Table 1.
Respiratory exacerbations from enrolment to 5 years of age
| Parameters | Total number | Incidence per person-years | IRR | 95% CI | p Value* |
|---|---|---|---|---|---|
| Total respiratory exacerbations (n=2080) | |||||
| Gender | |||||
| Boys (n=88) | 1123 | 3.83 | 1.10 | 0.93 to 1.30 | 0.261 |
| Girls (n=80) | 957 | 3.48 | |||
| Group | |||||
| BAL (n=84) | 1047 | 3.68 | 1.01 | 0.85 to 1.19 | 0.940 |
| Std (n=84) | 1033 | 3.65 | |||
| Anti-staphylococcal antibiotic prophylaxis for at least the first year of life | |||||
| Yes (n=54) | 516 | 2.94 | 0.74 | 0.62 to 0.88 | 0.001 |
| No (n=114) | 1564 | 3.99 | |||
| Pseudomonas aeruginosa | |||||
| Ever (n=101) | 1293 | 3.90 | 1.17 | 0.99 to 1.38 | 0.062 |
| Never (n=67) | 787 | 3.34 | |||
| Maternal smoking | |||||
| Yes (n=41) | 471 | 3.30 | 0.87 | 0.72 to 1.05 | 0.151 |
| No (n=127) | 1609 | 3.79 | |||
| Highest parental education level for both parents | |||||
| Completed year 10 (n=24) | 283 | 3.47 | 1.00 | 0.766 | |
| Completed secondary education (n=39) | 449 | 3.46 | 1.00 | 0.72 to 1.38 | |
| Trade (n=76) | 946 | 3.66 | 1.05 | 0.79 to 1.39 | |
| Completed tertiary education (n=17) | 236 | 3.98 | 1.14 | 0.83 to 1.58 | |
| Age | |||||
| 0–1 year (n=168) | 284 | 3.02 | 1.00 | 0.007 | |
| >1–2 years (n=165) | 411 | 3.36 | 1.11 | 0.94 to 1.31 | |
| >2–3 years (n=161) | 412 | 3.47 | 1.14 | 0.96 to 1.37 | |
| >3–4 years (n=159) | 468 | 4.10 | 1.36 | 1.12 to 1.64 | |
| >4–5+ years (n=158) | 505 | 4.20 | 1.39 | 1.15 to 1.68 | |
| Total exacerbations (n=2080) | |||||
| QLD (n=60) | 735 | 3.49 | <0.001 | ||
| VIC (n=40) | 657 | 5.14 | |||
| NSW and SA (n=42) | 385 | 2.85 | |||
| NZ (n=26) | 303 | 3.22 | |||
| Exacerbations reported by clinic doctor (n=1263) | |||||
| QLD (n=60) | 568 | 2.52 | <0.001 | ||
| VIC (n=40) | 202 | 1.21 | |||
| NSW and SA (n=42) | 290 | 2.03 | |||
| NZ (n=26) | 203 | 2.02 | |||
| Total/number children† | Incidence per person-years | IRR | 95% CI | p Value* | |
| Respiratory exacerbations resulting in hospital admission (n=413) | |||||
| Parameters | |||||
| Boys (n=88) | 225/64 | 0.62 | 1.11 | 0.81 to 1.52 | 0.507 |
| Girls (n=80) | 188/69 | 0.55 | |||
| Group | |||||
| BAL (n=84) | 227/72 | 0.64 | 1.22 | 0.87 to 1.72 | 0.240 |
| Std (n=84) | 186/61 | 0.53 | |||
| Anti-staphylococcal antibiotic prophylaxis for at least the first year of life | |||||
| Yes (n=54) | 100/41 | 0.47 | 0.74 | 0.54 to 1.02 | 0.066 |
| No (n=114) | 313/92 | 0.63 | |||
| Pseudomonas aeruginosa | |||||
| Ever (n=101) | 315/92 | 0.76 | 2.27 | 1.61 to 3.19 | <0.001 |
| Never (n=67) | 98/41 | 0.34 | |||
| Maternal smoking | |||||
| Yes (n=41) | 124/36 | 0.71 | 1.31 | 0.97 to 1.77 | 0.075 |
| No (n=127) | 289/97 | 0.54 | |||
| Highest parental education level for both parents | |||||
| Completed year 10 (n=24) | 82/18 | 0.83 | 1.00 | 0.385 | |
| Completed secondary education (n=39) | 82/29 | 0.51 | 0.62 | 0.34 to 1.14 | |
| Trade (n=76) | 180/62 | 0.56 | 0.68 | 0.38 to 1.21 | |
| Completed tertiary education (n=17) | 34/13 | 0.46 | 0.55 | 0.27 to 1.14 | |
| Age | |||||
| 0–1 year (n=168) | 64/46 | 0.58 | 1.00 | 0.778 | |
| >1–2 years (n=165) | 88/69 | 0.59 | 1.01 | 0.73 to 1.40 | |
| >2–3 years (n=161) | 95/80 | 0.66 | 1.13 | 0.79 to 1.62 | |
| >3–4 years (n=159) | 80/68 | 0.55 | 0.96 | 0.66 to 1.38 | |
| >4–5+ years (n=158) | 86/72 | 0.55 | 0.95 | 0.65 to 1.38 | |
| Total exacerbations | |||||
| QLD (n=60) | 183/54 | 0.71 | 0.021 | ||
| VIC (n=40) | 102/27 | 0.60 | |||
| NSW and SA (n=42) | 70/32 | 0.43 | |||
| NZ (n=26) | 58/20 | 0.51 | |||
| Exacerbations reported by clinic doctor | |||||
| QLD (n=60) | 151/51 | 0.57 | 0.083 | ||
| VIC (n=40) | 55/21 | 0.31 | |||
| NSW and SA (n=42) | 66/31 | 0.40 | |||
| NZ (n=26) | 53/18 | 0.46 | |||
*p Value for Poisson regression test of null hypothesis that incidence rates are equal across categories.
†Total number of exacerbations resulting in hospital admission/number of children having at least one exacerbation resulting in hospital admission.
BAL, bronchoalveolar lavage; IRR, incidence rate ratio; NSW, New South Wales; NZ, New Zealand; QLD, Queensland; SA, South Australia, VIC, Victoria.