Improved vaccine coverage for First Nations children receiving first dose on-reserve: a retrospective cohort study in western Canada

INTRODUCTION

Fragmentation in immunisation reporting systems pose challenges in measuring vaccine coverage for First Nations children in Canada. Some Nations have entered into data-sharing agreements with the province of Alberta's health ministry, enabling novel opportunities to calculate coverage.

METHODS

Partnering with a First Nations community in Alberta, this retrospective cohort study calculated routine childhood vaccine coverage. Administrative data for vaccines delivered within and outside the community were linked to calculate partial and complete immunisation coverage in 2013-2019 at ages 2 and 7 years for children living in the community. We also compared vaccine coverage each year for (a) children who were and were not continuous community residents and (b) children who received or not their first vaccine at the on-reserve community health centre. We also calculated the mean complete coverage across all study years with 95% CIs.

RESULTS

For most vaccines, coverage was higher (p<0.05) at ages 2 and 7 years for children that received their first vaccine at the First Nations health centre, compared with those who received their first dose elsewhere. For example, for pneumococcal vaccine, the mean level of complete coverage in 2-year-olds was 55.7% (52.5%-58.8%) for those who received their first vaccine in the community, compared with 33.3% (29.4%-37.3%) for those who did not; it was also higher at 7 years (75.6%, 72.7%-78.5%, compared with 55.5%, 49.7%-61.3%).

CONCLUSION

Initiating the vaccine series at the on-reserve community health centre had a positive impact on coverage. The ability to measure accurate coverage through data-sharing agreements and vaccine record linkage will support First Nations communities in identifying individual and community immunity. The findings also support the transfer of health funding and service delivery to First Nations to improve childhood immunisation uptake.

Effectiveness of maternal influenza vaccination during pregnancy against laboratory-confirmed seasonal influenza among infants under 6 months of age in Ontario, Canada

BACKGROUND

Randomized trials conducted in low- and middle-income settings demonstrated efficacy of influenza vaccination during pregnancy against influenza infection among infants <6 months of age. However, vaccine effectiveness (VE) estimates from settings with different population characteristics and influenza seasonality remain limited.

METHODS

We conducted a test-negative study in Ontario, Canada. All influenza virus tests among infants <6 months from 2010-2019 were identified and linked with health databases to ascertain information on maternal-infant dyads. VE was estimated from the odds ratio for influenza vaccination during pregnancy among cases versus controls, computed using logistic regression with adjustment for potential confounders.

RESULTS

Among 23,806 infants tested for influenza, 1,783 (7.5%) were positive and 1,708 (7.2%) were born to mothers vaccinated against influenza during pregnancy. VE against laboratory-confirmed infant influenza infection was 64% (95% confidence interval [CI]: 50%-74%). VE was similar by trimester of vaccination (1st/2nd: 66%, 40%-80%; 3rd: 63%, 46%-74%), infant age at testing (0-<2 months: 63%, 46%-75%; 2-<6 months: 64%, 36%-79%), and gestational age at birth (≥37 weeks: 64%, 50%-75%;  < 37 weeks: 61%, 4%-86%). VE against influenza hospitalization was 67% (95%CI: 50%-78%).

CONCLUSIONS

Influenza vaccination during pregnancy offers effective protection to infants <6 months, for whom vaccines are not currently available.

Individualized Prospective Prediction of Opioid Use Disorder

OBJECTIVE

Opioid use disorder (OUD) is a chronic relapsing disorder with a problematic pattern of opioid use, affecting nearly 27 million people worldwide. Machine learning (ML)-based prediction of OUD may lead to early detection and intervention. However, most ML prediction studies were not based on representative data sources and prospective validations, limiting their potential to predict future new cases. In the current study, we aimed to develop and prospectively validate an ML model that could predict individual OUD cases based on representative large-scale health data.

METHOD

We present an ensemble machine-learning model trained on a cross-linked Canadian administrative health data set from 2014 to 2018 (n  =  699,164), with validation of model-predicted OUD cases on a hold-out sample from 2014 to 2018 (n  =  174,791) and prospective prediction of OUD cases on a non-overlapping sample from 2019 (n  =  316,039). We used administrative records of OUD diagnosis for each subject based on International Classification of Diseases (ICD) codes.

RESULTS

With 6409 OUD cases in 2019 (mean [SD], 45.34 [14.28], 3400 males), our model prospectively predicted OUD cases at a high accuracy (balanced accuracy, 86%, sensitivity, 93%; specificity 79%). In accord with prior findings, the top risk factors for OUD in this model were opioid use indicators and a history of other substance use disorders.

CONCLUSION

Our study presents an individualized prospective prediction of OUD cases by applying ML to large administrative health datasets. Such prospective predictions based on ML would be essential for potential future clinical applications in the early detection of OUD.

One child, one appointment: how institutional discourses organize the work of parents and nurses in the provision of childhood vaccination for First Nations children

To effectively support childhood vaccine programs for First Nations Peoples, Canada's largest population of Indigenous Peoples, it is essential to understand the context, processes, and structures organizing vaccine access and uptake. Rather than assuming that solutions lie in compliance with current regulations, our aim was to identify opportunities for innovation by exploring the work that nurses and parents must do to have children vaccinated. In partnership with a large First Nations community, we used an institutional ethnography approach that included observing vaccination clinic appointments, interviewing individuals involved in childhood vaccinations, and reviewing documented vaccination processes and regulations (texts). We found that the 'work' nurses engage in to deliver childhood vaccines is highly regulated by standardized texts that prioritize discourses of safety and efficiency. Within the setting of nursing practice in a First Nations community, these regulations do not always support the best interests of families. Nurses and parents are caught between the desire to vaccinate multiple children and the requirement to follow institutionally authorized processes. The success of the vaccination program, when measured solely by the number of children who follow the vaccine schedule, does not take into consideration the challenges nurses encounter in the clinic or the work parents do to get their children vaccinated. Exploring new ways of approaching the processes could lead to increased vaccination uptake and satisfaction for parents and nurses.

Text Message Reminders to Improve Immunization Appointment Attendance in Alberta, Canada: The Childhood Immunization Reminder Project Pilot Study

BACKGROUND

Vaccine coverage for 18-month-old children in Canada is often below the recommended level, which may be partially because of parental forgetfulness. SMS text message reminders have been shown to potentially improve childhood immunization uptake but have not been widely used in Alberta, Canada. In addition, it has been noted that language barriers may impede immunization service delivery but continue to remain unaddressed in many existing reminder and recall systems.

OBJECTIVE

This study aimed to assess the effectiveness and acceptability of using SMS text messages containing a link to web-based immunization information in different languages to remind parents of their child's 18-month immunization appointment.

METHODS

The Childhood Immunization Reminder Project was a pilot intervention at 2 public health centers, one each in Lethbridge and Edmonton, Alberta, Canada. Two SMS text message reminders were sent to parents: a booking reminder 3 months before their child turned 18 months old and an appointment reminder 3 days before their scheduled appointment. Booking reminders included a link to the study website hosting immunization information in 9 languages. To evaluate intervention effectiveness, we compared the absolute attendance no-show rates before the intervention and after the intervention. The acceptability of the intervention was evaluated through web-based surveys completed by parents and public health center staff. Google Analytics was used to determine how often web-based immunization information was accessed, from where, and in which languages.

RESULTS

Following the intervention, the health center in Edmonton had a reduction of 6.4% (95% CI 3%-9.8%) in appointment no-shows, with no change at the Lethbridge Health Center (0.8%, 95% CI -1.4% to 3%). The acceptability surveys were completed by 222 parents (response rate: 23.9%) and 22 staff members. Almost all (>95%) respondents indicated that the reminders were helpful and provided useful suggestions for improvement. All surveyed parents (222/222, 100%) found it helpful to read web-based immunization information in their language of choice. Google Analytics data showed that immunization information was most often read in English (118/207, 57%), Punjabi (52/207, 25.1%), Arabic (13/207, 6.3%), Spanish (12/207, 5.8%), Italian (4/207, 1.9%), Chinese (4/207, 1.9%), French (2/207, 0.9%), Tagalog (1/207, 0.5%), and Vietnamese (1/207, 0.5%).

CONCLUSIONS

The study's findings support the use of SMS text message reminders as a convenient and acceptable method to minimize parental forgetfulness and potentially reduce appointment no-shows. The diverse languages accessed in web-based immunization information suggest the need to provide appropriate translated immunization information. Further research is needed to evaluate the impact of SMS text message reminders on childhood immunization coverage in different settings.

Association between influenza vaccination and risk of stroke in Alberta, Canada: a population-based study

BACKGROUND

Respiratory infection can be an immediate precursor to stroke and myocardial infarction. Influenza vaccination is associated with reduced risk of myocardial infarction and hospitalisation for cardiac disease, and influenza vaccination is strongly recommended for patients with heart disease. Evidence on whether the same protective association exists for stroke, and whether this potential effect is consistent across age and risk groups, is conflicting. We aimed to assess the risk of stroke after influenza vaccination in adults.

METHODS

We obtained administrative data from the Alberta Health Care Insurance Plan (which covers all residents of Alberta, Canada) beginning on Sept 30, 2009, or May 15 of the year in which residents were recorded as being 18 years of age. Individuals were censored at the earliest of three events: death, recorded outmigration, or Dec 31, 2018. The outcome of interest was any stroke event, comprising acute ischaemic stroke, intracerebral haemorrhage, subarachnoid haemorrhage, and transient ischaemic attack. We used Andersen-Gill Cox models to analyse the hazard of any stroke event for individuals with recent (&lt;182 days) influenza vaccination compared with those without recent influenza vaccination, with adjustment for age, sex, anticoagulant use, atrial fibrillation, chronic obstructive pulmonary disease, diabetes, hypertension, income quintile, and rural or urban home location. Two-way interaction terms between each individual covariate and vaccination status were used to assess for effect modification by risk factor. The association between vaccination and risk of each type of stroke was also modelled, adjusting for baseline covariates.

FINDINGS

The study sample consisted of 4 141 209 adults (29 687 899 person-years of observation time) registered under the provincial health-care system between Sept 30, 2009, and Dec 31, 2018. 1 769 565 (42·73%) individuals received at least one vaccination during the study period, and 38 126 stroke events were recorded. Adjusted for demographics and comorbidities, recent influenza vaccination significantly reduced the hazard of stroke (hazard ratio 0·775 [95% CI 0·757-0·793]). This association persisted across all stroke types. We found effect modification by each covariate examined except for home location; however, vaccination was associated with a reduced risk of stroke overall across all ages and risk profiles with the exception of individuals without hypertension.

INTERPRETATION

The risk of stroke is reduced among people who have recently been vaccinated against influenza compared with those who have not. This association extended to the entire adult population and was not limited to individuals with a baseline high risk of stroke. Further studies in a variety of settings are needed to evaluate whether influenza vaccination could be used as a public health strategy to prevent stroke.

FUNDING

None.

Evaluating the Individual Healthcare Costs and Burden of Disease Associated with RSV Across Age Groups

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of acute respiratory infection (ARI), with high morbidity and mortality worldwide. RSV costing and burden estimates can highlight the potential benefits of future vaccination programs and are essential for economic evaluations.

OBJECTIVE

We aimed to determine RSV healthcare costs across age groups and the overall disease burden of medically attended RSV in Canada.

METHODS

We conducted a retrospective case-control study to estimate the attributable healthcare costs per RSV case in Alberta. We used two case definitions to capture diversity in case severity: laboratory-confirmed RSV and ARI attributable to RSV. Matching occurred on five criteria: (1) age, (2) urban/rural status, (3) sex, (4) prematurity and (5) Charlson Comorbidity Index score. We calculated the age-specific burden of medically attended RSV in Canada from 2010 to 2019 by multiplying the weekly age-specific incidence of medically attended ARI with the RSV positivity rate.

RESULTS

Costs per laboratory-confirmed RSV case were (in Canadian dollars [CAD], year 2020 values) $CAD12,713 and 40,028 in the first 30 and 365 days following diagnosis, respectively, whereas a case of ARI potentially attributable to RSV cost $CAD316 and 915, in 30 and 365 days, respectively. Older (aged ≥ 65 years) and younger (aged < 90 days) age groups had the highest case costs. The average medically attended RSV incidence rate across nine seasons was 1743 cases per 100,000 people per year.

CONCLUSIONS

RSV is a common and expensive infection at the extremes of life, and the development of immunization programs targeting older and younger ages may be important for the reduction of RSV burden and cost.

Seropositivity to SARS-CoV-2 in Alberta, Canada in a post-vaccination period (March 2021-July 2021)

BACKGROUND

The COVID-19 pandemic has necessitated the need to rapidly make public health decisions. We systematically evaluated SARS-CoV-2 seropositivity to understand local COVID-19 epidemiology and support evidence-based public health decision making.

METHODS

Residual blood samples were collected for SARS-CoV-2 receptor binding domain (RBD) IgG testing over a 1-5 day period monthly from 26 February 2021-9 July 2021 from six clinical laboratories across the province of Alberta, Canada. Monthly crude and adjusted (for age and gender) seropositivity were calculated. Results were linked to provincial administrative, laboratory, and vaccine databases.

RESULTS

60,632 individual blood samples were tested. Vaccination data were available for 98.8% of samples. Adjusted RBD IgG positivity rose from 11.9% (95% confidence interval [CI] 11.9-12.0%) in March 2021 to 70.2% (95% CI 70.2-70.3%) in July 2021 (p < .0001). Seropositivity rose from 9.4% (95% CI 9.3-9.4%) in March 2021 to 20.2% (95% CI 20.1-20.2%) in July 2021 in unvaccinated Albertans. Unvaccinated seropositive individuals were from geographic areas with significantly (p < .001) lower median household income, lower proportion of married/common-law relationships, larger average household size and higher proportions of visible minorities compared to seronegative unvaccinated individuals. In July 2021, the age groups with the lowest and highest seropositivity in unvaccinated Albertans were those ≥80 years (12.0%, 95% CI 5.3-18.6%) and 20-29 years (24.2%, 95% CI 19.6-28.8%), respectively. Of seropositive unvaccinated individuals, 50.2% (95% CI 45.9-54.5%) had no record of prior SARS-CoV-2 molecular testing.

CONCLUSIONS

Longitudinal surveillance of SARS-CoV-2 seropositivity with data linkage is valuable for decision-making during the pandemic.

Impact of the COVID-19 pandemic on vaccine coverage for early childhood vaccines in Alberta, Canada: a population-based retrospective cohort study

OBJECTIVE

To assess the impact of the COVID-19 pandemic on early childhood vaccination coverage in Alberta, Canada.

SETTING

Alberta, a western Canadian province, which has a population of 4.4 million and approximately 50 000 births annually.

DESIGN

In this retrospective cohort study, population-based administrative health data were analysed to determine the vaccination coverage for measles-containing, pertussis-containing and rotavirus vaccines.

PRIMARY OUTCOME MEASURE

We measured monthly and cumulative vaccine coverage. We assessed the absolute difference in monthly and cumulative coverage for each vaccine dose by comparing children due for vaccination in each month of 2019 and 2020, with follow-up to determine if missed doses were caught up later.

PARTICIPANTS

We included 114 178 children in the 2019 analysis cohort and 106 530 children in the 2020 analysis cohort.

RESULTS

Monthly vaccination coverage in 2020 was higher than 2019 until March, when coverage significantly declined. Comparing April 2020 to 2019, coverage was 9.9% (95% CI 7.9% to 12.0%) lower for measles vaccine; 4.9% (95% CI 3.3% to 6.5%), 7.1% (95% CI 5.2% to 9.1%), 5.2% (95% CI 3.1% to 7.4%) and 8.8% (95% CI 6.6% to 10.9%) lower for first, second, third and fourth doses of pertussis-containing vaccine, respectively; and 4.0% (95% CI 2.3% to 5.7%), 7.1% (95% CI 5.1% to 9.2%) and 4.6% (95% CI 2.4% to 6.7%) lower for first, second and third doses of rotavirus vaccine, respectively. Monthly coverage improved during May to July 2020; however, some doses experienced a second decline during September to October 2020. The cumulative coverage analysis showed that the measles-containing vaccine had the largest difference in coverage at the end of follow-up.

CONCLUSIONS

Children who were due for vaccination early in the pandemic and in Fall 2020, especially those due for measles vaccination, may require additional catch-up.

COVID-19 Vaccination Uptake among individuals with Immune-Mediated Inflammatory Diseases in Ontario, Canada between December 2020 and October 2021: A population-based analysis

OBJECTIVE

We assessed COVID-19 vaccine uptake among individuals with immune-mediated inflammatory diseases (IMID) and the Ontario general population.

METHODS

We studied all residents 16 years and older who were alive and enrolled in Ontario's universal health insurance plan as of December 14, 2020 when vaccination commenced (n=12,435,914). Individuals with rheumatoid arthritis (RA), ankylosing spondylitis (AS), psoriatic arthritis (PsA), psoriasis (PsO), and inflammatory bowel disease (IBD) were identified using established disease-specific case definitions applied to health administrative data. Vaccination status was extracted from the provincial COVaxON registry. Weekly cumulative proportions of first and second doses up until October 3, 2021 were expressed as the vaccinated percentage of each disease group, and compared to the general Ontario population, and stratified by age.

RESULTS

By October 3, 2021, the cumulative percentage with at least one dose was 82.1% for the general population, 88.9% for RA, 87.4% for AS, 90.6% for PsA, 87.3% for PsO, and 87.0% for IBD. There was also a higher total cumulative percentage with two doses among IMIDs (83.8-88.2%) vs the general population (78.0%). The difference was also evident when stratifying by age. Individuals with IMIDs in the youngest age group initially had earlier uptake than the general population but remain the lowest age group with two doses (70.6% in the general population vs. 73.7-79.2% across IMID groups).

CONCLUSION

While implementation of COVID-19 vaccination programs has differed globally, these Canadian estimates are the first to reassuringly show higher COVID-19 vaccine uptake among individuals with IMIDs.

Disease-modifying drugs for multiple sclerosis and subsequent health service use

Objective:

We assessed the relationship between the multiple sclerosis (MS) disease-modifying drugs (DMDs) and healthcare use.

Methods:

Persons with MS (aged ⩾18 years) were identified using linked population-based health administrative data in four Canadian provinces and were followed from the most recent of their first MS/demyelinating event or 1 January 1996 until the earliest of death, emigration, or study end (31 December 2017 or 31 March 2018). Prescription records captured DMD exposure, examined as any DMD, then by generation (first-generation (the injectables) or second-generation (orals/infusions)) and individual DMD. The associations with subsequent all-cause hospitalizations and physician visits were examined using proportional means model and negative binomial regression.

Results:

Of 35,894 MS cases (72% female), mean follow-up was 12.0 years, with person-years of DMD exposure for any, or any first- or second-generation DMD being 63,290, 54,605 and 8685, respectively. Any DMD or any first-generation DMD exposure (versus non-exposure) was associated with a 24% lower hazard of hospitalization (adjusted hazard ratio, aHR: 0.76; 95% confidence intervals (CIs): 0.71–0.82), rising to 29% for the second-generation DMDs (aHR: 0.71; 95% CI: 0.58–0.88). This ranged from 18% for teriflunomide (aHR: 0.82; 95% CI: 0.67–1.00) to 44% for fingolimod (aHR: 0.56; 95% CI: 0.36–0.87). In contrast, DMD exposure was generally not associated with substantial differences in physician visits.

Conclusion:

Findings provide real-world evidence of a beneficial relationship between DMD exposure and hospitalizations.

A multi-country investigation of influenza vaccine coverage in pregnant individuals, 2010-2016

BACKGROUND

Many countries recommend influenza vaccination during pregnancy. Despite this recommendation, influenza vaccine among pregnant individuals remains under-utilized and uptake varies by country. Factors associated with influenza vaccine uptake during pregnancy may also vary across countries.

METHODS

As members of the Pregnancy Influenza Vaccine Effectiveness Network (PREVENT), five sites from four countries (Australia, Canada, Israel, and the United States) retrospectively identified cohorts of individuals aged 18-50 years who were pregnant during pre-defined influenza seasons. Influenza vaccine coverage estimates were calculated for the 2010-11 through 2015-16 northern hemisphere and the 2012 through 2015 southern hemisphere influenza seasons, by site. Sites used electronic health records, administrative data, and immunization registries to collect information on pregnancy, health history, demographics, and vaccination status. Each season, vaccination coverage was calculated as the percentage of individuals who received influenza vaccine among the individuals in the cohort that season. Characteristics were compared between those vaccinated and unvaccinated, by site.

RESULTS

More than two million pregnancies were identified over the study period. Influenza vaccination coverage ranged from 5% to 58% across sites and seasons. Coverage increased consistently over the study period at three of the five sites (Western Australia, Alberta, and Israel), and was highest in all seasons at the United States study site (39-58%). Associations with vaccination varied by country and across seasons; where available, parity >0, presence of a high-risk medical condition, and urban residence were consistently associated with increased likelihood of vaccination.

CONCLUSIONS

Though increasing, uptake of influenza vaccine among pregnant individuals remains lower than recommended. Coverage varied substantially by country, suggesting an ongoing need for targeted strategies to improve influenza vaccine uptake in this population.

COVID-19 pandemic impact on childhood vaccination coverage in Quebec, Canada

Response measures to mitigate the coronavirus disease 2019 pandemic impacted access to routine vaccination services. We evaluate the impact of the pandemic on routine infant vaccination uptake by comparing vaccination coverage, vaccine delays and doses administered in 2019 and 2020, in Quebec, Canada. Using a population-based vaccination registry, we compared vaccination coverage at 3, 5, 13 and 19 months of age between 2019 and 2020 cohorts each month from January to November. For vaccine delays, we measured the cumulative proportion vaccinated in each targeted cohort monthly. We also compared the measles-containing vaccines administered before 24 months of age between the same period in 2019 and 2020. A decline in vaccination coverage and children vaccinated on time was observed in all cohorts during the first months of the pandemic. The greatest impact was observed for the 18-month vaccination visit with a difference in vaccination coverage between both cohorts of 30.9% in May. Measles-containing doses administered during the first months of the pandemic were lower in 2020 compared with 2019: −21.1% in March (95%CI-21.6;-20.4), and −39.2% in April (95%CI-40.0;-38.2). After May, the coverage increased for all cohorts to reach pre-pandemic levels after a few months for most target ages. Routine childhood vaccinations were affected during the first months of the pandemic, but catch-up occurred thereafter and vaccination coverage in affected cohorts were very close to levels of 2019 after a few months of follow-up. Real-time monitoring of childhood vaccination is essential but also for other vaccination programs, severely affected by the pandemic.

Exploring the reasons for low pertussis vaccine effectiveness in Ontario, Canada, 2006-2008: a Canadian Immunization Research Network study

OBJECTIVES

Although pertussis vaccines have been widely used for many decades, a burden of illness persists. Resurgences in Ontario, Canada, have not been substantial in the past decade, but an outbreak of pertussis occurred in Toronto between 1 October 2005 and 31 March 2006. Previous Ontario studies found high vaccine effectiveness (VE) in the initial years post-immunization. In order to explore the impact of outbreaks and external factors on VE, we investigated pertussis VE during the period 2006-2008.

METHODS

We assessed pertussis VE using a frequency-matched case-control study for the period 1 March 2006 to 31 December 2008. We used logistic regression to estimate VE by age, time since last vaccination, and vaccination status according to the Ontario recommended schedule. We compared analyses including and excluding cases from Toronto, and to two recent Ontario pertussis VE studies.

RESULTS

We included 1797 confirmed cases and 7188 matched controls. Most cases were under 4 years of age during the study period. Pertussis VE was 3.8% (95% CI: - 21.0, 24.0) in the period 15-364 days following the last pertussis vaccine dose, and increased with increasing time since vaccination. Pertussis VE in the first 15-364 days excluding Toronto increased to 57.1% (95% CI: 26.0, 75.1), but the trend of increasing VE with time since vaccination persisted. Although VE was higher in older (6-11 years) than younger (0-5 years) children, it was lower at 12-13 years than after 14 years.

CONCLUSION

VE was lower in comparison with other studies conducted in Ontario, particularly in younger children. Various factors occurring during the study period may have influenced the results, including clinical testing of asymptomatic contacts, laboratory testing and methods and reporting practice, and a sensitive case definition. Further studies are needed to optimize methods for measuring VE to inform pertussis vaccine policy.

Effectiveness of BNT162b2 and mRNA-1273 covid-19 vaccines against symptomatic SARS-CoV-2 infection and severe covid-19 outcomes in Ontario, Canada: test negative design study

OBJECTIVE

To estimate the effectiveness of mRNA covid-19 vaccines against symptomatic infection and severe outcomes (hospital admission or death).

DESIGN

Test negative design study.

SETTING

Ontario, Canada between 14 December 2020 and 19 April 2021.

PARTICIPANTS

324 033 community dwelling people aged ≥16 years who had symptoms of covid-19 and were tested for SARS-CoV-2.

INTERVENTIONS

BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) vaccine.

MAIN OUTCOME MEASURES

Laboratory confirmed SARS-CoV-2 by reverse transcription polymerase chain reaction (RT-PCR) and hospital admissions and deaths associated with SARS-CoV-2 infection. Multivariable logistic regression was adjusted for personal and clinical characteristics associated with SARS-CoV-2 and vaccine receipt to estimate vaccine effectiveness against symptomatic infection and severe outcomes.

RESULTS

Of 324 033 people with symptoms, 53 270 (16.4%) were positive for SARS-CoV-2 and 21 272 (6.6%) received at least one dose of vaccine. Among participants who tested positive, 2479 (4.7%) were admitted to hospital or died. Vaccine effectiveness against symptomatic infection observed ≥14 days after one dose was 60% (95% confidence interval 57% to 64%), increasing from 48% (41% to 54%) at 14-20 days after one dose to 71% (63% to 78%) at 35-41 days. Vaccine effectiveness observed ≥7 days after two doses was 91% (89% to 93%). Vaccine effectiveness against hospital admission or death observed ≥14 days after one dose was 70% (60% to 77%), increasing from 62% (44% to 75%) at 14-20 days to 91% (73% to 97%) at ≥35 days, whereas vaccine effectiveness observed ≥7 days after two doses was 98% (88% to 100%). For adults aged ≥70 years, vaccine effectiveness estimates were observed to be lower for intervals shortly after one dose but were comparable to those for younger people for all intervals after 28 days. After two doses, high vaccine effectiveness was observed against variants with the E484K mutation.

CONCLUSIONS

Two doses of mRNA covid-19 vaccines were observed to be highly effective against symptomatic infection and severe outcomes. Vaccine effectiveness of one dose was observed to be lower, particularly for older adults shortly after the first dose.

Population coverage of the Canadian Chronic Disease Surveillance System: a survey of the contents of health insurance registries across Canada

Introduction

Health insurance registries, which capture insurance coverage and demographic information for entire populations, are a critical component of population health surveillance and research when using administrative data. Lack of standardization of registry information across Canada’s provinces and territories could affect the comparability of surveillance measures. We assessed the contents of health insurance registries across Canada to describe the populations covered and document registry similarities and differences.

Methods

A survey about the data and population identifiers in health insurance registries was developed by the study team and representatives from the Public Health Agency of Canada. The survey was completed by key informants from most provinces and territories and then descriptively analyzed.

Results

Responses were received from all provinces; partial responses were received from the Northwest Territories. Demographic information in health insurance registries, such as primary address, date of birth and sex, were captured in all jurisdictions. Data captured on familial relationships, ethnicity and socioeconomic status varied among jurisdictions, as did start and end dates of coverage and frequency of registry updates. Identifiers for specific populations, such as First Nations individuals, were captured in some, but not all jurisdictions.

Conclusion

Health insurance registries are a rich source of information about the insured populations of the provinces and territories. However, data heterogeneity may affect who is included and excluded in population surveillance estimates produced using administrative health data. Development of a harmonized data framework could support timely and comparable population health research and surveillance results from multi-jurisdiction studies.

A Call for Caution in Use of Pertussis Vaccine Effectiveness Studies to Estimate Waning Immunity: A Canadian Immunization Research Network Study

BACKGROUND

Vaccine effectiveness (VE) studies provide essential evidence on waning vaccine-derived immunity, a major threat to pertussis control. We evaluated how study design affects estimates by comparing 2 case-control studies conducted in Ontario, Canada.

METHODS

We compared results from a test-negative design (TND) with a frequency-matched design (FMD) case-control study using pertussis cases from 2005-2015. In the first study, we identified test-negative controls from the public health laboratory that diagnosed cases and, in the second, randomly selected controls from patients attending the same physicians that reported cases, frequency matched on age and year. We compared characteristics of cases and controls using standardized differences.

RESULTS

In both designs, VE estimates for the early years postimmunization were consistent with clinical trials (TND, 84%; FMD, 89% at 1-3 years postvaccination) but diverged as time since last vaccination increased (TND, 41%; FMD, 74% by 8 years postvaccination). Overall, we observed lower VE and faster waning in the TND than the FMD. In the TND but not FMD, controls differed from cases in important confounders, being younger, having more comorbidities, and higher healthcare use. Differences between the controls of each design were greater than differences between cases. TND controls were more likely to be unvaccinated or incompletely vaccinated than FMD controls (P < .001).

CONCLUSIONS

The FMD adjusted better for healthcare-seeking behavior than the TND. Duration of protection from pertussis vaccines is unclear because estimates vary by study design. Caution should be exercised by experts, researchers, and decision makers when evaluating evidence on optimal timing of boosters.

The impact of varicella vaccination on paediatric herpes zoster epidemiology: a Canadian population-based retrospective cohort study

The impact of universal varicella vaccination on herpes zoster (HZ) risk in unvaccinated and vaccinated children, and its long-term influence on HZ epidemiology, remains unknown. We conducted a retrospective cohort study using population-based administrative health data for children born between 1993 and 2018 (n = 924,124). We calculated age-specific cumulative HZ incidence rates by vaccination status for cohorts born before (1993–1999) and after (2000–2018) programme implementation; results were used to calculate relative risk of HZ by age group, vaccination status and vaccine availability period. Annual HZ incidence rates were calculated for 1993–2018. HZ risk was higher among unvaccinated children compared to vaccinated children across age groups; 64% higher before universal vaccination (RR: 0.36, 95% CI: 0.33, 0.39), and 32% higher after universal vaccination (RR: 0.68, 95% CI: 0.64, 0.73). Among unvaccinated children, HZ risk was 60% lower after vaccine programme implementation (RR: 0.40, 95% CI: 0.38, 0.43). Two-dose receipt corresponded with a 41% lower risk of HZ compared to one-dose receipt (RR: 0.59, 95% CI: 0.53, 0.65). Crude annual HZ incidence rates declined 64% after programme implementation, with decreases observed across age groups. Universal varicella vaccination programme implementation corresponds to decreased paediatric HZ incidence across age groups, in both vaccinated and unvaccinated individuals. Results from this study can be used to help inform varicella vaccination programme decision-making in other countries.

COVID-19 infection among international travellers: a prospective analysis

OBJECTIVES

This report estimates the risk of COVID-19 importation and secondary transmission associated with a modified quarantine programme in Canada.

DESIGN AND PARTICIPANTS

Prospective analysis of international asymptomatic travellers entering Alberta, Canada.

INTERVENTIONS

All participants were required to receive a PCR COVID-19 test on arrival. If negative, participants could leave quarantine but were required to have a second test 6 or 7 days after arrival. If the arrival test was positive, participants were required to remain in quarantine for 14 days.

MAIN OUTCOME MEASURES

Proportion and rate of participants testing positive for COVID-19; number of cases of secondary transmission.

RESULTS

The analysis included 9535 international travellers entering Alberta by air (N=8398) or land (N=1137) that voluntarily enrolled in the Alberta Border Testing Pilot Programme (a subset of all travellers); most (83.1%) were Canadian citizens. Among the 9310 participants who received at least one test, 200 (21.5 per 1000, 95% CI 18.6 to 24.6) tested positive. Sixty-nine per cent (138/200) of positive tests were detected on arrival (14.8 per 1000 travellers, 95% CI 12.5 to 17.5). 62 cases (6.7 per 1000 travellers, 95% CI 5.1 to 8.5; 31.0% of positive cases) were identified among participants that had been released from quarantine following a negative test result on arrival. Of 192 participants who developed symptoms, 51 (26.6%) tested positive after arrival. Among participants with positive tests, four (2.0%) were hospitalised for COVID-19; none required critical care or died. Contact tracing among participants who tested positive identified 200 contacts; of 88 contacts tested, 22 were cases of secondary transmission (14 from those testing positive on arrival and 8 from those testing positive thereafter). SARS-CoV-2 B.1.1.7 lineage was not detected in any of the 200 positive cases.

CONCLUSIONS

21.5 per 1000 international travellers tested positive for COVID-19. Most (69%) tested positive on arrival and 31% tested positive during follow-up. These findings suggest the need for ongoing vigilance in travellers testing negative on arrival and highlight the value of follow-up testing and contact tracing to monitor and limit secondary transmission where possible.

Progressive multifocal leukoencephalopathy and Creutzfeldt-Jakob disease: population-wide incidences, comorbidities, costs of care, and outcomes

Neurological disorders associated with chronic infections are often progressive as well as challenging to diagnose and manage. Among 4.4 million persons from 2004 to 2019 receiving universal health, progressive multifocal leukoencephalopathy (PML, n = 58) and Creutzfeldt-Jakob disease (CJD, n = 93) cases were identified, revealing stable yearly incidence rates with divergent comorbidities: HIV/AIDS affected 37.8% of PML cases while cerebrovascular disease affected 26.9% of CJD cases. Most CJD cases died within 1 year (73%) although PML cases lived beyond 5 years (34.1%) despite higher initial costs of care. PML and CJD represent important neurological disorders with evolving risk variables and impact on health care.

Direct health system costs for systemic lupus erythematosus patients in Alberta, Canada

Systemic lupus Erythematosus (SLE) is a chronic multi-system autoimmune disease that can affect a person's physical, mental, and social life. It imposes a substantial economic burden up on patients, carers, healthcare systems, and wider society. This is the first study to examine the direct health care costs of SLE in Alberta using real-world data. Alberta maintains a publicly funded, universally available health care system. Health service use and direct healthcare costs of SLE and non-SLE cases were determined from inpatient hospital services, fee-for-physician services, emergency services, and ambulatory care services. All costs were estimated for calendar year 2016. Data were analysed using central measures specifically the mean to determine the annual costs of SLE and non-SLE. A total number of 10,932 (Male = 2,546; Female = 8,386), and 41,851,36 (Male = 21,157,76; Female = 20,693,60) of SLE and non-SLE cases, respectively were included in this study. The mean annual costs of SLE, and non-SLE per case were $7,740.19 (Male = $7,986.59; Female = $7,665.38), and $2,479.53 (Male = $2,265.57; Female = $2,698.30), (p < 0.001) respectively. The mean annual costs of fee-for-physician services (SLE = $2,160.03; non-SLE = $840.00) (p < 0.001), inpatient hospital services (SLE = $3,462.86; non-SLE = $1,007.29), (p < 0.001) emergency services (SLE = $440.28; non-SLE = $176.65), (p < 0.001) and ambulatory care services (SLE = $1,677.03; non-SLE = $455.05) (p < 0.001) per case were estimated. The findings showed that the costs of SLE were considerably high for patients and healthcare system. This highlights the importance of appropriate treatment and management of SLE. Further studies are required to fully investigate both the direct and indirect economic burden of SLE including out-of-pocket expenses, costs to patients and caregivers and productivity loss.

Characterizing Pain in Children with Acute Gastroenteritis Who Present for Emergency Care

OBJECTIVE

To characterize the pain experienced by children with acute gastroenteritis (AGE) in the 24 hours before emergency department (ED) presentation. Secondary objectives included characterizing ED pain, discharge recommendations, overall analgesic use, and factors that influenced analgesic use and pain severity.

STUDY DESIGN

A prospective cohort was recruited from 2 pediatric EDs (December 2014 to September 2017). Eligibility criteria included <18 years of age, AGE (≥3 episodes of diarrhea or vomiting in the previous 24 hours), and symptom duration <7 days at presentation.

RESULTS

We recruited 2136 patients, median age 20.8 months (IQR 10.4, 47.4) and 45.8% (979/2136) female. In the 24 hours before enrollment, most caregivers reported moderate (28.6% [610/2136, 95% CI 26.7-30.5]) or severe (46.2% [986/2136, CI 44.0-48.3]) pain for their child. In the ED, they reported moderate (31.1% [664/2136, 95% CI 29.1-33.1]) or severe ([26.7% [571/2136, 95% CI 24.9-28.7]) pain; analgesia was provided to 21.2% (452/2131). The most common analgesics used in the ED were acetaminophen and ibuprofen. At discharge, these were also most commonly recommended. Factors associated with greater analgesia use in the ED were high pain scores during the index visit, having a primary care physician, earlier presentation to emergency care, fewer diarrheal episodes, presence of fever, and hospitalization at index visit.

CONCLUSIONS

Most caregivers of children presenting to the ED with AGE reported moderate or severe pain, both before and during their visit. Future research should focus on the development of effective, safe, and timely pain management plans.

Characteristics of a population-based multiple sclerosis cohort treated with disease-modifying drugs in a universal healthcare setting

Background: Relatively little is known about the use of disease-modifying drugs (DMDs) for multiple sclerosis (MS) in the population-based universal healthcare setting. This study aimed to describe the characteristics of a population-based cohort with MS and their DMD exposure in four Canadian provinces. Methods: We identified all adults (aged ≥18 years) with MS using linked population-based health administrative data. Individuals were followed from the most recent of their first MS or demyelinating event or 1 January 1996(study entry), to the earliest of death, emigration, or 31 March 2018(study end). Cohort characteristics examined included sex, age, socioeconomic status, and comorbidity burden. Results: Overall, 10,418/35,894 (29%) of MS cases filled a DMD prescription during the 22-year study period. Most were women (n = 7,683/10,418;74%), and 17% (n = 1,745/10,418) had some comorbidity (Charlson Comorbidity Index≥1) at study entry. Nearly 20% (n = 1,745/10,418) were aged ≥50 when filling their first DMD; the mean age was 39.6 years. Conclusions: Almost 1 in 6 people with MS had at least some comorbidity, and nearly 1 in 6 were ≥50 years old at the time of their first DMD. As these individuals are typically excluded from clinical trials, findings illustrate the need to understand the harms and benefits of DMD use in these understudied groups.

Developments in asthma incidence and prevalence in Alberta between 1995 and 2015

BACKGROUND

Asthma is a chronic respiratory disease characterized by reversible bronchoconstriction and airway inflammation. According to Statistics Canada in 2014, 8.1% of Canadians aged 12 and older reported having asthma diagnosed by a health care professional. Therefore, in 2014 there were an estimated 274,661 persons with asthma in Alberta. Most epidemiological studies estimate prevalence and incidence using survey-based data, which has limitations. The Ontario Asthma Surveillance Information System (OASIS) group has developed and validated an algorithm for epidemiologic asthma studies using provincial health databases. In Alberta, there are some studies using provincial databases, but most are restricted to emergency department visits and do not represent the entire asthma population. Using the validated asthma definition for epidemiologic studies, we performed an analysis of the Alberta Health administrative databases to investigate and report province-wide asthma prevalence, incidence and mortality in Alberta from 1995 to 2015.

METHODS

Data from administrative databases, provided by Alberta Health, was analyzed to determine age and sex specific prevalence, incidence and mortality of the asthma population. The population cohort was all individuals residing in the province of Alberta, ages 0 to 99 from 1995-2015. Kendall's Tau coefficient test was used to ascertain whether the observed trends were statistically significant.

RESULTS

Between 1995 and 2015, the age-standardized incidence of asthma decreased by more than 50% in both males and females. Prevalence, however, increased threefold over the 20 years (for both genders) from 3.9 to 12.3% (Tau = 1.00, p < 0.0001) in females and from 3.5 to 11.6% (Tau = 1.00, p < 0.0001) in males. Thus, in 2015 there were 496,927 people with asthma in Alberta. All-cause mortality in the asthma population decreased over time, in both females (Tau = - 0.71, p < 0.0001) and males (Tau = - 0.69, p = 0.0001). For the last several years, all-cause mortality was higher in those with asthma. There were ~ 7 deaths/1000 in the population with asthma versus ~ 5 deaths/1000 in those without asthma.

CONCLUSIONS

The incidence of asthma decreased in both females and males while prevalence continued to increase, although at a slower rate than previously. All-cause mortality in asthma patients was higher than in those without asthma, but both decreased over time.

Influenza Vaccine Effectiveness in Preventing Influenza-associated Hospitalizations During Pregnancy: A Multi-country Retrospective Test Negative Design Study, 2010-2016

BACKGROUND

To date, no study has examined influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza-associated hospitalizations during pregnancy.

METHODS

The Pregnancy Influenza Vaccine Effectiveness Network (PREVENT) consisted of public health or healthcare systems with integrated laboratory, medical, and vaccination records in Australia, Canada (Alberta and Ontario), Israel, and the United States (California, Oregon, and Washington). Sites identified pregnant women aged 18 through 50 years whose pregnancies overlapped with local influenza seasons from 2010 through 2016. Administrative data were used to identify hospitalizations with acute respiratory or febrile illness (ARFI) and clinician-ordered real-time reverse transcription polymerase chain reaction (rRT-PCR) testing for influenza viruses. Overall IVE was estimated using the test-negative design and adjusting for site, season, season timing, and high-risk medical conditions.

RESULTS

Among 19450 hospitalizations with an ARFI discharge diagnosis (across 25 site-specific study seasons), only 1030 (6%) of the pregnant women were tested for influenza viruses by rRT-PCR. Approximately half of these women had pneumonia or influenza discharge diagnoses (54%). Influenza A or B virus infections were detected in 598/1030 (58%) of the ARFI hospitalizations with influenza testing. Across sites and seasons, 13% of rRT-PCR-confirmed influenza-positive pregnant women were vaccinated compared with 22% of influenza-negative pregnant women; the adjusted overall IVE was 40% (95% confidence interval = 12%-59%) against influenza-associated hospitalization during pregnancy.

CONCLUSION

Between 2010 and 2016, influenza vaccines offered moderate protection against laboratory-confirmed influenza-associated hospitalizations during pregnancy, which may further inform the benefits of maternal influenza vaccination programs.

The ecology of medical care for adults in Alberta, 2002/03 to 2016/17: a retrospective cohort study

BACKGROUND

If we are to improve the patient experience, knowing where and with whom people receive professional health advice and treatment (the ecology of medical care) is the first step. We designed this study to define the ecology of medical care in Alberta and to examine whether province-wide implementation of 5 policy changes between 2003 and 2012 changed patterns of care among adults in the province.

METHODS

This was a retrospective cohort study of adults (age ≥ 18 yr) in Alberta using routinely collected data from 6 linked administrative health databases, the 2016 Canadian Community Health Survey and the Alberta Health Link teletriage system. We collected data on all encounters with pharmacists, primary care physicians, specialists, emergency departments and hospitals in 2002/03, 2009/10 and 2016/17.

RESULTS

Between 2002/03 and 2016/17, the community-dwelling adult population of Alberta increased from 2.66 million to 3.84 million; the median age increased from 41 to 43 years, and the proportion with at least 1 ambulatory-care-sensitive condition increased from 20.6% to 27.8%. The proportion who saw a primary care physician decreased significantly (from 70.8% to 68.2%, p < 0.001), as did the proportion who visited an emergency department (from 20.6% to 19.2%, p < 0.001); the declines were seen in all subgroups examined. The proportion who saw a specialist as an outpatient increased from 31.9% to 33.2% (p < 0.001), and the proportion who received at least 1 medication dispensation increased from 54.9% to 60.2% (p < 0.001). The proportion admitted to an acute care hospital (5.6%-6.5%) or academic hospital (1.2%) was relatively stable over time.

INTERPRETATION

Despite implementation of 5 system-wide changes designed to affect the delivery of primary and specialty medical care as well as the use of pharmacist and nursing services in Alberta, patterns of health care delivery changed little between 2002/03 and 2016/17. Rather than searching for a policy "magic bullet," health care planners may be better served by focusing on upscaling and implementing interventions proven to be efficacious.

Measurement of coverage, compliance and determinants of uptake in a publicly funded rotavirus vaccination programme: a retrospective cohort study

OBJECTIVES

In June 2015, Alberta, Canada instituted a universal publicly funded rotavirus vaccination programme (Rotarix, RV1), with vaccine doses scheduled for 2 and 4 months of age. Vaccination was restricted so that infants were only allowed to receive first dose between 6 and 20 weeks of age, and second dose before eight calendar months of age. We assessed the coverage and schedule non-compliance of rotavirus vaccination for babies born between June 2015 and August 2016, that is, since the inception of the publicly funded rotavirus vaccination programme, and determined factors associated with rotavirus vaccine uptake.

DESIGN

Retrospective cohort study using linked administrative health data.

SETTING

Alberta, Canada.

PARTICIPANTS

Cohort of 66 689 children. PRIMARY AND SECONDARY OUTCOME MEASURES: (1) First and second dose rotavirus vaccination coverage, (2) percent of children non-compliant with recommended vaccine schedule and (3) adjusted ORs for factors associated with vaccination status.

RESULTS

For the 66 689 children included in the study, coverage levels for one-dose and two-dose rotavirus vaccination were 87% and 83%, respectively. In comparison, two-dose diphtheria-tetanus-pertussis-polio-Haemophilus influenzae type b vaccine coverage was 92%, despite having the same dosing schedule. Schedule non-compliance during the publicly funded programme was very low. We observed socioeconomic disparities in the uptake of the vaccine, with income, location of residence and number of children in the household all contributing to the odds of a child being vaccinated with rotavirus.

CONCLUSIONS

Compliance to the recommended rotavirus schedule was very high, suggesting that even with the restrictive rotavirus vaccine schedule, the vaccine can be delivered on-time. However, rotavirus vaccine coverage remained lower than DTaP, a similarly scheduled childhood vaccination. We also observed socioeconomic disparities in vaccine uptake. These findings raise concerns about rotavirus protection in the groups at highest risk for gastrointestinal illness, including low-income and rural populations.

Comparative effectiveness and cost-effectiveness analysis of a urine metabolomics test vs. alternative colorectal cancer screening strategies

PURPOSE

Despite the success of provincial screening programs, colorectal cancer (CRC) is still the third most common cancer in Canada and the second most common cause of cancer-related death. Fecal-based tests, such as fecal occult blood test (FOBT) and fecal immunochemical test (FIT), form the foundation of the provincial CRC screening programs in Canada. However, those tests have low sensitivity for CRC precursors, adenomatous polyps and have low adherence. This study evaluated the effectiveness and cost-effectiveness of a new urine metabolomic-based test (UMT) that detects adenomatous polyps and CRC.

METHODS

A Markov model was designed using data from the literature and provincial healthcare databases for Canadian at average risk for CRC; calibration was performed against statistics data. Screening strategies included the following: FOBT every year, FIT every year, colonoscopy every 10 years, and UMT every year. The costs, quality adjusted life years (QALY) gained, and incremental cost-effectiveness ratios (ICERs) for each strategy were estimated and compared.

RESULTS

Compared with no screening, a UMT strategy reduced CRC mortality by 49.9% and gained 0.15 life years per person at $42,325/life year gained in the base case analysis. FOBT reduced CRC mortality by 14.9% and gained 0.04 life years per person at $25,011/life year gained. FIT reduced CRC mortality by 35.8% and gained 0.11 life years per person at $25,500/life year while colonoscopy reduced CRC mortality by 24.7% and gained 0.08 life years per person at $50,875/life year.

CONCLUSIONS

A UMT strategy might be a cost-effective strategy when used in programmatic CRC screening programs.

Using population-wide administrative and laboratory data to estimate type- and subtype-specific influenza vaccine effectiveness: a surveillance protocol

INTRODUCTION

The appropriateness of using routinely collected laboratory data combined with administrative data for estimating influenza vaccine effectiveness (VE) is still being explored. This paper outlines a protocol to estimate influenza VE using linked laboratory and administrative data which could act as a companion to estimates derived from other methods.

METHODS AND ANALYSIS

We will use the test-negative design to estimate VE for each influenza type/subtype and season. Province-wide individual-level records of positive and negative influenza tests at the Provincial Laboratory for Public Health in Alberta will be linked, by unique personal health numbers, to administrative databases and vaccination records held at the Ministry of Health in Alberta to determine covariates and influenza vaccination status, respectively. Covariates of interests include age, sex, immunocompromising chronic conditions and healthcare setting. Cases will be defined based on an individual's first positive influenza test during the season, and potential controls will be defined based on an individual's first negative influenza test during the season. One control for each case will be randomly selected based on the week the specimen was collected. We will estimate VE using multivariable logistic regression.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the University of Alberta's Health Research Ethics Board-Health Panel under study ID Pro00075997. Results will be disseminated by public health officials in Alberta.

The association between influenza vaccination and socioeconomic status in high income countries varies by the measure used: a systematic review

Background

The purpose of this paper is to systematically review the literature on the relationship between socioeconomic status (SES) and influenza immunization and to examine how certain measures of SES may influence interpretations of this relationship.

Methods

We conducted a systematic review of existing peer-reviewed literature to evaluate the above relationship in the general population. Electronic databases (MEDLINE and EMBASE) were searched from January 2012 to May 2017 to identify English-language studies relevant to this review. Studies were included where influenza vaccination was explicitly reported as the dependent variable and SES as the independent variable. We limited our review to measures of SES that focus on education, income, social class, occupation, and deprivation. Studies that measured SES using other variables (e.g., race, ethnicity, geographic location, rural or urban status, or insurance status) were excluded. Studies were also excluded if they did not report on the human population or did not analyze original data. The population of interest included all age groups, levels of health status, and sociodemographic backgrounds. The review was also limited to World Bank high-income countries. Two authors independently screened full-text articles after obtaining a Kappa score of K = 0.867. The methodological quality of manuscripts was assessed using the appraisal tools developed by the Joanna Briggs Institute. Results were qualitatively reported and synthesized.

Results

Of the 42 articles included in this review, 52.4% (n = 22) found that higher levels of SES resulted in higher levels of influenza vaccination; 4.5% (n = 2) reported a negative association; and 14.3% (n = 6) found no association. Just over a quarter (26.2%, n = 12) of articles reported mixed results.

Conclusions

There was consistently a relationship between SES and influenza immunization, which varied according to how SES was measured. It is recommended that authors be explicit in defining the SES concept they are trying to capture and that they utilize multiple measures of SES (e.g., education, income, class).

Electronic supplementary material

The online version of this article (10.1186/s12874-019-0801-1) contains supplementary material, which is available to authorized users.

Medical Information Commons to Support Learning Healthcare Systems: Examples From Canada

We explore how principles predicting the success of a medical information commons (MIC) advantaged or disadvantaged three MIC initiatives in three Canadian provinces. Our MIC case examples demonstrate that practices and policies to promote access to and use of health information can help improve individual healthcare and inform a learning health system. MICs were constrained by heterogenous health information protection laws across jurisdictions and risk-averse institutional cultures. A networked approach to MICs would unlock even more potential for national and international data collaborations to improve health and healthcare.

At-a-glance - The role of opioid toxicity in suicide deaths in Alberta, 2000 to 2016

Given the current opioid crisis in Canada, there is interest in the role of opioid toxicity in suicide deaths, particularly in whether any observed patterns are similar to those of unintentional deaths. The present analysis examined characteristics of opioid-toxicity suicide, and its role in relation to other suicide methods, from 2000 to 2016 in Alberta. It does not appear that the opioid crisis has resulted in a disproportionately higher number of suicides in Alberta. Individuals who die from unintentional opioid toxicity and those who die by opioid-toxicity suicide are likely distinct populations, requiring nuanced public health responses for prevention.

Are we speaking the same language? an argument for the consistent use of terminology and definitions for childhood vaccination indicators

Vaccination indicators are used to measure the health status of individuals or populations and to evaluate the effectiveness of vaccination programs or policies. Ensuring that vaccination indicators are clearly and consistently defined is important for effective communication of outcomes, accurate program evaluation, and comparison between different populations, times, and contexts. The purpose of this commentary is to describe commonly used vaccination indicators and to highlight inconsistencies in how childhood vaccine researchers use and define these terms. The indicators we describe are vaccine coverage, uptake, and rate; vaccination status, initiation, and completion; and up-to-date, timely, partial, and incomplete vaccination. We conclude that many vaccination indicators are not explicitly defined within published research studies and/or are used quite differently across studies. We also note that the choice of indicator in a given study is often driven by program or vaccine specific factors, may be constrained by data availability, and should be chosen to best reflect the outcome of interest. We conclude that the use of consistent language and definitions would promote more effective communication of research findings. We also propose some standardized definitions for common indicators, with the goal of provoking discussion and debate on the issue.

2454. Pertussis Vaccine Effectiveness and Waning Immunity in Alberta, Canada: 2004–2015

Background

Despite childhood vaccination coverage rates exceeding 75%, pertussis is still frequently reported in Canada. In Alberta, pertussis incidence ranged from 1.8 to 20.5 cases per 100,000 persons for 2004–2015. Most cases occurred in those aged < 15 years. We investigated pertussis vaccine effectiveness (VE) using a test-negative designed (TND) study.

Methods

All individuals who had undergone a real-time PCR laboratory test for Bordetella pertussis between January 1, 2004 and August 31, 2015, in the province of Alberta, Canada were included. Vaccination history was obtained from Alberta’s immunization repository. Vaccination status was classified as complete, incomplete, or not vaccinated, based on the province’s vaccination schedule. Multivariable logistic regression models were used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (95% CI) for pertussis infection by time since last vaccination, comparing those with complete or incomplete vaccination to those not vaccinated. We adjusted for age, sex, income, urban/rural status, and the presence of a co-morbid condition. Vaccine effectiveness (VE) was calculated as [(1-aOR)*100].

Results

Of 28,154 individuals tested, 2,297 (12.3%) tested positive for B. pertussis. Among those with complete vs. no vaccination, VE was 88% (95% CI 85–91%) at 1 year, 83% (95% CI 79–86%) at 1 to 3 years, 70% (95% CI 63–76%) at 4 to 6 years, 28% (95% CI 12–42%) at 7 to 9 years, and -4% (95% CI -53 to 29%) at 10 or more years since a last dose of a pertussis vaccine (Figure 1). VE was similar but attenuated in the incompletely vaccinated group, with a comparable waning of immunity.

Conclusion

Pertussis VE was high in the first year after vaccination, then declined noticeably after 5 years. Our results suggest there is a large number of adolescents and adults susceptible to pertussis. Regular boosters throughout childhood, adolescence, and during pregnancy are critical to protect those at greatest risk of infection and complications. Further validation of the strengths and weaknesses of the TND for assessing pertussis VE is needed.

Disclosures

M. L. Russell, Novartis Pharmaceuticals Canada Inc.: Grant Investigator and Unconditional Research Grant, Grant recipient. Merck Frosst Canada Inc.: Grant Investigator and Unconditional Research Grant, Grant recipient.

The Canadian Chronic Disease Surveillance System: A model for collaborative surveillance

Chronic diseases have a major impact on populations and healthcare systems worldwide. Administrative health data are an ideal resource for chronic disease surveillance because they are population-based and routinely collected. For multi-jurisdictional surveillance, a distributed model is advantageous because it does not require individual-level data to be shared across jurisdictional boundaries. Our objective is to describe the process, structure, benefits, and challenges of a distributed model for chronic disease surveillance across all Canadian provinces and territories (P/Ts) using linked administrative data. The Public Health Agency of Canada (PHAC) established the Canadian Chronic Disease Surveillance System (CCDSS) in 2009 to facilitate standardized, national estimates of chronic disease prevalence, incidence, and outcomes. The CCDSS primarily relies on linked health insurance registration files, physician billing claims, and hospital discharge abstracts. Standardized case definitions and common analytic protocols are applied to the data for each P/T; aggregate data are shared with PHAC and summarized for reports and open access data initiatives. Advantages of this distributed model include: it uses the rich data resources available in all P/Ts; it supports chronic disease surveillance capacity building in all P/Ts; and changes in surveillance methodology can be easily developed by PHAC and implemented by the P/Ts. However, there are challenges: heterogeneity in administrative databases across jurisdictions and changes in data quality over time threaten the production of standardized disease estimates; a limited set of databases are common to all P/Ts, which hinders potential CCDSS expansion; and there is a need to balance comprehensive reporting with P/T disclosure requirements to protect privacy. The CCDSS distributed model for chronic disease surveillance has been successfully implemented and sustained by PHAC and its P/T partners. Many lessons have been learned about national surveillance involving jurisdictions that are heterogeneous with respect to healthcare databases, expertise and analytical capacity, population characteristics, and priorities.

Effectiveness of Live Attenuated vs Inactivated Influenza Vaccines in Children During the 2012-2013 Through 2015-2016 Influenza Seasons in Alberta, Canada: A Canadian Immunization Research Network (CIRN) Study

IMPORTANCE

Recent observational studies report conflicting results regarding the effectiveness of live attenuated influenza vaccine (LAIV), particularly against influenza A(H1N1)pdm09.

OBJECTIVE

To compare the effectiveness of LAIV and inactivated influenza vaccine (IIV) against laboratory-confirmed influenza.

DESIGN, SETTING, AND PARTICIPANTS

A test-negative study to estimate influenza vaccine effectiveness (VE) using population-based, linked, individual-level laboratory, health administrative, and immunization data. Data were obtained from 10 169 children and adolescents aged 2 to 17 years (children) who were tested for influenza in inpatient or outpatient settings during periods when influenza was circulating based on a threshold level of 5% weekly test positivity for the province during the 4 influenza seasons spanning from November 11, 2012, to April 30, 2016, in Alberta, Canada. Logistic regression was used to estimate VE by vaccine type, influenza season, and influenza type and subtype. The relative effectiveness of each vaccine type was assessed by comparing the odds of laboratory-confirmed influenza infection for LAIV recipients with that for IIV recipients.

EXPOSURES

The primary exposure was receipt of LAIV or IIV before testing for influenza.

MAIN OUTCOMES AND MEASURES

The primary outcome was influenza case status as determined by reverse-transcriptase polymerase chain reaction testing.

RESULTS

A total of 10 779 respiratory specimens (from 10 169 children) collected and tested for influenza during the 4 influenza seasons were included, with 53.4% from males; the mean (SD) age was 7.0 (4.6) years. Across the 4 influenza seasons, 3161 children tested positive for influenza. Combining the 4 influenza seasons, the adjusted VE against influenza A(H1N1)pdm09 was 69% (95% CI, 56%-78%) for LAIV compared with 79% (95% CI, 70%-86%) for IIV. Vaccine effectiveness against influenza A(H3N2) was 36% (95% CI, 14%-53%) for LAIV and 43% (95% CI, 22%-59%) for IIV. Against influenza B, VE was 74% (95% CI, 62%-82%) for LAIV and 56% (95% CI, 41%-66%) for IIV. There were no significant differences in the odds of influenza infection for LAIV recipients compared with IIV recipients except for influenza B during the 2015-2016 season, when LAIV recipients had lower odds of infection than IIV recipients (odds ratio, 0.36; 95% CI, 0.17-0.76).

CONCLUSIONS AND RELEVANCE

There was no evidence to support the lack of effectiveness of LAIV against influenza A(H1N1)pdm09. These results support administration of either vaccine type in this age group.

Narcolepsy and adjuvanted pandemic influenza A (H1N1) 2009 vaccines - Multi-country assessment

BACKGROUND

In 2010, a safety signal was detected for narcolepsy following vaccination with Pandemrix, an AS03-adjuvanted monovalent pandemic H1N1 influenza (pH1N1) vaccine. To further assess a possible association and inform policy on future use of adjuvants, we conducted a multi-country study of narcolepsy and adjuvanted pH1N1 vaccines.

METHODS

We used electronic health databases to conduct a dynamic retrospective cohort study to assess narcolepsy incidence rates (IR) before and during pH1N1 virus circulation, and after pH1N1 vaccination campaigns in Canada, Denmark, Spain, Sweden, Taiwan, the Netherlands, and the United Kingdom. Using a case-control study design, we evaluated the risk of narcolepsy following AS03- and MF59-adjuvanted pH1N1 vaccines in Argentina, Canada, Spain, Switzerland, Taiwan, and the Netherlands. In the Netherlands, we also conducted a case-coverage study in children born between 2004 and 2009.

RESULTS

No changes in narcolepsy IRs were observed in any periods in single study sites except Sweden and Taiwan; in Taiwan incidence increased after wild-type pH1N1 virus circulation and in Sweden (a previously identified signaling country), incidence increased after the start of pH1N1 vaccination. No association was observed for Arepanrix-AS03 or Focetria-MF59 adjuvanted pH1N1 vaccines and narcolepsy in children or adults in the case-control study nor for children born between 2004 and 2009 in the Netherlands case-coverage study for Pandemrix-AS03.

CONCLUSIONS

Other than elevated narcolepsy IRs in the period after vaccination campaigns in Sweden, we did not find an association between AS03- or MF59-adjuvanted pH1N1 vaccines and narcolepsy in children or adults in the sites studied, although power to evaluate the AS03-adjuvanted Pandemrix brand vaccine was limited in our study.

Relationship between enteric pathogens and acute gastroenteritis disease severity: a prospective cohort study

OBJECTIVES

To evaluate the relationship between individual bacterial and viral pathogens and disease severity.

METHODS

Children <18 years with three or more episodes of vomiting and/or diarrhoea were enrolled in two Canadian paediatric emergency departments between December 2014 and August 2016. Specimens were analysed employing molecular panels, and outcome data were collected 14 days after enrolment. The primary outcome was severe disease over the entire illness (symptom onset until 14-day follow-up), quantified employing the Modified Vesikari Scale (MVS) score. The score was additionally analysed in two other time periods: index (symptom onset until enrolment) and follow-up (enrolment until 14-day follow-up).

RESULTS

Median participant age was 20.7 (IQR: 11.3, 44.2) months; 47.4% (518/1093) and 73.4% (802/1093) of participants had index and total MVS scores ≥11, respectively. The most commonly identified pathogens were rotavirus (289/1093; 26.4%) and norovirus (258/1093; 23.6%). In multivariable analysis, severe disease over the entire illness was associated with rotavirus (OR = 9.60; 95%CI: 5.69, 16.19), Salmonella (OR = 6.61; 95%CI: 1.50, 29.17), adenovirus (OR = 2.53; 95%CI: 1.62, 3.97), and norovirus (OR = 1.43; 95%CI: 1.01, 2.01). Pathogens associated with severe disease at the index visit were: rotavirus only (OR = 6.13; 95%CI: 4.29, 8.75), Salmonella (OR = 4.59; 95%CI: 1.71, 12.29), adenovirus only (OR = 2.06; 95%CI: 1.41, 3.00), rotavirus plus adenovirus (OR = 3.15; 95%CI: 1.35, 7.37), and norovirus (OR = 0.68; 95%CI: 0.49, 0.94). During the follow-up period, rotavirus (OR = 2.21; 95%CI: 1.50, 3.25) and adenovirus (OR = 2.10; 95%CI: 1.39, 3.18) were associated with severe disease.

CONCLUSIONS

In children presenting for emergency department care with acute gastroenteritis, pathogens identified were predominantly viruses, and several of which were associated with severe disease. Salmonella was the sole bacterium independently associated with severe disease.

Under-reporting of pertussis in Ontario: A Canadian Immunization Research Network (CIRN) study using capture-recapture

Introduction

Under-reporting of pertussis cases is a longstanding challenge. We estimated the true number of pertussis cases in Ontario using multiple data sources, and evaluated the completeness of each source.

Methods

We linked data from multiple sources for the period 2009 to 2015: public health reportable disease surveillance data, public health laboratory data, and health administrative data (hospitalizations, emergency department visits, and physician office visits). To estimate the total number of pertussis cases in Ontario, we used a three-source capture-recapture analysis stratified by age (infants, or aged one year and older) and adjusting for dependency between sources. We used the Bayesian Information Criterion to compare models.

Results

Using probable and confirmed reported cases, laboratory data, and combined hospitalizations/emergency department visits, the estimated total number of cases during the six-year period amongst infants was 924, compared with 545 unique observed cases from all sources. Using the same sources, the estimated total for those aged 1 year and older was 12,883, compared with 3,304 observed cases from all sources. Only 37% of infants and 11% for those aged 1 year and over admitted to hospital or seen in an emergency department for pertussis were reported to public health. Public health reporting sensitivity varied from 2% to 68% depending on age group and the combination of data sources included. Sensitivity of combined hospitalizations and emergency department visits varied from 37% to 49% and of laboratory data from 1% to 50%.

Conclusions

All data sources contribute cases and are complementary, suggesting that the incidence of pertussis is substantially higher than suggested by routine reports. The sensitivity of different data sources varies. Better case identification is required to improve pertussis control in Ontario.

Temporal Trends in the Use and Comparative Effectiveness of Direct Oral Anticoagulant Agents Versus Warfarin for Nonvalvular Atrial Fibrillation: A Canadian Population-Based Study

BACKGROUND

Direct oral anticoagulants (DOACs) are noninferior to warfarin for stroke prevention in atrial fibrillation (AF). We aimed to determine the population risk of stroke and death in incident AF, stratified by anticoagulation status and type, and the temporal trends of oral anticoagulation practice in the post-DOAC approval period.

METHODS AND RESULTS

We conducted a population-based cohort study of incident nonvalvular AF cases using administrative health data in Alberta, Canada. We used Cox proportional hazards modeling with anticoagulation status as a time-varying exposure and adjusted for age (continuous), sex, congestive heart failure, hypertension, diabetes mellitus, prior transient ischemic attack or ischemic stroke, myocardial infarction, peripheral artery disease, and chronic kidney disease. Primary outcome was the composite of stroke and death. Among 34 965 patients with incident AF (56.0% male, median age 73 years), relative to warfarin, DOAC use was associated with decreased risk of all stroke and death (hazard ratio: 0.90; 95% confidence interval, 0.83-0.97) and decreased hemorrhagic stroke (hazard ratio: 0.60; 95% confidence interval, 0.40-0.91]) but a similar risk of ischemic stroke (hazard ratio: 1.12; 95% confidence interval, 0.94-1.34]). During this time period, DOAC use increased rapidly, surpassing warfarin, but the total oral anticoagulation use in the population remained stable, even in the subgroup with the highest thromboembolic risk.

CONCLUSIONS

In a real-world population-based study of patients with incident AF, anticoagulation with DOACs was associated with decreased risk of stroke and death compared with warfarin. Despite a rapid uptake of DOACs in clinical practice, the total proportion of AF patients on anticoagulation has remained stable, even in high-risk patients.

Relationship Between Enteropathogen and Acute Gastroenteritis Disease Severity: A Prospective Cohort Study

Background

Little is known about the association between specific enteropathogens and disease severity in outpatient children with acute gastroenteritis. Recent advances in diagnostics enabling the rapid and simultaneous detection of common enteropathogens have become readily available. While such knowledge can be used to optimize therapy it also has the potential to predict disease severity. Such knowledge can aid clinical decision making, can clarify guidance and expectations provided to families, and can guide public health policy.

Methods

We conducted a prospective cohort study of children with acute gastroenteritis who were brought for emergency department care. The primary outcome measure was the 20-point Modified Vesikari Scale (MVS) score calculated from symptom onset until day14 of follow-up (total MVS score). Stool and/or rectal swab specimens were collected and analyzed for 18 unique pathogens by molecular diagnostic assays (in-house 5 virus panel, Luminex xTAG Gastrointestinal Pathogen Panel) and/or bacterial culture. An enteropathogen was deemed to be present if a candidate pathogen was identified in the rectal swab or stool specimens by any testing method. Binary logistic regression was performed to assess the association between pathogens (including all pathogens as present or not) and disease severity with the dependent variable being the total MVS score categorized as severe (11–20 points) vs.. non-severe (0–10 points).

Results

The mean total MVS score (SD) was 12.8 (3.2) and 73.0% (807/1102) of participants experienced severe disease. A pathogen was identified in 72.8% (802/1102) of study participants. Rotavirus, norovirus GII and adenovirus were identified in 26.6% (293/1102), 23.0% (253/1102) and 16.0% (176/1102) of participants respectively. After adjusting for other pathogens significant predictors of severe disease were: rotavirus (OR=8.0; 95% CI: 4.8, 13.2), Salmonella (OR=5.4; 95% CI: 1.2, 24.4), adenovirus (OR=2.1; 95% CI: 1.3, 3.3), and norovirus GII (OR=1.8; 95% CI: 1.3, 2.6). Clostridium difficile (OR=1.6; 95% CI: 0.96, 2.6) and Aeromonas (OR=0.97; 95% CI: 0.2, 4.7) were not significantly associated with severe disease.

Conclusion

In children with acute gastroenteritis, the enteropathogens associated with severe disease included rotavirus, Salmonella, adenovirus and norovirus GII.

Disclosures

All authors: No reported disclosures.

How well do ICD-9 physician claim diagnostic codes identify confirmed pertussis cases in Alberta, Canada? A Canadian Immunization Research Network (CIRN) Study

Background

Rates of Bordetella pertussis have been increasing in Alberta, Canada despite vaccination programs. Waning immunity from existing acellular component vaccines may be contributing to this. Vaccine effectiveness can be estimated using a variety of data sources including diagnostic codes from physician billing claims, public health records, reportable disease and laboratory databases. We sought to determine if diagnostic codes from billing claims (administrative data) are adequately sensitive and specific to identify pertussis cases among patients who had undergone disease-specific laboratory testing.

Methods

Data were extracted for 2004–2014 from a public health communicable disease database that contained data on patients under investigation for B. pertussis (both those who had laboratory tests and those who were epidemiologically linked to laboratory-confirmed cases) in Alberta, Canada. These were deterministically linked using a unique lifetime person identifier to the provincial billing claims database, which contains International Classification of Disease version 9 (ICD-9) diagnostic codes for physician visits. We examined visits within 90 days of laboratory testing. ICD-9 codes 033 (whooping cough), 033.0 (Bordetella pertussis), 033.1 (B. parapertussis), 033.8 (whooping cough, other specified organism), and 033.9 (whooping cough, other unspecified organism) in any of the three diagnostic fields for a claim were classified as being pertussis-specific codes. We calculated sensitivity, specificity, positive (PPV) and negative (NPV) predictive values.

Results

We identified 22,883 unique patients under investigation for B. pertussis. Of these, 22,095 underwent laboratory testing. Among those who had a laboratory test, 2360 tested positive for pertussis. The sensitivity of a pertussis-specific ICD-9 code for identifying a laboratory-confirmed case was 38.6%, specificity was 76.9%, PPV was 16.0%, and NPV was 91.6%.

Conclusion

ICD-9 codes from physician billing claims data have low sensitivity and moderate specificity to identify laboratory-confirmed pertussis among persons tested for pertussis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12913-017-2321-1) contains supplementary material, which is available to authorized users.

Epidemiology of pertussis in Alberta, Canada 2004-2015

BACKGROUND

We describe the epidemiology of pertussis in Alberta, Canada by person, place, and time between 2004 and 2015, identify outbreak years, and examine vaccination coverage and vaccination timeliness.

METHODS

We used health data from Alberta's Communicable Disease Registry System for the period of January 1, 2004 through August 31, 2015 to identify unique cases of pertussis. Unique cases were deterministically linked to data in Alberta's immunization repository and health care insurance plan registry. Population estimates and vaccination coverage were extracted from Alberta's online Interactive Health Data Application. We estimated pertussis incidence rates per 100,000 persons by year, age group, gender, and health zone. Outbreak years were identified using a one-sided cumulative sum (CUSUM) analysis by comparing annual incidence rates to baseline rates.

RESULTS

Over the period, 3510 cases of pertussis were confirmed by laboratory testing or epidemiological linkage. Incidence rates per 100,000 persons were highest in 2004 (20.5), 2005 (13.6), and 2015 (10.4) for all age groups. Incidence rates were highest among the youngest age groups and decreased as age groups increased. Based on CUSUM analysis, 2008 and 2012 met the criteria for outbreak years. Vaccination coverage was over 90% among the general population, however only 61% of cases received at least one dose. About 60% of cases were diagnosed 5+ years after receiving the vaccine. Approximately 87-91% of vaccinated cases did not receive the first three vaccine doses in a timely manner.

CONCLUSION

Pertussis incidence rates fluctuated over the period across all age groups. The majority of cases had no record of vaccination or were delayed in receiving vaccines. CUSUM analysis was an effective method for identifying outbreaks.

Effect of human papillomavirus vaccination on cervical cancer screening in Alberta

BACKGROUND

A school-based program with quadrivalent human papillomavirus (HPV) vaccination was implemented in Alberta in 2008. We assessed the impact of this program on Pap test cytology results using databases of province-wide vaccination and cervical cancer screening.

METHODS

We conducted a nested case-control study involving a cohort of women in Alberta born between 1994 and 1997 who had at least 1 Pap test between 2012 and 2015. Women with negative cytology results were controls. Women with low-grade (atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion) and high-grade (atypical squamous cells, cannot rule out a high-grade lesion; or high-grade squamous intraepithelial lesion) cervical abnormalities were cases. Exposure status was assigned according to records of HPV vaccination. Odds ratios (ORs) for abnormal cytology results by vaccination status were adjusted for neighbourhood income, laboratory service, rural versus urban residency, and age.

RESULTS

The total study population was 10 204. Adjusting for age, vaccinated women had a higher screening rate than unvaccinated women (13.0% v. 11.4%, p < 0.001). Among women who received full vaccination (≥ 3 doses), the adjusted OR for cervical abnormalities was 0.72 (95% confidence interval [CI] 0.63-0.82). For high-grade lesions, the adjusted OR was 0.50 (95% CI 0.30-0.85). With 2-dose HPV vaccination, the adjusted OR for cervical abnormalities was 1.08 (95% CI 0.84-1.38).

INTERPRETATION

Quadrivalent HPV vaccination significantly reduced high-grade cervical abnormalities but required 3 doses. Vaccination against HPV was associated with screening uptake. Population-based vaccination and screening programs should work together to optimize cervical cancer prevention.

Physical comorbidities increase the risk of psychiatric comorbidity in multiple sclerosis

BACKGROUND

Risk factors for psychiatric comorbidity in multiple sclerosis (MS) are poorly understood.

OBJECTIVE

We evaluated the association between physical comorbidity and incident depression, anxiety disorder, and bipolar disorder in a MS population relative to a matched general population cohort.

METHODS

Using population-based administrative data from Alberta, Canada we identified 9624 persons with MS, and 41,194 matches. Using validated case definitions, we estimated the incidence of depression, anxiety disorder, and bipolar disorder, and their association with physical comorbidities using Cox regression, adjusting for age, sex, socioeconomic status, and index year.

RESULTS

In both populations, men had a lower risk of depression and anxiety disorders than women, as did individuals who were ≥45 years versus <45 years at the index date. The risk of bipolar disorder declined with increasing age. The risks of incident depression (HR 1.92; 1.82-2.04), anxiety disorders (HR 1.52; 1.42-1.63), and bipolar disorder (HR 2.67; 2.29-3.11) were higher in the MS population than the matched population. These associations persisted essentially unchanged after adjustment for covariates including physical comorbidities. Multiple physical comorbidities were associated with psychiatric disorders in both populations.

CONCLUSION

Persons with MS are at increased risk of psychiatric comorbidity generally, and some physical comorbidities are associated with additional risk.

Regional variation of multiple sclerosis prevalence in Canada

Objective: To describe the regional distribution of multiple sclerosis (MS) prevalence in Canada, controlling for age and sex. Methods: This study used data from the Canadian Community Health Survey, a large general health survey (n=131,535) conducted in 2000/2001. Subjects aged 18 and over were included in the current analysis (n=116,109). The presence of MS was determined by self-report. Prevalence was computed in five regions (Atlantic, Quebec, Ontario, Prairies and British Columbia). Logistic regression was used to compare regions and examine for confounding/interaction by age and sex. Results: The overall Canadian MS prevalence was 240 per 100 000 (95%CI: 210-280). Prevalence ranged from 180 (95%CI: 90-260) in Quebec to 350 (95%CI: 230-470) in Atlantic Canada. Logistic regression revealed no statistical difference between the odds of MS in Quebec, Ontario and British Columbia adjusted for age and sex. The adjusted odds of MS in the Prairies and Atlantic regions were significantly higher than in the other regions combined, with odds ratios of 1.7 (95%CI: 1.1-2.4, p<0.01) and 1.6 (95%CI: 1.1-2.4, p<0.05) respectively. Sensitivity analysis demonstrated similar prevalence in the nonaboriginal/nonimmigrant group (n=96 219). Conclusion: Results suggest that Canadian MS prevalence differs by region. If validated, these regional differences may facilitate investigation of environmental influences.