CHARLESTON, SC-- Differentiating acute bronchitis from viral upper respiratory tract infection (URI) can be a challenge because the symptoms and signs of the two conditions are similar. A new investigation suggests that acute bronchitis and URI may, in fact, be different manifestations of a single clinical syndrome.[1]

"This study sought to determine what characteristics of patients with acute bronchitis distinguished them from people with colds," lead author William J. Hueston, MD, explained in a recent interview with PULMONARY REVIEWS. "When we found no clear differences, we began to wonder if they really are different," added Dr. Hueston, Professor and Chairman of the Department of Family Medicine at the Medical University of South Carolina, in Charleston.

Dr. Hueston and colleagues carried out a retrospective chart audit on 135 patients who had been diagnosed with acute bronchitis and 409 patients diagnosed with URI. All patients had presented for treatment between June 1996 and December 1998.

Clinical findings were found to be poor predictors of which diagnosis a patient was given. Although cough was more common in bronchitis patients, it was present in most URI patients as well. Chest pain, shortness of breath, and a history of wheezing were associated more often with bronchitis than with URI, but each symptom was seen in only 8% to 12% of bronchitis patients. Symptoms that were more specific to URI included sore throat and runny nose, yet neither symptom was present in most URI patients.

Physical findings were no better in pinpointing a diagnosis. An erythematous throat was found in about half the URI patients, but also in a quarter of the bronchitis patients. Chest wheezing was more common in bronchitis patients, and nasal erythema in URI patients, but neither sign was present in more than 30% of either group.

None of the physical findings, alone or in combination, could clearly distinguish between the two disorders. For example, the sensitivity of cough for acute bronchitis was 98%, but its specificity was only 29%. When the authors performed logistic modeling, they found that physical findings explained only 37% of the difference between the two diagnoses.

Dr. Hueston and his colleagues therefore investigated other factors that might be involved in selecting a diagnosis, and they discovered that the level of physician training influenced the decision. Only 19% of the patients examined by residents were given a diagnosis of acute bronchitis, compared with 33% of those seen by attending physicians.

TREATMENT DECISIONS

The authors also studied whether clinicians were using a diagnosis to influence treatment decisions. They found that the acute bronchitis patients were eight times more likely to receive bronchodilators than was the URI group and six times more likely to receive antibiotics. URI patients were twice as likely to receive decongestants.

Dr. Hueston observed that even though there is limited evidence that antibiotics are of any benefit, physicians often prescribe them for acute bronchitis. He added that "if acute bronchitis is reconceptualized as a cold in the chest, then the treatment should be the same as for a cold anywhere else. We don't prescribe antibiotics for runny noses or viral sore throats, and we should not prescribe them for viral chest colds."

--Stanley Nelson

Reference
1. Hueston WJ, Mainous AG III, Dacus EN, Hopper JE. Does acute bronchitis really exist? A reconceptualization of acute viral respiratory infections. J Fam Pract. 2000;49:401-406.