Evaluation and Treatment of the Patient with Acute Undifferentiated Respiratory Tract Infection

The term acute upper respiratory tract infection (ARTI) refers to an infection, almost always viral,¹ predominantly involving the nasopharynx, sinuses, and large bronchi. It encompasses what is frequently referred to as the common cold, sinusitis, pharyngitis, bronchitis, and otitis media. This review will focus primarily on the common cold, or undifferentiated ARTI, but there will be considerable overlap with the other diagnoses. The rationale for grouping these traditionally separate diagnostic categories together is straightforward. ARTI almost always presents with some combination of nasal congestion, rhinnorrhea, sore throat, and cough. Sometimes one or another of these symptoms predominates, but there is good reason to suggest that the traditional diagnostic distinctions are arbitrary.² The overlap between the clinical signs, symptoms, and x-ray findings is so extensive that these terms are not very useful diagnostically. This symptom complex is among the top 3 reasons for visits to primary care doctors³ and accounts for approximately 100 million office visits in the United States per year⁴ at an annual cost of considerably more than 1 billion dollars.⁵ Overuse of antibiotics adds more than $11 to the cost of each encounter for ARTI.⁵

This review will summarize the evidence that patients who present with undifferentiated ARTI usually have self-limited disease, that complications are rare, effective treatments for symptoms are available, and antibiotics are not often indicated. The evidence is based on only adults and children over age 2 who have normal immune systems and do not have chronic respiratory disease. (J Fam Pract; 50:1070-1077)

Pathophysiology

Patients with undifferentiated ARTI present with any or all of the following symptoms: rhinnorrhea (which may be either clear or colored), nasal congestion, cough, sore throat, facial pain, malaise, headache, or fever. The etiology is almost always viral, most commonly rhinovirus, but other viruses have been implicated as well, particularly corona-viruses, parainfluenza, and influenza.⁶ Bacterial infection is rare in undifferentiated ARTI, occurring in approximately 2% of patients.¹ The most common bacteria implicated are group A Streptococcus, Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis.⁷ Chlamydia pnuemoniae and Mycoplasma pnuemoniae have rarely been identified as well.⁶ Bordatella pertussis can occasionally be the cause of persistent cough in children and adults.^{8, 9}

Diagnosis

The major diagnostic consideration in a patient who presents with ARTI symptoms is to rule out a more serious illness which would require aggressive treatment. These include pneumonia, pharyngitis caused by group A streptococci, and bacterial sinusitis. The traditional symptoms and signs that physicians use to distinguish viral from bacterial infection have not been determined helpful in making this distinction. Both a history of colored nasal discharge and maxillary sinus tenderness to palpation have a positive likelihood ratio (LR+) near 1 in predicting computed tomography–based diagnosis of acute bacterial sinusitis (a likelihood ratio of 1 indicates that the result does not change the likelihood of disease).¹⁰ Purulent sputum does not distinguish between viral ARTI and bacterial pneumonia.¹¹ Combinations of symptoms, however, in the form of clinical decision rules, can be useful at ruling out more serious conditions.

Nasal Discharge

In patients who present primarily with nasal discharge, a study that correlated computed tomography (CT) scans with direct sinus puncture demonstrated that 90% of primary care patients with CT findings of total opacification or air fluid level in the maxillary sinuses have a bacterial etiology.¹² Unfortunately, there is no combination of clinical signs or symptoms that reliably predicts opacification or air fluid levels.¹² There have been 3 decision rules published based on clinical findings that may be useful, particularly in helping clinicians identify the most important symptoms on which they should focus during their examination. However, 2 of the rules require a sedimentation rate or C-reactive protein value,^10,12 not typically available in a routine office visit. The only other rule based on clinical findings included adult men and used x-ray as the reference standard, making it less useful.¹³

The suspicion of sinusitis by a generalist is actually quite accurate diagnostically, since about 40% of patients with suspected sinusitis have the diagnosis confirmed by aspiration or CT imaging.¹⁴ One must therefore be guided by overall clinical judgment in these patients, but a practical approach to empiric treatment is presented in the section on treatment.

Sore Throat

In patients who present primarily with sore throat, the important consideration is to rule out group A streptococcus as the etiology. The prevalence of streptococcal pharyngitis varies markedly with age, season of the year, and presence or absence of an outbreak in the community. For children prevalences have been reported ranging from 12% to 35%. Prevalence seems to peak in the 5 years to 9 years age range, and in the autumn. Reported prevalences for adults range from 5% to 15%.^15-20