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

A recent systematic review noted nine published decision rules for diagnosis of streptococcal pharyngitis,²¹ but the only one that has been prospectively validated in a primary care population of both children and adults is by McIssac^22,23Table 1. Patients with a low risk of GABHS require no further testing; those with an intermediate risk should undergo rapid strep antigen testing; and those with a high risk of GABHS should either under rapid strep antigen testing with culture follow-up or empiric therapy. Culture for group A streptococcus is the most reliable means of diagnosis, but requires withholding treatment for 48 hours while awaiting the result.²⁴

Infectious mononucleosis can also cause exudative pharyngitis. Palatine petechiae, posterior auricular and posterior cervical adenopathy, marked axillary adenopathy, and inguinal adenopathy are all associated with infectious mononucleosis,²⁵ and if any of these signs are present a heterophile antibody test may be indicated to confirm the diagnosis.

Cough

Many patients with ARTI present with cough as a primary symptom. While the differential diagnosis for undifferentiated cough is long, in the setting of ARTI the primary diagnostic consideration is to rule out pneumonia. Decision rules by Heckerling¹¹ and Diehr²⁶ have been well validated Table 2, Table 3. If the patient does not have temperature higher than 100 ÞF, pulse rate higher than 100, rales, decreased breath sounds, or absence of wheezing, then pneumonia is very unlikely (negative likelihood ratio = 0.06). As the number of signs increases, the likelihood ratio increases, but the decision rule does not have sufficient positive predictive value to be used as a basis for antibiotic treatment. Purulent sputum is not predictive of pneumonia (LR+=1.3).^11,27 Empiric antibiotics for pneumonia should not be given without a confirmatory chest x-ray.¹

Treatment

Undifferentiated ARTI

The level of evidence supporting different interventions is summarized in Table 4, and each is discussed in more detail below.

Antibiotics. There have been numerous double blind placebo controlled randomized trials of antibiotics in patients with undifferentiated ARTI symptoms. All of these trials have been evaluated in a recent Cochrane systematic review.²⁸ The review concludes that there is no consistent evidence of benefit from any antibiotic treatment and that there is a significant increase in adverse effects associated with antibiotic use. Increased cost and increased bacterial resistance in the patient and community are additional concerns.

Education. One of the reasons for inappropriate antibiotic use in ARTI is patient pressure for antibiotics. This can be subtle as well as direct and is difficult for physicians to resist.²⁹ Several studies have shown that patient expectation for antibiotics is related to having been given antibiotics for respiratory infections in the past.^30-32 Furthermore, McFarlane has shown that simple patient education techniques reduce both visits for ARTI and antibiotic usage.³³ An essential part of treatment of these infections, therefore, is educating patients about the viral nature of the illness, the usual course and duration of symptoms (10 days for most, up to 3 weeks for some), the ineffectiveness of antibiotics for treatment, and the harm antibiotics can cause both to the patient and the community. Patient satisfaction has been shown to increase after this sort of intervention, even when patients initially had an expectation for antibiotic prescription.^30,34 Some have advocated avoiding terms such as sinusitis and bronchitis with patients, instead using the terms head cold and chest cold to emphasize the viral nature of these illnesses.

Naproxen Sodium. Naproxen sodium was evaluated in a well-designed randomized placebo controlled trial using experimentally induced rhinovirus infections in volunteers.³⁵ A statistically significant 29% reduction in total 5-day symptom scores was found. Specific symptoms that improved included sneezing, rhinnorrhea, nasal obstruction, sore throat, cough, headache, malaise and chilliness.

Vitamin C. A Cochrane Library meta-analysis of all the trials for ascorbic acid showed a small but significant effect on decreasing duration (.55 days per episode) and a modest effect on severity of symptoms.³⁶ There was no evidence for an effect when taken prophylactically.

Zinc. Randomized trials of zinc have shown marked heterogeneity, but this may have been due to use of different preparations with different bioavailability.³⁷ A more recent randomized trial used zinc acetate lozenges.³⁸ Increased plasma zinc levels were documented in the treatment group. The lozenges contained 42.96 mg of zinc acetate dihydrate, and were administered every 2 to 3 hours, beginning 24 hours or less after the onset of symptoms. The treatment group had a reduction from 8.1 to 4.5 days in total duration of symptoms (number needed to treat [NNT] =3 at 5 days) and a 50% reduction in symptom scores compared to the placebo group. Symptoms included in the score were sore throat, nasal discharge, nasal congestion, sneezing, cough, scratchy throat, hoarseness, muscle ache, fever, and headache.