TABLE 1

Selected Risk Factors for Outcomes of Bronchiolitis in 3 Prospective Studies of Outpatients

Shaw et al38 (1991)Mansbach et al40 (2008)Voets et al39 (2006)
OutcomeSevere diseaseaHospitalizationHospitalization
Risk factors
    Age
        <2 mo4.5/0.78
        <3 mo2.2/0.75
        <6 mo2.2/0.53
    Prematurity
        <34 wk5.4/0.77
        <35 wk1.5/0.96
    Ill appearance3.2/0.32
    Oxygen saturation
        <94%5.4/0.77
        <95%16/0.695.2/0.37
    Respiratory rate
        >45 breaths per min3.8/0.39
        At or higher than normal for age (40–45 breaths per min according to age)1.3/0.61
        ≥70 breaths per min5.8/0.75
    Work of breathing
        Accessory muscle use2.2/0.42
        Moderate/severe retractions3.2/0.76
    Chest radiograph result
        Atelectasis10.5/0.81
        Abnormal1.2/0.73
  • Risk factors are presented as positive or negative likelihood ratios (+LR/−LR). The likelihood ratio can be multiplied by the pretest odds (ratio of the risk/1-risk) to obtain the posttest odds. For example, with a previous risk of hospitalization of 33% (odds of 0.33/0.66 = 0.5), a finding with a positive likelihood ratio of 4 increases the odds to 2 (4 × 0.5), corresponding to a posttest risk of 67% (2/2 + 1).

  • a Severe disease was defined as unable to maintain alert, active, and well hydrated while taking oral fluids throughout the illness.

  • Adapted with permission from Zorc JJ. Recent Advances in Paediatrics. London, United Kingdom: Royal Society of Medicine Press; 2009:19.