A randomized study of standard versus double dose oseltamivir for treating influenza in the community

A cross-sectional study of participant recruitment rates in published phase III influenza therapeutic randomized controlled trials conducted in the clinical setting

OBJECTIVE

A recent academic-government partnership demonstrated the feasibility of utilizing Emergency Departments (ED) as a primary site for subject enrollment in clinical trials and achieved high rates of recruitment in two U.S. EDs. Given the ongoing need to test new therapeutics for influenza and other emerging infections, we sought to describe the historical rates of participant recruitment into influenza Phase III therapeutic RCTs in various clinical venues, including EDs.

STUDY DESIGN

A cross-sectional study was performed of influenza therapeutic Phase III RCTs published in PubMed, Embase, Scopus, and Clinicaltrials.gov from January 2000 to June 2019.

MAIN OUTCOME

To estimate the weighted-average number of influenza-positive participants enrolled per site per season in influenza therapeutic RCT conducted in clinical settings, and to describe basic trial site characteristics.

RESULTS

47 (0.7%) of 7008 articles were included for review of which 43 of 47 (91%) included information regarding enrollment sites; of these, 2 (5%) recruited exclusively from EDs with the remainder recruiting from mixed clinical settings (inpatient, outpatient, and ED). The median enrollment per study was 326 (IQR: 110, 502.5) with a median of 11 sites per study (IQR: 2, 59.5). Included studies reported a median of 201 (IQR: 74, 344.5) confirmed influenza-positive participants per study. The pooled number of participants enrolled per site per season was 11 (95% CI: 10, 12). The pooled enrollment numbers per clinical site after excluding the two 'ED only recruitment' studies were less [10.7 (95% CI: 9.9, 11.6)] than the pooled enrollment numbers per clinical site for the two 'ED only recruitment' studies [89.5 (95% CI 89.2-89.27)].

CONCLUSION AND RELEVANCE

Published RCTs evaluating influenza therapeutics in clinical settings recruit participants from multiple sites but enroll relatively few participants, per site, per season. The few ED-based studies reported recruited more subjects per site per season. Untapped opportunities likely exist for EDs to participate and/or lead therapeutic RCTs for influenza or other emerging respiratory pathogens.

Detection of H275Y Mutation Conferring Oseltamivir Drug Resistance in Influenza A (H1N1) pdm09 Virus

In the treatment of influenza, Neuraminidase inhibitors (NAIs) (Oseltamivir and Zanamivir) play a major role. The emergence of variants of influenza A (H1N1) pdm09 virus resistant to Oseltamivir is a matter of great concern as it limits its usage. Therefore, vigilant monitoring for Oseltamivir-resistant viruses has been recommended by the World Health Organization (WHO). Our study aimed to screen the influenza A (H1N1) pdm09 virus for NAI drug resistance during the outbreak of 2015-16 in North-Western India. A total of 640 H1N1pdm09 virus-positive samples were screened for drug resistance to Oseltamivir by WHO allelic discrimination real-time RT-PCR protocol. The allelic discrimination PCR protocol can detect the presence of single nucleotide polymorphisms (SNPs), the H275Y mutation is detected by this method which causes resistance to Oseltamivir. Sanger sequencing of partial fragment of NA gene (fragment IV), of 90 samples were performed to confirm the presence of NA-H275Y mutation. Neuraminidase susceptibility of 20 randomly selected isolates to Oseltamivir was tested using NA inhibition chemiluminiscence based assay. Among 640 H1N1pdm09 positive samples tested, H275Y mutation was detected in one sample (0.15%) by PCR and confirmed by Sanger sequencing also. All the 20 isolates tested for NAI susceptibility by NA star assay were found to be sensitive to Oseltamivir. WHO allelic discrimination PCR is an easy, rapid and sensitive method for high-throughput detection of resistance to Oseltamivir. Systematic regular drug resistance surveillance of Influenza A is essential to monitor the emergence and spread of drug-resistant strains.

Comparison of double-dose vs standard-dose oseltamivir in the treatment of influenza: A systematic review and meta-analysis

WHAT IS KNOWN AND OBJECTIVE

The effect of double-dose oseltamivir on mortality in patients with influenza remains controversial. We systematically reviewed the literature to investigate whether double-dose oseltamivir influences mortality in patients with influenza.

METHODS

PubMed, Excerpta Medica Database (Embase) and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for randomized controlled trials (RCTs) and observational studies regarding the effect of double-dose oseltamivir on mortality in patients with influenza. The primary outcome was all-cause mortality. The Mantel-Haenszel method with random effects model was used to calculate pooled odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS AND DISCUSSION

Ten studies (four RCTs and six observational studies), involving 20 947 patients, were included. Pooled analysis suggested that double-dose oseltamivir was not associated with decreased mortality in patients with influenza, both in RCTs (OR, 1.29; 95% CI, 0.52-3.15; P = .58) and observational studies (OR, 1.59; 95% CI, 0.79-3.19; P = .20; I²  = 51%). Double-dose oseltamivir did not show statistical benefit on the virologic clearance rate (OR, 1.26; 95% CI, 0.85-1.88; P = .25; I²  = 0%) or the incidence of adverse events (AEs) (OR, 1.52; 95% CI, 0.85-2.72; P = .15; I²  = 59%).

WHAT IS NEW AND CONCLUSION

Current evidence indicates that double-dose oseltamivir does not decrease mortality or have advantages on the outcome of virologic clearance rate and incidence of AEs. However, the finding largely relied on the data from observational studies, which may potentially have led to selection bias. Therefore, high-quality and adequately powered RCTs are warranted.

Influenza and antiviral resistance: an overview

Influenza affects approximately 1 billion individuals each year resulting in between 290,000 and 650,000 deaths. Young children and immunocompromised individuals are at a particularly high risk of severe illness attributable to influenza and these are also the groups of individuals in which reduced susceptibility to neuraminidase inhibitors is most frequently seen. High levels of resistance emerged with previous adamantane therapy for influenza A and despite no longer being used to treat influenza and therefore lack of selection pressure, high levels of adamantane resistance continue to persist in currently circulating influenza A strains. Resistance to neuraminidase inhibitors has remained at low levels to date and the majority of resistance is seen in influenza A H1N1 pdm09 infected immunocompromised individuals receiving oseltamivir but is also seen less frequently with influenza A H3N2 and B. Rarely, resistance is also seen in the immunocompetent. There is evidence to suggest that these resistant strains (particularly H1N1 pdm09) are able to maintain their replicative fitness and transmissibility, although there is no clear evidence that being infected with a resistant strain is associated with a worse clinical outcome. Should neuraminidase inhibitor resistance become more problematic in the future, there are a small number of  alternative novel agents within the anti-influenza armoury with different mechanisms of action to neuraminidase inhibitors and therefore potentially effective against neuraminidase inhibitor resistant strains. Limited data from use of novel agents such as baloxavir marboxil and favipiravir, does however show that resistance variants can also emerge in the presence of these drugs.

Influenza A-associated severe pneumonia in hospitalized patients: Risk factors and NAI treatments

OBJECTIVE

The risk factors and the impact of NAI treatments in patients with severe influenza A-associated pneumonia remain unclear.

METHODS

A multicenter, retrospective, observational study was conducted in Zhejiang, China during a severe influenza epidemic in August 2017-May 2018. Clinical records of patients (>14 y) hospitalized with laboratory-confirmed influenza A virus infection and who developed severe pneumonia were compared to those with mild-to-moderate pneumonia. Risk factors related to pneumonia severity and effects of NAI treatments (monotherapy and combination of peramivir and oseltamivir) were analyzed.

RESULTS

202 patients with influenza A-associated severe pneumonia were enrolled, of whom 84 (41.6%) had died. Male gender (OR = 1.782; 95% CI: 1.089-2.917; P = 0.022), chronic pulmonary disease (OR = 2.581; 95% CI: 1.447-4.603; P = 0.001) and diabetes mellitus (OR = 2.042; 95% CI: 1.135-3.673; P = 0.017) were risk factors related to influenza A pneumonia severity. In cox proportional hazards model, severe pneumonia patients treated with double dose oseltamivir (300mg/d) had a better survival rate compared to those receiving a single dose (150 mg/d) (HR = 0.475; 95%CI: 0.254-0.887; P = 0.019). However, different doses of peramivir (300 mg/d vs. 600 mg/d) and combination therapy (oseltamivir-peramivir vs. monotherapy) showed no differences in 60-day mortality (P = 0.392 and P = 0.658, respectively).

CONCLUSIONS

Patients with male gender, chronic pulmonary disease, or diabetes mellitus were at high risk of developing severe pneumonia after influenza A infection. Double dose oseltamivir might be considered in treating influenza A-associated severe pneumonia.

Safety, Resistance, and Efficacy Results from a Phase IIIb Study of Conventional- and Double-Dose Oseltamivir Regimens for Treatment of Influenza in Immunocompromised Patients

INTRODUCTION

Immunocompromised patients infected with influenza exhibit prolonged viral shedding and higher risk of resistance. Optimized treatment strategies are needed to reduce the risk of antiviral resistance. This phase IIIb, randomized, double-blind study (NCT00545532) evaluated conventional-dose or double-dose oseltamivir for the treatment of influenza in immunocompromised patients.

METHODS

Patients with primary or secondary immunodeficiency and influenza infection were randomized 1:1 to receive conventional-dose oseltamivir (75 mg adolescents/adults [≥ 13 years]; 30-75 mg by body weight in children [1-12 years]) or double-dose oseltamivir (150 or 60-150 mg, respectively), twice daily for an extended period of 10 days. Nasal/throat swabs were taken for virology assessments at all study visits. Co-primary endpoints were safety/tolerability and viral resistance. Secondary endpoints included time to symptom alleviation (TTSA) and time to cessation of viral shedding (TTCVS).

RESULTS

Of 228 patients enrolled between February 2008 and May 2017, 215 (199 adults) were evaluable for safety, 167 (151 adults) for efficacy, and 152 (138 adults) for resistance. Fewer patients experienced an adverse event (AE) in the conventional-dose group (50.5%) versus the double-dose group (59.1%). The most frequently reported AEs were nausea, diarrhea, vomiting, and headache. Fifteen patients had post-baseline resistance, more commonly in the conventional-dose group (n  = 12) than in the double-dose group (n  = 3). In adults, median TTSA was similar between arms, while median TTCVS was longer with conventional dosing.

CONCLUSIONS

Oseltamivir was well tolerated, with a trend toward better safety/tolerability for conventional dosing versus double dosing. Resistance rates were higher with conventional dosing in this immunocompromised patient population.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00545532.

FUNDING

F. Hoffmann-La Roche Ltd.

Influenza virus-related critical illness: prevention, diagnosis, treatment

Annual seasonal influenza epidemics of variable severity result in significant morbidity and mortality in the United States (U.S.) and worldwide. In temperate climate countries, including the U.S., influenza activity peaks during the winter months. Annual influenza vaccination is recommended for all persons in the U.S. aged 6 months and older, and among those at increased risk for influenza-related complications in other parts of the world (e.g. young children, elderly). Observational studies have reported effectiveness of influenza vaccination to reduce the risks of severe disease requiring hospitalization, intensive care unit admission, and death. A diagnosis of influenza should be considered in critically ill patients admitted with complications such as exacerbation of underlying chronic comorbidities, community-acquired pneumonia, and respiratory failure during influenza season. Molecular tests are recommended for influenza testing of respiratory specimens in hospitalized patients. Antigen detection assays are not recommended in critically ill patients because of lower sensitivity; negative results of these tests should not be used to make clinical decisions, and respiratory specimens should be tested for influenza by molecular assays. Because critically ill patients with lower respiratory tract disease may have cleared influenza virus in the upper respiratory tract, but have prolonged influenza viral replication in the lower respiratory tract, an endotracheal aspirate (preferentially) or bronchoalveolar lavage fluid specimen (if collected for other diagnostic purposes) should be tested by molecular assay for detection of influenza viruses.Observational studies have reported that antiviral treatment of critically ill adult influenza patients with a neuraminidase inhibitor is associated with survival benefit. Since earlier initiation of antiviral treatment is associated with the greatest clinical benefit, standard-dose oseltamivir (75 mg twice daily in adults) for enteric administration is recommended as soon as possible as it is well absorbed in critically ill patients. Based upon observational data that suggest harms, adjunctive corticosteroid treatment is currently not recommended for children or adults hospitalized with influenza, including critically ill patients, unless clinically indicated for another reason, such as treatment of asthma or COPD exacerbation, or septic shock. A number of pharmaceutical agents are in development for treatment of severe influenza.

Influenza virus-related critical illness: prevention, diagnosis, treatment

Annual seasonal influenza epidemics of variable severity result in significant morbidity and mortality in the United States (U.S.) and worldwide. In temperate climate countries, including the U.S., influenza activity peaks during the winter months. Annual influenza vaccination is recommended for all persons in the U.S. aged 6 months and older, and among those at increased risk for influenza-related complications in other parts of the world (e.g. young children, elderly). Observational studies have reported effectiveness of influenza vaccination to reduce the risks of severe disease requiring hospitalization, intensive care unit admission, and death. A diagnosis of influenza should be considered in critically ill patients admitted with complications such as exacerbation of underlying chronic comorbidities, community-acquired pneumonia, and respiratory failure during influenza season. Molecular tests are recommended for influenza testing of respiratory specimens in hospitalized patients. Antigen detection assays are not recommended in critically ill patients because of lower sensitivity; negative results of these tests should not be used to make clinical decisions, and respiratory specimens should be tested for influenza by molecular assays. Because critically ill patients with lower respiratory tract disease may have cleared influenza virus in the upper respiratory tract, but have prolonged influenza viral replication in the lower respiratory tract, an endotracheal aspirate (preferentially) or bronchoalveolar lavage fluid specimen (if collected for other diagnostic purposes) should be tested by molecular assay for detection of influenza viruses.Observational studies have reported that antiviral treatment of critically ill adult influenza patients with a neuraminidase inhibitor is associated with survival benefit. Since earlier initiation of antiviral treatment is associated with the greatest clinical benefit, standard-dose oseltamivir (75 mg twice daily in adults) for enteric administration is recommended as soon as possible as it is well absorbed in critically ill patients. Based upon observational data that suggest harms, adjunctive corticosteroid treatment is currently not recommended for children or adults hospitalized with influenza, including critically ill patients, unless clinically indicated for another reason, such as treatment of asthma or COPD exacerbation, or septic shock. A number of pharmaceutical agents are in development for treatment of severe influenza.

Use of antiviral drugs for seasonal influenza: Foundation document for practitioners-Update 2019

This document updates the previous AMMI Canada Foundation Guidance (2013) on the use of antiviral therapy for influenza.

Post-transplant Viral Respiratory Infections in the Older Patient: Epidemiology, Diagnosis, and Management

Organ and stem cell transplantation has been one of the greatest advances in modern medicine, and is the primary treatment modality for many end-stage diseases. As our population ages, so do the transplant recipients, and with that comes many new challenges. Respiratory viruses have been a large contributor to the mortality and morbidity of solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients. Respiratory viruses are generally a long-term complication of transplantation and primarily acquired in the community. With the emergence of molecular methods, newer respiratory viruses are being detected. Respiratory viruses appear to cause severe disease in the older transplant population. Influenza vaccine remains the mainstay of prevention in transplant recipients, although immunogenicity of current vaccines is suboptimal. Limited therapies are available for other respiratory viruses. The next decade will likely bring newer antivirals and vaccines to the forefront. Our goal is to provide the most up to date knowledge of respiratory viral infections in our aging transplant population.