Critical Appraisal Of The Literature
A literature review was carried out with PubMed and Ovid MEDLINE® for articles on croup, acute laryngotracheitis, and acute laryngotracheobronchitis with limits on all child: 0-18 years. Pertinent, well-designed randomized controlled trials were included as well as commonly referenced and older publications on the topic. A search in the Cochrane Database of Systematic Reviews yielded 3 important publications relating to the treatment of croup.1-3 One relevant review was not included in this issue as it had been withdrawn from the Cochrane Library because the authors were unable to update it.4 The website of the Canadian Pediatric Society (http://www.cps.ca/) and the American Academy of Pediatrics (AAP) (http://www.aap.org/) were consulted for guidelines, but none were found. The only document concerning croup from these organizations that was written for professionals is a position statement from the Canadian Pediatric Society dating back to 1992 on steroid administration for patients admitted to the hospital.5 The AAP website yielded several patient education sheets but no official guidelines or clinical decision algorithms. Additionally, the most often referenced guidelines on diagnosis and management of croup in the literature, published in 2007 by the Alberta Medical Association, were reviewed.6
The literature on croup underwent a drastic update in the early 1990s with the introduction of corticosteroids, which were first used in hospitalized patients and then in ambulatory patients. The literature predating this introduction focused mostly on management of severe cases of upper airway obstruction from croup and on distinguishing this entity from other common childhood illnesses in the preimmunization period that cause upper airway obstruction (most notably, epiglottitis caused by Haemophilus influenzae type b). Several small underpowered studies demonstrated a small benefit in improvement of symptoms and a reduction in the rate of intubation with the treatment of hospitalized patients with upper airway obstruction using corticosteroids.7-12 These results were largely ignored by most of the pediatric medical community until 1989, when Kairys et al published a meta-analysis based on 10 randomized trials with a total of 1286 patients that supported the use of corticosteroids to lower the morbidity associated with croup.13 Based on these results, appropriately powered randomized controlled trials showing the effectiveness and safety of corticosteroids in croup were conducted.
Recently updated meta-analyses confirmed these results. More-recent studies have focused on determining the best administration modality and dosage to maximize effectiveness while minimizing harm to the patient. Multiple randomized controlled trials are currently trying to determine whether a lower corticosteroid dose is as effective as the one traditionally recommended. There are also several newer modalities, such as heliox, under investigation for the treatment of more-severe cases of croup. With the widespread use of corticosteroids, the rates of hospitalization and of admission to the ICU for croup have steadily decreased in the past 2 decades, limiting research in this area.2