What is the number needed to treat (NNT) for azithromycin (Zithromax) in upper respiratory infection (URI)?

From the Guidelines

The number needed to treat (NNT) for azithromycin in upper respiratory infections (URIs) is likely to be very high, possibly 18 or more, indicating limited effectiveness. Antibiotics, including azithromycin, are generally not recommended for most URIs as they are typically viral in nature. For the majority of URI cases, symptomatic treatment and supportive care are the mainstays of management. If an antibiotic is deemed necessary due to suspected bacterial infection, azithromycin is not usually the first choice due to concerns about antibiotic resistance. When prescribed, a typical adult dose is 500 mg once daily for 3 days or 500 mg on day 1, followed by 250 mg daily for 4 days. However, clinicians should carefully consider the necessity of antibiotic treatment for URIs, as the risks (including side effects and contribution to antibiotic resistance) often outweigh the benefits in most cases. The high NNT reflects the fact that many patients would need to be treated with azithromycin for one to benefit, underscoring the importance of judicious antibiotic use in URIs, as suggested by studies such as 1 and 1.

Key Points to Consider

• The majority of URIs are viral in nature and do not require antibiotic treatment.
• Azithromycin is not typically the first choice for antibiotic treatment in URIs due to concerns about antibiotic resistance.
• Symptomatic treatment and supportive care are the mainstays of management for most URI cases.
• Clinicians should carefully consider the necessity of antibiotic treatment for URIs, weighing the potential benefits against the risks of side effects and contribution to antibiotic resistance.
• A meta-analysis of adults with acute rhinosinusitis showed that the number needed to treat was 18 for 1 patient to be cured rapidly, but the number needed to harm from adverse effects from antibiotics was 8, as noted in 1 and 1.

Management Strategies

• Reserve antibiotic treatment for patients with persistent symptoms or signs of severe infection.
• Use supportive care, such as analgesics and antipyretics, to manage symptoms.
• Consider adjunctive therapies, such as intranasal saline irrigation or intranasal corticosteroids, to alleviate symptoms and potentially decrease antibiotic use, as suggested by 1 and 1.

Conclusion is not allowed, so the response ends here.

From the Research

Number Needed to Treat (NNT) for Azithromycin in Upper Respiratory Infection (URI)

• The NNT for azithromycin in URI is not directly stated in the provided studies 2, 3, 4, 5, 6.
• However, study 5 reports that with 5 days of azithromycin therapy, significant reduction in proportion of patients reporting URTI symptoms and signs was noted, with 95.8% of patients reporting sore throat at baseline and 10.4% at day 5.
• Study 6 reports clinical cure rates in azithromycin-treated subjects with CARTI caused by azithromycin-susceptible or azithromycin-resistant Streptococcus pneumoniae, with an overall clinical cure rate of 86.2% (324/376) 6.
• To estimate the NNT, more information on the control group and the specific outcome measures would be needed, which is not provided in the given studies 2, 3, 4, 5, 6.

Clinical Cure Rates and Azithromycin Resistance

• Study 6 reports that clinical cure rates in CARTI subjects treated with azithromycin were higher for azithromycin-susceptible SPN (89.4%) versus azithromycin-resistant SPN (78.6%; P = 0.003) 6.
• The same study found that at the observed prevalence of azithromycin-resistant SPN of 28.9%, an additional 3.1 clinical failures would be predicted, as a consequence of azithromycin resistance, per 100 subjects treated empirically with azithromycin 6.

Azithromycin Efficacy in Upper Respiratory Tract Infections

• Study 3 reports that a 3-day oral regimen of once-daily azithromycin has been shown to be as effective as 5- to 10-day courses of other more frequently administered antibacterial agents in patients with acute exacerbations of chronic bronchitis, pneumonia, sinusitis, pharyngitis, tonsillitis, and otitis media 3.
• Study 4 found that a 3-day azithromycin regimen produces a satisfactory clinical response and the eradication of key pathogens, and was acceptable for children with otitis media 4.
• Study 5 demonstrates that azithromycin shows significant improvement in clinical manifestations of URTIs, with a low incidence of adverse events 5.