Article

The use of over-the-counter medications to treat influenza symptoms may help mitigate the socioeconomic burden of the disease

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Abstract

The increasing use of over-the-counter (OTC) medications to treat various conditions, including mild to moderate influenza symptoms, is one aspect of a growing movement toward medical self care. Moreover, as patients do not need to visit their physician, the use of OTC medications to treat influenza reduces the use of the healthcare system, which may help mitigate the socioeconomic burden of the disease. Pharmacists can enable responsible self care by providing information on OTC medications for patients with a low risk of influenza complications, and advising those with a high risk of complication to seek prompt medical attention.

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BACKGROUND: Neuraminidase inhibitors (NIs) are stockpiled and recommended by public health agencies for treating and preventing seasonal and pandemic influenza. They are used clinically worldwide. OBJECTIVE: To describe the potential benefits and harms of NIs for influenza in all age groups by reviewing all clinical study reports of published and unpublished randomised, placebo-controlled trials and regulatory comments. METHODS Search methods: We searched trial registries, electronic databases (to 22 July 2013) and regulatory archives, and corresponded with manufacturers to identify all trials. We also requested clinical study reports. We focused on the primary data sources of manufacturers but we checked that there were no published randomised controlled trials (RCTs) from non-manufacturer sources by running electronic searches in the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, MEDLINE (Ovid), EMBASE, Embase.com, PubMed (not MEDLINE), the Database of Reviews of Effects, the NHS Economic Evaluation Database and the Health Economic Evaluations Database. Selection criteria: Randomised, placebo-controlled trials on adults and children with confirmed or suspected exposure to naturally occurring influenza. Data collection and analysis: We extracted clinical study reports and assessed risk of bias using purpose-built instruments. We analysed the effects of zanamivir and oseltamivir on time to first alleviation of symptoms, influenza outcomes, complications, hospitalisations and adverse events in the intention-to-treat (ITT) population. All trials were sponsored by the manufacturers. MAIN RESULTS: We obtained 107 clinical study reports from the European Medicines Agency (EMA), GlaxoSmithKline and Roche. We accessed comments by the US Food and Drug Administration (FDA), EMA and Japanese regulator. We included 53 trials in Stage 1 (a judgement of appropriate study design) and 46 in Stage 2 (formal analysis), including 20 oseltamivir (9623 participants) and 26 zanamivir trials (14,628 participants). Inadequate reporting put most of the zanamivir studies and half of the oseltamivir studies at a high risk of selection bias. There were inadequate measures in place to protect 11 studies of oseltamivir from performance bias due to non-identical presentation of placebo. Attrition bias was high across the oseltamivir studies and there was also evidence of selective reporting for both the zanamivir and oseltamivir studies. The placebo interventions in both sets of trials may have contained active substances. Time to first symptom alleviation. For the treatment of adults, oseltamivir reduced the time to first alleviation of symptoms by 16.8 hours (95% confidence interval (CI) 8.4 to 25.1 hours, P < 0.0001). This represents a reduction in the time to first alleviation of symptoms from 7 to 6.3 days. There was no effect in asthmatic children, but in otherwise healthy children there was (reduction by a mean difference of 29 hours, 95% CI 12 to 47 hours, P = 0.001). Zanamivir reduced the time to first alleviation of symptoms in adults by 0.60 days (95% CI 0.39 to 0.81 days, P < 0.00001), equating to a reduction in the mean duration of symptoms from 6.6 to 6.0 days. The effect in children was not significant. In subgroup analysis we found no evidence of a difference in treatment effect for zanamivir on time to first alleviation of symptoms in adults in the influenza-infected and non-influenza-infected subgroups (P = 0.53). Hospitalisations. Treatment of adults with oseltamivir had no significant effect on hospitalisations: risk difference (RD) 0.15% (95% CI -0.78 to 0.91). There was also no significant effect in children or in prophylaxis. Zanamivir hospitalisation data were unreported. Serious influenza complications or those leading to study withdrawal. In adult treatment trials, oseltamivir did not significantly reduce those complications classified as serious or those which led to study withdrawal (RD 0.07%, 95% CI -0.78 to 0.44), nor in child treatment trials; neither did zanamivir in the treatment of adults or in prophylaxis. There were insufficient events to compare this outcome for oseltamivir in prophylaxis or zanamivir in the treatment of children. Pneumonia. Oseltamivir significantly reduced self reported, investigator-mediated, unverified pneumonia (RD 1.00%, 95% CI 0.22 to 1.49); number needed to treat to benefit (NNTB) = 100 (95% CI 67 to 451) in the treated population. The effect was not significant in the five trials that used a more detailed diagnostic form for pneumonia. There were no definitions of pneumonia (or other complications) in any trial. No oseltamivir treatment studies reported effects on radiologically confirmed pneumonia. There was no significant effect on unverified pneumonia in children. There was no significant effect of zanamivir on either self reported or radiologically confirmed pneumonia. In prophylaxis, zanamivir significantly reduced the risk of self reported, investigator-mediated, unverified pneumonia in adults (RD 0.32%, 95% CI 0.09 to 0.41); NNTB = 311 (95% CI 244 to 1086), but not oseltamivir. Bronchitis, sinusitis and otitis media. Zanamivir significantly reduced the risk of bronchitis in adult treatment trials (RD 1.80%, 95% CI 0.65 to 2.80); NNTB = 56 (36 to 155), but not oseltamivir. Neither NI significantly reduced the risk of otitis media and sinusitis in both adults and children. Harms of treatment. Oseltamivir in the treatment of adults increased the risk of nausea (RD 3.66%, 95% CI 0.90 to 7.39); number needed to treat to harm (NNTH) = 28 (95% CI 14 to 112) and vomiting (RD 4.56%, 95% CI 2.39 to 7.58); NNTH = 22 (14 to 42). The proportion of participants with four-fold increases in antibody titre was significantly lower in the treated group compared to the control group (RR 0.92, 95% CI 0.86 to 0.97, I2 statistic = 0%) (5% absolute difference between arms). Oseltamivir significantly decreased the risk of diarrhoea (RD 2.33%, 95% CI 0.14 to 3.81); NNTB = 43 (95% CI 27 to 709) and cardiac events (RD 0.68%, 95% CI 0.04 to 1.0); NNTB = 148 (101 to 2509) compared to placebo during the on-treatment period. There was a dose-response effect on psychiatric events in the two oseltamivir "pivotal" treatment trials, WV15670 and WV15671, at 150 mg (standard dose) and 300 mg daily (high dose) (P = 0.038). In the treatment of children, oseltamivir induced vomiting (RD 5.34%, 95% CI 1.75 to 10.29); NNTH = 19 (95% CI 10 to 57). There was a significantly lower proportion of children on oseltamivir with a four-fold increase in antibodies (RR 0.90, 95% CI 0.80 to 1.00, I2 = 0%). Prophylaxis. In prophylaxis trials, oseltamivir and zanamivir reduced the risk of symptomatic influenza in individuals (oseltamivir: RD 3.05% (95% CI 1.83 to 3.88); NNTB = 33 (26 to 55); zanamivir: RD 1.98% (95% CI 0.98 to 2.54); NNTB = 51 (40 to 103)) and in households (oseltamivir: RD 13.6% (95% CI 9.52 to 15.47); NNTB = 7 (6 to 11); zanamivir: RD 14.84% (95% CI 12.18 to 16.55); NNTB = 7 (7 to 9)). There was no significant effect on asymptomatic influenza (oseltamivir: RR 1.14 (95% CI 0.39 to 3.33); zanamivir: RR 0.97 (95% CI 0.76 to 1.24)). Non-influenza, influenza-like illness could not be assessed due to data not being fully reported. In oseltamivir prophylaxis studies, psychiatric adverse events were increased in the combined on- and off-treatment periods (RD 1.06%, 95% CI 0.07 to 2.76); NNTH = 94 (95% CI 36 to 1538) in the study treatment population. Oseltamivir increased the risk of headaches whilst on treatment (RD 3.15%, 95% CI 0.88 to 5.78); NNTH = 32 (95% CI 18 to 115), renal events whilst on treatment (RD 0.67%, 95% CI -2.93 to 0.01); NNTH = 150 (NNTH 35 to NNTB > 1000) and nausea whilst on treatment (RD 4.15%, 95% CI 0.86 to 9.51); NNTH = 25 (95% CI 11 to 116). AUTHORS' CONCLUSIONS: Oseltamivir and zanamivir have small, non-specific effects on reducing the time to alleviation of influenza symptoms in adults, but not in asthmatic children. Using either drug as prophylaxis reduces the risk of developing symptomatic influenza. Treatment trials with oseltamivir or zanamivir do not settle the question of whether the complications of influenza (such as pneumonia) are reduced, because of a lack of diagnostic definitions. The use of oseltamivir increases the risk of adverse effects, such as nausea, vomiting, psychiatric effects and renal events in adults and vomiting in children. The lower bioavailability may explain the lower toxicity of zanamivir compared to oseltamivir. The balance between benefits and harms should be considered when making decisions about use of both NIs for either the prophylaxis or treatment of influenza. The influenza virus-specific mechanism of action proposed by the producers does not fit the clinical evidence.
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The substantial economic impact of influenza on society results primarily from lost work time and reduced productivity of patients and caregivers and increased use of medical resources. Additionally, since the 1980s, aging of the US population has meant rising influenza-related morbidity and mortality. According to the most current published data on this topic, in 2003 the total economic burden of influenza epidemics in the USA across all age groups was US87.1billion.AsofFebruary2013,overallvaccineeffectivenessforthe2012/2013seasonwasestimatedtobe5687.1 billion. As of February 2013, overall vaccine effectiveness for the 2012/2013 season was estimated to be 56 %. The Centers for Disease Control and Prevention's National Center for Immunization and Respiratory Diseases has concluded that more effective vaccines and vaccination strategies are needed. Moderate efficacy of the influenza vaccine, continued questions regarding the value of treatment with antivirals, and a growing self-care movement have led to increased use of over-the-counter (OTC) medicines, which play a vital role in managing symptoms associated with mild to moderate influenza and provide an estimated US102 billion in annual savings for the US healthcare system. A primary benefit to society of using OTC medicines to manage influenza is decreased use of the healthcare system, thereby mitigating the socioeconomic burden of influenza. Considering the stresses placed on the US healthcare system and the substantial productivity losses resulting from seasonal influenza as well as the growing self-care movement, OTC medicines will play an important role in the course of future influenza epidemics.
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Guidelines for the treatment of persons with influenza virus infection were prepared by an Expert Panel of the Infectious Diseases Society of America. The evidence-based guidelines encompass diagnostic issues, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal (interpandemic) influenza. They are intended for use by physicians in all medical specialties with direct patient care, because influenza virus infection is common in communities during influenza season and may be encountered by practitioners caring for a wide variety of patients.
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To evaluate costs of inappropriate oral antibiotic prescribing in a managed care population with influenza. This was a retrospective (January 1, 2005, through December 31, 2009) analysis of the US Impact National Benchmark Database. Patients with an influenza diagnosis (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] code 487.xx) and continuous health plan enrollment for >12 months before and 1 month after the index influenza diagnosis date were included. We identified patients with an antibiotic prescription claim within 3 days before or 3 days after the index influenza diagnosis date. Patients were classified as having received appropriate antibiotic treatment if a secondary respiratory infection was observed within the 2-week postindex period or if there was a previous comorbid diagnosis of diabetes, congestive heart failure, chronic obstructive pulmonary disease, asthma, acute myocardial infarction, or sickle cell anemia as identified by ICD-9-CM codes. We identified 270,057 subjects with influenza (mean age, 31.6 years). Antibiotics were prescribed in 58,477 (21.65%) patients. Among patients receiving antibiotics, 99% did not have a follow-up diagnosis for a respiratory bacterial infection and 79% had neither a secondary infection nor evidence of a comorbidity (ie, received inappropriate antibiotic treatment). Based on a conservative annual seasonal influenza rate of 10%, we estimated that inappropriate antibiotic prescribing for influenza costs the United States approximately $211 million annually. Empiric antibiotics were inappropriately prescribed in a high percentage of influenza patients. This represents a significant financial burden to the US healthcare system and may contribute to increased antibiotic resistance.
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Background: Different types of influenza vaccines are currently produced worldwide. Vaccination of pregnant women is recommended internationally, while healthy adults are targeted in North America. Objectives: To identify, retrieve and assess all studies evaluating the effects (efficacy, effectiveness and harm) of vaccines against influenza in healthy adults, including pregnant women. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 2), MEDLINE (January 1966 to May 2013) and EMBASE (1990 to May 2013). Selection criteria: Randomised controlled trials (RCTs) or quasi-RCTs comparing influenza vaccines with placebo or no intervention in naturally occurring influenza in healthy individuals aged 16 to 65 years. We also included comparative studies assessing serious and rare harms. Data collection and analysis: Two review authors independently assessed trial quality and extracted data. Main results: We included 90 reports containing 116 data sets; among these 69 were clinical trials of over 70,000 people, 27 were comparative cohort studies (about eight million people) and 20 were case-control studies (nearly 25,000 people). We retrieved 23 reports of the effectiveness and safety of vaccine administration in pregnant women (about 1.6 million mother-child couples).The overall effectiveness of parenteral inactivated vaccine against influenza-like illness (ILI) is limited, corresponding to a number needed to vaccinate (NNV) of 40 (95% confidence interval (CI) 26 to 128). The overall efficacy of inactivated vaccines in preventing confirmed influenza has a NNV of 71 (95% CI 64 to 80). The difference between these two values depends on the different incidence of ILI and confirmed influenza among the study populations: 15.6% of unvaccinated participants versus 9.9% of vaccinated participants developed ILI symptoms, whilst only 2.4% and 1.1%, respectively, developed laboratory-confirmed influenza.No RCTs assessing vaccination in pregnant women were found. The only evidence available comes from observational studies with modest methodological quality. On this basis, vaccination shows very limited effects: NNV 92 (95% CI 63 to 201) against ILI in pregnant women and NNV 27 (95% CI 18 to 185) against laboratory-confirmed influenza in newborns from vaccinated women.Live aerosol vaccines have an overall effectiveness corresponding to a NNV 46 (95% CI 29 to 115).The performance of one-dose or two-dose whole virion pandemic vaccines was higher, showing a NNV of 16 (95% CI 14 to 20) against ILI and a NNV of 35 (95% CI 33 to 47) against influenza, while a limited impact on hospitalisation was found (NNV 94, 95% CI 70 to 1022).Vaccination had a modest effect on time off work and had no effect on hospital admissions or complication rates. Inactivated vaccines caused local harms. No evidence of association with serious adverse events was found, but the harms evidence base was limited.The overall risk of bias in the included trials is unclear because it was not possible to assess the real impact of bias. Authors' conclusions: Influenza vaccines have a very modest effect in reducing influenza symptoms and working days lost in the general population, including pregnant women. No evidence of association between influenza vaccination and serious adverse events was found in the comparative studies considered in the review. This review includes 90 studies, 24 of which (26.7%) were funded totally or partially by industry. Out of the 48 RCTs, 17 were industry-funded (35.4%).
Article
Background: Three different types of influenza vaccines are currently produced world wide. None is traditionally targeted to healthy adults. Despite the publication of a large number of clinical trials, there is still substantial uncertainty about the clinical effectiveness of influenza vaccines and this has negative impact on the vaccines acceptance and uptake. Objectives: To identify, retrieve and assess all studies evaluating the effects of vaccines on influenza in healthy adults. To assess the effectiveness of vaccines in preventing cases of influenza in healthy adults. To estimate the frequency of adverse effects associated with influenza vaccination in healthy adults. Search strategy: MEDLINE was searched using the strategy of the Cochrane Acute Respiratory Infections Group. The bibliography of retrieved articles, the Cochrane Controlled Trials Register (CCTR), and EMBASE (1990 to 1997) were also searched. Handsearch of the journal Vaccine from its first issue to the end of 1997 (Jefferson and Jefferson, 1996; Jefferson, 1998). We wrote to vaccine manufacturers and first or corresponding authors of studies in the review. Selection criteria: Any randomised or quasi-randomised studies comparing influenza vaccines in humans with placebo, control vaccines or no intervention, or comparing types, doses or schedules of influenza vaccine. Live, attenuated or killed vaccines or fractions thereof administered by any route, irrespective of antigenic configuration were considered. Only studies assessing protection from exposure to naturally occurring influenza in healthy individuals aged 14 to 60 (irrespective of influenza immune status) were considered. Data collection and analysis: Both clinically defined cases and serologically confirmed cases of influenza were considered as outcomes according to the authors' definitions. Time off work, complication and hospitalisation rates were considered, together with adverse effects. Vaccine schedules were analysed including one component matching the recommended vaccine (WHO or government recommendations) for the year of the study, and whether they matched the circulating viral subtypes. Main results: The recommended live aerosol vaccines reduced the number of cases of serologically confirmed influenza A by 48% (95% confidence interval 24% to 64%), whilst recommended inactivated parenteral vaccines had a vaccine efficacy of 68% (95% confidence interval 49% to 79%). The vaccines were less effective in reducing clinical influenza cases, with efficacies of 13% and 24% respectively. Use of the vaccine significantly reduced time off work, but only by 0.4 days for each influenza episode (95% confidence interval 0.1 to 0.8 days). Analysis of vaccines matching the circulating strain gave higher estimates of efficacy, whilst inclusion of all other vaccines reduced the efficacy. Reviewer's conclusions: Influenza vaccines are effective in reducing serologically confirmed cases of influenza A. However, they are not as effective in reducing cases of clinical influenza. The use of WHO recommended vaccines appears to enhance their effectiveness in practice.
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