Dena L Schanzer

• B. Math, M.Sc, P.Stat
• Statistician at Public Health Agency of Canada

There is accumulating evidence suggesting that children may drive the spread of influenza epidemics. The objective of this study was to quantify the lead time by age using laboratory-confirmed cases of influenza A for the 1995/1996-2005/2006 seasons from Canadian communities and laboratory-confirmed hospital admissions for the H1N1/2009 pandemic st...

Background: Much of the recent increase in hospital admission rates and mortality associated with hepatitis C in Canada is believed to be because of a higher prevalence of hepatitis C virus infection among those born between 1945 and 1965 (the baby boomer generation). We explored the effects of birth cohort on the rates of and projected trends in...

Poisson regression modelling has been widely used to estimate the disease burden attributable to influenza, though not without concerns that some of the excess burden could be due to other causes. This study aims to provide annual estimates of the mortality and hospitalization burden attributable to both seasonal influenza and the 2009 A/H1N1 pande...

Most evaluations of epidemic thresholds for influenza have been limited to internal criteria of the indicator variable. We aimed to initiate discussion on appropriate methods for evaluation and the value of cross-validation in assessing the performance of a candidate indicator for influenza activity.Hospital records of in-patients with a diagnosis...

The literature on best practices for evidence-informed decision-making has seen considerable growth from both knowledge users tasked with assessing the quality of the evidence and knowledge creators wishing to make a stronger contribution to evidence-based decisions. The knowledge translation process is highly dependent on the quality of the origin...

Importance Achievement of the World Health Organization (WHO) target of eliminating hepatitis C virus (HCV) by 2030 will require an increase in key services, including harm reduction, HCV screening, and HCV treatment initiatives in member countries. These data are not available for Canada but are important for informing a national HCV elimination s...

Objective The acellular pertussis vaccine was introduced into the routine childhood immunization schedule across Canada in 1997–98 and adolescent booster doses were added between 1999 and 2005. We sought to assess the impact of these changes on infant pertussis hospitalizations and admissions to intensive care units (ICU) in Canada. Methods Hospit...

Backgrounds: Hospitalizations associated with hepatitis C virus (HCV) infection and liver disease increased on average by 6.0% per year from 2004 to 2010 in Canada and were projected (in 2010) to increase by another 4% by 2016. The first generation of direct-acting antivirals (DAAs) became available in 2012. In 2014, a second generation of effecti...

Background While combination antiretroviral therapy (cART) has significantly improved survival times for persons diagnosed with HIV, estimation of life expectancy (LE) for this cohort remains a challenge, as mortality rates are a function of both time since diagnosis and age, and mortality rates for the oldest age groups may not be available. Meth...

SAS macros, sample program and documentation. (ZIP)

Excel workbook with supporting tables and data corresponding to figures. (XLSX)

Background: A regression-based study design has commonly been used to estimate the influenza burden; however, these estimates are not timely and many countries lack sufficient virological data. Alternative approaches that would permit a timelier assessment of the burden, including a sentinel surveillance approach recommended by the World Health Or...

Background: Estimates of influenza-associated mortality are important for national and international decision making on public health priorities. Previous estimates of 250 000-500 000 annual influenza deaths are outdated. We updated the estimated number of global annual influenza-associated respiratory deaths using country-specific influenza-assoc...

Disease modeling is increasingly being used to evaluate the effect of health intervention strategies, particularly for infectious diseases. However, the utility and application of such models are hampered by the inconsistent use of infectious disease modeling terms between and within disciplines. We sought to standardize the lexicon of infectious d...

Background Assessing the mortality impact of the 2009 influenza A H1N1 virus (H1N1pdm09) is essential for optimizing public health responses to future pandemics. The World Health Organization reported 18,631 laboratory-confirmed pandemic deaths, but the total pandemic mortality burden was substantially higher. We estimated the 2009 pandemic mortali...

We aimed to assess the potential prevention benefits of HIV treatment as prevention (TasP) in resource-rich countries and examine the potential interactions between TasP and other prevention strategies by reviewing mathematical models of TasP. Multiple databases were searched for mathematical models published in the previous 5years (from July 2007...

The Canadian National Antiviral Stockpile (NAS) contains treatment for 17.5% of Canadians. This assumes no concurrent intervention strategies and no wastage due to non-influenza respiratory infections. A dynamic model can provide a mechanism to consider complex scenarios to support decisions regarding the optimal NAS size under uncertainty. We deve...

Objectives: Weekly influenza-like illness (ILI) consultation rates are an integral part of influenza surveillance. However, in most health care settings, only a small proportion of true influenza cases are clinically diagnosed as influenza or ILI. The primary objective of this study was to estimate the number and rate of visits to the emergency de...

Background The number of admissions to hospital for which influenza is laboratory confirmed is considered to be a substantial underestimate of the true number of admissions due to an influenza infection. During the 2009 pandemic, testing for influenza in hospitalized patients was a priority, but the ascertainment rate remains uncertain. Methods The...

As observed during the 2009 pandemic, a novel influenza virus can spread globally before the epidemic peaks locally. As consistencies in the relative timing and direction of spread could form the basis for an early alert system, the objectives of this study were to use the case-based reporting system for laboratory confirmed influenza from the Cana...

As many respiratory viruses are responsible for influenza like symptoms, accurate measures of the disease burden are not available and estimates are generally based on statistical methods. The objective of this study was to estimate absenteeism rates and hours lost due to seasonal influenza and compare these estimates with estimates of absenteeism...

To estimate the number of prevalent and incident HIV infections in Canada in 2008. We applied multiple methods to estimate national HIV prevalence and incidence in Canada, including the workbook method, two statistical modelling methods, and an iterative spreadsheet model. The estimated number of people living with diagnosed or undiagnosed HIV infe...

Empirical data on laboratory-confirmed seasonal influenza is limited by very low and possibly non-systematic case ascertainment as well as geographical variation. To provide a visual representation of an influenza epidemic at the community and regional level using empirical data and to describe the epidemic characteristics. Weekly influenza A confi...

The weekly proportion of laboratory tests that are positive for influenza is used in public health surveillance systems to identify periods of influenza activity. We aimed to estimate the sensitivity of influenza testing in Canada based on results of a national respiratory virus surveillance system. The weekly number of influenza-negative tests fro...

The elderly and persons with specific chronic conditions are known to face elevated morbidity and mortality risks resulting from an influenza infection, and hence are routinely recommended for annual influenza vaccination. However, risk-specific mortality rates have not been established. We estimated age-specific influenza-attributable mortality ra...

We sought to estimate age-specific hospitalization rates attributed to influenza and other virus for adults. Admissions from Canada's national hospitalization database (Canadian Institute of Health Information), from 1994/95 to 1999/2000, were modeled as a function of proxy variables for influenza, respiratory syncytial virus (RSV) and other viral...

The number of deaths attributable to influenza is believed to be considerably higher than the number certified by vital statistics registration as due to influenza. Weekly mortality data for Canada from the 1989/1990 to the 1998/1999 influenza seasons were analysed by cause of death, age group, and place of death to estimate the impact of influenza...

Although it is recommended that pregnant women at risk for influenza complications receive influenza vaccine, it is not clear if healthy pregnant women are at increased risk for adverse outcomes. We aimed to estimate the rate of hospitalization attributable to influenza for healthy pregnant women and for those with known co-morbidities. Hospital ad...

Background: Hospital admission records do not necessarily identify the viral agent responsible for most respiratory admissions. We aimed to estimate the impact of RSV and influenza viruses on hospital admissions in adults older than 65 years. Methods: Weekly hospital admissions by diagnostic categories, 1994-1999 (Canadian Institute of Health Info...

We sought to estimate the incidence of hospitalization attributable to influenza virus infection in Canadian children while controlling for the impact of other respiratory viruses. Hospital admissions for children and youth 0 to 19 years of age, 1994-2000, were modeled as a function of proxy variables for influenza, respiratory syncytial virus (RSV...

The Late Effects Study of the Canadian Childhood Cancer Surveillance and Control Program was designed to assess psychosocial and physical health outcomes among survivors of childhood cancer compared to general population controls. The objectives of this paper are to describe the design and methodology of the multi-centre, retrospective cohort study...

To monitor Canadian HIV/AIDS mortality following the introduction of antiretroviral therapies in 1996, and to compare this with the US experience. Deaths were extracted by underlying cause of death, age, sex, marital status and place of residence at time of death. Age-specific leading causes of death, potential years of life lost before age 65, and...

Objective: To monitor Canadian HIV/AIDS mortality following the introduction of antiretroviral therapies in 1996, and to compare this with the US experience. Methods: Deaths were extracted by underlying cause of death, age, sex, marital status and place of residence at time of death. Age-specific leading causes of death, potential years of life los...

The main purpose of this study is to estimate the medical care costs of childhood and adolescent cancer in Manitoba, and to determine the elements that influence these costs. Retrospective chart reviews were done to obtain all the information. A total of 118 childhood (age 0-14 years) and 41 adolescent (age 15-19 years) cancer patients were include...

Mutual concurrent validity of 2 generic measures of health-related quality of life (HRQL), the Child Health Questionnaire (CHQ) and the Health Utilities Index Mark 2 (HUI2) and HUI3, was assessed. Data were from 3 centers participating in a Canadian multi-center retrospective cohort study currently in progress to assess psycho-social and physical l...

Mutual concurrent validity of 2 generic measures of health-related quality of life (HRQL), the Child Health Questionnaire (CHQ) and the Health Utilities Index Mark 2 (HUI2) and HUI3, was assessed. Data were from 3 centers participating in a Canadian multi-center retrospective cohort study currently in progress to assess psycho-social and physical l...

To examine kidney cancer incidence and mortality patterns since 1969 in Canada. Linear regression of the log rates was used to estimate secular trends by age group and sex, and age-period-cohort models were fitted to examine changes in kidney cancer and renal adenocarcinoma incidence rates. A substantial increase in incidence rates was observed amo...

Purpose: To examine kidney cancer incidence and mortality patterns since 1969 in Canada. Method: Linear regression of the log rates was used to estimate secular trends by age group and sex, and age-period-cohort models were fitted to examine changes in kidney cancer and renal adenocarcinoma incidence rates. Results: A substantial increase in incide...

The commenter notes that in the above-titled paper, Y.E. Shimabukuro and J.A. Smith (ibid., vol.29, pp.16-20, Jan 1991) address the issue of numerical solutions to the problem of constraining the mixture proportions to the zero one interval and ensuring that the sum of proportions is equal to one. The commenter suggests a method whereby unconstrain...

Le présent article expose la théorie du critère de réflectance relative homogène (CRRH) ainsi que son application à une méthode automatisée de détection des nuages et de la neige, incluant le brouillard, la fumée et les pixels partiellement couverts de nuages sur des images du capteur thématique de Landsat. La méthode de classification a été éprouv...

Summary form only given. Experiments to investigate errors in digital terrain models (DTMs) have been conducted. A DTM expert system which is integrated into a multi-expert system for advising on satellite image interpretation has been developed. This expert system is written in Prolog and controls processes written in Prolog and controls processes...