Table 4

Risk factors for viral detection in healthy infants and infants with cystic fibrosis (CF) separately

Healthy infantsInfants with CF
Exposure: risk factorOR95% CIpOR95% CIp
Gender*1.090.68 to 1.740.70.760.48 to 1.210.3
Breast feeding1.260.78 to to 1.480.8
Siblings§1.340.77 to 2.320.31.120.73 to 1.970.5
3–6 months
1.270.80 to to 2.320.3
6–9 months1.310.79 to to 2.820.2
9–12 months2.141.18 to 3.880.0131.801.81 to 3.410.08#
Season‡ spring0.960.62 to 1.490.90.730.43 to 1.250.3
Summer1.100.70 to 1.710.71.030.62 to 1.730.9
Fall0.950.61 to 1.470.81.220.73 to 2.050.5
Antibiotics§0.630.33 to 1.200.2
CF genotype¶0.760.54 to 1.070.1
Childcare1.460.80 to 2.670.2
  • Adjusted OR for viral detection investigating different risk factors, stratified for CF status from multilevel logistic regression. Results are displayed after adjustment for all tested risk factors, outcome was viral detection in general (yes/no), reference category samples free of virus, analysis was done separately for healthy infants and infants with CF. p = p value, reference category for exposures: *baseline = male; §baseline = no siblings; †baseline = age 0–3 months, ‡baseline = winter; §baseline = before any antibiotics (AB) compared with samples during AB; samples after first application of AB are not shown, no different result to samples before first AB application; ¶baseline = no residual Cystic Fibrosis Transmembrane conductance Regulator function.

  • p Value for interaction between listed exposures and healthy infants and infants with CF, model including all children always p>0.3, #= trend after adjustment for all confounders, in a model only considering age and season, significant (OR 2.04; 95% CI 1.12 to 3.70; p=0.019).