BACKGROUND: Considerable overlap exists in patient presentations and physical findings in viral upper respiratory tract infections (URIs) and acute bronchitis. Our goal was to determine whether there are any clinical cues that could help physicians differentiate between these 2 conditions.
METHODS: We performed a retrospective chart audit on 135 patients who had been given a diagnosis of acute bronchitis and a random sample of 409 patients with URIs over a 2.5-year period. Patient and provider characteristics, patient symptoms, and physical findings were compared with bivariate analyses and then entered into a logistic regression model.
RESULTS: In bivariate analyses, a number of demographic variables, symptoms, and signs were associated with acute bronchitis. Multivariate analysis showed that the strongest independent predictors of acute bronchitis were cough (adjusted odds ratio [AOR]=21.12; 95% confidence interval [CI], 6.01-74.26), and wheezing on examination (AOR=12.16; 95% CI, 5.39-27.42). Nausea was the strongest independent predictor that the diagnosis would not be acute bronchitis (AOR=0.01; 95% CI, 0.01-0.85). However, there was considerable overlap between the 2 conditions, and the logistic model explained only 37% of the variation between the diagnoses.
CONCLUSIONS: We hypothesize that sinusitis, URI, and acute bronchitis are all variations of the same clinical condition (acute respiratory infection) and should be conceptualized as a single clinical entity, with primary symptoms related to different anatomic areas rather than as different conditions.
Acute bronchitis and upper respiratory infections (URIs) represent 2 of the most common diagnoses made by primary care physicians.1,2 It is frequently difficult for clinicians to differentiate between these conditions, since a considerable amount of overlap exists. This confusion is similar to our previous findings that URIs and sinusitis are very similar in their clinical presentation.3
As we observed with sinusitis, it is possible that the diagnosis of acute bronchitis is made primarily to justify treatment decisions. A study of children suggests that the diagnosis of bronchitis may depend on a physician’s desire to justify antibiotic treatment.4 Although antibiotics are of only minimal benefit at best to bronchitis patients,5-7 data from a variety of studies demonstrate that physicians prescribe antibiotics for bronchitis at much higher rates than for URIs.8,9
Four previous studies have provided some indication of clinicians’ opinions about what signs and symptoms constitute acute bronchitis. However, those studies reveal divergent opinions among primary care physicians. For example, in a survey of family physicians concerning what criteria was used to make the diagnosis of acute bronchitis, Oeffinger and colleagues10 found that 58% of physicians made the diagnosis of acute bronchitis only if the patient had a productive cough; 39%, however, stated that whether the cough was productive did not influence their diagnosis. A similar survey of physicians in the Netherlands suggested that clinicians did not rely on any specific sign or symptom but instead relied on the total number of symptoms to define acute bronchitis.11 This implies that the conditions may not be different and that acute bronchitis may really be a “bad cold.” Our work suggests that most physicians diagnosed simulated cases as acute bronchitis and treated them with antibiotics if the sputum had some discoloration,12 a finding that represents inflammation and is not predictive of antibiotic response.13 A previous study that examined clinicians’ reports from patient encounters suggested that patients thought to have acute bronchitis were more likely to have a productive cough, purulent sputum, and abnormal findings on lung examination.14 However, the study had fewer than 50 patients (29 with bronchitis and 19 with upper respiratory tract infection) and was completed before much of the information on the lack of benefit from antibiotics was reported.
The purpose of our study was to explore whether any clinical signs and symptoms predict the diagnosis of acute bronchitis rather than URI. We hypothesized that these 2 conditions would have few clinical differences and that the patients with acute bronchitis would differ from those with URI primarily on the basis of treatments rendered rather than clinical presentation. This would support the hypothesis that acute bronchitis and the common cold constitute the same clinical condition, differing only in the severity of cough and the desire for a condition amenable to treatment.
Methods
We selected subjects for this study from the population of patients who presented for care at the Department of Family Medicine at the Medical University of South Carolina. Two clinical sites for the department serve approximately 48,000 ambulatory patient encounters each year. The Department of Family Medicine uses family practice residents, physician faculty, nurse practitioners, and physician assistants to provide patient care. The design of the study was a case-control model with acute bronchitis patients representing cases and URI patients serving as control subjects.