Effects of oseltamivir on influenza-related complications in children with chronic medical conditions

Influenza in Children and Adolescents: Epidemiology, Management, and Prevention

EDUCATION GAP

Influenza is among the most common infectious causes of pediatric emergency department visits and hospitalizations. Clinicians should use evidence-based guidelines to learn how to identify, manage, prevent, and treat influenza cases. Disease caused by influenza virus can be mitigated with appropriate treatment and prevention efforts.

OBJECTIVES After completing this article, readers should be able to:

1. Describe the virology and epidemiology of influenza.

2. List the clinical features and complications of influenza infections.

3. List the benefits and limitations of testing modalities for the diagnosis of influenza.

4. Appropriately apply American Academy of Pediatrics, Infectious Diseases Society of America, and Centers for Disease Control and Prevention (CDC) treatment guidelines for influenza or suspected influenza.

5. Describe the importance of influenza vaccination.

Guideline-Concordant Antiviral Treatment in Children at High Risk for Influenza Complications

BACKGROUND

National guidelines recommend antiviral treatment for children with influenza at high risk for complications regardless of symptom duration. Little is known about concordance of clinical practice with this recommendation.

METHODS

We performed a cross-sectional study of outpatient children (aged 1-18 years) at high risk for complications who were diagnosed with influenza during the 2016-2019 influenza seasons. High-risk status was determined using an existing definition that includes age, comorbidities, and residence in a long-term care facility. The primary outcome was influenza antiviral dispensing within 2 days of influenza diagnosis. We determined patient- and provider-level factors associated with guideline-concordant treatment using multivariable logistic regression.

RESULTS

Of the 274 213 children with influenza at high risk for influenza complications, 159 350 (58.1%) received antiviral treatment. Antiviral treatment was associated with the presence of asthma (aOR, 1.13; 95% confidence interval [CI], 1.11-1.16), immunosuppression (aOR, 1.10; 95% CI, 1.05-1.16), complex chronic conditions (aOR, 1.04; 95% CI, 1.01-1.07), and index encounter in the urgent care setting (aOR, 1.3; 95% CI, 1.26-1.34). Factors associated with decreased odds of antiviral treatment include age 2-5 years compared with 6-17 years (aOR, 0.95; 95% CI, .93-.97), residing in a chronic care facility (aOR, .61; 95% CI, .46-.81), and index encounter in an emergency department (aOR, 0.66; 95% CI, .63-.71).

CONCLUSIONS

Among children with influenza at high risk for complications, 42% did not receive guideline-concordant antiviral treatment. Further study is needed to elucidate barriers to appropriate use of antivirals in this vulnerable population.

Platelet Abnormalities in Children with Laboratory-Confirmed Influenza

BACKGROUND

The role of platelets in the immune response against influenza has been raised, and a diagnostic or prognostic value of platelet parameter abnormalities, including platelet count (PLT), or mean platelet volume (MPV), has been suggested. The study aimed to analyze the prognostic value of platelet parameters in children hospitalized due to laboratory-confirmed influenza.

METHODS

We retrospectively verified the platelet parameters (PLT, MPV, MPV/PLT, and PLT/lymphocyte ratio regarding the influenza complications (acute otitis media, pneumonia, and lower respiratory tract infection-LRTI), and the clinical course (antibiotic treatment, tertiary care transfer, and death).

RESULTS

An abnormal PLT was observed in 84 out of 489 laboratory-confirmed cases (17.2%, 44 thrombocytopaenia cases, and 40 thrombocytoses). Patients' age correlated negatively with PLT (rho = -0.46) and positively with MPV/PLT (rho = 0.44), while MPV was not age-dependent. The abnormal PLT correlated with increased odds of complications (OR = 1.67), including LRTI (OR = 1.89). Thrombocytosis was related to increased odds of LRTI (OR = 3.64), and radiologically/ultrasound-confirmed pneumonia (OR = 2.15), mostly in children aged under 1 year (OR = 4.22 and OR = 3.79, respectively). Thrombocytopaenia was related to antibiotic use (OR = 2.41) and longer hospital stays (OR = 3.03). A lowered MPV predicted a tertiary care transfer (AUC = 0.77), while MPV/PLT was the most versatile parameter in predicting LRTI (AUC = 0.7 in <1 yo), pneumonia (AUC = 0.68 in <1 yo), and antibiotic treatment (AUC = 0.66 in 1-2 yo and AUC = 0.6 in 2-5 yo).

CONCLUSIONS

Platelet parameters, including PLT count abnormalities and MPV/PLT ratio, are related to the increased odds of complications and a more severe disease course, and may add important data in assessing pediatric influenza patients, but should be interpreted cautiously due to age-related specificities.

Evaluating Confounding Control in Estimations of Influenza Antiviral Effectiveness in Electronic Health Plan Data

Observational studies of oseltamivir use and influenza complications could suffer from residual confounding. Using negative control risk periods and a negative control outcome, we examined confounding control in a health-insurance-claims-based study of oseltamivir and influenza complications (pneumonia, all-cause hospitalization, and dispensing of an antibiotic). Within the Food and Drug Administration's Sentinel System, we identified individuals aged ≥18 years who initiated oseltamivir use on the influenza diagnosis date versus those who did not, during 3 influenza seasons (2014-2017). We evaluated primary outcomes within the following 1-30 days (the primary risk period) and 61-90 days (the negative control period) and nonvertebral fractures (the negative control outcome) within days 1-30. We estimated propensity-score-matched risk ratios (RRs) per season. During the 2014-2015 influenza season, oseltamivir use was associated with a reduction in the risk of pneumonia (RR = 0.72, 95% confidence interval (CI): 0.70, 0.75) and all-cause hospitalization (RR = 0.54, 95% CI: 0.53, 0.55) in days 1-30. During days 61-90, estimates were near-null for pneumonia (RR = 1.04, 95% CI: 0.95, 1.15) and hospitalization (RR = 0.94, 95% CI: 0.91, 0.98) but slightly increased for antibiotic dispensing (RR = 1.14, 95% CI: 1.08, 1.21). The RR for fractures was near-null (RR = 1.09, 95% CI: 0.99, 1.20). Estimates for the 2016-2017 influenza season were comparable, while the 2015-2016 season had conflicting results. Our study suggests minimal residual confounding for specific outcomes, but results differed by season.

Optimizing antiviral treatment for seasonal influenza in the USA: a mathematical modeling analysis

BACKGROUND

Seasonal influenza remains a major cause of morbidity and mortality in the USA. Despite the US Centers for Disease Control and Prevention recommendation promoting the early antiviral treatment of high-risk patients, treatment coverage remains low.

METHODS

To evaluate the population-level impact of increasing antiviral treatment timeliness and coverage among high-risk patients in the USA, we developed an influenza transmission model that incorporates data on infectious viral load, social contact, and healthcare-seeking behavior. We modeled the reduction in transmissibility in treated individuals based on their reduced daily viral load. The reduction in hospitalizations following treatment was based on estimates from clinical trials. We calibrated the model to weekly influenza data from Texas, California, Connecticut, and Virginia between 2014 and 2019. We considered in the baseline scenario that 2.7-4.8% are treated within 48 h of symptom onset while an additional 7.3-12.8% are treated after 48 h of symptom onset. We evaluated the impact of improving the timeliness and uptake of antiviral treatment on influenza cases and hospitalizations.

RESULTS

Model projections suggest that treating high-risk individuals as early as 48 h after symptom onset while maintaining the current treatment coverage level would avert 2.9-4.5% of all symptomatic cases and 5.5-7.1% of all hospitalizations. Geographic variability in the effectiveness of earlier treatment arises primarily from variabilities in vaccination coverage and population demographics. Regardless of these variabilities, we found that when 20% of the high-risk individuals were treated within 48 h, the reduction in hospitalizations doubled. We found that treatment of the elderly population (> 65 years old) had the highest impact on reducing hospitalizations, whereas treating high-risk individuals aged 5-19 years old had the highest impact on reducing transmission. Furthermore, the population-level benefit per treated individual is enhanced under conditions of high vaccination coverage and a low attack rate during an influenza season.

CONCLUSIONS

Increased timeliness and coverage of antiviral treatment among high-risk patients have the potential to substantially reduce the burden of seasonal influenza in the USA, regardless of influenza vaccination coverage and the severity of the influenza season.

Rate of use and effectiveness of oseltamivir in the treatment of influenza illness in high-risk populations: A systematic review and meta-analysis

BACKGROUND

Oseltamivir is recommended in the treatment of influenza illness in high-risk populations, including those with chronic heart and lung diseases.

OBJECTIVES

We conducted a systematic review and meta-analysis to determine the rate of use and effectiveness of oseltamivir in these groups of patients.

METHODS

The protocol for the systematic review was registered on PROSPERO (CRD42019125998). Medline, EMBASE, Cochrane CENTRAL, and CINAHL were searched for observational studies and randomized controlled trials published up to 16 February 2020. Quality appraisal of final studies was conducted using GRADE guidelines. Data were extracted using a predeveloped template. Main outcomes measured included the rate of use of oseltamivir for influenza-like-illness and its effectiveness in reducing disease severity in patients with cardiopulmonary diseases. Outcomes measured for effectiveness were influenza-related complications (respiratory infections and asthma exacerbations), hospitalization rates, and time to freedom from illness. Risk of bias was assessed using Cochrane's Risk of Bias 2.0 tool for randomized trials and Cochrane's Risk of Bias in nonrandomized Studies of Interventions tool for nonrandomized trials. Where data were available, pooled analyses were conducted. Dichotomous variables were evaluated using the Mantel-Hansel method. A random effect model was applied. Summary measures were reported as risk ratios where relevant.

RESULTS

Our systematic review identified nine studies. Oseltamivir use ranged from 25% to 100%. When oseltamivir group was compared to placebo, rates of respiratory tract infections reduced by 28% (RR = 0.72, 95% CI = 0.59-0.90), hospitalization reduced by 52% (RR = 0.48, 95% CI = 0.28-0.80) and median time to illness alleviation decreased by 10.4 to 120 hours. There was no significant reduction in asthma exacerbation rates.

CONCLUSIONS

Our systematic review suggests that the use of oseltamivir is beneficial in reducing disease severity, however, its use in high-risk population remains suboptimal.

Antiviral use is associated with a decrease in the rate of influenza-related complications, health care resource utilization, and costs

AIMS

To determine the effect of antiviral agents on influenza-related complications, health care resource utilization (HRU), and costs over three influenza seasons (2014-2016).

METHODS

This retrospective cohort study used claims data from the U.S. MarketScan Research Databases. Patients with a diagnosis code for influenza during the 2014-2016 seasons in an outpatient setting, with continuous enrollment from 1 year before to 91 d after diagnosis, were included. Patients who received an antiviral within 48 h of diagnosis were identified and propensity score-matched to a comparator cohort of untreated patients on baseline demographics, comorbid conditions, and HRU. Outcomes were assessed at days 30 and 90 after diagnosis and included respiratory-related complications (all respiratory-related and selected respiratory-related conditions [influenza, asthma, chronic obstructive pulmonary disease, or infection]), HRU, and costs.

RESULTS

Treated and matched untreated cohorts each consisted of 362,818 patients. HRU was significantly lower in the treated cohort compared with the untreated cohort at 30 and 90 d after diagnosis, respectively (hospitalizations: 0.6% vs. 0.8% and 1.2% vs. 1.6%; emergency department [ED] visits: 4.1% vs. 4.9% and 7.9% vs. 9.2%; intensive care unit/critical care unit (ICU/CCU) admissions: 0.2% vs. 0.4% and 0.4% vs. 0.6%). Respiratory-related HRU was lower in the treated cohort at both 30 and 90 d after diagnosis (p < .0001 for both periods). Mean all-cause total costs (including prescription costs) were significantly reduced in the treated group (day 30: $633 vs. $778; day 90: $1778 vs. $2119), despite higher prescription costs in the treated group.

LIMITATIONS

The study was retrospective and subject to residual selection bias, despite propensity score matching. Additionally, despite its potential relevance to influenza severity, vaccination status was not available in our data.

CONCLUSIONS

Antiviral influenza treatment is associated with a significant reduction in complications, HRU, and costs at 30 and 90 d after diagnosis.

Suspected Pediatric Influenza Risk-Stratification Algorithm: A Clinical Decision Tool

BACKGROUND AND OBJECTIVES

Influenza causes significant annual burden among children. Current guidelines recommend empiric treatment for a broadly defined group of children at high risk for influenza complications, resulting in overtreatment or costly viral testing. This study creates an algorithm for clinicians to risk stratify children with influenza-like illness (ILI) according to likelihood of influenza infection.

METHODS

A retrospective analysis was performed on 818 children seen in the emergency department from November 2012 to April 2013 for ILI. We reviewed medical records for symptoms, influenza risk factors, and viral assay results. Classification and regression tree analyses were performed separately for children older and younger than 2 years.

RESULTS

In children younger than 2 years, populations likely to test positive were those with an influenza-positive contact, unimmunized children, and those presenting in high-incidence influenza periods. In this subgroup, immunized patients in low-incidence seasons and those with absence of cough are low risk for influenza infection. For children 2 years and older, high-risk populations were unimmunized children, those presenting in high-incidence influenza periods and those with myalgia or absence of diarrhea.

CONCLUSIONS

These risk-stratification analyses were summarized into Suspected Pediatric Influenza Risk-Stratification Algorithm (SPIRA). For those in whom influenza infection is likely, clinicians may consider empiric treatment. Conversely, patients whom SPIRA identifies as unlikely to be infected with influenza are candidates for viral testing and targeted treatment. In assessing children with ILI, SPIRA aids clinicians in determining who to test versus treat empirically, saving children from costly viral testing or unnecessary antiviral exposure.

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.

Early Use of Anti-influenza Medications in Hospitalized Children With Tracheostomy

BACKGROUND

Early administration of anti-influenza medications is recommended for all children hospitalized with influenza. We investigated whether early use of anti-influenza medications is associated with improved outcomes in children with tracheostomy hospitalized with influenza.

METHODS

We performed a multicenter retrospective cohort study through the Pediatric Health Information System database for patients aged 30 days to 19 years who were discharged between October 1, 2007, and September 30, 2015 with diagnostic codes for both influenza and tracheostomy. Our primary predictor was receipt of anti-influenza medications on hospital day 0 or 1. We used propensity score matching to adjust for confounding by indication. Primary outcomes were length of stay (LOS) and 30-day all-cause revisit rate (emergency department visit or hospital admission).

RESULTS

Of 1436 discharges screened, 899 met inclusion criteria. The median admission age was 5 years (interquartile range: 2-10). The majority had multiple complex chronic conditions (median 3; interquartile range: 3-4) and technology dependence, such as gastrostomy tube (73.6%). After matching 772 unique admissions by propensity score, LOS was shorter for the cohort receiving early anti-influenza medications (6.4 vs 7.5 days; P = .01) without increase in revisit rate (27.5% vs 24.1%; P = .28). More than 80% in both cohorts received empirical antibiotics, and the duration of antibiotic therapy was similar (5.0 vs 5.6 days; P = .11).

CONCLUSIONS

Early use of anti-influenza medications in children with tracheostomy hospitalized with influenza is associated with shorter LOS, but these children continue to receive antibiotics despite identification and treatment of their viral infections.

Effectiveness of a pharmacist-physician collaborative program to manage influenza-like illness

OBJECTIVES

To examine the effectiveness of collaborative physician-community pharmacist programs to treat influenza-like illness (ILI) with respect to clinical outcomes and health care utilization.

DESIGN

Prospective multicenter cohort study.

SETTING

Fifty-five pharmacies in Michigan, Minnesota, and Nebraska.

PATIENTS

Adult patients presenting to the pharmacy with ILI during the 2013-14 influenza season (October 1, 2013 to May 30, 2014).

INTERVENTION

Pharmacists screened adult patients presenting with ILI, completed a brief physical assessment, performed a point-of-care rapid influenza diagnostic test (RIDT), and provided appropriate referral or treatment per an established collaborative practice agreement (CPA) with a licensed prescriber. Pharmacists followed-up with patients 24 to 48 hours after the encounter to assess patient status and possible need for further intervention.

MAIN OUTCOME MEASURES

Number of patients screened, tested, and treated for influenza.

RESULTS

Of the 121 patients screened, 45 (37%) were excluded and referred to their primary care provider or an urgent care facility for management. Of the 75 patients (62%) eligible for participation, 8 (11%) had a positive RIDT and were managed according to the CPA. Of the patients tested, 34.6% had no primary care physician and 38.7% visited the pharmacy outside of normal office hours. Only 3% of patients reported feeling worse at follow-up.

CONCLUSION

This study describes a physician-pharmacist collaborative model for treating ILI. Using an evidence-based CPA, pharmacists were able to provide timely treatment to patients with and without influenza.

Antiviral Treatments

Most viral respiratory tract infections are caused by classic respiratory viruses, including influenza, respiratory syncytial virus, human metapneumovirus, parainfluenza, rhinovirus, and adenovirus, whereas other viruses, such as herpes simplex, cytomegalovirus, and measles virus, can opportunistically affect the respiratory tract. The M2 inhibitors, amantadine and rimantadine, were historically effective for the prevention and treatment of influenza A but all circulating strains are currently resistant to these drugs. Neuraminidase inhibitors are the sole approved class of antivirals to treat influenza. Ribavirin, especially when combined with intravenous antibody, reduces morbidity and mortality among immunosuppressed patients.

Effects of antiviral treatment on influenza-related complications over four influenza seasons: 2006-2010

PURPOSE

The objective of the study is to evaluate the effect of antiviral treatment, pre-existing diseases, and sociodemographic factors on the risk of influenza-related complications and healthcare utilization.

METHODS

Case data was obtained from U.S. MarketScan Research Databases. Cases had a clinical diagnosis of influenza between 2006 and 2010 and continuous healthcare insurance from 90 days before to 30 days after diagnosis. Logistic regression models were applied to explore the impact of antiviral treatment on complications and healthcare utilization. Modified generalized estimating equation regression models in propensity score matched samples were used to address the robustness of the study.

RESULTS

Analyses included 1,557,437 cases from four influenza seasons. In each season, 34.82%-43.42% of patients received antiviral treatment, mostly oseltamivir. On average, 1.86% of patients were hospitalized, 9.56% visited the emergency room and 41.14% made ≥2 outpatient visits. The incidence of complications ranged from 17.62 to 19.67 per 100 patient-months. The relative risk of complications was increased in patients aged 0-4 years and those with pre-existing diseases, including asthma, Parkinson's disease, and cystic fibrosis. Overall, patients receiving antiviral treatment had an 11% reduction in the risk of complications. Among oseltamivir-treated patients, the risk of complications was significantly reduced by 81% in those treated ≤2 days after diagnosis compared with later. Antiviral treatment significantly reduced the risk of hospitalization, emergency room visits and need for ≥2 outpatient visits by 29%, 24% and 11%, respectively. The propensity score matching method improved the strength of the study.

CONCLUSIONS

Early treatment with antivirals, and specifically oseltamivir, significantly reduced the risk of influenza-related complications and healthcare utilization. However, lacking information about disease severity and the time from onset of symptoms to fulfillment of a prescription may bias the outcomes.

Oseltamivir for influenza infection in children: risks and benefits

Influenza is a common disease affecting many children each year. In a number of cases, particularly in children <2 years old and in those with severe chronic underlying disease, influenza can be complicated by lower respiratory tract infections, acute otitis media, rhinosinusitis, febrile seizures, dehydration or encephalopathy. Oseltamivir is the influenza virus drug that is most commonly studied in children for both the treatment and prevention of influenza. To avoid the risk that children with mild influenza or patients suffering from different viral infections receive oseltamivir, oseltamivir treatment should be recommended only in severe influenza cases, especially if confirmed by reliable laboratory tests. However, therapy must be initiated considering the risk of complications and the presence of severe clinical manifestations at age- and weight-appropriate doses. Because the vaccine remains the best option for preventing influenza and its complications, prophylaxis using oseltamivir should only be considered in select patients.

Impact of time to treatment of oseltamivir on influenza hospitalization cost among Korean children

BACKGROUND

Although oseltamivir is a common influenza treatment, there is a lack of data on the economic benefits of timely oseltamivir treatment.

METHODS

From February 2004 through June 2007, 116 hospitalized children ≤ 15 years of age with laboratory-confirmed influenza who received oseltamivir were identified via retrospective medical chart review. Demographic, clinical, and cost data were abstracted and multivariate linear regression was used to assess the association between oseltamivir time to treatment and treatment-related costs among hospitalized children with laboratory-confirmed influenza.

RESULTS

Overall, 28% (n = 33) of patients were treated with oseltamivir ≥ day 3 of admission. Rapid influenza diagnostic test was used in a significantly lower proportion of patients treated with oseltamivir ≥ day 3 of admission compared with those who received oseltamivir earlier. On multivariate linear regression, initiation of oseltamivir ≥ day 3 of admission was associated with a 60.84% increase (95%CI: 32.59-95.11) in treatment-related hospital costs, compared with initiation on admission.

CONCLUSION

Delayed initiation of oseltamivir was found to be associated with increased treatment-related hospital costs among children hospitalized with laboratory-confirmed influenza.

Hospital Readmissions Among Children With H1N1 Influenza Infection

OBJECTIVES

To describe readmissions among children hospitalized with H1N1 (influenza subtype, hemagglutinin1, neuraminidase 1) pandemic influenza and secondarily to determine the association of oseltamivir during index hospitalization with readmission.

METHODS

We reviewed data from 42 freestanding children's hospitals contributing to the Pediatric Health Information System from May through December 2009 when H1N1 was the predominant influenza strain. Children were divided into 2 groups by whether they experienced complications of influenza during index hospitalization. Primary outcome was readmission at 3, 7, and 30 days among both patient groups. Secondary outcome was the association of oseltamivir treatment with readmission.

RESULTS

The study included 8899 children; 6162 patients had uncomplicated index hospitalization, of whom 3808 (61.8%) received oseltamivir during hospitalization, and 2737 children had complicated influenza, of whom 1055 (38.5%) received oseltamivir. Median 3-, 7-, and 30-day readmission rates were 1.6%, 2.5%, and 4.7% for patients with uncomplicated index hospitalizations and 4.3%, 5.8%, and 10.3% among patients with complicated influenza. The 30-day readmission rates did not differ by treatment group among patients with uncomplicated influenza; however, patients with complicated index hospitalizations who received oseltamivir had lower all-cause 30-day readmissions than untreated patients. The most common causes of readmission were pneumonia and asthma exacerbations.

CONCLUSIONS

Oseltamivir use for hospitalized children did not decrease 30-day readmission rates in children after uncomplicated index hospitalization but was associated with a lower 30-day readmission rate among children with complicated infections during the 2009 H1N1 pandemic. Readmission rates for children who had complicated influenza infection during index hospitalizations are high.

Influenza vaccination and treatment in children with neurologic disorders

Influenza viruses cause substantial morbidity in children each year, especially among children with specific chronic conditions. In particular, neurologic disorders have emerged as a strong risk factor for influenza-related complications. Children with these disorders may be vulnerable due to diminished respiratory muscle strength, decreased muscle tone or impaired mobility, which can compromise pulmonary function and the ability to handle secretions. Although they represent a small fraction of the general pediatric population, children with neurologic disorders make up a disproportionately high number of those children who are hospitalized and die as a result of influenza-associated complications. Annual vaccination is the most effective way to prevent influenza and its complications, and is recommended for all children 6 months through 18 years of age, including children with neurologic disorders. Family members and those who work with these children in institutional, educational and daycare settings should also be vaccinated against influenza annually. However, there have been few studies of influenza vaccination specifically in this population. In addition, vaccine effectiveness may vary from year to year and vaccination will not prevent all infections. Early empiric antiviral treatment should be started promptly in these children if they present to healthcare providers with symptoms suspicious for influenza. This article reviews influenza epidemiology in children with neurologic disorders and what is known about vaccines and other methods of protecting this vulnerable population from influenza-related complications.

Antiviral treatment of influenza in children: a retrospective cohort study

INTRODUCTION

Influenza is a common and potentially serious disease in children. This retrospective cohort study examined the incidence of complications and associated risk factors in this population, and the effects of antiviral treatment.

METHODS

Data for children aged ≤17 years with a clinical diagnosis of influenza (ICD-9-CM codes 487.xx or 488.xx) during the 2006-2010 influenza seasons (including the 2009-2010 pandemic season) were obtained from US insurance claims databases. Unconditional logistic regression was used to evaluate the effect of antiviral treatment on the incidence of complications and healthcare resource utilization during the 30 days post the index influenza diagnosis. A sub-analysis in children aged <1 year was performed.

RESULTS

Antiviral treatment was used in 315,128 (39.53%) of 797,284 cases. The risk of complications was higher in children with pre-existing conditions, e.g., asthma (odds ratio [OR] = 1.86) or cystic fibrosis (OR = 1.67) than otherwise healthy children. Antiviral treatment reduced the 30-day risk of complications, hospitalization, emergency department visits, and ≥2 outpatient visits versus no treatment (ORs = 0.76, 0.69, 0.76, and 0.81, respectively); 30-day risks were further reduced by early treatment (within 2 days of diagnosis). The sub-analysis included 19,666 children aged <1 year; 7.38% received antiviral treatment during the pre-pandemic seasons and 33.00% during the pandemic season. Findings were similar to the main analyses; however, healthcare resource utilization was only significantly reduced by early treatment.

CONCLUSIONS

Antiviral treatment is associated with reduced risk of complications and healthcare resource utilization in children of all ages with influenza, especially when initiated early.

Antivirals for influenza: a summary of a systematic review and meta-analysis of observational studies

Despite the use of antivirals to treat patients with severe influenza, questions remain with respect to effects and safety. Although a recent systematic review has provided some indication of benefit, the analysis is limited by the quality of the available evidence from randomized controlled trials. To supplement the existing information, the authors conducted a systematic review of observational studies of antiviral treatment for influenza. This report summarises the findings of that review. Similar to the randomised trials, the confidence in the estimates of the effects for decision-making is low to very low primarily due to the risk of selection and publication bias in the observational studies. From these observational studies, the summary estimates suggest that oseltamivir may reduce mortality, hospitalisation and duration of symptoms compared with no treatment. Inhaled zanamivir may also reduce symptom duration and hospitalisations, but patients may experience more complications compared with no treatment. Earlier treatment with antivirals is generally associated with better outcomes than later treatment. Further high-quality evidence is needed to inform treatment guidelines because of the overall low to very low quality of evidence.

Therapeutics against influenza

Despite 75 years of research into prevention and treatment of influenza, the viruses that cause this disease continue to rank as some of the most important pathogens afflicting humans today. Progress in development of therapeutics for influenza has been slow for much of that time, but has accelerated in pace over the last two decades. Two classes of antiviral medications are used in humans at present, but each has limitations in scope and effectiveness of use. New strategies involving these licensed agents, including alternate forms of delivery and combination therapy with other drugs, are currently being explored. In addition, several novel antiviral compounds are in various clinical phases of development. Together with strategies designed to target the virus itself, new approaches to interrupt host–pathogen interactions or modulate detrimental aspects of the immune response have been proposed. Therapy for influenza will likely undergo substantial changes in the decades to come, evolving with our knowledge of pathogenesis as new approaches become viable and are validated clinically.

Neuraminidase inhibitors for influenza: a review and public health perspective in the aftermath of the 2009 pandemic

OBJECTIVES

The objectives of this study were to: (1) reflect on key stages in the discovery, development and pre-pandemic use of neuraminidase inhibitors (NAIs), (2) summarise the evidence of NAI effectiveness for treatment and prophylaxis of seasonal influenza prior to the 2009 pandemic, and (3) summarise the evidence base generated during the 2009 pandemic period.

DESIGN

A rapid systematic review of evidence published to June 2010 was conducted where existing high-quality systematic reviews formed a baseline and were supplemented with data from other reviews, randomised controlled trials (RCTs) and observational studies.

MAIN OUTCOME MEASURES

Severity and duration of symptoms; rates of severe illness, complications and death following treatment for influenza or influenza-like illness; rates of influenza and influenza-like illness following long-term prophylaxis or post-exposure prophylaxis of household contacts.

RESULTS

Prior to the 2009 pandemic, evidence from RCTs conducted in seasonal influenza epidemics indicated that NAIs used to treat laboratory-confirmed influenza in healthy adults reduced the duration of illness by one day. NAIs provide high levels of protective efficacy in adults when given long-term or in household-based post-exposure prophylaxis for seasonal influenza. Several 2009 pandemic period observational studies suggest that early treatment may reduce rates of hospitalisation and in-hospital mortality, but data from that period do not substantially increase the evidence base on prophylaxis, although they confirm effectiveness.

CONCLUSIONS

NAIs should be deployed during a future pandemic for either post-exposure prophylaxis or treatment depending on national policy considerations and logistics. The existing evidence base on effectiveness against severe outcomes requires supplementation.

Pulmonary bacterial coinfection in infants and children with viral respiratory infection

The true incidence of pulmonary bacterial coinfection in infants and children hospitalized with a viral respiratory infection is difficult to ascertain but can vary widely from under 1 to 44%. For the same patient group admitted to pediatric intensive care units and/or requiring ventilatory support, the evidence is more convincing, with reported incidences of 17-39%. Studies covering influenza and respiratory syncytial virus infection dominate the recent literature. Whether treatment (or 'cover') with antibiotics is indicated/justified lies in the balance of risk of pulmonary bacterial coinfection (or risk of not diagnosing it), severity of disease and the patient setting. The balance between the overprescription of antibiotics and the possible sequelae associated with bacterial coinfection in infants and children continues to fuel debate.

Protecting pediatric oncology patients from influenza

Influenza is a common respiratory pathogen. Its severity can be unpredictable, but people with chronic illness are at increased risk of severe infection, complications, and death from influenza. This review examines evidence to support various strategies to protect pediatric oncology patients from influenza-related morbidity. Influenza vaccination should be considered standard. Additional evidence-supported measures include antiviral treatment, antiviral prophylaxis, cohorting of patients, and hospital infection control measures. Data from other high-risk populations support the vaccination of family members, double-dose or high-dose vaccination, and the use of barrier methods. These measures have the potential to optimize patient outcomes because there will be fewer treatment interruptions for acute illness. These strategies can also protect patients from prolonged hospitalizations and morbidity related to influenza.

Employer-incurred health care costs and productivity losses associated with influenza

The primary objective of this study was to assess trends in employer expenditures for both direct medical costs and indirect productivity losses associated with influenza. A retrospective analysis was performed using two of the MarketScan family of databases for 2005-2009. Patients with at least one diagnosis claim for influenza during an influenza season were selected. We estimated seasonal incidence of influenza in the employed population from the MarketScan Commercial Claims and Encounters database. Health care utilization and costs and productivity losses were assessed during the 21-d period following the influenza diagnosis date. Compared with the 2005-2006 season (493 per 100,000 plan members), influenza incidence increased during the 2006-2007 (598 per 100,000 plan members) and 2007-2008 (1,142 per 100,000 plan members) seasons and had a dramatic increase during the pandemic season of 2008-2009 (1,715 per 100,000 plan members) . The total influenza-related employer spending per 100,000 plan members also increased by over 400% during the 2008-2009 influenza season [$623,248; confidence interval (CI]):$601,518-$644,991], compared with 2005-2006 ($145,834; 95% CI: $135,067-$156,603). The primary drivers of the increased costs were emergency room, outpatient and inpatient visits. Total costs associated with influenza-related missed work time per 100,000 plan members increased over 4-fold from $26,479 in the 2005-2006 influenza season to $122,811 in 2008-2009. Overall, as expected, considerably higher direct and indirect costs were observed during the 2008-2009 influenza pandemic season than during other influenza seasons. In recent years, the influenza-related employer burden has increased considerably. In future, employers may need efficient resource allocation in order to address the productivity losses and increasing direct medical costs associated with increased influenza incidence. One of the strategies that employers may consider is increasing influenza vaccination rates among employees, which likely will help lower the influenza incidence and the associated downstream direct and indirect costs.

Pediatric hospitalizations with influenza A infection during the 2009-2010 pandemic in five hospitals in Japan

BACKGROUND

The aim of this study was to identify the clinical characteristics of hospitalized children with the 2009 pandemic influenza virus infection in Japan.

METHODS

We retrospectively reviewed cases of hospitalized children younger than 16 years with laboratory-confirmed influenza A virus infection during the 2009-2010 pandemic season in five hospitals in Japan.

RESULTS

A total of 515 cases were included in the analysis. The median age was 6.3 years (range 0-15), and 216 subjects (41.9%) had one or more underlying medical conditions. There were no fatalities, but 16 patients (3.1%) required intensive care. More than 93% of the subjects received neuraminidase inhibitors, and more than 87% received these medications within 48 h of the onset of symptoms. Approximately 80% of all subjects were admitted to hospital within 48 h of the onset of symptoms.

CONCLUSIONS

There were no fatalities, and the proportion of patients with serious illness was substantially lower than previously reported from other countries. Good access to medical services and proactive treatment may have contributed to the lower disease burden of the 2009 influenza pandemic on Japanese children.

Evaluation and management of seasonal influenza in the emergency department

Seasonal influenza causes significant morbidity and mortality, primarily due to increased complication rates among the elderly population and patients with chronic diseases. Timely diagnosis of influenza and early recognition of an influenza outbreak or epidemic are key components in preventing influenza-related complications, hospitalizations, and deaths. Emergency departments are the most frequent points of entry for most influenza cases and are well positioned to identify and manage influenza community outbreaks and epidemics. Emergency departments need specific infection control measures to curb the spread of influenza in the Emergency Department and hospital during the influenza season.

Antivirals for treatment of influenza: a systematic review and meta-analysis of observational studies

BACKGROUND

Systematic reviews of randomized, controlled trials in patients with influenza suggest a lack of evidence about the effects of antiviral therapy on several patient-important outcomes of influenza.

PURPOSE

To systematically review observational studies for benefits and harms of oseltamivir, zanamivir, amantadine, or rimantadine in the treatment of influenza.

DATA SOURCES

MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, CINAHL, SIGLE, the Chinese Biomedical Literature Database, Panteleimon, and LILACS up to November 2010; contact with pharmaceutical companies; and reference lists.

STUDY SELECTION

Observational studies in any language that compared single antiviral therapy with no therapy or other antiviral therapy, or that had no comparator, for influenza or influenza-like illness.

DATA EXTRACTION

Two independent investigators extracted data. Confidence in the estimates of the obtained effects (quality of evidence) was assessed by using the Grading of Recommendations Assessment, Development, and Evaluation approach.

DATA SYNTHESIS

74 studies fulfilled the inclusion criteria. Meta-analyses of the few studies providing effects with adjustment for confounders suggest that, in high-risk populations, oral oseltamivir may reduce mortality (odds ratio, 0.23 [95% CI, 0.13 to 0.43]; low-quality evidence), hospitalization (odds ratio, 0.75 [CI, 0.66 to 0.89]; low-quality evidence), and duration of symptoms (33 hours [CI, 21 to 45 hours]; very low-quality evidence) compared with no treatment. Earlier treatment with oseltamivir was generally associated with better outcomes. Inhaled zanamivir may lead to shorter symptom duration (23 hours [CI, 17 to 28 hours]; moderate-quality evidence) and fewer hospitalizations (odds ratio, 0.66 [CI, 0.37 to 1.18]) but more complications than no treatment. Direct comparison of oral oseltamivir and inhaled zanamivir suggests no important differences in key outcomes. Data from 1 study suggest that oral amantadine may reduce mortality and pneumonia associated with influenza A. No included study evaluated rimantadine.

LIMITATIONS

Mortality was assessed in high-risk patients, and generalizability is limited. The overall body of evidence is limited by risk for confounding and selection, reporting, and publication bias.

CONCLUSION

Therapy with oral oseltamivir and inhaled zanamivir may provide a net benefit over no treatment of influenza. However, as with the randomized trials, the confidence in the estimates of the effects for decision making is low to very low. PRIMARY FUNDING SOURCES: World Health Organization and McMaster University.

Antiviral treatment of influenza in children

Influenza causes substantial morbidity in children in the United States each year. The 2009 influenza A (H1N1) pandemic disproportionately affected the pediatric population and resulted in a substantially increased number of hospitalizations and deaths among children. Early influenza antiviral treatment reduces the duration of illness, frequency of complications, antibiotic use, and health care utilization costs attributable to influenza. A comprehensive strategy to reduce influenza-associated hospitalizations and deaths among children should include empiric antiviral treatment for suspected or confirmed influenza of any severity in children who are hospitalized; who have severe, complicated, or progressive illness; or who are at high risk for influenza complications. Here, we summarize data on the burden of influenza among children in the United States, the indications for influenza antiviral treatment among children, the available evidence for influenza antiviral treatment, and antiviral treatment considerations, including resistance and adverse events.

The use of antiviral drugs for influenza: Guidance for practitioners 2012/2013

The present article addresses the use of antiviral drugs in the management of seasonal influenza illness for the 2012/2013 season. It updates the previous document published in 2011 (1). Noteworthy guidance updates since 2011 include the following: Seasonal influenza in 2012/2013 is predicted to be caused by two human influenza A and one influenza B strain, all of which are anticipated to remain generally susceptible to oseltamivir.The predicted strains are A/California/7/2009 (H1N1) pdm09-like, A/Victoria/361/2011 (H3N2)-like and B/Wisconsin/1/2010-like (Yamagata lineage). All are included in the seasonal influenza vaccine and are susceptible to oseltamivir.Swine-variant H3N2v, which has rarely caused infection in humans exposed to infected swine within the past year in the United States, is susceptible to oseltamivir. It is not included in the current seasonal influenza vaccine.It is still considered that initiation of antiviral therapy more than 36 h to 48 h after onset of symptoms is beneficial in patients hospitalized with complicated influenza and severe illness.Oseltamivir continues to be recommended for the treatment of influenza in pregnant women.The use of antiviral drugs among measures to control outbreaks of influenza in closed facilities such as correctional institutions is now included in the present document.

Oseltamivir in seasonal, pandemic, and avian influenza: a comprehensive review of 10-years clinical experience

Oseltamivir (Tamiflu®; F. Hoffmann-La Roche Ltd, Basel, Switzerland) is an orally administered antiviral for the treatment and prevention of influenza A and B infections that is registered in more than 100 countries worldwide. More than 83 million patients have been exposed to the product since its introduction. Oseltamivir is recommended by the World Health Organization (WHO) for use in the clinical management of pandemic and seasonal influenza of varying severity, and as the primary antiviral agent for treatment of avian H5N1 influenza infection in humans. This article is a nonsystematic review of the experience gained from the first 10 years of using oseltamivir for influenza infections since its launch in early 2000, emphasizing recent advances in our understanding of the product and its clinical utility in five main areas. The article reviews the pharmacokinetics of oseltamivir and its active metabolite, oseltamivir carboxylate, including information on special populations such as children and elderly adults, and the co-administration of oseltamivir with other agents. This is followed by a summary of data on the effectiveness of oseltamivir treatment and prophylaxis in patients with all types of influenza, including pandemic (H1N1) 2009 and avian H5N1 influenza. The implications of changes in susceptibility of circulating influenza viruses to oseltamivir and other antiviral agents are also described, as is the emergence of antiviral resistance during and after the 2009 pandemic. The fourth main section deals with the safety profile of oseltamivir in standard and special patient populations, and reviews spontaneously reported adverse event data from the pandemic and pre-pandemic periods and the topical issue of neuropsychiatric adverse events. Finally, the article considers the pharmacoeconomics of oseltamivir in comparison with vaccination and usual care regimens, and as a component of pandemic influenza mitigation strategies.

Oseltamivir shortens hospital stays of critically ill children hospitalized with seasonal influenza: a retrospective cohort study

BACKGROUND

Antiviral therapy reduces symptom duration and hospitalization risk among previously healthy and chronically ill children infected with seasonal influenza. The effect of oseltamivir on outcomes of hospitalized children is unknown. The primary objective of this study was to determine whether oseltamivir improves outcomes of critically ill children hospitalized with influenza.

METHODS

We performed a retrospective cohort study of children with influenza infection admitted to a pediatric intensive care unit during 6 consecutive winter seasons (2001-2007). We used the Pediatric Health Information System database, which contains resource utilization data from 41 children's hospitals. We matched oseltamivir-treated patients with oseltamivir-nontreated patients by the probability of oseltamivir exposure using a propensity score we derived from patient and hospital characteristics. We subsequently compared the outcomes of critically ill children treated with oseltamivir within 24 hours of admission with propensity score matched children who were not treated with oseltamivir.

RESULTS

We identified 1257 children with influenza infection, 264 of whom were treated with oseltamivir within 24 hours of hospital admission. Multivariable analysis of 252 oseltamivir-treated patients and 252 propensity score-matched untreated patients demonstrated that patients treated with oseltamivir experienced an 18% reduction in total hospital days (time ratio: 0.82, P = 0.02), whereas intensive care unit stay, in-hospital mortality, and readmission rates did not differ.

CONCLUSION

For critically ill children infected with seasonal influenza, treatment with oseltamivir within 24 hours of hospitalization was associated with a shorter duration of hospital stay. Additional study is needed to determine the effect of delayed initiation of oseltamivir on clinical outcomes.

Influenza pharmacotherapy: present situation, strategies and hopes

INTRODUCTION

Influenza is a serious health threat for people of all ages. The causative virus is evolving continuously and the risk of an unexpected mutant, which cannot be controlled by seasonal vaccination, is real. New and more effective antiviral drugs are needed.

AREAS COVERED

This review examines the antiviral drugs with confirmed efficacy in combating influenza, as well as newer compounds that are currently undergoing testing and will hopefully be marketed in the near future. A comprehensive, state-of-the-art picture of drug therapy for influenza is presented, including novel solutions and effective strategies for prescribing currently available antiviral drugs, with emphasis on the importance of updated local epidemiological data, clinical assessment and laboratory testing.

EXPERT OPINION

Current anti-influenza drug research is no longer tied solely to viral envelope protein targets like haemagglutinin and neuraminidase. New drugs act on the viral RNA polymerase complex, which is involved in transcription and replication of the viral genome, and can prevent the maturation, replication and dissemination of numerous viral subtypes. Combating this infection and reducing the duration of symptoms also has important socioeconomic implications related to health-care spending (including hospitalization for complications) and sick-leave pay for workers.

Preventing and treating secondary bacterial infections with antiviral agents

Bacterial super-infections contribute to the significant morbidity and mortality associated with influenza and other respiratory virus infections. There are robust animal model data, but only limited clinical information on the effectiveness of licensed antiviral agents for the treatment of bacterial complications of influenza. The association of secondary bacterial pathogens with fatal pneumonia during the recent H1N1 influenza pandemic highlights the need for new development in this area. Basic and clinical research into viral-bacterial interactions over the past decade has revealed several mechanisms that underlie this synergism. By applying these insights to antiviral drug development, the potential exists to improve outcomes by means other than direct inhibition of the virus.

2009 pandemic influenza A (H1N1) virus infection in pediatric oncology and hematopoietic stem cell transplantation patients

BACKGROUND

Pediatric oncology and hematopoietic stem cell transplantation (HSCT) patients are at high risk for influenza infection and its associated complications. Little is known about infection with novel 2009 influenza A (H1N1) in this population.

PROCEDURE

Prospective laboratory surveillance identified all children with positive influenza test results from 4/27/09-12/5/09. 2009 H1N1 infection was confirmed by PCR subtyping; cases in which subtyping was not performed were considered probable. Medical records of all pediatric oncology and HSCT cases were reviewed.

RESULTS

Thirty children with cancer or HSCT had laboratory-confirmed influenza A. Patients with ALL (18), CNS tumors (4), CML (1), Ewing sarcoma (1), Hodgkin lymphoma (1), LCH (1), severe aplastic anemia (1), and HSCT (3), had confirmed (5) and probable (25) H1N1 by rapid (22; 73%), DFA (4; 13%), or RVP (4; 13%) assays. Most frequent presenting signs and symptoms were fever (93%; median 38.6°C), cough (97%), and rhinorrhea (83%). Ten patients required hospitalization for a median of 5 days, most commonly for fever and neutropenia (8). Imaging demonstrated lower respiratory tract involvement in three patients. There were no concomitant bacteremias; one patient had rhinovirus co-infection. Three patients required ICU care; 1 developed ARDS, multi-organ failure, and died after 5 days. Chemotherapy was delayed in five patients. Oseltamivir was administered to 28 patients; 1 patient developed an oseltamivir-resistant strain and was treated with zanamivir.

CONCLUSIONS

2009 influenza A H1N1 infection in children with cancer and HSCT is mild in most patients, but can lead to serious complications.

Lessons from the swine flu: pandemic, panic and/or pandemonium?

The 2009 pandemic of swine-origin A/H1N1 influenza (swine flu) spread rapidly in Australia and there was a prolonged winter outbreak lasting 18 weeks. For Australian children, the case fatality rate of swine flu was no higher than for severe seasonal influenza. Because of the high number of children infected with swine flu, however, there were more children admitted to hospital than usual and more children died. Health-care services (emergency departments, medical wards and intensive care units) were stretched. The introduction of special influenza clinics helped services cope. Pregnant women were at high risk of severe swine flu and seven pregnant women and seven of their babies died. Future pandemic planning should consider severity of influenza, in addition to rapidity of spread, as a criterion for escalating interventions.

Oseltamivir in seasonal influenza: cumulative experience in low- and high-risk patients

Seasonal influenza viruses cause annual disease epidemics that affect individuals at low and high risk for secondary illnesses. Influenza vaccines are widely used in high-risk patients to prevent infection, but the protection afforded varies by population; uptake is also limited in some groups. Antiviral drugs for influenza are now readily available. Oseltamivir is the most widely used antiviral for the treatment and prophylaxis of seasonal influenza, and its efficacy and safety are now well established in a variety of populations. In addition to decreasing the severity and duration of the symptoms of influenza, clinical and epidemiological studies demonstrate that oseltamivir significantly reduces the frequency of secondary illnesses and exacerbation of underlying conditions; survival is also significantly improved in seriously ill patients who are hospitalized with severe influenza. Resistant viruses are isolated with a low frequency during oseltamivir treatment (0.33% in adults and 4.0% in children among almost 2000 oseltamivir-treated patients enrolled onto Roche-sponsored clinical trials of oseltamivir treatment during the oseltamivir development programme). However, an oseltamivir-resistant influenza A (H1N1) virus emerged in Europe during the 2007-08 season and circulated in the southern and northern hemispheres in 2008-09. No link with oseltamivir usage could be detected, and the clinical impact of these viruses was limited. Oseltamivir-susceptible pandemic (H1N1) 2009 viruses now predominate in many countries. Oseltamivir is generally well tolerated, with a similar adverse event profile to placebo.

Performance of a rapid influenza test in children during the H1N1 2009 influenza a outbreak

OBJECTIVE

To evaluate the performance of a rapid influenza diagnostic test (RIDT) in detecting H1N1 2009 influenza A virus in respiratory samples from pediatric patients in comparison to that of real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) and viral culture. Methodology. This was a cross-sectional diagnostic-accuracy study conducted at a tertiary care children's hospital. Patients for whom the RIDT (BinaxNOW [Binax, Inc, Portland, ME]), viral culture, and rRT-PCR results were known were included. Sensitivity, specificity, and likelihood ratios (LRs) were calculated.

RESULTS

A total of 3030 specimens had RIDT results paired with both rRT-PCR and viral culture results. With rRT-PCR as the reference, overall test sensitivity was 45% (95% confidence interval [CI]: 43.3%-46.3%) and specificity was 98.6% (95% CI: 98.1%-99%). Positive and negative LRs were 32.9 (95% CI: 22.9-45.4) and 0.56 (95% CI: 0.54-0.58), respectively. RIDT sensitivity was significantly higher in young infants and children younger than 2 years than in older children. Using viral culture as the reference standard, RIDT sensitivity was 55.5% (95% CI: 51.9%-95.6%) and specificity was 95.6% (95% CI: 95%-96.1%). The positive and negative LRs were 12.6 and 0.47, respectively.

CONCLUSIONS

The RIDT had relatively poor sensitivity but excellent specificity in this consecutive series of respiratory specimens obtained from pediatric patients. Although a positive RIDT result was highly accurate in predicting infection with influenza type A H1N1 2009 in children, a negative RIDT result did not preclude a child having H1N1. Therefore, for children at high risk with influenza-like illnesses during high-prevalence periods of influenza, empiric initiation of antiviral therapy should be considered for patients with a negative RIDT result.

Fever

PURPOSE OF REVIEW

The present review presents novel infections and better evidence on current practices related to fever in children.

RECENT FINDINGS

Studies using more accurate diagnostic methods have provided evidence for prevalence of certain diseases, their clinical presentation and anticipated complications. Answers to certain clinical dilemmas related to febrile children in a pediatric office practice have been addressed recently. Some studies have explored current issues like immunization of pregnant women with influenza vaccine and the outbreak investigation of the swine H1N1 influenza.

SUMMARY

Fever still remains the most common reason for visits to the pediatrician or emergency room. Better diagnostic methods; appropriate therapeutic or preventive strategies; and continued surveillance for novel infections have improved outcomes from both an individual and public health perspective.