Diagnosis and testing in bronchiolitis: a systematic review

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Bordley WC, Viswanathan M, King VJ, Sutton SF, Jackman AM, Sterling L, et al. Arch Pediatr Adolesc Med 2004;158:119-26

Context The diagnosis of bronchiolitis is based on typical history and results of a physical examination. The indications for and utility of diagnostic and supportive laboratory testing (eg, chest radiograph films, complete blood cell counts, and respiratory syncytial virus [RSV] testing) are unclear.

Objectives To review the data on diagnostic and supportive testing in the management of bronchiolitis and to assess the utility of such testing.

Design Systematic review of studies addressing diagnostic and supportive testing for bronchiolitis.

Main outcome measures Sensitivity and specificity of various diagnostic tests, and impact of these tests on clinical outcome.

Study identificationIn conjunction with an expert panel, the authors derived relevant terms to search the literature published from 1980 to November 2002 in MEDLINE and the Cochrane Collaboration Database of Controlled Clinical Trials.

Studies reviewed Of the 797 abstracts identified, 82 trials met the authors' inclusion criteria (17 are primary articles on diagnosis of bronchiolitis and 65 are reports of treatment or prevention trials).

Results Numerous studies demonstrate that rapid RSV tests have acceptable sensitivity and specificity, but no data show that RSV testing affects clinical outcomes in typical cases of the disease. Seventeen studies presented chest radiographic film data. Abnormalities on chest radiographs ranged from 20% to 96%. Insufficient data exist to show that chest radiographs reliably distinguish between viral and bacterial disease or predict severity of disease. Ten studies included complete blood cell counts, but most did not present specific results. In one study, white blood cell counts correlated with radiologically defined disease categories of bronchiolitis.

Conclusions A large number of studies include diagnostic and supportive testing data. However, these studies do not define clear indications for such testing or the impact of testing on relevant patient outcomes. Given the high prevalence of bronchiolitis, prospective studies of the utility of such testing are needed and feasible.

Comment Bronchiolitis is one of the most common childhood diseases and has been variably diagnosed over decades with differing sobriquets such as “infectious asthma,” “wheezy bronchitis,” and “infectious bronchitis.” Nevertheless, no gold standard exists for its diagnosis. With our current technologic advances, the diagnosis of this clinical entity has become increasingly laboratory-based, but not evidence-based, according to Bordley et al.

Over 12 years only 82 trials met the inclusion criteria for their review, and presumably there would have been fewer if they had limited the age to that usually applied to the diagnosis of bronchiolitis—the first two years of life. Of these studies, diagnosis was the primary focus of only 17, and none evaluated the usefulness of supportive testing in diagnosing bronchiolitis. The other 65 studies were primarily on treatment and prevention but contained some data on diagnosis and testing. The included populations, however, had differing or poorly defined inclusion criteria. Most required an etiologic diagnosis, but none asked or answered whether knowing RSV to be the cause affected the clinical outcome. Most focused on disease severity assessed by clinical scales, the reliability of which may be more dependent on the assessor than what is assessed. Bordley et al, recognizing these differences and deficits, concluded that the studies did not “define clear indications for such testing or for the impact of testing on relevant patient outcomes.“ This may be interpreted, though incorrectly in my opinion, as evidence against the use of supportive diagnostic testing. One may conclude that specific or supportive testing in managing bronchiolitis seems unlikely to be beneficial for most children, but may be warranted in individual circumstances, which currently are not able to be defined. Second, the best diagnostic method currently available is the “test of time,” performed by an experienced clinician. Third, this analysis substantiates the authors' suggestion that prospective trials of the value of such testing are needed. However, although they state that such studies are feasible, they do not define how to do them. The design, implementation, and funding of such a trial will I hope be the subject of a future publication from this group.