Severe influenza treatment guideline

Influenza and Aging: Clinical Manifestations, Complications, and Treatment Approaches in Older Adults

Influenza, a highly contagious respiratory viral illness, poses significant global health risks, particularly affecting older and those with chronic health conditions. Influenza viruses, primarily types A and B, are responsible for seasonal human infections and exhibit a propensity for antigenic drift and shift, contributing to seasonal epidemics and pandemics. The severity of influenza varies, but severe cases often lead to pneumonia, acute respiratory distress syndrome, and multiorgan failure. Older adults, especially those over 65 years of age, face increased risks of immune senescence, chronic comorbidities, and decreased vaccine efficacy. Globally, influenza affects millions of people annually, with significant morbidity and mortality among older. Epidemiological patterns vary with climate, and risk factors include age, immunocompromised status, and preexisting chronic conditions. In older adults, influenza frequently results in hospitalization and death, which is exacerbated by immunosenescence and biological organ changes associated with aging. Clinical manifestations range from mild symptoms to severe complications such as viral pneumonia and multiorgan failure. Diagnosis often relies on antigen or molecular tests, with radiological examination aiding in severe cases. Treatment primarily involves antiviral agents, such as oseltamivir and peramivir, with the greatest benefit observed when initiated early. Management of severe cases may require hospitalization and supportive care, including addressing complications, such as secondary bacterial infections and cardiovascular events. This article highlights the need for improved vaccination strategies and novel treatments, including monoclonal antibodies and adoptive T cell therapies, to better manage severe influenza infections in vulnerable populations such as older.

Influenza epidemiology and treatment in people with a visual disability: A retrospective cohort study

BACKGROUND

Visual disabilities (VD) are expected to rise with an aging population. Persons with VD experience a higher prevalence of chronic and acute diseases. Despite the significance of influenza to this population, there is limited data comparing influenza care disparities between those with VD and those without.

OBJECTIVE

The study aimed to determine the influenza burden and associated healthcare utilization in individuals with VD compared to those without disabilities.

METHODS

A retrospective cohort study was conducted using the Korean National Health Information Database, encompassing three influenza seasons (2011-2012 to 2013-2014). The influenza incidence and incidence rate ratio (IRR) was calculated. Adjusted IRRs were calculated using a zero-inflated Poisson model. We assessed the risk of admissions and 30-day post-influenza mortality, employing logistic regression or survival analysis.

RESULTS

A total of 504,374 patients (252,964 patients with VD and 251,410 controls) were followed for 1,471,480 person-years. The influenza incidence was higher in the VD cohort than in the control (8.8 vs. 7.8 cases per 1000 person-years). VD cohort had a higher influenza IRR (adjusted IRR 1·13, 95% confidence interval [CI] 1·02-1·25). Severe VD exhibited higher hospitalization risk (adjusted odds ratio [OR] 1·29, 95% CI 1·10-1·20) and increased medical costs. Severe VD was a significant risk factor for mortality (adjusted Hazard Ratio 1·89, 95% CI 1·04-3·45).

CONCLUSIONS

People with VD have a higher influenza incidence, while their outcomes are comparable to those without. Nevertheless, severe VD significantly contributes more to hospitalization, mortality, and medical costs than controls.

Mammalian Target of Rapamycin Complex 1 Activation in Macrophages Contributes to Persistent Lung Inflammation following Respiratory Tract Viral Infection

Respiratory tract virus infections cause millions of hospitalizations worldwide each year. Severe infections lead to lung damage that coincides with persistent inflammation and a lengthy repair period. Vaccination and antiviral therapy help to mitigate severe infections before or during the acute stage of disease, but there are currently limited specific treatment options available to individuals experiencing the long-term sequelae of respiratory viral infection. Herein, C57BL/6 mice were infected with influenza A/PR/8/34 as a model for severe viral lung infection and allowed to recover for 21 days. Mice were treated with rapamycin, a well-characterized mammalian target of rapamycin complex 1 (mTORC1) inhibitor, on days 12 to 20 after infection, a time period after viral clearance. Persistent inflammation following severe influenza infection in mice was primarily driven by macrophages and T cells. Uniform manifold approximation and projection analysis of flow cytometry data revealed that lung macrophages had high activation of mTORC1, an energy-sensing kinase involved in inflammatory immune cell effector functions. Rapamycin treatment reduced lung inflammation and the frequency of exudate macrophages, T cells, and B cells in the lung, while not impacting epithelial progenitor cells or adaptive immune memory. These data highlight mTORC1's role in sustaining persistent inflammation following clearance of a viral respiratory pathogen and suggest a possible intervention for post-viral chronic lung inflammation.

Infectious Disease Emergencies

COVID-19 has added new relevance to the relationship between the world’s public health and infectious diseases and makes timely the topic of this chapter, that is, infectious disease emergencies. When patients have infectious diseases and present in-hospital with life-threatening symptoms (e.g., septic shock), prompt response is crucial to saving their lives. This chapter approaches rapid response activation from the perspective of five infectious disease emergencies: sepsis and septic shock, acute hypoxemic respiratory failure due to severe pneumonia, hypovolemic shock due to acute infectious diarrheal illness, acute respiratory failure due to influenza virus infection, and acute respiratory failure due to COVID-19 (coronavirus disease of 2019) pneumonia. The highly detailed information (e.g., predisposing conditions, initial measures to take, diagnostic work-ups, and treatment) is presented in a fashion that immediately puts pertinent information at the fingertips of those who need it.

Comparison of Clinical Characteristics for Distinguishing COVID-19 From Influenza During the Early Stages in Guangdong, China

Background: To explore the differences in clinical manifestations and infection marker determination for early diagnosis of coronavirus disease-2019 (COVID-19) and influenza (A and B).

Methods: A hospital-based retrospective cohort study was designed. Patients with COVID-19 and inpatients with influenza at a sentinel surveillance hospital were recruited. Demographic data, medical history, laboratory findings, and radiographic characteristics were summarized and compared between the two groups. The chi-square test or Fisher's exact test was used for categorical variables, and Kruskal–Wallis H-test was used for continuous variables in each group. Receiver operating characteristic curve (ROC) was used to differentiate the intergroup characteristics. The Cox proportional hazards model was used to analyze the predisposing factors.

Results: About 23 patients with COVID-19 and 74 patients with influenza were included in this study. Patients with influenza exhibited more symptoms of cough and sputum production than COVID-19 (p < 0.05). CT showed that consolidation and pleural effusion were more common in influenza than COVID-19 (p < 0.05). Subgroup analysis showed that patients with influenza had high values of infection and coagulation function markers, but low values of blood routine and biochemical test markers than patients with COVID-19 (mild or moderate groups) (p < 0.05). In patients with COVID-19, the ROC analysis showed positive predictions of albumin and hematocrit, but negative predictions of C-reactive protein (CRP), procalcitonin (PCT), lactate dehydrogenase (LDH), hydroxybutyrate dehydrogenase (HBDH), and erythrocyte sedimentation rate. Multivariate analysis revealed that influenza might associate with risk of elevated CRP, PCT, and LDH, whereas COVID-19 might associated with high HBDH.

Conclusion: Patients with influenza had more obvious clinical symptoms but less common consolidation lesions and pleural effusion than those with COVID-19. These findings suggested that influenza likely presents with stronger inflammatory reactions than COVID-19, which provides some insights into the pathogenesis of these two contagious respiratory illnesses.

Two-stage prediction model for in-hospital mortality of patients with influenza infection

BACKGROUND

Infleunza is a challenging issue in public health. The mortality and morbidity associated with epidemic and pandemic influenza puts a heavy burden on health care system. Most patients with influenza can be treated on an outpatient basis but some required critical care. It is crucial for frontline physicians to stratify influenza patients by level of risk. Therefore, this study aimed to create a prediction model for critical care and in-hospital mortality.

METHODS

This retrospective cohort study extracted data from the Chang Gung Research Database. This study included the patients who were diagnosed with influenza between 2010 and 2016. The primary outcome of this study was critical illness. The secondary analysis was to predict in-hospital mortality. A two-stage-modeling method was developed to predict hospital mortality. We constructed a multiple logistic regression model to predict the outcome of critical illness in the first stage, then S1 score were calculated. In the second stage, we used the S1 score and other data to construct a backward multiple logistic regression model. The area under the receiver operating curve was used to assess the predictive value of the model.

RESULTS

In the present study, 1680 patients met the inclusion criteria. The overall ICU admission and in-hospital mortality was 10.36% (174 patients) and 4.29% (72 patients), respectively. In stage I analysis, hypothermia (OR = 1.92), tachypnea (OR = 4.94), lower systolic blood pressure (OR = 2.35), diabetes mellitus (OR = 1.87), leukocytosis (OR = 2.22), leukopenia (OR = 2.70), and a high percentage of segmented neutrophils (OR = 2.10) were associated with ICU admission. Bandemia had the highest odds ratio in the Stage I model (OR = 5.43). In stage II analysis, C-reactive protein (OR = 1.01), blood urea nitrogen (OR = 1.02) and stage I model's S1 score were assocaited with in-hospital mortality. The area under the curve for the stage I and II model was 0.889 and 0.766, respectively.

CONCLUSIONS

The two-stage model is a efficient risk-stratification tool for predicting critical illness and mortailty. The model may be an optional tool other than qSOFA and SIRS criteria.

A brief review of influenza virus infection

Influenza is an acute viral respiratory infection that affects all age groups and is associated with high mortality during pandemics, epidemics, and sporadic outbreaks. Nearly 10% of the world's population is affected by influenza annually, with about half a million deaths each year. Influenza vaccination is the most effective method for preventing influenza infection and its complications. The influenza vaccine's efficacy varies each season based on the circulating influenza strains and vaccine uptake rates. Currently, three antiviral drugs targeting the influenza virus surface glycoprotein neuraminidase are available for treatment and prophylaxis of disease. Given the significant burden of influenza infection globally, this review is focused on the latest findings in the etiology, epidemiology, transmission, clinical manifestation, diagnosis, prevention, and treatment of influenza.

Predictors and Outcomes of Hospitalization for Influenza: Real-World Evidence from the United States Medicare Population

INTRODUCTION

The purpose of this study was to identify predictors of initial hospitalization and describe the outcomes of high-risk patients hospitalized with influenza.

METHODS

Data were taken from the 5% national US Medicare database from 2012 to 2015. Patients (aged at least 13 years) were required to have at least one diagnosis for influenza and have continuous health plan enrollment for 6 months before (baseline) and 3 months (follow-up) after the date of influenza diagnosis. Patients who died during follow-up were included. Patients were categorized as initially hospitalized if hospitalized within 0-1 day of diagnosis. High-risk initially hospitalized patients were defined as patients aged at least 65 years or those that had a diagnostic code for chronic lung disease, cardiovascular or cerebrovascular disease, or weakened immune system during baseline period. Logistic regression models were developed to determine predictors of initial hospitalization.

RESULTS

The study population included 8127 high-risk patients who were initially hospitalized and 16,784 who were not hospitalized. Among high-risk patients, 89.3% were diagnosed in the emergency room, whereas 7.5% and 3.2% were diagnosed in a physician's office or other Medicare settings, respectively. Chronic obstructive pulmonary disorder, congestive heart failure, chronic kidney disease, older age, being male, other comorbidities, number of comorbidities, and baseline healthcare resource use were the predictors of hospitalization. Median length of stay for the hospitalization was 5.0 days, and the 30-day readmission rate was 14%. All-cause mortality rate was 5.1% during the inpatient stay and 9.2% within 30 days of diagnosis. Hospitalized patients with influenza incurred an increase of $16,568 per patient in total all-cause healthcare costs from pre-influenza to post-influenza diagnosis.

CONCLUSION

The study characterized the burden of hospitalization for influenza and found that hospitalized high-risk patients experience greater comorbidity burden, higher likelihood of multiple inpatient admissions, and costly medical interventions compared to patients who were not hospitalized.

Influenza infection, SARS, MERS and COVID-19: Cytokine storm - The common denominator and the lessons to be learned

The outbreak of COVID-19 reminds us that the emerging and reemerging respiratory virus infections pose a continuing threat to human life. Cytokine storm syndromes of viral origin seem to have a common pathogenesis of the imbalanced immune response with the exaggerated inflammatory reaction combined with the reduction and functional exhaustion of T cells. Immunomodulatory therapy is gaining interest in COVID-19, but this strategy has received less attention in other respiratory viral infections than it deserved. In this review we suggest that based on the similarities of the immune dysfunction in the severe cases of different respiratory viral infections, some lessons from the immunomodulatory therapy of COVID-19 (particularly regarding the choice of an immunomodulatory drug, the selection of patients and optimal time window for this kind of therapy) could be applied for some cases of severe influenza infection and probably for some future outbreaks of novel severe respiratory viral infections.

Potential Immunotherapeutic Targets for Hypoxia Due to COVI-Flu

The world is currently embroiled in a pandemic of coronavirus disease 2019 (COVID-19), a respiratory illness caused by the novel betacoronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The severity of COVID-19 disease ranges from asymptomatic to fatal acute respiratory distress syndrome. In few patients, the disease undergoes phenotypic differentiation between 7 and 14 days of acute illness, either resulting in full recovery or symptom escalation. However, the mechanism of such variation is not clear, but the facts suggest that patient's immune status, comorbidities, and the systemic effects of the viral infection (potentially depending on the SARS-CoV-2 strain involved) play a key role. Subsequently, patients with the most severe symptoms tend to have poor outcomes, manifest severe hypoxia, and possess elevated levels of pro-inflammatory cytokines (including IL-1β, IL-6, IFN-γ, and TNF-α) along with elevated levels of the anti-inflammatory cytokine IL-10, marked lymphopenia, and elevated neutrophil-to-lymphocyte ratios. Based on the available evidence, we propose a mechanism wherein SARS-CoV-2 infection induces direct organ damage while also fueling an IL-6-mediated cytokine release syndrome (CRS) and hypoxia, resulting in escalating systemic inflammation, multi-organ damage, and end-organ failure. Elevated IL-6 and hypoxia together predisposes patients to pulmonary hypertension, and the presence of asymptomatic hypoxia in COVID-19 further compounds this problem. Due to the similar downstream mediators, we discuss the potential synergistic effects and systemic ramifications of SARS-CoV-2 and influenza virus during co-infection, a phenomenon we have termed "COVI-Flu." Additionally, the differences between CRS and cytokine storm are highlighted. Finally, novel management approaches, clinical trials, and therapeutic strategies toward both SARS-CoV-2 and COVI-Flu infection are discussed, highlighting host response optimization and systemic inflammation reduction.

Pharmacologic effects of oseltamivir in immunocompromised adult patients as assessed by population PK/PD analysis and drug-disease modelling for dosing regimen optimization

Aim

Pharmacologic effects were analysed to determine a dose recommendation for oseltamivir in immunocompromised (IC) adults with influenza.

Methods

Quantitative clinical pharmacology methods were applied to data from 160 adult IC patients (aged 18‐78 years) from two studies (NV20234, 150 patients; NV25118, 10 patients) who received oseltamivir 75‐200 mg twice daily for up to 10 days. An established population‐pharmacokinetic (PK) model with additional effects on oseltamivir and oseltamivir carboxylate (OC) clearance described the PK characteristics of oseltamivir in IC patients versus otherwise healthy (OwH) patients from previous clinical trials. Estimated PK parameters were used to evaluate exposure‐response relationships for virologic endpoints (time to cessation of viral shedding, viral load measures and treatment‐emergent resistance). A drug‐disease model characterized the viral kinetics of influenza accounting for the effect of OC on viral production.

Results

Oseltamivir clearance was 32.5% lower (95% confidence interval [CI], 26.1‐38.8) and OC clearance was 33.7% lower (95% CI, 23.2‐44.1) in IC versus OwH patients. No notable exposure‐response relationships were identified for exposures higher than those achieved after conventional dose oseltamivir 75 mg, which appeared to be close to the maximum effect of oseltamivir. Simulations of the drug‐disease model predicted that initiating treatment within 48 hours of symptom onset had maximum impact, and a treatment duration of 10 days was favourable over 3‐5 days to limit viral rebound.

Conclusions

Our findings support the use of conventional‐dose oseltamivir 75 mg twice daily for 10 days in the treatment of IC adult patients with influenza.

Anti-Influenza Hyperimmune Immunoglobulin Enhances Fc-Functional Antibody Immunity During Human Influenza Infection

Background

New treatments for severe influenza are needed. Passive transfer of influenza-specific hyperimmune pooled immunoglobulin (Flu-IVIG) boosts neutralizing antibody responses to past strains in influenza-infected subjects. The effect of Flu-IVIG on antibodies with Fc-mediated functions, which may target diverse influenza strains, is unclear.

Methods

We studied the capacity of Flu-IVIG, relative to standard IVIG, to bind to Fcγ receptors and mediate antibody-dependent cellular cytotoxicity in vitro. The effect of Flu-IVIG infusion, compared to placebo infusion, was examined in serial plasma samples from 24 subjects with confirmed influenza infection in the INSIGHT FLU005 pilot study.

Results

Flu-IVIG contains higher concentrations of Fc-functional antibodies than IVIG against a diverse range of influenza hemagglutinins. Following infusion of Flu-IVIG into influenza-infected subjects, a transient increase in Fc-functional antibodies was present for 1-3 days against infecting and noninfecting strains of influenza.

Conclusions

Flu-IVIG contains antibodies with Fc-mediated functions against influenza virus, and passive transfer of Flu-IVIG increases anti-influenza Fc-functional antibodies in the plasma of influenza-infected subjects. Enhancement of Fc-functional antibodies to a diverse range of influenza strains suggests that Flu-IVIG infusion could prove useful in the context of novel influenza virus infections, when there may be minimal or no neutralizing antibodies in the Flu-IVIG preparation.

Poor outcomes among elderly patients hospitalized for influenza-like illness

BACKGROUND AND OBJECTIVE

Global Influenza Hospital Surveillance Network is a worldwide initiative that aims to document the burden of influenza infections among acute admissions and vaccine effectiveness in particular countries. As a partner of this platform, we aimed to determine the frequency of influenza infections among acute admissions with influenza-like illness and the outcomes of enrolled patients during the 2015-2016 influenza season in selected hospitals in Turkey.

PATIENTS AND METHODS

The investigators screened the hospital admission registries, chart review or available records, and screened all patients hospitalized in the previous 24-48 hours or overnight in the predefined wards or emergency room. A total of 1351 patients were screened for enrollment in five tertiary care referral hospitals in Ankara and 774 patients (57.3% of the initial screened population) were eligible for swabbing. All of the eligible patients who consented were swabbed and tested for influenza with real-time polymerase chain reaction (PCR) based methods.

RESULTS

Overall, influenza positivity was detected in 142 patients (18.4%). The predominant influenza strain was A H1N1pdm09. Outcomes were worse among elderly patients, regardless of the presence of the influenza virus. Half of the patients over 65 years of age were admitted to the intensive care unit, while one third required any mode of mechanical ventilation and one fourth died in the hospital in that particular episode.

CONCLUSION

These findings can guide hospitals to plan and prepare for the influenza season. Effective influenza vaccination strategies, particularly aimed at the elderly and adults with chronic diseases, can provide an opportunity for prevention of deaths due to influenza-like illness.

Effects of influenza immunization on pneumonia in the elderly

Influenza virus is a common pathogen implicated in respiratory tract infections, annually affecting up to 20% of the general population, and pneumonia is a leading cause of death after influenza infection. Post-influenza pneumonia is especially common in the elderly and chronically ill patients. The risk of post-influenza pneumonia is significantly increased according to the number of concurrent comorbidities. Vaccination is the primary measure used to abate influenza epidemics and associated complications. In meta-analyses, influenza vaccine significantly reduces pneumonia- and influenza-related hospitalizations, with a vaccine effectiveness of 25-53%. However, considering the poor effectiveness of conventional influenza vaccines in the elderly, several highly immunogenic influenza vaccines have been developed. Further evaluations of the comparative effectiveness of diverse vaccine formulations are warranted to assess their utility for preventing influenza infection, post-influenza pneumonia, and related hospitalization/mortality. Based on cost-effectiveness and budget impact analysis, influenza vaccination strategies should be tailored in the elderly.

Infectious complications after hematopoietic stem cell transplantation: current status and future perspectives in Korea

Hematopoietic stem cell transplantation (HSCT) is a treatment for hematologic malignancies, immune deficiencies, or genetic diseases, ect. Recently, the number of HSCTs performed in Korea has increased and the outcomes have improved. However, infectious complications account for most of the morbidity and mortality after HSCT. Post-HSCT infectious complications are usually classified according to the time after HSCT: pre-engraftment, immediate post-engraftment, and late post-engraftment period. In addition, the types and risk factors of infectious complications differ according to the stem cell source, donor type, conditioning intensity, region, prophylaxis strategy, and comorbidities, such as graft-versushost disease and invasive fungal infection. In this review, we summarize infectious complications after HSCT, focusing on the Korean perspectives.

Antibody immunoprophylaxis and immunotherapy for influenza virus infection: Utilization of monoclonal or polyclonal antibodies?

Control programs for emerging influenza are in urgent need of novel therapeutic strategies to mitigate potentially devastating threats from pathogenic strains with pandemic potential. Current vaccines and antivirals have inherent limitations in efficacy, especially with rapid evolutionary changes of influenza viruses. Antibody-based antiviral protection harnesses the natural power of the immune system. Antibodies present prophylactic and therapeutic intervention options for prevention and control of influenza, especially for at-risk populations. Specific monoclonal antibodies are well defined in purity and initial efficacy but polyclonal antibodies are easier to scale-up and cost-effective with long-term efficacy, using batches with broadly neutralizing properties against influenza variants. This review presents the pros and cons of monoclonal versus polyclonal antibody therapy for influenza.

Preserved antiviral adaptive immunity following polyclonal antibody immunotherapy for severe murine influenza infection

Passive immunotherapy may have particular benefits for the treatment of severe influenza infection in at-risk populations, however little is known of the impact of passive immunotherapy on the formation of memory responses to the virus. Ideally, passive immunotherapy should attenuate the severity of infection while still allowing the formation of adaptive responses to confer protection from future exposure. In this study, we sought to determine if administration of influenza-specific ovine polyclonal antibodies could inhibit adaptive immune responses in a murine model of lethal influenza infection. Ovine polyclonal antibodies generated against recombinant PR8 (H1N1) hemagglutinin exhibited potent prophylactic capacity and reduced lethality in an established influenza infection, particularly when administered intranasally. Surviving mice were also protected against reinfection and generated normal antibody and cytotoxic T lymphocyte responses to the virus. The longevity of ovine polyclonal antibodies was explored with a half-life of over two weeks following a single antibody administration. These findings support the development of an ovine passive polyclonal antibody therapy for treatment of severe influenza infection which does not affect the formation of subsequent acquired immunity to the virus.

Antiviral therapy in seasonal influenza and 2009 H1N1 pandemic influenza: Korean experiences and perspectives

Influenza is a major cause of substantial morbidity and mortality in humans every year. Vaccination is the main strategy to prevent influenza infection, but antiviral agents also play an important role in the control of both seasonal and pandemic influenza. During the influenza A/H1N1 pandemic in 2009, early prompt antiviral therapy may have reduced the severity of the influenza outcomes including pneumonia, hospitalization and mortality in the Republic of Korea. Since the 2009 H1N1 pandemic, there have been increasing usages of antiviral agents for the treatment of patients with seasonal influenza. Although currently rare, antiviral resistance among influenza viruses may emerge and increase with increased use of neuraminidase inhibitors. New agents with different modes of action are under investigation, including favipiravir, DAS181, nitazoxanide and broad-spectrum neutralizing monoclonal antibodies. Data are limited with respect to high-dose and combination antiviral therapies. So, clinical trials are warranted to evaluate diverse antiviral combinations that may be synergistic and less likely to induce breakthrough resistance.

Antiviral treatment of influenza in South Korea

Antiviral therapy has an important role in the treatment and chemoprophylaxis of influenza. At present, two classes of antiviral agents, adamantanes and neuraminidase inhibitors, are available for the treatment and chemoprophylaxis of influenza in Korea. Because of the widespread resistance against adamantanes, neuraminidase inhibitors are mainly used. Because each country has a unique epidemiology of influenza, the proper use of antiviral agents should be determined based on local data. Decisions on the clinical practice in the treatment of influenza in South Korea are guided by the local surveillance data, practice guidelines, health insurance system and the resistance patterns of the circulating influenza viruses. This review highlights the role of antiviral agents in the treatment and outcome of influenza in Korea by providing comprehensive information of their clinical usage in Korea.

Do corticosteroids reduce the mortality of influenza A (H1N1) infection? A meta-analysis

Introduction

Corticosteroids are used empirically in influenza A (H1N1) treatment despite lack of clear evidence for effective treatment. This study aims to assess the efficacy of corticosteroids treatment for H1N1 infection.

Methods

Systematic review and meta-analysis were used to estimate the efficacy of corticosteroids for the prevention of mortality in H1N1 infection. Databases searched included MEDLINE, EMBASE, PubMed, Cochrane Central Register of Controlled Clinical Trials and so on, and bibliographies of retrieved articles, from April 2009 to October 2014. We included both cohort studies and case-control studies reported in English or Chinese that compared treatment effects between corticosteroids and non-corticosteroids therapy in inpatients with H1N1 virus infection. Cohort studies employed mortality as outcome, and case-control studies employed deaths as cases and survivors as controls; both were assessed in this meta-analysis.

Results

In total twenty-three eligible studies were included. Both cohort studies (nine studies, n = 1,405) and case-control studies (14 studies, n = 4,700) showed a similar trend toward increased mortality (cohort studies relative risk was 1.85 with 95% confidence interval (CI) 1.46 to 2.33; case-control studies odds ratio was 4.22 with 95% CI 3.10 to 5.76). The results from both subgroup analyses and sensitive analyses were consistent with each other, showing that steroid treatment is associated with mortality. However, considering the fact that corticosteroids were tend to be used in sickest case-patients and heterogeneity was observed between studies, we cannot make a solid conclusion.

Conclusions

Available evidence did not support the use of corticosteroids as standard care for patients with severe influenza. We conclude that further research is required.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0764-5) contains supplementary material, which is available to authorized users.