Impact of zanamivir treatment on productivity, health status and healthcare resource use in patients with influenza. Zanamivir Study Group

Switching from trivalent to quadrivalent inactivated influenza vaccines in Uruguay: a cost-effectiveness analysis

We evaluated the cost-utility of replacing trivalent influenza vaccine (TIV) with quadrivalent influenza vaccine (QIV) in the current target populations in Uruguay. An existing decision-analytic static cost-effectiveness model was adapted for Uruguay. The population was stratified into age groups. Costs and outcomes were estimated for an average influenza season, based on observed rates from 2013 to 2019 inclusive. Introducing QIV instead of TIV in Uruguay would avoid around 740 additional influenza cases, 500 GP consultations, 15 hospitalizations, and three deaths, and save around 300 workdays, for the same vaccination coverage during an average influenza season. Most of the influenza-related consultations and hospitalizations would be avoided among children ≤4 and adults ≥65 years of age. Using QIV rather than TIV would cost an additional ~US$729,000, but this would be partially offset by savings in consultations and hospitalization costs. The incremental cost per quality-adjusted life-year (QALY) gained with QIV would be in the order of US$18,000 for both the payor and societal perspectives, for all age groups, and around US$12,000 for adults ≥65 years of age. The main drivers influencing the incremental cost-effectiveness ratio were the vaccine efficacy against the B strains and the percentage of match each season with the B strain included in TIV. Probabilistic sensitivity analysis showed that switching to QIV would provide a favorable cost-utility ratio for 50% of simulations at a willingness-to-pay per QALY of US$20,000. A switch to QIV is expected to be cost-effective for the current target populations in Uruguay, particularly for older adults.

Cost Utility of Switching From Trivalent to Quadrivalent Influenza Vaccine in Turkey

OBJECTIVES

Trivalent influenza vaccines (TIVs) are widely used but protect against only 1 of the 2 co-circulating influenza B virus lineages. Quadrivalent influenza vaccines (QIVs) include a B strain from each lineage to overcome mismatches. The main objective of this study was to determine the cost-utility and budget impact of switching from vaccination with TIV to QIV in the population recommended for influenza vaccination in Turkey.

METHODS

A static cohort cost-effectiveness model was developed to predict influenza-related costs and outcomes under a QIV versus a TIV program during an influenza season. The model was informed by data from Turkey on influenza strain distribution, influenza-attributable outcomes, and associated costs over the seasons 2010/2011 to 2016/2017. The effectiveness of each strategy was measured through quality-adjusted life-years (QALYs), and comparisons were based on the incremental cost-effectiveness ratio.

RESULTS

In an average influenza season, the model showed that switching from TIV to QIV would prevent an additional 15 092 cases of influenza, 6311 general practitioner visits, 94 hospitalizations, 13 deaths, and gain 440 QALYs. From the societal perspective, this amounted to total cost savings of international dollars (I$) 1102 710 (US$388 643). The incremental cost-effectiveness ratio when using QIV over TIV was I$55 248/QALY gained. Switching to QIV is mostly cost-effective among older adults with I$36 413.38/QALY. Sensitivity analysis showed that vaccine effectiveness, B strain mismatch, and influenza visits highly impact the cost-effectiveness results.

CONCLUSION

Switching from TIV to QIV is likely to be cost-effective in Turkey, yet highly dependent on the severity of the influenza season, B strain epidemiology, and vaccine effectiveness.

A population-based estimate of the economic burden of influenza in Peru, 2009-2010

Introduction

Influenza disease burden and economic impact data are needed to assess the potential value of interventions. Such information is limited from resource‐limited settings. We therefore studied the cost of influenza in Peru.

Methods

We used data collected during June 2009–December 2010 from laboratory‐confirmed influenza cases identified through a household cohort in Peru. We determined the self‐reported direct and indirect costs of self‐treatment, outpatient care, emergency ward care, and hospitalizations through standardized questionnaires. We recorded costs accrued 15‐day from illness onset. Direct costs represented medication, consultation, diagnostic fees, and health‐related expenses such as transportation and phone calls. Indirect costs represented lost productivity during days of illness by both cases and caregivers. We estimated the annual economic cost and the impact of a case of influenza on a household.

Results

There were 1321 confirmed influenza cases, of which 47% sought health care. Participants with confirmed influenza illness paid a median of $13 [interquartile range (IQR) 5–26] for self‐treatment, $19 (IQR 9–34) for ambulatory non‐medical attended illness, $29 (IQR 14–51) for ambulatory medical attended illness, and $171 (IQR 113–258) for hospitalizations. Overall, the projected national cost of an influenza illness was $83–$85 millions. Costs per influenza illness represented 14% of the monthly household income of the lowest income quartile (compared to 3% of the highest quartile).

Conclusion

Influenza virus infection causes an important economic burden, particularly among the poorest families and those hospitalized. Prevention strategies such as annual influenza vaccination program targeting SAGE population at risk could reduce the overall economic impact of seasonal influenza.

Economic evaluations of neuraminidase inhibitors to control influenza

Up to 10% of individuals present influenza-like illness each year. Neuraminidase inhibitors significantly reduce the median duration of influenza symptoms by 1.38 days and median time to return to normal activities by 0.9 days in adults. This review presents the economic evaluations of neuraminidase inhibitors in adults. The choice of key parameter estimates in cost-effectiveness and cost-benefit analysis is sensitive to the perspective of analysis: healthcare payer or societal, including productivity gains. This review discusses, among other key parameters, the proportion of influenza-like illness due to the influenza virus (targeted by neuraminidase inhibitors and influenza vaccine), and the measure of health benefits by either quality-adjusted life years gained or willingness-to-pay for a day of symptoms averted. Overall, neuraminidase inhibitors are worth their costs and do not challenge annual influenza vaccination but should be seen as a complementary option to reduce the burden of influenza.

Methodological considerations for future controlled influenza treatment trials in complementary and alternative medicine

BACKGROUND

The continuous threat of influenza pandemic, as well as the ongoing costs to human life and health care systems from yearly epidemics, create a continual need for progress in this area of public health. The diversity of available complementary and alternative medicine (CAM) treatment options are well known to the CAM profession, but poorly understood and accepted in mainstream medicine. This situation comes as no surprise given conventional medicine's reliance on repeated, large-scale randomized controlled trials of standardized design to support evidence-based clinical use of influenza antiviral drugs. The relatively low volume of well-conducted clinical trials on the treatment of influenza with CAM therapies compared to the high availability of conventional antiviral drug trials magnifies this problem.

OBJECTIVES

The aim of this article is to provide structured guidelines for future CAM influenza studies based on a thorough review of consistent and standard design elements present in the controlled-trial design of conventional antiviral influenza therapies.

RESULTS

A selection of high-quality, influenza antiviral controlled trials from the published literature is reviewed, and important design elements are extracted and summarized to show both the consistency and the flexibility within study design elements.

CONCLUSIONS

The standardized elements from influenza antiviral trials can be considered and mirrored in future CAM studies. In this way, CAM therapies might be looked at on similar grounds as conventional medicines in terms of potential usefulness and benefit in the treatment of influenza.

Neuraminidase inhibitors for preventing and treating influenza in healthy adults

BACKGROUND

Neuraminidase inhibitors (NI) are recommended for use against influenza and its complications in inter-pandemic years and during pandemics.

OBJECTIVES

To assess the effects of NIs in preventing and treating influenza, its transmission, and its complications in otherwise healthy adults, and to estimate the frequency of adverse effects.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 3) which contains the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1950 to August 2009) and EMBASE (1980 to August 2009).

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-randomised placebo-controlled trials of NIs in healthy adults exposed to naturally occurring influenza.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied inclusion criteria, assessed trial quality, and extracted data. We structured the comparisons into prophylaxis, treatment, and adverse events, with further subdivision by outcome and dose.

MAIN RESULTS

We identified four prophylaxis, 12 treatment and four post-exposure prophylaxis trials. In prophylaxis compared to placebo, NIs had no effect against influenza-like illnesses (ILI) (risk ratio (RR) ranging from 1.28 for oral oseltamivir 75 mg daily to 0.76 for inhaled zanamivir 10 mg daily). The efficacy of oral oseltamivir against symptomatic influenza was 76% (at 75 mg daily), and 73% (at 150 mg daily). Inhaled zanamivir 10 mg daily performed similarly. Neither NI had a significant effect on asymptomatic influenza. Oseltamivir induced nausea (odds ratio (OR) 1.79, 95% CI 1.10 to 2.93). Oseltamivir for post-exposure prophylaxis had an efficacy of 58% and 84% in two trials for households. Zanamivir performed similarly. The hazard ratios for time to alleviation of symptoms were in favour of the treated group 1.20 (1.06 to 1.35) for oseltamivir and 1.24 (1.13 to 1.36) for zanamivir. Because of the exclusion of a review of mainly unpublished trials of oseltamivir, insufficient evidence remained to reach a conclusion on the prevention of complications requiring antibiotics in influenza cases (RR 0.57, 95% CI 0.23 to 1.37). Analysis of the US FDA and Japan's PMDA regulators' pharmacovigilance dataset, revealed incomplete reporting and description of harms preventing us from reaching firm conclusions on the central nervous system toxicity of neuraminidase inhibitors.

AUTHORS' CONCLUSIONS

Numerous inconsistencies detected in the available evidence, followed by an inability to adequately access the data, has undermined confidence in our previous conclusions for oseltamivir. Independent RCTs to resolve these uncertainties are needed.

Neuraminidase inhibitors for preventing and treating influenza in healthy adults: systematic review and meta-analysis

OBJECTIVES

To update a 2005 Cochrane review that assessed the effects of neuraminidase inhibitors in preventing or ameliorating the symptoms of influenza, the transmission of influenza, and complications from influenza in healthy adults, and to estimate the frequency of adverse effects. Search strategy An updated search of the Cochrane central register of controlled trials (Cochrane Library 2009, issue 2), which contains the Acute Respiratory Infections Group's specialised register, Medline (1950-Aug 2009), Embase (1980-Aug 2009), and post-marketing pharmacovigilance data and comparative safety cohorts. Selection criteria Randomised placebo controlled studies of neuraminidase inhibitors in otherwise healthy adults exposed to naturally occurring influenza.

MAIN OUTCOME MEASURES

Duration and incidence of symptoms; incidence of lower respiratory tract infections, or their proxies; and adverse events.

DATA EXTRACTION

Two reviewers applied inclusion criteria, assessed trial quality, and extracted data. Data analysis Comparisons were structured into prophylaxis, treatment, and adverse events, with further subdivision by outcome and dose.

RESULTS

20 trials were included: four on prophylaxis, 12 on treatment, and four on postexposure prophylaxis. For prophylaxis, neuraminidase inhibitors had no effect against influenza-like illness or asymptomatic influenza. The efficacy of oral oseltamivir against symptomatic laboratory confirmed influenza was 61% (risk ratio 0.39, 95% confidence interval 0.18 to 0.85) at 75 mg daily and 73% (0.27, 0.11 to 0.67) at 150 mg daily. Inhaled zanamivir 10 mg daily was 62% efficacious (0.38, 0.17 to 0.85). Oseltamivir for postexposure prophylaxis had an efficacy of 58% (95% confidence interval 15% to 79%) and 84% (49% to 95%) in two trials of households. Zanamivir performed similarly. The hazard ratios for time to alleviation of influenza-like illness symptoms were in favour of treatment: 1.20 (95% confidence interval 1.06 to 1.35) for oseltamivir and 1.24 (1.13 to 1.36) for zanamivir. Eight unpublished studies on complications were ineligible and therefore excluded. The remaining evidence suggests oseltamivir did not reduce influenza related lower respiratory tract complications (risk ratio 0.55, 95% confidence interval 0.22 to 1.35). From trial evidence, oseltamivir induced nausea (odds ratio 1.79, 95% confidence interval 1.10 to 2.93). Evidence of rarer adverse events from pharmacovigilance was of poor quality or possibly under-reported.

CONCLUSION

Neuraminidase inhibitors have modest effectiveness against the symptoms of influenza in otherwise healthy adults. The drugs are effective postexposure against laboratory confirmed influenza, but this is a small component of influenza-like illness, so for this outcome neuraminidase inhibitors are not effective. Neuraminidase inhibitors might be regarded as optional for reducing the symptoms of seasonal influenza. Paucity of good data has undermined previous findings for oseltamivir's prevention of complications from influenza. Independent randomised trials to resolve these uncertainties are needed.

Prescription of anti-influenza drugs for healthy adults: a systematic review and meta-analysis

In publicly funded health systems with finite resources, management decisions are based on assessments of clinical effectiveness and cost-effectiveness. The UK National Institute for Health and Clinical Excellence commissioned a systematic review to inform their 2009 update to guidance on the use of antiviral drugs for the treatment of influenza. We searched databases for studies of the use of neuraminidase inhibitors for the treatment of seasonal influenza. We present the results for healthy adults (ie, adults without known comorbidities) and people at-risk of influenza-related complications. There was an overall reduction in the median time to symptom alleviation in healthy adults by 0.57 days (95% CI -1.07 to -0.08; p=0.02; 2701 individuals) with zanamivir, and 0.55 days (95% CI -0.96 to -0.14; p=0.008; 1410 individuals) with oseltamivir. In those at risk, the median time to symptom alleviation was reduced by 0.98 days (95% CI -1.84 to -0.11; p=0.03; 1252 individuals) with zanamivir, and 0.74 days (95% CI -1.51 to 0.02; p=0.06; 1472 individuals) with oseltamivir. Little information was available on the incidence of complications. In view of the advantages and disadvantages of different management strategies for controlling seasonal influenza in healthy adults recommending the use of antiviral drugs for the treatment of people presenting with symptoms is unlikely to be the most appropriate course of action.

The impact of influenza on working days lost: a review of the literature

Seasonal influenza is a prevalent and highly contagious acute respiratory disease that, year on year, results in increased morbidity and mortality on a global scale. Because of the widespread and debilitating nature of the disease, annual influenza epidemics result in substantial workplace absenteeism, and the associated cost of lost productivity is a significant component of the substantial financial burden of the disease to society. The objective of this review was to identify studies that had attempted to quantify the impact of influenza upon otherwise healthy adults in terms of working days lost associated with an episode of influenza.Studies were included if they reported estimates of working days lost due to clinical, physician and/or self-diagnosis in adult patients or their dependants, or where this figure could be estimated from the data. Searches were conducted in MEDLINE, EMBASE, BIOSIS and the Cochrane Collaboration for articles published since 1995 in English, French or German. Of the 289 papers identified in the search, 28 (9.7%) met the inclusion criteria. The studies, involving study sites in North America, Western Europe, Asia and Australia, were categorized into three groups: (i) those reporting influenza diagnoses confirmed by laboratory testing, i.e. studies where influenza was the unambiguous cause of the working days lost (n = 7 studies reported in ten publications); (ii) those where influenza was confirmed by a physician without an accompanying laboratory test (n = 4 studies); and (iii) those where influenza was self-reported by study participants (n = 14 studies). Qualitative reporting of results was performed because of the large degree of heterogeneity observed between studies, potentially complicating the interpretation of any meta-analysis.The results from studies involving a laboratory-confirmed influenza diagnosis suggested that the mean number of working days lost ranged between 1.5 and 4.9 days per episode. Those papers that detailed working days lost per episode following physician diagnosis of influenza reported a range of 3.7-5.9 days per episode. Finally, estimates from papers reporting working days lost per episode of self-reported influenza ranged from <1 day to 4.3 days per episode.Influenza imposes a significant burden on society, and this review highlights the significant economic impact it causes, i.e. the loss of productivity caused by both absenteeism and by staff functioning at reduced capacity even after they have returned to work. A number of prophylaxis and treatment options exist for influenza and should be given serious consideration in an attempt to reduce the economic burden on society.

The cost-effectiveness of influenza vaccination for people aged 50 to 64 years: an international model

OBJECTIVES

Routine influenza vaccination is currently recommended in several countries for people aged more than 60 or 65 years or with high risk of complications. A lower age threshold of 50 years has been recommended in the United States since 1999. To help policymakers consider whether such a policy should be adopted more widely, we conducted an economic evaluation of lowering the age limit for routine influenza vaccination to 50 years in Brazil, France, Germany, and Italy.

METHODS

The probabilistic model was designed to compare in a single season the costs and clinical outcomes associated with two alternative vaccination policies for persons aged 50 to 64 years: reimbursement only for people at high risk of complications (current policy), and reimbursement for all individuals in this age group (proposed policy). Two perspectives were considered: third-party payer (TPP) and societal. Model inputs were obtained primarily from the published literature and validated through expert opinion. The historical distribution of annual influenza-like illness (ILI) incidence was used to simulate the uncertain incidence in any given season. We estimated gains in unadjusted and quality-adjusted life expectancy, and the cost per quality-adjusted life-year (QALY) gained. Deterministic and probabilistic sensitivity analyses were conducted.

RESULTS

Comparing the proposed to the current policy, the estimated mean costs per QALY gained were R$4,100, EURO 13,200, EURO 31,400 and EURO 15,700 for Brazil, France, Germany, and Italy, respectively, from a TPP perspective. From the societal perspective, the age-based policy is predicted to yield net cost savings in Germany and Italy, whereas the cost per QALY decreased to R$2800 for Brazil and EURO 8000 for France. The results were particularly sensitive to the ILI incidence rate, vaccine uptake, influenza fatality rate, and the costs of administering vaccination. Assuming a cost-effectiveness threshold ratio of EURO 50,000 per QALY gained, the probabilities of the new policy being cost-effective were 94% and 95% for France, 72% and near 100% for Germany, and 89% and 99% for Italy, from the TPP and societal perspectives, respectively.

CONCLUSIONS

Extending routine influenza vaccination to people more than 50 years of age is likely to be cost-effective in all four countries studied.

Impact of influenza treatment with oseltamivir on health, sleep and daily activities of otherwise healthy adults and adolescents

OBJECTIVE

To determine the effect of oseltamivir (75mg twice daily) on time to return to baseline health, sleep and activity in patients with laboratory-confirmed influenza infection.

PATIENTS AND METHODS

Data from 1642 otherwise healthy adults (aged 13-64 years), who had experienced a febrile influenza-like illness (>38 degrees C) of up to 36 hours' duration together with at least one respiratory and one systemic/constitutional symptom, were pooled from four randomised, double-blind, placebo-controlled clinical trials. Patients in these trials had been randomised to receive either oseltamivir or placebo for 5 days and had been allowed unlimited use of symptom-relief medications. The primary analysis examined the effect of oseltamivir treatment on patients' general health status, sleep and normal activities as measured by visual analogue scales. Secondary analyses examined the possible effects of gender, influenza type, smoking, employment status and time to treatment (< or = or >24 hours) on these endpoints.

RESULTS

Oseltamivir significantly reduced the time taken to return to baseline health, sleep and activity across all pooled patients (p < 0.0001) and increased the proportion of patients returning to full activity within the first 7 days following treatment start. Gender, smoking status, time to treatment, influenza subtype and employment status had no appreciable effect on the effectiveness of oseltamivir.

CONCLUSIONS

In otherwise healthy adults, oseltamivir reduces the time to return to pre-illness levels of health, sleep and activity, and may help to decrease the overall burden of influenza on society. This provides an important rationale for the early use of antiviral treatment, such as oseltamivir, for the treatment of influenza in otherwise healthy adults and adolescents.

Neuraminidase inhibitors for preventing and treating influenza in healthy adults

BACKGROUND

Neuraminidase inhibitors (NI) are recommended for use against influenza and its complications in interpandemic years and in a pandemic.

OBJECTIVES

To assess the effects of NIs in preventing or ameliorating influenza, its transmission and its complications in healthy adults and to estimate the frequency of adverse effects.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2005), MEDLINE (2004 to September, Week 4 2005), EMBASE (2003 to June 2005) and contacted manufacturers, researchers in the field, and authors of studies evaluated in the review.

SELECTION CRITERIA

Randomised or quasi-randomised placebo-controlled studies of NIs in healthy adults exposed to naturally occurring influenza.

DATA COLLECTION AND ANALYSIS

Two authors applied inclusion criteria, assessed trial quality and extracted data. We structured the comparisons into prophylaxis, treatment and adverse events with further subdivision by outcome and dose.

MAIN RESULTS

We identified four prophylaxis, 13 treatment and four post-exposure prophylaxis (PEP) trials. In prophylaxis compared to placebo, NIs have no effect against influenza-like illnesses (ILI) (relative risk (RR) 1.28, 95% confidence interval (CI) 0.45 to 3.66 for oral oseltamivir 75 mg daily; RR 1.51, 95% CI 0.77 to 2.95 for inhaled zanamivir 10 mg daily). The efficacy of oral oseltamivir 75 mg daily against symptomatic influenza is 61% (RR 0.39, 95% CI 0.18 to 0.85), or 73% (RR 0.27, 95% CI 0.11 to 0.67) at 150 mg daily. Inhaled zanamivir 10 mg daily is 62% efficacious (RR 0.38, 95% CI 0.17 to 0.85). Neither NI has a significant effect on asymptomatic influenza. Oseltamivir induces nausea (odds ratio (OR) 1.79, 95% CI 1.10 to 2.93). Oseltamivir for PEP has an efficacy of 58.5% (15.6% to 79.6) for households and of 68% (34.9 to 84.2%) to 89% in contacts of index cases. Zanamivir has similar performance. The hazard ratios for time to alleviation of influenza symptoms were in favour of the treated group 1.33 (1.29 to 1.37) for zanamivir and 1.30 (1.13 to 1.50) for oseltamivir. Viral nasal titres were significantly diminished by both NIs. Oseltamivir 150 mg daily prevented lower respiratory tract complications (OR 0.32, 95% CI 0.18 to 0.57). We could find no comparative data on the effects of oseltamivir on avian influenza.

AUTHORS' CONCLUSIONS

Because of their low effectiveness, NIs should not be used in routine seasonal influenza control. In a serious epidemic or pandemic, NIs should be used with other public health measures. We are unsure of the generalisability of our conclusions from seasonal to pandemic or avian influenza.

Antivirals for influenza in healthy adults: systematic review

BACKGROUND

Use of antivirals is recommended for the control of seasonal and pandemic influenza. Our aim was to review the evidence of efficacy, effectiveness, and safety of registered antivirals against naturally occurring influenza in healthy adults.

METHODS

We searched various Databases to October, 2005, and contacted manufacturers and corresponding authors. We included randomised controlled trials comparing prophylactic (n=27) or treatment (n=27) efficacy against symptomatic or asymptomatic influenza. We did a meta-analysis and expressed prophylactic efficacy as a proportion (1-relative risk [RR]). For treatment trials, because of inconsistent and non-standardised reporting, we expressed continuous outcomes either as means or as hazard ratios.

FINDINGS

We included 51 reports of 52 randomised controlled trials. Amantadine prevented 61% (95% CI 35-76) of influenza A cases and 25% (13-36) of cases of influenza-like illness, but caused nausea (OR 2.56, 1.37-4.79), insomnia and hallucinations (2.54, 1.50-4.31), and withdrawals because of adverse events (2.54, 1.60-4.06). There was no effect on asymptomatic cases (RR 0.85, 0.40-1.80). In treatment, amantadine significantly shortened duration of fever compared with placebo (by 0.99 days, -1.26 to -0.71), but had no effect on nasal shedding of influenza A viruses (0.93, 0.71-1.21). The fewer data for rimantadine showed comparable effects. In prophylaxis, compared with placebo, neuraminidase inhibitors have no effect against influenza-like illness (1.28, 0.45-3.66 for oral oseltamivir 75 mg daily, 1.51, 0.77-2.95 for inhaled zanamivir 10 mg daily). Higher doses appear to make no difference. The efficacy of oral oseltamivir 75 mg daily against symptomatic influenza is 61% (15-82), or 73% (33-89) at 150 mg daily. Inhaled zanamivir 10 mg daily is 62% efficacious (15-83). Neither neuraminidase inhibitor appeared effective against asymptomatic influenza. Oseltamivir induces nausea (OR 1.79, 1.10-2.93), especially at higher prophylactic doses (2.29, 1.34-3.92). Oseltamivir in a post-exposure prophylaxis role has a protective efficacy of 58.5% (15.6-79.6) for households and from 68% (34.9-84.2) to 89% (67-97) in contacts of index cases. In influenza cases, compared with placebo the hazard ratios for time to alleviation of symptoms were 1.33, 1.29-1.37 for zanamivir; 1.30, 1.13-1.50 for oseltamivir provided medication was started within 48 h of symptom onset. Viral nasal titres were significantly diminished by both drugs (weighted mean difference -0.62, -0.82 to -0.41). Oseltamivir at 150 mg daily was effective in preventing lower respiratory tract complications in influenza cases (OR 0.32, 0.18-0.57). We could find no credible data on the effects of oseltamivir on avian influenza.

INTERPRETATION

The use of amantadine and rimantadine should be discouraged. Because of their low effectiveness, neuraminidase inhibitors should not be used in seasonal influenza control and should only be used in a serious epidemic or pandemic alongside other public-health measures.

Messung der gesundheitsbezogenen Lebensqualität mit dem SF-8

The SF-8, a relatively new instrument for measuring health-related quality of life, was used in the German National Telephone Health Survey 2003. The SF-8 provides results which are comparable to those of the SF-36, the instrument most commonly used internationally. The German National Telephone Health Survey provides nationally representative data for the residential population in Germany aged 18 and older. In addition to the measurement of health-related quality of life, comprehensive information on chronic illnesses and complaints, health care needs, utilisation of health care, risk factors, risk behaviour and social status is also collected, making differentiated analyses possible. According to the data collected, men rate their quality of life in all dimensions higher than women. With increasing age, quality of life for both men and women decreases in the physical dimensions, while increasing in the mental health dimensions. Apart from chronic disease and pain having a negative impact on health-related quality of life, social differences are also observable, in that worse health-related quality of life is reported by respondents with lower socioeconomic status.

[Assessment of health-related quality of life with the German SF-8. A comparison of telephone and postal survey modes]

Within a comprehensive comparison of telephone and postal survey methods the SF-8 was applied to assess adult's health-related quality of life. The 1690 subjects were randomly assigned to a telephone survey and a postal survey. Comparisons across the different modes of administration addressed the response rates, central tendency, deviation, ceiling and floor effects observed in the SF-8 scores as well as the inter-item correlation. The importance of age and gender as moderating factors was investigated. Results indicate no or small statistically significant differences in the responses to the SF-8 depending on the actual mode of administration and the health aspect questioned. It was concluded that further investigations should focus on the exact nature of these deviations and try to generate correction factors.

Colds and Influenza-Like Illnesses in University Students: Impact on Health, Academic and Work Performance, and Health Care Use

BACKGROUND

Upper respiratory tract illnesses (URIs) are a major cause of morbidity among adults, with substantial direct and indirect costs to society, but their impact among university students has not been well described. We sought to assess the impact of URIs (colds and influenza-like illnesses [ILIs]) on the health, academic and work performance, and health care use of university students.

METHODS

This was a cohort study of college students at the University of Minnesota, Twin Cities campus (Minneapolis-St. Paul), who were recruited during October 2002 and followed up from November 2002 through April 2003. All 42,000 registered students were invited via e-mail to participate. Baseline information was obtained in October 2002. Monthly follow-up information about colds or ILIs was obtained for the period of November 2002 through April 2003. Data were collected by use of Internet-based questionnaires.

RESULTS

Of 4919 volunteers, 3249 completed all follow-up surveys. The mean age was 22.7 years; 68% of the volunteers were female. Ninety-one percent had > or = 1 URI (83% had > or = 1 cold, and 36.7% had > or = 1 ILI). These URIs caused 6023 bed-days, 4263 missed school days, 3175 missed work days, and 45,219 days of illness. Of the cohort, 22.2% had > or = 1 health care visit, and 15.8% used antibiotics to treat a URI; 27.8% did poorly on a test and 46.3% did poorly on a class assignment. ILIs versus colds had a much greater impact on all parameters (e.g., general health level was 55%-60% lower with ILI vs. no URI and 33%-39% lower for colds vs. no URI; P < .001 for each).

CONCLUSION

Colds and ILIs were common and associated with substantial morbidity in university students. Enhanced efforts to prevent and control URIs, especially influenza vaccination, could improve the health and well-being of the 17 million college and university students in this country.

Pharmacoeconomics of Antiviral Therapy for Influenza in a Japanese Hospital Setting

OBJECTIVES

We constructed a cost-effectiveness decision model to determine a hypothetical 'best treatment' pathway for patients presenting at our institution with influenza virus infection when the choice of treatment was either oseltamivir, zanamivir or a control therapy not active against influenza.

METHODS

The decision model was constructed using DATA 3.5 for evaluating the cost-effectiveness analysis of neuraminidase inhibitors from the perspective of the healthcare payer. The time horizon was set at 14 days based on the general duration of influenza infection in Japan. Clinical outcomes were mainly derived from reports and guidance published by the National Institute for Clinical Excellence in the UK. Japan-specific cost parameters incorporated into the decision model were taken from the Medical Fee Point Survey conducted at St Luke's International Hospital in accordance with medical fee receipts kept at our institution. The study included four professionals and a supporter who gathered information required for the analysis.

RESULTS

In otherwise healthy adults, cost savings of yen831.6 (approximately $US6.72; 2002 values) in the oseltamivir group and an increment in cost of yen40.5 (approximately $US0.33) in the zanamivir group were achieved in comparison with the control group. In contrast, an incremental cost of yen288.4 (approximately $US2.33) was incurred in the oseltamivir group versus the control group when at-risk patients were assessed, but cost savings of yen159.8 (approximately $US1.29) were achieved in the zanamivir group. As a result of cost-effectiveness and cost-utility analyses in otherwise healthy adults, oseltamivir dominated the control therapy because cost savings in the oseltamivir group were made. In the zanamivir group the cost was incremental and the Incremental Cost-Utility Ratio (ICUR) compared with the control group was about yen13 000 (approximately $US107.34)/quality-adjusted life-year (QALY) gained. As a result of cost-effectiveness and cost-utility analyses in at-risk patients, in the oseltamivir group the cost was incremental and the ICUR compared with the control group was about yen230 000 (approximately $US2138.77)/QALY gained. As cost savings were made, zanamivir dominated the control therapy.

CONCLUSION

While the cost effectiveness (from the perspective of a healthcare payer) of the neuraminidase inhibitors was superior to that of the control group in the treatment of otherwise healthy adults with influenza in our study, it seemed necessary to take other factors into consideration before recommending one agent over the other as a first-line therapy. On the other hand, we suggest that zanamivir is the drug of choice for use in at-risk patients, and we recommend, in the light of our results, that if zanamivir is not available another therapy should be given rather than oseltamivir. Since with influenza infections deaths and hospitalisations of at-risk patients impact on the Japanese community, decision-making on the appropriate therapy should take into account the particular patient group involved.

Antiviral agents for influenza: a comparison of cost-effectiveness data

The economic burden of influenza-related illness has been estimated to be 71.3-166 billion US dollars in the US, the majority of which is attributable to indirect costs as a result of lost productivity. There are currently four antiviral drugs available for the treatment of influenza: two ion channel blockers, amantadine and rimantadine; and two neuraminidase inhibitors, zanamivir and oseltamivir. The objective of this paper was to review the studies evaluating the cost effectiveness of currently available antiviral treatment and prophylaxis management strategies for influenza. Published studies that reported both costs and effectiveness of influenza management were extracted using MEDLINE, pre-MEDLINE and EMBASE. To facilitate a broad comparison, all costs were inflated to 2003 US dollars. Fifteen studies met the inclusion criteria of the review, with 14 analyses based on decision-analytic modelling and one economic analysis performed alongside a clinical trial. Management strategies included antiviral influenza prophylaxis or vaccination, empiric treatment of suspected disease, or antiviral treatment following rapid influenza testing. Study populations included healthy adults, adults at risk of influenza-related adverse outcomes, institutionalised and non-institutionalised elderly, and children. The comparator in all studies was standard care (i.e. over-the-counter medications only), and analyses were carried out from both the societal and payer perspectives. The only dominant strategy relative to standard care was vaccination of the institutionalised elderly. All other strategies in all populations were both more costly and more effective than standard care. Depending on the population and the perspective, the incremental cost-effectiveness ratios (ICERs) for antiviral treatment strategies ranged from 5000 US dollars/QALY for amantadine in test-and-treat studies to >400,000 US dollars/QALY for zanamivir or oseltamivir treatment in children. Sensitivity analysis in all studies consistently reported a strong influence of the population prevalence or diagnostic accuracy of influenza on the cost effectiveness of all strategies. Baseline influenza prevalence varied widely between studies, ranging from 15% to 68%. There was also a wide variation in the assumption about the disutility of influenza (ranging from -0.137 to -0.983 for the elderly requiring hospitalisation), which also impacted the cost effectiveness. Given the variation in the ICERs of antiviral treatment and prophylaxis, the uncertainty around many model parameters, and the dynamic nature of influenza from year to year, one can only conclude that antiviral treatment or prophylaxis for influenza is likely to be more cost effective in specific populations at specific times during the influenza season, and during influenza seasons when the population prevalence reaches epidemic levels or there is mismatch between the vaccine and the circulating virus.

Neuraminidase inhibitors in patients with underlying airways disease

Influenza virus infection accounts for significant morbidity, mortality, and healthcare expenditures among persons worldwide. Approximately 20,000 to 40,000 people in the US die each year as a result of influenza. Individuals most susceptible to adverse outcomes include the elderly and those with asthma, chronic obstructive pulmonary disease (COPD), heart disease, renal failure, malignancy, or immunosuppression. Prior to the AIDS epidemic, underlying respiratory disease was the greatest risk factor for influenza-related hospitalization ranking third to heart disease and malignancy for risk of mortality. Although the influenza vaccine can help prevent pneumonia and hospitalization, it is limited by less than ideal immunization rates and the possibility of viral antigenic shifts that render the vaccine ineffective. Pharmacologic interventions play an important role in the management of influenza virus infection by shortening the duration of symptoms. The advent of the neuraminidase inhibitors (NAIs) zanamivir and oseltamivir has significantly affected the treatment of influenza. Unlike NAIs, the older therapeutic options amantadine and rimantadine may cause significant central nervous system adverse effects. In addition, amantadine and rimantadine are not active against influenza B viruses, whereas NAIs are active against both influenza A and B. Post-marketing surveillance of the NAIs has revealed that bronchospasm may occur in patients with underlying respiratory disease treated with the NAI zanamivir. Recent data suggest zanamivir is effective in patients with underlying respiratory disease, but the data are insufficient to elucidate the true risk of bronchospasm. Based on post-marketing reports, zanamivir should be used with caution in patients with asthma or COPD. Although oseltamivir has not been associated with any significant respiratory adverse effects, no data exist on the safety and efficacy of this NAI in patients with underlying respiratory disease.

Health-related quality of life of adults with upper respiratory tract infections

OBJECTIVE

To determine the impact that upper respiratory tract infections have on patients' physical, social, and emotional functioning, we measured the health-related quality of life (HRQL) of adults with upper respiratory tract infections.

SETTING

Acute care clinic from November 2001 to February 2002.

DESIGN

Prospectively administered survey. To measure HRQL, we used the Acute Form of the Short Form-36, version 2 (SF-36). For all 8 SF-36 subscales, we used norm-based scoring, in which the general U.S. population has a mean of 50.

PATIENTS

Adults who had symptoms for fewer than 30 days completed the SF-36; and were diagnosed with nonspecific upper respiratory infection, viral syndrome, otitis media, sinusitis, nonstreptococcal pharyngitis, streptococcal pharyngitis, or acute bronchitis.

MEASUREMENTS AND MAIN RESULTS

The sample of 318 patients was 63% female, 81% white, and had a mean age of 35 years. The primary diagnoses were nonspecific upper respiratory infection (42%), acute bronchitis (16%), sinusitis (12%), viral syndrome (9%), nonstreptococcal pharyngitis (8%), otitis media (7%), and streptococcal pharyngitis (6%). Patients had a mean general health subscale score of 50.9, which is not significantly different from the mean population value of 50 (P =.09). However, there were significant decrements in the remaining 7 subscales of the SF-36: physical functioning (45.5), role-physical (38.5), bodily pain (42.6), vitality (40.8), social functioning (37.8), role-emotional (46.8), and mental health (46.8; P <.0001 for all 7 subscales compared with normative values). Results were similar for the subset of patients with no comorbid illnesses (P <.001 for the same 7 subscales) and patients diagnosed with nonspecific upper respiratory infection (P <.001 for the same 7 subscales). These decrements were similar in magnitude, but somewhat different in subscale pattern, to those of adults with chronic lung disease, osteoarthritis, and depression.

CONCLUSIONS

Physicians should remember that adults who seek care for upper respiratory tract infections have measurable, significant decrements in HRQL. For researchers, HRQL is an attractive, potential measure of outcome in future trials of established and novel therapies for upper respiratory tract infections.

Pharmaceuticals and worker productivity loss: a critical review of the literature

Many chronic illnesses that affect the working population can cause losses in productivity. The extent to which these productivity losses can be reduced by pharmacological treatment is of particular interest to employers, who bear the productivity costs and subsidize the cost of employees' health care. In the past several years, the effects of pharmaceuticals on productivity losses have been tested in numerous studies, including randomized, double-blind, placebo-controlled trials. In this article, we summarize and critically review these studies and, where appropriate, provide quantitative overviews. The evidence is very good for about a dozen drug classes that pharmaceuticals reduce productivity losses caused by respiratory illnesses (ie, asthma, allergic disorders, bronchitis, upper respiratory infections, and influenza) diabetes, depression, dysmenorrhea, and migraine. We also discuss the calculation of productivity costs, reductions in which may partially or completely offset the costs of treatment. This information should be helpful to occupational physicians who are increasingly providing recommendations on employer benefit plan designs and pharmaceutical benefits.

Bedside rapid flu test and zanamivir prescription in healthy working adults: a cost-benefit analysis

BACKGROUND

Zanamivir, a neuraminidase inhibitor, reduces the number of days of illness in influenza-positive patients. New bedside rapid flu tests (RFT) should increase the number of influenza-positive patients whom receive zanamivir appropriately.

OBJECTIVE

To estimate the economic effects of implementing RFT and zanamivir among unvaccinated healthy working adults who consult within 2 days of the onset of influenza-like symptoms.

METHODS

We constructed a decision tree to perform a cost-benefit analysis from a societal perspective. Clinical outcome, i.e. number of influenza days averted, and societal costs were compared for three strategies: RFT and conditional zanamivir prescription;systematic zanamivir prescription; and no zanamivir. A two-way sensitivity analysis was performed including the proportion of influenza-positive patients.

RESULTS

During influenza epidemics, systematic zanamivir prescription provided the best health outcome (0.81 influenza days averted) and minimised societal costs (reduced by 29.80 US dollars per person compared with no zanamivir; 1999 values). RFT with conditional zanamivir averted 0.65 influenza days and saved 14.40 US dollars per person. When the proportion of influenza-positive patients was under 39%, the no zanamivir strategy yielded the greatest societal savings; otherwise, systematic zanamivir was the dominant strategy. Medical costs associated with no zanamivir were 88.70 US dollars per patient consulting with influenza-like illness, and increased to 125.50 US dollars with systematic zanamivir and to 127.60 US dollars with RFT and conditional zanamivir.

CONCLUSIONS

Due to poor sensitivity of current RFT, systematic zanamivir prescription without RFT for unvaccinated healthy working adults should be recommended during influenza epidemics.

Productivity losses related to the common cold

Health-related productivity assessments typically focus on chronic conditions; however, acute conditions, particularly colds, have the potential to cause substantial health-related productivity losses because of their high prevalence in working-age groups. This article presents the findings of a study conducted to estimate productivity loss due to cold by using a telephone-administered survey that measured three sources of loss: absenteeism, on-the-job productivity, and caregiver absenteeism. Each cold experienced by a working adult caused an average of 8.7 lost work hours (2.8 absenteeism hours; 5.9 hours of on-the-job loss), and 1.2 work hours were lost because of attending to children under the age of 13 who were suffering from colds. We conclude that the economic cost of lost productivity due to the common cold approaches $25 billion, of which $16.6 billion is attributed to on-the-job productivity loss, $8 billion is attributed to absenteeism, and $230 million is attributed to caregiver absenteeism.

Neuraminidase inhibitors: zanamivir and oseltamivir

OBJECTIVE

To review the pharmacology, pharmacokinetics, efficacy, and safety of zanamivir and oseltamivir for the prophylaxis and treatment of influenza.

DATA SOURCES

A MEDLINE search restricted to English-language journals was conducted (1980-May 2000).

STUDY SELECTION AND DATA EXTRACTION

All efficacy and safety trials were included if conducted in humans and published in a journal. Abstracts were included if no other data source was available.

DATA SYNTHESIS

Zanamivir and oseltamivir block influenza neuraminidase and prevent the cleavage of sialic acid residues, thus interfering with progeny virus dispersement within the mucosal secretions and reducing viral infectivity. The neuraminidase trials for prophylaxis and treatment of influenza enrolled predominantly young (mean age 29-37 y), healthy, mostly unvaccinated individuals who were at the lowest risk of influenza and its complications. When zanamivir 10 mg inhaled twice daily or oseltamivir 75 mg orally twice daily were used for treatment, systemic symptoms such as myalgias, fever, and headache were reduced by approximately 0.7-1.5 days. Greater efficacy (symptom reduction by 1.5-2.0 d) was noted in proven cases of influenza infection, in febrile patients, and in patients who received the treatment medication within 30 hours of symptom onset. Clinical efficacy did not increase when doses higher than the treatment dose approved by the Food and Drug Administration were used. When given for prophylaxis, zanamivir 10 mg inhaled once daily or oseltamivir 75 mg orally once daily was used for four to six weeks and achieved protective clinical efficacy for laboratory-confirmed influenza ranging from 67% to 74%, depending on whether culture or serologic tests were performed. The most common adverse effects (usually < 5%) included upper respiratory tract symptoms. Patients with asthma or chronic obstructive pulmonary disease who received zanamivir had an increased incidence of a > 20% decline in forced expiratory volume in one second or peak expiratory flow rates. Headaches, nausea, and vomiting were more frequent in the oseltamivir groups than in placebo groups. The most common gastrointestinal adverse effects, nausea and vomiting, were reduced to approximately 10% by administering the medication with food.

CONCLUSIONS

Zanamivir and oseltamivir are more effective in preventing culture-positive influenza or for treatment of culture-positive influenza in febrile (> or = 37.8 degrees C) individuals. Treatment is more effective if initiated within 30 hours of symptom onset in febrile individuals; however, it is difficult to meet these criteria. More realistically, clinical efficacy is closer to 60-70% and, for treatment started within 48 hours for laboratory-confirmed influenza, symptom reduction is approximately 0.7-1.5 days. If used appropriately to minimize the development of resistance, the neuraminidase inhibitors represent a new and unique class of antiinfluenza agents that can potentially reduce the morbidity associated with influenza.