Background:

Influenza is a significant public health challenge, characterized by severe disease progression and considerable societal burden. Patients at high risk of influenza-related complications require special attention in routine clinical practice.

Objectives:

This study aimed to compare the effects of antiviral treatments for influenza on the incidence of bacterial complications, adverse events, and disease duration in high-risk outpatients.

Design:

Multicenter, non-interventional, observational cohort study.

Methods:

The study was conducted during the 2023–2024 influenza epidemic season and included 1867 high-risk outpatients treated with oseltamivir, umifenovir, kagocel, or imidazolyl ethanamide pentanedioic acid.

Results:

Bacterial complications occurred in 18.87% (n = 335) of high-risk patients, with 17.41% (n = 309) requiring antibacterial therapy. The hospitalization rate was 1.24% (n = 22), and the average disease duration was 8 days. The incidence of bacterial complications varied among treatment groups: oseltamivir (18.96%, n = 102), umifenovir (12.17%%, n = 51), kagocel (22.00%%, n = 110), and imidazolyl ethanamide pentanedioic acid (22.64%%, n = 72). Adverse events were reported in 4.76% (n = 84) of patients, most commonly gastrointestinal disorders (91.67%, n = 77), followed by allergic reactions (8.33%, n = 7). The incidence of adverse events was significantly higher in the oseltamivir group compared to other treatments.

Conclusion:

The etiotropic agents oseltamivir and umifenovir demonstrated comparable efficacy in managing influenza in high-risk patients, as reflected by their impact on bacterial complication rates and disease duration. Both drugs may be recommended for the treatment of high-risk influenza patients.

Plain language summary

Antiviral treatments for influenza in high-risk patients: comparing effectiveness and safety

Some individuals are at a higher risk of developing serious complications from influenza. The global scientific community is increasingly concerned about the limited effectiveness of vaccines and the growing resistance to antiviral medications. These challenges highlight the importance of finding new ways to prevent and treat influenza, as well as evaluating the effectiveness of existing antiviral drugs.

This study included approximately 2000 high-risk outpatients in Russia who were treated with one of four antiviral medications: oseltamivir, umifenovir, kagocel, or imidazolyl ethanamide pentanedioic acid. Among these patients, 19% developed bacterial complications, and 17% required antibiotics. The rate of bacterial complications varied between treatments, with oseltamivir having the highest rate and umifenovir the lowest.

Adverse effects were reported in about 5% of patients, most commonly gastrointestinal issues, while allergic reactions were less frequent. Side effects were more common in the oseltamivir group compared to the other treatments.

In conclusion, oseltamivir and umifenovir were found to be similarly effective in reducing influenza complications. These findings suggest that both drugs are suitable treatment options for patients at high risk of complications.

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Antiviral therapy for influenza in high-risk outpatients: a multicenter observational study of routine clinical practice in Russia