Impact of influenza vaccination on mortality risk among the elderly

Influenza vaccine coverage and factors associated with non-vaccination among caregiving and care-receiving adults in the Canadian Longitudinal Study on Aging (CLSA)

BACKGROUND

Influenza vaccination is recommended for those at increased risk of influenza complications and their household contacts to help reduce influenza exposure. Adults who require care often experience health issues that could increase the risk of severe influenza and have close contact with caregivers. Assessing influenza vaccination prevalence in caregivers and care recipients can provide important information about uptake.

OBJECTIVES

We aimed to (1) estimate influenza non-vaccination prevalence and (2) assess factors associated with non-vaccination among caregivers aged ≥ 45 years and among care recipients aged ≥ 65 years.

METHODS

We conducted an analysis of cross-sectional data from the Canadian Longitudinal Study on Aging collected 2015-2018. We estimated non-vaccination prevalence and reported adjusted odds ratios with 95% confidence intervals from logistic regression models to identify factors associated with non-vaccination among caregivers and care recipients.

RESULTS

Of the 23,500 CLSA participants who reported providing care, 41.4% (95% CI: 40.8%, 42.0%) reported not receiving influenza vaccine in the previous 12 months. Among the 5,559 participants who reported receiving professional or non-professional care, 24.8% (95% CI: 23.7%, 26.0%) reported not receiving influenza vaccine during the same period. For both groups, the odds of non-vaccination were higher for those who had not visited a family doctor in the past year, were daily smokers, and those who identified as non-white.

DISCUSSION

Identifying groups at high risk of severe influenza and their close contacts can inform public health efforts to reduce the risk of influenza. Our results suggest sub-optimal influenza vaccination uptake among caregivers and care recipients. Efforts are needed to increase influenza vaccination and highlight the direct and indirect benefits for caregiver-care recipient pairs.

CONCLUSION

The proportions of both caregivers and care recipients who had not been vaccinated for influenza was high, despite the benefits of vaccination. Influenza vaccination campaigns could target undervaccinated, high-risk groups to increase coverage.

Effectiveness of influenza vaccination on in-hospital death in older adults with respiratory diseases

Influenza vaccination is associated with lower risk of hospitalization outcomes among older adults with respiratory diseases, but there is limited evidence by disease subtypes and patients' characteristics. This study included patients aged ≥60 years hospitalized for respiratory diseases from the Beijing Urban Employee Basic Medical Insurance database during 6 influenza seasons. Vaccination status was assessed by linking with the Beijing Elderly Influenza Vaccination database. Multi-variable logistic regression was performed to calculate effect estimates. After adjusting for measured and unmeasured confounders, influenza vaccination was associated with a lower risk of in-hospital death among older adults hospitalized for respiratory diseases (odds ratio [95% confidence interval], 0.70 [0.62-0.80]). The protective association was observed among patients with chronic obstructive pulmonary disease (0.67 [0.47-0.98]) as well as those with pneumonia or influenza (0.77 [0.64-0.93]). The protective association was stronger in younger patients (0.59 [0.43-0.81] for <75 and 0.72 [0.63-0.83] for ≥75) and those with fewer comorbidities (0.49 [0.16-1.62] for 0, 0.65 [0.50-0.86] for 1-2, and 0.72 [0.63-0.83] for ≥3 comorbidities). Influenza vaccination was associated with lower risk of in-hospital death among older patients hospitalized for respiratory diseases, with stronger associations in patients with younger age and fewer comorbidities.

Antigenic drift and epidemiological severity of seasonal influenza in Canada

Seasonal influenza epidemics circulate globally every year with varying levels of severity. One of the major drivers of this seasonal variation is thought to be the antigenic drift of influenza viruses, resulting from the accumulation of mutations in viral surface proteins. In this study, we aimed to investigate the association between the genetic drift of seasonal influenza viruses (A/H1N1, A/H3N2 and B) and the epidemiological severity of seasonal epidemics within a Canadian context. We obtained hemagglutinin protein sequences collected in Canada between the 2006/2007 and 2019/2020 flu seasons from GISAID and calculated Hamming distances in a sequence-based approach to estimating inter-seasonal antigenic differences. We also gathered epidemiological data on cases, hospitalizations and deaths from national surveillance systems and other official sources, as well as vaccine effectiveness estimates to address potential effect modification. These aggregate measures of disease severity were integrated into a single seasonal severity index. We performed linear regressions of our severity index with respect to the inter-seasonal antigenic distances, controlling for vaccine effectiveness. We did not find any evidence of a statistical relationship between antigenic distance and seasonal influenza severity in Canada. Future studies may need to account for additional factors, such as co-circulation of other respiratory pathogens, population imprinting, cohort effects and environmental parameters, which may drive seasonal influenza severity.

Effectiveness of influenza vaccination on in-hospital death and recurrent hospitalization in older adults with cardiovascular diseases

OBJECTIVES

There is limited evidence on the effectiveness of influenza vaccination on hospitalization outcomes by cardiovascular disease (CVD) subtypes or comorbidities.

METHODS

This study involved 713,488 records of hospitalization of adults ≥60 years with CVD from the Beijing Urban Employee Basic Medical Insurance database. Logistic regression with generalized estimating equations was conducted to estimate the effectiveness of influenza vaccination on in-hospital death and recurrent hospitalization, adjusting for unmeasured confounders.

RESULTS

The coverage of influenza vaccination was only 13.3% among older adults hospitalized for CVD. Influenza vaccination was associated with 15% (odds ratios 0.85 [0.74, 0.99]) lower risk of in-hospital death among patients with CVD, with stronger associations in patients with stroke. Influenza vaccination was associated with 6% (0.94 [0.88, 0.99]) and 28% (0.72 [0.56, 0.93]) lower risks of recurrent hospitalization for ischemic heart disease (IHD) and respiratory disease in patients with IHD, but there were no clear associations in patients with stroke. For in-hospital death, the protective association of influenza vaccination was stronger in patients with fewer comorbidities and was similar to that of joint vaccinations of influenza and pneumococcal vaccinations.

CONCLUSION

The protective association of influenza vaccination on CVD hospitalization outcomes serves as the evidence base to increase the uptake of influenza vaccination among older adults in China.

Impact of Patient Portal Messaging Reminders with Self-Scheduling Option on Influenza Vaccination Rates: a Prospective, Randomized Trial

BACKGROUND

Patient portal messages have been used in a variety of ways to facilitate improved communication between provider and patient. These platforms have shown promise in many ways for improving various health outcomes and overall communication between patient and provider.

OBJECTIVE

Assess the impact of automated portal reminder messages and self-scheduling options on increasing rates of annual influenza vaccination.

DESIGN

This is a prospective, randomized, controlled study.

PARTICIPANTS

All patients who receive their primary care through an ambulatory primary care clinic at a large, multidisciplinary, academic health center.

INTERVENTIONS

One group of patients received a portal message reminder to undergo influenza vaccination. A second group received the same message with instructions to self-schedule the vaccination appointment. A third group received no portal message (control).

MAIN MEASURES

Rates of influenza vaccination in each group for previously unvaccinated patients in the 2019-2020 influenza season.

KEY RESULTS

For the group receiving the message with self-scheduling option (n=5408), the in-study vaccination rate was significantly greater than the group receiving no message (n=5621) (15.7% vs. 13.5%; p=0.002). For the group receiving a message alone (without self-scheduling) (n=5699), the in-study vaccination rate was significantly greater than the group receiving no message (15.1% vs. 13.5%; p=0.01). There was no significant difference in vaccination rate between the two intervention groups receiving messages (15.7% vs. 15.1%; p=0.549).

CONCLUSIONS

Portal messaging reminders increase annual influenza vaccination rates, but the addition of a self-scheduling option did not further increase rates.

KEY WORDS

vaccination patient portal messaging influenza.

Seasonal influenza vaccination is associated with reduced risk of death among Medicare beneficiaries☆

BACKGROUND

Influenza causes substantial mortality, especially among older persons. Influenza vaccines are rarely more than 50% effective and rarely reach more than half of the US Medicare population, which is primarily an aged population. We wished to estimate the association between vaccination and mortality reduction.

METHOD

We used the US Center for Medicare and Medicaid Services (CMS) DataLink Project to determine vaccination status and timing during the 2017-2018 influenza season for more than 26 million Medicare enrollees. Patient-level demographic, health, co-morbidity, hospitalization, vaccination, and healthcare utilization claims data were supplied as covariates to general linear models in order to isolate and estimate the association between participation in the vaccination program and relative risk of death.

FINDINGS

The 2017-2018 seasonal influenza vaccine reduced (Relative Risk Ratio [RRR] 0.936 [95% CI = 0.918-0.954]) the risk of all-cause death among beneficiaries following a hospitalization for sepsis and moreover the risk of death without a prior hospitalization during the 2.5-month outcome window (RRR 0.870 [95% CI = 0.853-0.887]). We estimate the number needed to vaccinate (NNV) to prevent a death in the ten-week outcome window is between 1,515 beneficiaries (95% CI = 1,351-1,754; derived from the average treatment effect of augmented inverse probability weighting) and 1,960 beneficiaries (95% CI = 1,695-2,381; derived from the average marginal effect of logistic regression). Among beneficiaries requiring hospitalization, the greatest death risk reduction accrued to those 85 + years of age who were hospitalized with sepsis, RRR 0.92 [95% CI = 0.89-0.95]. No apparent benefit was realized by beneficiaries who required custodial (nursing home) care.

INTERPRETATION

Seasonal influenza immunization is associated with relative reduction of death risk among non-institutionalized Medicare beneficiaries.

FUNDING

All authors are full-time or contractual employees of the United States Federal Government, Department of Health and Human Services, the funding agency.

The role of health determinants in the influenza vaccination uptake among older adults (65+): a scope review

Background

Although the burden of influenza infection is the highest in older adults, vaccination coverage remains low, despite this age group being more vulnerable than others.

Aims

Given the current pandemic of SARS-CoV-2, it was the aim of this scope review to update knowledge on factors affecting seasonal influenza vaccine uptake among older adults to strengthen prevention approaches in the context of an overall burden of infectious diseases.

Methods

We searched bibliographic databases from 2012 to 2019. All studies reviewed one or more social determinant of health listed by WHO, or factors affecting the decision-making process whether to accept influenza vaccine or not.

Results

Overall, 44 studies were included, 41 determinants were extracted and summarized into six categories. Older age and constitutional factors including multiple chronic diseases as well as preventive lifestyle and frequent routine healthcare utilization positively affected vaccination uptake (VU). Living and working conditions are also researched determinants of influenza vaccine uptake. A small number of studies explored the role of social inclusion and system-based interventions.

Discussion and conclusions

This scope review provides a comprehensive overview on factors affecting seasonal influenza vaccination uptake among older citizens. The review also clearly shows gaps for evidence on system-based level or political strategies to improve vaccination uptake.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40520-021-01793-3.

Longitudinal Assessment of Immune Responses to Repeated Annual Influenza Vaccination in a Human Cohort of Adults and Teenagers

Background: The overall performance of a multiple component vaccine assessed by the vaccine-elicited immune responses across various strains in a repeated vaccination setting has not been well-studied, and the comparison between adults and teenagers is yet to be made.

Methods: A human cohort study was conducted at the University of Georgia, with 140 subjects (86 adults and 54 teenagers) repeatedly vaccinated in the 2017/2018 and 2018/2019 influenza seasons. Host information was prospectively collected, and serum samples were collected before and after vaccination in each season. The association between host factors and repeated measures of hemagglutination inhibition (HAI) composite scores was assessed by generalized linear models with generalized estimating equations.

Results: The mean HAI composite scores for the entire sample (t = 4.26, df = 139, p < 0.001) and the teenager group (t = 6.44, df = 53, p < 0.001) declined in the second season, while the changes in the adults were not statistically significant (t = −1.14, df = 85, p = 0.26). A mixture pattern of changes in both directions was observed in the adults when stratified by prior vaccination. In addition, the regression analysis suggested an interactive effect of age and BMI on the HAI composite scores in the overall population (beta = 0.005; 95% CI, 0.0008–0.01) and the adults (beta = 0.005; 95% CI, 0.0005–0.01).

Conclusions: Our study found distinct vaccine-elicited immune responses between adults and teenagers when both were repeatedly vaccinated in consecutive years. An interactive effect of age and BMI on the HAI composite scores were identified in the overall population and the adults.

Impact of influenza vaccination on amoxicillin prescriptions in older adults: A retrospective cohort study using primary care data

Background

Bacterial infections of the upper and lower respiratory tract are a frequent complication of influenza and contribute to the widespread use of antibiotics. Influenza vaccination may help reduce both appropriate and inappropriate prescribing of antibiotics. Electronic health records provide a rich source of information for assessing secondary effects of influenza vaccination.

Methods

We conducted a retrospective study to estimate effects of influenza vaccine on antibiotic (amoxicillin) prescription in the elderly based on data from the Clinical Practice Research Datalink. The introduction of UK policy to recommend the influenza vaccine to older adults in 2000 led to a substantial increase in uptake, creating a natural experiment. Of 259,753 eligible patients that were unvaccinated in 1999 and aged≥65y by January 2000, 88,519 patients received influenza vaccination in 2000. These were propensity score matched 1:1 to unvaccinated patients. Time-to-amoxicillin was analysed using the Prior Event Rate Ratio (PERR) Pairwise method to address bias from time-invariant measured and unmeasured confounders. A simulation study and negative control outcome were used to help strengthen the validity of results.

Results

Compared to unvaccinated patients, those from the vaccinated group were more likely to be prescribed amoxicillin in the year prior to vaccination: hazard ratio (HR) 1.90 (95% confidence interval 1.83, 1.98). Following vaccination, the vaccinated group were again more likely to be prescribed amoxicillin, HR 1.64 (1.58,1.71). After adjusting for prior differences between the two groups using PERR Pairwise, overall vaccine effectiveness was 0.86 (0.81, 0.92). Additional analyses suggested that provided data meet the PERR assumptions, these estimates were robust.

Conclusions

Once differences between groups were taken into account, influenza vaccine had a beneficial effect, lowering the frequency of amoxicillin prescribing in the vaccinated group. Ensuring successful implementation of national programmes of vaccinating older adults against influenza may help contribute to reducing antibiotic resistance.

A Hospital-Based Nonconcurrent Cohort Study on Factors Associated with in-Hospital Mortality in Patients with Laboratory Confirmed Influenza

Background and Aim:

Influenza is a disease with varied clinical presentation and varied mortality reported in existing literature. The study aimed to determine the factors associated with mortality in patients hospitalized with influenza infection.

Materials and Methods:

This was a 5-year nonconcurrent cohort study done in a tertiary care center in Southern India. Patients with laboratory confirmed influenza infection diagnosed between January 2013 and October 2018 were recruited into the study.

Results:

A total of 130 patients were recruited. Diabetes (45.4%) and chronic obstructive pulmonary disease (COPD) (26.1%) were the most common comorbid illnesses. Thirty-one patients (23.8%) required admission to the intensive care unit (ICU) and 58 patients required ventilation (noninvasive/mechanical ventilation [MV] – 44.6%). Influenza A was the most common isolated strain (46.9%). Univariate analysis demonstrated that a high pneumonia severity index (P < 0.0001), CURB 65 > 2 (P < 0.0001), MV dependency (P < 0.0001), need for ICU stay (P < 0.0001), low PF ratio (P < 0.0001), COPD (P = 0.021), secondary bacterial pneumonia (P < 0.0001), acute respiratory distress syndrome (P = 0.0004), and acute kidney injury (P = 0.0006) were the significant factors associated with in-hospital mortality. Multivariate analysis demonstrated that new onset/worsening renal dysfunction was the only factor significantly associated with in-hospital mortality in patients admitted with influenza.

Conclusions:

Our study showed a mortality of 12.3% (n= 16) and new onset/worsening renal dysfunction was the only patient factor associated with mortality. Early recognition of complications and appropriate treatment may reduce mortality in patients admitted with severe influenza. We recommend influenza vaccination for at-risk populations to reduce severity and mortality.

Influenza Vaccination and Hospitalization Outcomes Among Older Patients With Cardiovascular or Respiratory Diseases

BACKGROUND

Influenza vaccination has been suggested to protect against death and recurrent events among patients with cardiovascular disease or chronic obstructive respiratory disease, but there is limited evidence in older adults, who have higher risks of influenza-associated hospitalization and mortality.

METHODS

Patients aged ≥60 years hospitalized for cardiovascular or respiratory diseases from the Beijing Urban Employee Basic Medical Insurance database during 3 influenza seasons (2013-2014 through 2015-2016) were pooled to estimate the effects of influenza vaccination on hospitalization outcomes. Vaccination status was ascertained through cross-referencing the Beijing Elderly Influenza Vaccination database. The summer months (June-August) were used as a reference period to adjust for unmeasured confounders during influenza seasons.

RESULTS

After adjustment for both measured and unmeasured confounders, influenza vaccination was associated with lower risks of in-hospital deaths among patients hospitalized for cardiovascular (odds ratio [95% confidence interval], 0.85 [.68-1.06]) or respiratory diseases (0.66 [.54-.82]). Influenza vaccination was associated with a lower risk of readmission among patients with cardiovascular (odds ratio [95% confidence interval], 0.81 [.69-.95]) but not respiratory diseases (1.12 [.92-1.35]). Influenza vaccination was also associated with lower direct medical costs, but not with length of stay.

CONCLUSIONS

Influenza vaccination protected against hospitalization outcomes among older adults with cardiovascular or respiratory diseases.

Vaccine effectiveness against influenza A(H3N2) and B among laboratory-confirmed, hospitalised older adults, Europe, 2017-18: A season of B lineage mismatched to the trivalent vaccine

Background

Influenza A(H3N2), A(H1N1)pdm09 and B viruses co‐circulated in Europe in 2017‐18, predominated by influenza B. WHO‐recommended, trivalent vaccine components were lineage‐mismatched for B. The I‐MOVE hospital network measured 2017‐18 seasonal influenza vaccine effectiveness (IVE) against influenza A(H3N2) and B among hospitalised patients (≥65 years) in Europe.

Methods

Following the same generic protocol for test‐negative design, hospital teams in nine countries swabbed patients ≥65 years with recent onset (≤7 days) severe acute respiratory infection (SARI), collecting information on demographics, vaccination status and underlying conditions. Cases were RT‐PCR positive for influenza A(H3N2) or B; controls: negative for any influenza. “Vaccinated” patients had SARI onset >14 days after vaccination. We measured pooled IVE against influenza, adjusted for study site, age, sex, onset date and chronic conditions.

Results

We included 3483 patients: 376 influenza A(H3N2) and 928 B cases, and 2028 controls. Most (>99%) vaccinated patients received the B lineage‐mismatched trivalent vaccine. IVE against influenza A(H3N2) was 24% (95% CI: 2 to 40); 35% (95% CI: 6 to 55) in 65‐ to 79‐year‐olds and 14% (95% CI: −22 to 39) in ≥80‐year‐olds. Against influenza B, IVE was 30% (95% CI: 16 to 41); 37% (95% CI: 19 to 51) in 65‐ to 79‐year‐olds and 19% (95% CI: −7 to 38) in ≥80‐year‐olds.

Conclusions

IVE against influenza B was similar to A(H3N2) in hospitalised older adults, despite trivalent vaccine and circulating B lineage mismatch, suggesting some cross‐protection. IVE was lower in those ≥80 than 65‐79 years. We reinforce the importance of influenza vaccination in older adults as, even with a poorly matched vaccine, it still protects one in three to four of this population from severe influenza.

The effects of age on clinical characteristics, hospitalization and mortality of patients with influenza-related illness at a tertiary care centre in Malaysia

Background

Age is an established risk factor for poor outcomes in individuals with influenza‐related illness, and data on its influence on clinical presentations and outcomes in the South‐East Asian settings are scarce. The aim of this study was to determine the above among adults with influenza‐related upper respiratory tract infection at a teaching hospital in Malaysia.

Methods

A retrospective case‐note analysis was conducted on a cohort of 3935 patients attending primary care at the University Malaya Medical Centre, Malaysia from February 2012 till May 2014 with URTI symptoms. Demographics, clinical characteristics, medical and vaccination history were obtained from electronic medical records, and mortality data from the National Registration Department. Comparisons were made between those aged <25, ≥25 to <65 and ≥65 years.

Results

470 (11.9%) had PCR‐confirmed influenza virus infection. Six (1.3%) received prior influenza vaccination. Those aged ≥65 years were more likely to have ≥2 comorbidities (P < .001) and were less likely to present with fever (P = .004). One‐third of those aged ≥65 years experienced hospitalization, intensive care admission or death within a year compared to 10% in the ≥25 to <65 years. Age ≥65 years was an independent predictor of hospitalization and death (OR = 9.97; 95% CI = 3.11‐31.93) compared to those aged <25 years.

Conclusion

Older patients in our cohort were more likely to have comorbidities and present with atypical features, with older age being an independent predictor of poor health outcomes. Our findings will now inform future health policies on older persons and economic modelling of adult vaccination programmes.

Pharmacists' Scope of Practice: Supports for Canadians with Diabetes

OBJECTIVES

The pharmacists' role in Canada has significantly advanced over the past decade, resulting in increasing access to primary care services. This study aimed to characterize pharmacists' expanded scope of practice as it relates to providing services to Canadians with diabetes.

METHODS

This environmental scan characterized services that could be useful to Canadians with diabetes in each of the provinces (excluding the territories): immunizations, medication prescribing, ordering and interpreting laboratory tests, and medication reviews. Researchers also collected information on pharmacists' access to health information. Data were collected from regulatory authorities in each province, from pharmacy stakeholders and through a web search.

RESULTS

Pharmacists' scope of practice varies widely across the Canadian provinces. Three provinces have medication-review programs focused specifically on diabetes, and many people with diabetes can access publicly funded medication reviews. Other than in Quebec, pharmacists can provide influenza (publicly funded) and pneumococcal vaccinations (publicly funded in British Columbia, Alberta and Manitoba). All pharmacists in Canadian provinces can renew prescriptions to ensure continuity of therapy. Pharmacists have varying levels of other prescriptive authority. Pharmacists in all provinces (except Ontario) can access provincial prescription information; in 4 provinces, they can access laboratory results, and in 3 provinces, they can order and interpret laboratory results, such as glycated hemoglobin levels.

CONCLUSIONS

Canadians with diabetes can expect to receive influenza vaccines and have medications renewed at their pharmacies. Many patients with diabetes qualify for a publicly funded medication review, and some provinces allow pharmacists to order and interpret laboratory results. This expanded scope provides greater opportunities for pharmacists to help support patients with diabetes in conjunction with other health-care team members.

Preventive Interventions for the Second Half of Life: A Systematic Review

OBJECTIVE

Recent improvements in life expectancy globally require intensified focus on noncommunicable diseases and age-related conditions. The purpose of this article is to inform the development of age-specific prevention guidelines for adults aged 50 and above, which are currently lacking.

DATA SOURCE

PubMed, Cochrane database, and Google Scholar and explicit outreach to experts in the field.

STUDY INCLUSION AND EXCLUSION CRITERIA

Meta-analyses, intervention-based, and prospective cohort studies that reported all-cause mortality, disease-specific mortality, or morbidity in adults were included.

DATA EXTRACTION

A systematic review was undertaken in 2015 using search terms of a combination of <risk factor> and "intervention," "mortality," "reduction," "improvement," "death," and "morbidity."

DATA SYNTHESIS

Interventions were categorized according to the Center for Evidence-Based Medicine Level of Evidence framework.

RESULTS

A summary table reports for each intervention the impact, strength of evidence, initiation, duration, and details of the intervention. Age-decade-specific preventive recommendations have been proposed relating to physical activity, diet, tobacco and alcohol use, medication adherence, screening and vaccination, and mental and cognitive health.

CONCLUSION

Clear recommendations have been made according to the existing evidence base, but further research investment is needed to fill the many gaps. Further, personalized approaches to healthy aging complemented by population-wide approaches and broader cross-sector partnerships will help to ensure greater longevity is an opportunity, rather than a burden, for society.

Sensitivity analysis for the effects of multiple unmeasured confounders

PURPOSE

Observational studies are prone to (unmeasured) confounding. Sensitivity analysis of unmeasured confounding typically focuses on a single unmeasured confounder. The purpose of this study was to assess the impact of multiple (possibly weak) unmeasured confounders.

METHODS

Simulation studies were performed based on parameters estimated from the British Women's Heart and Health Study, including 28 measured confounders and assuming no effect of ascorbic acid intake on mortality. In addition, 25, 50, or 100 unmeasured confounders were simulated, with various mutual correlations and correlations with measured confounders.

RESULTS

The correlated unmeasured confounders did not need to be strongly associated with exposure and outcome to substantially bias the exposure-outcome association at interest, provided that there are sufficiently many unmeasured confounders. Correlations between unmeasured confounders, in addition to the strength of their relationship with exposure and outcome, are key drivers of the magnitude of unmeasured confounding and should be considered in sensitivity analyses. However, if the unmeasured confounders are correlated with measured confounders, the bias yielded by unmeasured confounders is partly removed through adjustment for the measured confounders.

CONCLUSIONS

Discussions of the potential impact of unmeasured confounding in observational studies, and sensitivity analyses to examine this, should focus on the potential for the joint effect of multiple unmeasured confounders to bias results.

Effectiveness of the influenza vaccine in preventing admission to hospital and death in people with type 2 diabetes

BACKGROUND

The health burden caused by seasonal influenza is substantial. We sought to examine the effectiveness of influenza vaccination against admission to hospital for acute cardiovascular and respiratory conditions and all-cause death in people with type 2 diabetes.

METHODS

We conducted a retrospective cohort study using primary and secondary care data from the Clinical Practice Research Datalink in England, over a 7-year period between 2003/04 and 2009/10. We enrolled 124 503 adults with type 2 diabetes. Outcome measures included admission to hospital for acute myocardial infarction (MI), stroke, heart failure or pneumonia/influenza, and death. We fitted Poisson regression models for influenza and off-season periods to estimate incidence rate ratios (IRR) for cohorts who had and had not received the vaccine. We used estimates for the summer, when influenza activity is low, to adjust for residual confounding.

RESULTS

Study participants contributed to 623 591 person-years of observation during the 7-year study period. Vaccine recipients were older and had more comorbid conditions compared with nonrecipients. After we adjusted for covariates and residual confounding, vaccination was associated with significantly lower admission rates for stroke (IRR 0.70, 95% confidence interval [CI] 0.53-0.91), heart failure (IRR 0.78, 95% CI 0.65-0.92) and pneumonia or influenza (IRR 0.85, 95% CI 0.74-0.99), as well as all-cause death (IRR 0.76, 95% CI 0.65-0.83), and a nonsignificant change for acute MI (IRR 0.81, 95% CI 0.62-1.04) during the influenza seasons.

INTERPRETATION

In this cohort of patients with type 2 diabetes, influenza vaccination was associated with reductions in rates of admission to hospital for specific cardiovascular events. Efforts should be focused on improvements in vaccine uptake in this important target group as part of comprehensive secondary prevention.

Frequency and impact of confounding by indication and healthy vaccinee bias in observational studies assessing influenza vaccine effectiveness: a systematic review

Background

Evidence on influenza vaccine effectiveness (VE) is commonly derived from observational studies. However, these studies are prone to confounding by indication and healthy vaccinee bias. We aimed to systematically investigate these two forms of confounding/bias.

Methods

Systematic review of observational studies reporting influenza VE and indicators for bias and confounding. We assessed risk of confounding by indication and healthy vaccinee bias for each study and calculated ratios of odds ratios (crude/adjusted) to quantify the effect of confounder adjustment. VE-estimates during and outside influenza seasons were compared to assess residual confounding by healthy vaccinee effects.

Results

We identified 23 studies reporting on 11 outcomes. Of these, 19 (83 %) showed high risk of bias: Fourteen due to confounding by indication, two for healthy vaccinee bias, and three studies showed both forms of confounding/bias. Adjustment for confounders increased VE on average by 12 % (95 % CI: 7–17 %; all-cause mortality), 9 % (95 % CI: 4–14 %; all-cause hospitalization) and 7 % (95 % CI: 4–10 %; influenza-like illness). Despite adjustment, nine studies showed residual confounding as indicated by significant off-season VE-estimates. These were observed for five outcomes, but more frequently for all-cause mortality as compared to other outcomes (p = 0.03) and in studies which indicated healthy vaccinee bias at baseline (p = 0.01).

Conclusions

Both confounding by indication and healthy vaccinee bias are likely to operate simultaneously in observational studies on influenza VE. Although adjustment can correct for confounding by indication to some extent, the resulting estimates are still prone to healthy vaccinee bias, at least as long as unspecific outcomes like all-cause mortality are used. Therefore, cohort studies using administrative data bases with unspecific outcomes should no longer be used to measure the effects of influenza vaccination.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1154-y) contains supplementary material, which is available to authorized users.

A changing landscape: diagnosis and management of COPD

Chronic obstructive pulmonary disease (COPD) is a common and often particularly debilitating disease. Progressively worsening breathlessness can limit normal daily functioning, reduce quality of life (QoL) and increase the risk of premature death. Importantly, early diagnosis, improving symptoms and QoL, along with minimising exacerbations and hospital admissions, are primary goals of patient care. In recent years, the assessment of COPD has moved away from equating disease severity solely with the degree of obstructive lung impairment to include patient symptoms, exacerbation history and comorbidities, as well as smoking status. There are now more therapies that reduce symptoms and prevent exacerbations, thereby improving QoL. This review explores the diagnosis and management of COPD and positive clinical approaches to managing patients.

Using claims data to predict dependency in activities of daily living as a proxy for frailty

PURPOSE

Estimating drug effectiveness and safety among older adults in population-based studies using administrative health care claims can be hampered by unmeasured confounding as a result of frailty. A claims-based algorithm that identifies patients likely to be dependent, a proxy for frailty, may improve confounding control. Our objective was to develop an algorithm to predict dependency in activities of daily living (ADL) in a sample of Medicare beneficiaries.

METHODS

Community-dwelling respondents to the 2006 Medicare Current Beneficiary Survey, >65 years old, with Medicare Part A, B, home health, and hospice claims were included. ADL dependency was defined as needing help with bathing, eating, walking, dressing, toileting, or transferring. Potential predictors were demographics, International Classification of Diseases, Ninth Revision Clinical Modification diagnosis/procedure and durable medical equipment codes for frailty-associated conditions. Multivariable logistic regression was used to predict ADL dependency. Cox models estimated hazard ratios for death as a function of observed and predicted ADL dependency.

RESULTS

Of 6391 respondents, 57% were female, 88% white, and 38% were ≥80. The prevalence of ADL dependency was 9.5%. Strong predictors of ADL dependency were charges for a home hospital bed (OR = 5.44, 95%CI = 3.28-9.03) and wheelchair (OR = 3.91, 95%CI = 2.78-5.51). The c-statistic of the final model was 0.845. Model-predicted ADL dependency of 20% or greater was associated with a hazard ratio for death of 3.19 (95%CI: 2.78, 3.68).

CONCLUSIONS

An algorithm for predicting ADL dependency using health care claims was developed to measure some aspects of frailty. Accounting for variation in frailty among older adults could lead to more valid conclusions about treatment use, safety, and effectiveness.

Introduction to propensity scores

Although randomization provides a gold-standard method of assessing causal relationships, it is not always possible to randomly allocate exposures. Where exposures are not randomized, estimating exposure effects is complicated by confounding. The traditional approach to dealing with confounding is to adjust for measured confounding variables within a regression model for the outcome variable. An alternative approach--propensity scoring--instead fits a regression model to the exposure variable. For a binary exposure, the propensity score is the probability of being exposed, given the measured confounders. These scores can be estimated from the data, for example by fitting a logistic regression model for the exposure including the confounders as explanatory variables and obtaining the estimated propensity scores from the predicted exposure probabilities from this model. These estimated propensity scores can then be used in various ways-matching, stratification, covariate-adjustment or inverse-probability weighting-to obtain estimates of the exposure effect. In this paper, we provide an introduction to propensity score methodology and review its use within respiratory health research. We illustrate propensity score methods by investigating the research question: 'Does personal smoking affect the risk of subsequent asthma?' using data taken from the Tasmanian Longitudinal Health Study.

Effectiveness of A(H1N1)pdm09 influenza vaccine in adults recommended for annual influenza vaccination

INTRODUCTION

Because of variability in published A(H1N1)pdm09 influenza vaccine effectiveness estimates, we conducted a study in the adults belonging to the risk groups to assess the A(H1N1)pdm09 MF59-adjuvanted influenza vaccine effectiveness.

METHODS

VE against influenza and/or pneumonia was assessed in the cohort study (n>25000), and vaccine effectiveness against laboratory-confirmed A(H1N1)pdm09 influenza was assessed in a matched case-control study (16 pairs). Odds ratios (OR) and their 95% confidence intervals (95% CI) were calculated by using multivariate logistic regression; vaccine effectiveness was estimated as (1-odds ratio)*100%.

RESULTS

Vaccine effectiveness against laboratory-confirmed A(H1N1)pdm09 influenza and influenza and/or pneumonia was 98% (84-100%) and 33% (2-54%) respectively. The vaccine did not prevent influenza and/or pneumonia in 18-59 years old subjects, and was 49% (16-69%) effective in 60 years and older subjects.

CONCLUSIONS

Even though we cannot entirely rule out that selection bias, residual confounding and/or cross-protection has played a role, the present results indicate that the MF59-adjuvanted A(H1N1)pdm09 influenza vaccine has been effective in preventing laboratory-confirmed A(H1N1)pdm09 influenza and influenza and/or pneumonia, the latter notably in 60 years and older subjects.

Rituximab-treated patients have a poor response to influenza vaccination

The efficacy of influenza vaccination in patients treated with rituximab is a clinically important question. Rheumatology clinics are populated with patients receiving rituximab for a broad array of disorders. Although several studies have explored the efficacy of other vaccines in rituximab-treated populations, results have been conflicting. We wished to define influenza vaccine efficacy in a rituximab-treated cohort. We examined 17 evaluable subjects treated with rituximab for rheumatologic conditions. T cell subsets, B cells subsets, T cell function, and B cell function were evaluated at specific time points along with hemagglutinination inhibition titers after receiving the standard inactivated influenza vaccine. T cell subset counts were significantly different than controls but did not change with rituximab. B cells depleted in all patients but were in various stages of recovery at the time of vaccination. Influenza vaccine responsiveness was poor overall, with only 16 % of subjects having a four-fold increase in titer. Pre-existing titers were retained throughout the study, however. The ability to respond to the influenza vaccine appeared to be related to the degree of B cell recovery at the time of vaccination. This study emphasizes that antibody responses to vaccine are impaired in subjects treated with rituximab and supports the concept that B cell recovery influences influenza vaccine responsiveness.

Implementing an influenza vaccination programme for adults aged ≥65 years in Poland: a cost-effectiveness analysis

BACKGROUND AND OBJECTIVES

Influenza is a common respiratory disease occurring in seasonal patterns, and may lead to severe complications in frail populations such as the elderly. In Poland, influenza vaccination is recommended for people aged ≥65 years; however the vaccine coverage rate in the elderly is very low. The fact that influenza vaccine is neither reimbursed by the National Health Insurance (Narodowy Fundusz Zdrowia [NFZ]) nor financed via a National Immunization Program (NIP) could be a reason for the low coverage rate. This study assessed the cost effectiveness of the full reimbursement of an influenza vaccination programme in Poland for people aged ≥65 years.

METHODS

A decision-analytic model was developed to compare costs and outcomes associated with the current situation in which influenza vaccination is not reimbursed and a new situation in which it would be fully covered by the NFZ. The model was parameterized to Poland using data from the literature and from the Central Statistic Office of Poland. Within the elderly population, 50% were considered to be at high risk of influenza complications. An influenza attack rate of 3.5% was used for calculation purposes. Influenza-associated hospitalizations and death rates were estimated at 439.9 per 100 000 person-years and 79.1 per 100 000 person-years, respectively. Cost estimates were derived from a cost study conducted in Poland. Costs are presented in Polish Zloty (PLN) [2009 mean exchange rate: 1 PLN = €0.232]. Only direct medical costs were included to fit to the NFZ perspective. To reflect the seasonality of influenza, a time horizon of 1 year was chosen. Life-years and quality-adjusted life-years (QALYs) accumulated over future years were discounted at a rate of 5% as recommended by Polish guidelines. Deterministic and probabilistic sensitivity analyses were conducted.

RESULTS

In Poland, the introduction of the public funding of influenza vaccination for people aged ≥65 years would cost PLN 79 million when an increase in coverage rate from 13.5% to 40% is assumed. 23 900 cases of influenza, 1777 hospitalizations and 548 premature deaths would be averted each year due to the influenza vaccination programme. Fifty-seven persons would need to be vaccinated to prevent one case of influenza. To prevent one hospitalization and one death due to influenza, 842 and 2809 individuals would need to be vaccinated, respectively. The new strategy would be very cost effective compared with the current situation with an incremental cost-effectiveness ratio (ICER) of PLN26 118/QALY, which is below the 2009 yearly gross domestic product (GDP) per capita. Deterministic sensitivity analyses demonstrated that the most influential variables for the ICER were vaccine efficacy against death, excess hospitalization rate, utility norms, influenza attack rate, vaccine efficacy against hospitalization, and discount rates. All ICERs computed were below the threshold of 3 GDP per capita. From the probabilistic analysis, the proposed new influenza vaccination programme, if implemented, was predicted to be cost effective from the NFZ perspective with a probability of 100%, given the same threshold.

CONCLUSION

Implementing a vaccination programme in Poland in which influenza vaccination would be fully reimbursed by the NFZ for people aged ≥65 years would be a very cost-effective strategy.

[Influenza : clinical symptoms, diagnostics and therapy]

Influenza infections have important socio-economic consequences. Risk groups identified so far include small children and elderly adults with comorbidities. In recent years in addition to seasonal influenza an outbreak of avian influenza occurred in 2005 and the new H1N1 pandemic occurred in 2009. For the latter other at risk groups were affected and a different clinical course has been documented. The focus of this article is to give an overview on the epidemiology, clinical characteristics, diagnosis and therapy of influenza infections.

Vaccinations in Older Adults: Focus on Pneumococcal, Influenza and Herpes zoster infections

Pneumococcal, influenza and herpes zoster infections cause significant morbidity and mortality in the aging population. Effective vaccines are available in Canada to prevent and minimize illnesses caused by these infections. The purpose of this review is to provide an overview of the epidemiology of pneumococcal, influenza and herpes zoster infections in older adults, as well as available vaccines and recommended immunization schedules. In addition, the benefits of these vaccines on patient outcomes and the role of pharmacists in improving immunization rates are highlighted.

A literature review was conducted to examine the clinical outcomes related to the use of pneumococcal, influenza and herpes zoster vaccines in adults 65 years and older. All 3 vaccines are beneficial in reducing complications of these infections and are well tolerated in older adults. Studies have shown that the uptake of these vaccines remains suboptimal and the burden of illness caused by these infections continues to affect the quality of life of older adults. Pharmacists are well positioned to screen seniors for vaccine indications during routine assessments, as well as provide education to improve patient awareness, vaccine uptake and health outcomes in older adults.

Management of pneumonia in the nursing home

Pneumonia is a major cause of morbidity and mortality among nursing home residents. The approach to managing these patients has lacked uniformity because of the paucity of clinical trials, complexity of underlying comorbid diseases, and heterogeneity of administrative structures. The decision to hospitalize nursing home patients with pneumonia varies among institutions depending on staffing level, availability of diagnostic testing, and laboratory support. In the absence of comparative studies, choice of empirical antibiotic therapy continues to be based on expert opinion. Validated prognostic scoring models are needed for risk stratification. Pneumococcal and influenza vaccination are the primary prevention measures. As of January 2010, Medicare no longer pays for consultation codes; thus, practitioners must instead use existing evaluation and management service codes when providing these services.