-18 yr) | 18 | 13 | 72.2 (46.5-90.3) |
| Nasopharyngeal aspirates | |||
| All ages | 145 | 122 | 84.1 (77.2-89.7) |
| 1st age quartile (0-0.70 yr) | 36 | 32 | 88.9 (73.9-96.9) |
| 2nd age quartile (0.71-1.83 yr) | 36 | 33 | 89.2 (74.6-97.0) |
| 3rd age quartile (1.84-4.9 yr) | 36 | 33 | 91.7 (77.5-98.2) |
| 4th age quartile (5.0-18 yr) | 36 | 24 | 66.7 (49.0-81.4) |
a
There was a relationship between age and ICT positivity for NPAs (P = 0.003), but not for respiratory swabs (P = 0.45). This was evaluated by significance tests derived from a logistic regression model using Stata 9.0 (StataCorp, College Station, TX) and including age, specimen type, and an interaction term.