Table 4 Univariate and multivariate survival analyses of time to first event for different otitis outcomes, hazard ratios and 95% confidence intervals

Univariate

Vaccinated versus comparison group

1.17 (0.85 – 1.62)

0.80 (0.51 – 1.26)

0.84 (0.42 – 1.67)

0.57 (0.20 – 1.62)

Age at first examination (days)

0.98 (0.98 – 0.99)

1.00 (0.99 – 1.01)

n/a

n/a

Females/Males

0.79 (0.57 – 1.10)

1.06 (0.70 – 1.60)

0.99 (0.53 – 1.88)

0.36 (0.11 – 1.13)

Rate of non-respiratory illness*

1.09 (0.79 – 1.52)

1.08 (0.73 – 1.60)

1.07 (0.57 – 2.01)

0.98 (0.39 – 2.46)

Rate of prior antibiotic prescription*

0.71 (0.48 – 1.03)

0.91 (0.62 – 1.35)

0.95 (0.53 – 1.72)

1.63 (0.75 – 3.58)

Birth weight (kg)

0.99 (0.74 – 1.33)

1.04 (0.71 – 1.54)

0.90 (0.49 – 1.66)

0.94 (0.35 – 2.54)

Rate of well clinic visits*

1.10 (0.99 – 1.23)

1.32 (1.07 – 1.62)

1.09 (0.74 – 1.62)

1.10 (0.57 – 2.12)

Late immunisation

0.64 (0.36 – 1.17)

0.69 (0.39 – 1.22)

0.66 (0.31 – 1.40)

1.19 (0.40 – 3.54)

Multivariate

Vaccinated versus comparison group

0.90 (0.64 – 1.25)

1.01 (0.61 – 1.67)

0.83 (0.41 – 1.66)

0.56 (0.19 – 1.62)

Age at first examination (days)

0.98 (0.97 – 0.99)

n/a

n/a

n/a

Rate of non-respiratory illness*

1.14 (0.83 – 1.56)

1.04 (0.71 – 1.52)

1.09 (0.58 – 2.07)

1.04 (0.42 – 2.60)

Rate of well clinic visits*

n/a

1.32 (1.05 – 1.65)

n/a

n/a