Table 2. Multivariate Analysis of Variables Related to Antibiotic Prescription
VariablesPercentage Antibiotic PrescriptionBivariate AnalysisMultivariate Analysis
If Characteristic Is PresentIf Characteristic Is AbsentOR95% CIP ValueSelectionOR95% CIP Value
Patient characteristics
    Age: 3–6 monthsNANA0.150.03–0.63.01EA0.170.03–0.74.03
        6–12 months0.710.41––1.94.93
        >12 months (reference group)
Concerned parents at home visit36.1 (26/72)25.1 (89/354)1.700.99–2.91.05EA2.021.06–3.58.03
Number of children in householdNANA1.251.00–1.56.05SS1.160.90–1.48.25
Patient history (signs present at moment of contacting out-of-hours service)
    Duration of illness at presentation (days)NANA1.081.02–1.14.01EA1.050.99–1.12.11
    Fever in previous week35.5 (22/62)24.4 (73/299)1.580.82–3.04.17EA1.150.52–2.57.73
    Fever in past 6 months29.6 (85/287)20.3 (31/153)1.671.04–2.66.03SS1.330.78–2.26.30
    Vaccination in previous week10.7 (3/28)27.6 (114/413)0.320.10–1.10.07SS0.340.08–1.38.13
    Decreased urine production35.7 (40/112)22.6 (66/292)1.841.16–2.91<.01SS2.001.17–3.41.01
Physical examination
    Tachypnea19.1 (13/68)27.4 (75/274)0.710.36–1.40.33EA0.840.41–1.75.65
    Height of rectal temperatureNANA0.610.46–0.80<.01EA0.520.37–0.71<.01
    Ill appearance47.6 (20/42)24.4 (96/394)2.791.46–5.35<.01EA3.261.30–8.20.01
    YOS scoreNANA1.080.99–1.18.07EA1.020.91–1.15.69
    Earache resulting in altered behavioral or sleeping pattern43.3 (13/30)25.1 (95/378)2.271.08–4.79.03SS2.591.06–6.30.04
    Signs of throat infection36.4 (40/110)17.3 (38/220)2.501.50–4.18<.01SS2.371.35–4.15<.01
    Runny nose (patient history)32.6 (46/141)23.2 (69/297)1.591.02–2.49.04SS1.570.94–2.60.08
  • Bold: multivariate P < .05. The physical examination forms included categorical variables with possible answers: “no, little, very, very much.” These variables were dichotomized using a cutoff point between “little” and “very.” Decreased urine production was considered if micturition was much decreased or if there was no micturition at all.

  • NA indicates not applicable; EA, expected association; SS, bivariate statistical significance; YOS, Yale Observation Scale.