Clinical prediction rule adequately predicts nonbacterial conjunctivitis

Article Outline

• Question
• Design
• Setting
• Participants
• Intervention
• Outcomes
• Main Results
• Conclusions
• Commentary
• References
• Copyright

Meltzer JA, Kunkov S, Crain EF. Identifying children at low risk for bacterial conjunctivitis. Arch Pediatr Adolesc Med 2010;164:263-7.

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Question 

Among children with conjunctivitis, what clinical characteristics predict negative conjunctival culture for typical infectious bacteria?

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Design 

Prospective cohort (clinical prediction rule).

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Setting 

Pediatric emergency department in New York City.

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Participants 

Three hundred sixty-eight sequential children, ages 6 months to 17 years, presenting to the emergency department with conjunctivitis.

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Intervention 

Clinical characteristics on history and physical exam, as well as a standardized bacterial culture of the lower lid conjunctiva, were gathered on each child.

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Outcomes 

The primary outcome was a positive culture for a bacterium not considered to be normal conjunctival flora. Predictor variables showing an association to culture outcome on bivariate analysis were tested in a multivariate logistic regression model.

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Main Results 

Sixty-five percent of the conjunctival cultures were positive. Four variables were found to be strongly associated with negative culture: age >5 years, presentation in April through November, no or watery eye discharge, and no glued eye in the morning. Having all four of these predictors present had a probability of a negative conjunctival culture of 92% (95% confidence interval, 66.1% to 98.2%).

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Conclusions 

Four easily gathered variables on children presenting with conjunctivitis can adequately predict which children will have negative bacterial cultures of their conjunctiva.

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Commentary 

Meltzer et al performed a valid cohort study of sequential children presenting to the emergency department, in an effort to sort out which children would most reliably have negative cultures and therefore could be treated expectantly without topical antibiotics. The strengths of this study were the sequential gathering of subjects (even on nights and weekends), the checklist of signs and symptoms, and the objective, prospectively defined outcome of bacterial culture. What we do not know from the study is how good the inter-rater reliability was on gathering the predictive variables, because the variables were gathered by all providers in the emergency department: attendants, residents, and nurse practitioners. Overall this is a valid clinical prediction rule by the Users' Guides criteria¹ but can only be considered a level 4 prediction rule. To become more widely useful and validated, this rule must be restudied in other settings and ultimately studied to ensure that it changes physician behavior. Until it is validated by further studies, clinicians can use this rule with some caution when approaching children with conjunctivitis. Even with caution, however, the clinician can be reassured that bacterial conjunctivitis resolves spontaneously and topical antibiotic treatments only speed this natural healing process.²

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References 

1. McGinn TG, Guyatt GH, Wyer PC, Naylor CD, Stiell IG, Richardson WS. Users' guides to the medical literature: XXII: how to use articles about clinical decision rules. JAMA. 2000;284:79–84
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2. Sheikh A, Hurwitz B. Antibiotics versus placebo for acute bacterial conjunctivitis. Cochrane Database Syst Rev. 2006;(2):CD001211
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