Statins and influenza: can we move forward?

Statin use and medically attended acute respiratory illness among influenza vaccine recipients

BACKGROUND

Previous studies have suggested that statins decrease influenza vaccine effectiveness and increase risk of medically attended acute respiratory illness (MAARI).

OBJECTIVES

To examine the association of incident statin use and MAARI in a cohort of influenza vaccine recipients.

METHODS

This retrospective cohort study evaluated influenza vaccine recipients within the Tricare population. The primary outcome compared MAARI incidence during the follow-up period in a propensity score-matched cohort of incident statin users and statin non-users. Secondary analysis included propensity score-adjusted comparisons between incident statin users and statin non-users in the entire cohort and prespecified sub-cohorts with and without comorbidities. The propensity score was derived from 72 variables encompassing demographics, medical history, comorbidities, medication use, and healthcare utilization.

RESULTS

MAARI incidence in statin users was similar to non-users in the propensity score-matched cohort (odds ratio [OR] 0.92; 95% confidence interval [CI] 0.84-1.01). In contrast, statin users with lower comorbidity had lower OR for MAARI compared to non-users (Charlson Score zero cohort: 0.85 [CI 0.74-0.98]; No Diabetes cohort: 0.88 [CI 0.80-0.96]).

CONCLUSION

Incident statin use was not associated with increased MAARI incidence and may be associated with lower incidence of MAARI in those with less comorbidity. This study thus offers reassurance regarding the effectiveness of the influenza vaccine in statin users.

Skin immunization by microneedle patch overcomes statin-induced suppression of immune responses to influenza vaccine

Recent studies indicated that in elderly individuals, statin therapy is associated with a reduced response to influenza vaccination. The present study was designed to determine effects on the immune response to influenza vaccination induced by statin administration in a mouse model, and investigate potential approaches to improve the outcome of vaccination on the background of statin therapy. We fed middle aged BALB/c mice a high fat “western” diet (WD) alone or supplemented with atorvastatin (AT) for 14 weeks, and control mice were fed with the regular rodent diet. Mice were immunized with a single dose of subunit A/Brisbane/59/07 (H1N1) vaccine, either systemically or with dissolving microneedle patches (MNPs). We observed that a greater age-dependent decline in the hemagglutinin inhibition titers occurred in systemically-immunized mice than in MNP- immunized mice. AT dampened the antibody response in the animals vaccinated by either route of vaccine delivery. However, the MNP-vaccinated AT-treated animals had ~20 times higher total antibody levels to the influenza vaccine than the systemically vaccinated group one month postvaccination. We propose that microneedle vaccination against influenza provides an approach to ameliorate the immunosuppressive effect of statin therapy observed with systemic immunization.

Neuraminidase inhibitors, superinfection and corticosteroids affect survival of influenza patients

We aimed to study factors influencing outcomes of adults hospitalised for seasonal and pandemic influenza.  Individual-patient data from three Asian cohorts (Hong Kong, Singapore and Beijing; N=2649) were analysed. Adults hospitalised for laboratory-confirmed influenza (prospectively diagnosed) during 2008-2011 were studied. The primary outcome measure was 30-day survival. Multivariate Cox regression models (time-fixed and time-dependent) were used. Patients had high morbidity (respiratory/nonrespiratory complications in 68.4%, respiratory failure in 48.6%, pneumonia in 40.8% and bacterial superinfections in 10.8%) and mortality (5.9% at 30 days and 6.9% at 60 days). 75.2% received neuraminidase inhibitors (NAI) (73.8% received oseltamivir and 1.4% received peramivir/zanamivir; 44.5% of patients received NAI ≤2 days and 65.5% ≤5 days after onset of illness); 23.1% received systemic corticosteroids. There were fewer deaths among NAI-treated patients (5.3% versus 7.6%; p=0.032). NAI treatment was independently associated with survival (adjusted hazard ratio (HR) 0.28, 95% CI 0.19-0.43), adjusted for treatment-propensity score and patient characteristics. Superinfections increased (adjusted HR 2.18, 95% CI 1.52-3.11) and chronic statin use decreased (adjusted HR 0.44, 95% CI 0.23-0.84) death risks. Best survival was shown when treatment started within ≤2 days (adjusted HR 0.20, 95% CI 0.12-0.32), but there was benefit with treatment within 3-5 days (adjusted HR 0.35, 95% CI 0.21-0.58). Time-dependent analysis showed consistent results of NAI treatment (adjusted HR 0.39, 95% CI 0.27-0.57). Corticosteroids increased superinfection (9.7% versus 2.7%) and deaths when controlled for indications (adjusted HR 1.73, 95% CI 1.14-2.62). Early NAI treatment was associated with shorter length of stay in a subanalysis. NAI treatment may improve survival of hospitalised influenza patients; benefit is greatest from, but not limited to, treatment started within 2 days of illness. Superinfections and corticosteroids increase mortality. Antiviral and non-antiviral management strategies should be considered.

Lipids in innate antiviral defense

It is becoming apparent that infections by a major class of viruses, those with envelopes, can be inhibited during their entry at the step of fusion with cellular membranes. In this review, we discuss multiple innate immune mechanisms that have evolved to modify the lipid composition of cellular and viral membranes to inhibit virion fusion of enveloped viruses.

Clinical relevance of target identity and biology: implications for drug discovery and development

Many of the most commonly used drugs precede techniques for target identification and drug specificity and were developed on the basis of efficacy and safety, an approach referred to as classical pharmacology and, more recently, phenotypic drug discovery. Although substantial gains have been made during the period of focus on target-based approaches, particularly in oncology, these approaches have suffered a high overall failure rate and lower productivity in terms of new drugs when compared with phenotypic approaches. This review considers the importance of target identity and biology in clinical practice from the prescriber's viewpoint. In evaluating influences on prescribing behavior, studies suggest that target identity and mechanism of action are not significant factors in drug choice. Rather, patients and providers consistently value efficacy, safety, and tolerability. Similarly, the Food and Drug Administration requires evidence of safety and efficacy for new drugs but does not require knowledge of drug target identity or target biology. Prescribers do favor drugs with novel mechanisms, but this preference is limited to diseases for which treatments are either not available or suboptimal. Thus, while understanding of drug target and target biology is important from a scientific perspective, it is not particularly important to prescribers, who prioritize efficacy and safety.

Treating influenza with statins and other immunomodulatory agents

Statins not only reduce levels of LDL-cholesterol, they counteract the inflammatory changes associated with acute coronary syndrome and improve survival. Similarly, in patients hospitalized with laboratory-confirmed seasonal influenza, statin treatment is associated with a 41% reduction in 30-day mortality. Most patients of any age who are at increased risk of influenza mortality have chronic low-grade inflammation characteristic of metabolic syndrome. Moreover, differences in the immune responses of children and adults seem responsible for the low mortality in children and high mortality in adults seen in the 1918 influenza pandemic and in other acute infectious and non-infectious conditions. These differences probably reflect human evolutionary development. Thus the host response to influenza seems to be the major determinant of outcome. Outpatient statins are associated with reductions in hospitalizations and deaths due to sepsis and pneumonia. Inpatient statins are also associated with reductions in short-term pneumonia mortality. Other immunomodulatory agents--ACE inhibitors (ACEIs), angiotensin receptor blockers (ARBs), PPARγ and PPARα agonists (glitazones and fibrates) and AMPK agonists (metformin)--also reduce mortality in patients with pneumonia (ACEIs, ARBs) or in mouse models of influenza (PPAR and AMPK agonists). In experimental studies, treatment has not increased virus replication. Thus effective management of influenza may not always require targeting the virus with vaccines or antiviral agents. Clinical investigators, not systems biologists, have been the first to suggest that immunomodulatory agents might be used to treat influenza patients, but randomized controlled trials will be needed to provide convincing evidence that they work. To guide the choice of which agent(s) to study, we need new types of laboratory research in animal models and clinical and epidemiological research in patients with critical illness. These studies will have crucial implications for global public health. During the 2009 H1N1 influenza pandemic, timely and affordable supplies of vaccines and antiviral agents were unavailable to more than 90% of the world's people. In contrast, statins and other immunomodulatory agents are currently produced as inexpensive generics, global supplies are huge, and they would be available to treat patients in any country with a basic health care system on the first pandemic day. Treatment with statins and other immunomodulatory agents represents a new approach to reducing mortality caused by seasonal and pandemic influenza.

Human H5N1 influenza infections in Cambodia 2005-2011: case series and cost-of-illness

Background

Southeast Asia has been identified as a potential epicentre of emerging diseases with pandemic capacity, including highly pathogenic influenza. Cambodia in particular has the potential for high rates of avoidable deaths from pandemic influenza due to large gaps in health system resources. This study seeks to better understand the course and cost-of-illness for cases of highly pathogenic avian influenza in Cambodia.

Methods

We studied the 18 laboratory-confirmed cases of avian influenza subtype H5N1 identified in Cambodia between January 2005 and August 2011. Medical records for all patients were reviewed to extract information on patient characteristics, travel to hospital, time to admission, diagnostic testing, treatment and disease outcomes. Further data related to costs was collected through interviews with key informants at district and provincial hospitals, the Ministry of Health and non-governmental organisations. An ingredient-based approach was used to estimate the total economic cost for each study patient. Costing was conducted from a societal perspective and included both financial and opportunity costs to the patient or carer. Sensitivity analysis was undertaken to evaluate potential change or variation in the cost-of-illness.

Results

Of the 18 patients studied, 11 (61%) were under the age of 18 years. The majority of patients (16, 89%) died, eight (44%) within 24 hours of hospital admission. There was an average delay of seven days between symptom onset and hospitalisation with patients travelling an average of 148 kilometres (8-476 km) to the admitting hospital. Five patients were treated with oseltamivir of whom two received the recommended dose. For the 16 patients who received all their treatment in Cambodia the average per patient cost of H5N1 influenza illness was US$300 of which 85.0% comprised direct medical provider costs, including diagnostic testing (41.2%), pharmaceuticals (28.4%), hospitalisation (10.4%), oxygen (4.4%) and outpatient consultations (0.6%). Patient or family costs were US$45 per patient (15.0%) of total economic cost.

Conclusion

Cases of avian influenza in Cambodia were characterised by delays in hospitalisation, deficiencies in some aspects of treatment and a high fatality rate. The costs associated with medical care, particularly diagnostic testing and pharmaceutical therapy, were major contributors to the relatively high cost-of-illness.

The controversy over H5N1 transmissibility research: an opportunity to define a practical response to a global threat

Since December 2011, influenza virologists and biosecurity experts have been engaged in a controversial debate over research on the transmissibility of H5N1 influenza viruses. Influenza virologists disagreed with the NSABB's recommendation not to publish experimental details of their findings, whereas biosecurity experts wanted the details to be withheld and future research restricted. The virologists initially declared a voluntary moratorium on their work, but later the NSABB allowed their articles to be published, and soon transmissibility research will resume. Throughout the debate, both sides have had understandable views, but both have overlooked the more important question of whether anything could be done if one of these experimentally derived viruses or a naturally occurring and highly virulent influenza virus should emerge and cause a global pandemic. This is a crucial question, because during the 2009 H1N1 influenza pandemic, more than 90% of the world's people had no access to timely supplies of affordable vaccines and antiviral agents. Observational studies suggest that inpatient statin treatment reduces mortality in patients with laboratory-confirmed seasonal influenza. Other immunomodulatory agents (glitazones, fibrates and AMPK agonists) improve survival in mice infected with influenza viruses. These agents are produced as inexpensive generics in developing countries. If they were shown to be effective, they could be used immediately to treat patients in any country with a basic health care system. For this reason alone, influenza virologists and biosecurity experts need to join with public health officials to develop an agenda for laboratory and clinical research on these agents. This is the only approach that could yield practical measures for a global response to the next influenza pandemic.

Effect of statin treatments on highly pathogenic avian influenza H5N1, seasonal and H1N1pdm09 virus infections in BALB/c mice

Statins are used to control elevated cholesterol or hypercholesterolemia, but have previously been reported to have antiviral properties. AIMS: To show efficacy of statins in various influenza virus mouse models. MATERIALS & METHODS: BALB/c mice were treated intraperitoneally or orally with several types of statins (simvastatin, lovastatin, mevastatin, pitavastatin, atorvastatin or rosuvastatin) at various concentrations before or after infection with either influenza A/Duck/ MN/1525/81 H5N1 virus, influenza A/Vietnam/1203/2004 H5N1 virus, influenza A/ Victoria/3/75 H3N2 virus, influenza A/NWS/33 H1N1 virus or influenza A/CA/04/09 H1N1pdm09 virus. RESULTS: The statins administered intraperitoneally or orally at any dose did not significantly enhance the total survivors relative to untreated controls. In addition, infected mice receiving any concentration of statin were not protected against weight loss due to the infection. None of the statins significantly increased the mean day of death relative to mice in the placebo treatment group. Furthermore, the statins had relatively few ameliorative effects on lung pathology or lung weights at day 3 and 6 after virus exposure, although mice treated with simvastatin did have improved lung function as measured by arterial saturated oxygen levels in one experiment. CONCLUSION: Statins showed relatively little efficacy in any mouse model used by any parameter tested.