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.

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.

A cohort study of regional migration and the risks of attempted suicide and violent assault injury.

OBJECTIVES: We study the association between changing residence and risks of attempted suicide and violent assault injury in Alberta, Canada. Our primary objective is to understand whether a change in residence between urban, rural and semiurban areas is associated with increased risk of intentional injury. METHODS: Study subjects are a cohort of residents linked to data on emergency department and inpatient hospital admissions between 1999 and 2010. We used generalised estimating equations to model the effects of changing residence on risk of intentional injury while controlling for the influence of age, sex, socio-economic status, Aboriginal status and history of intentional injury. RESULTS: Changing residence is associated with an increase in the risk of both attempted suicide and violent assault injury. In the case of attempted suicide, this effect is strongest for persons between 20 and 35 years of age. For violent assault injuries, persons from rural regions that have recently moved to urban regions have higher risk of injuries, and women of rural origin are at higher risk of violent assault injury than women of urban origin. CONCLUSIONS: Our findings reveal an association between risk of intentional injuries and change of residence adjusting for geographical differences in injury risk. These findings suggest that intentional injury risk is associated with change in community at intraregional scales and that these populations may benefit from support that helps integrate them into their new communities.

The incidence rate of colectomy for medically refractory ulcerative colitis has declined in parallel with increasing anti-TNF use: a time-trend study.

BACKGROUND: Medical therapy is standard treatment for ulcerative colitis with colectomy reserved for medically refractory disease or malignancy. The introductions of ciclosporin in 1994 and anti-TNF therapy in 2005 have extended medical management options. AIM: To determine whether the colectomy incidence rate for medically refractory ulcerative colitis has changed since the introduction of anti-TNF therapy. METHODS: Adult patients with a diagnosis of ulcerative colitis and who subsequently underwent an urgent or elective colectomy for medically refractory disease in Edmonton, Canada between 1 January 1998 and 31 December 2011 were identified. Log-linear regression was used to estimate the annual percent change in the total colectomy incidence rate (urgent and elective combined) and the urgent and elective incidence rates individually, before and after 2005, the year infliximab was approved for use in ulcerative colitis. Temporal trends of drug utilisation in this study population were also described. RESULTS: During 1998-2011, 481 patients with ulcerative colitis underwent a colectomy for medically refractory disease. There was negligible change in the total colectomy incidence rate from 1998 to 2005, with an annual percent change of 4.4% (95% confidence interval (CI): -1.12% to 10.16%). From 2005-2011, following the approval and increasing use of anti-TNF therapy, the total colectomy incidence rate decreased by 16.1% (95% CI: -21.32% to -10.54%) every year to 0.9 per 100 ulcerative colitis patients in 2011. CONCLUSION: The total incidence rate of colectomy for medically refractory ulcerative colitis has declined substantially since 2005, paralleling the increased use of anti-TNF therapy in this patient population.

The role of systematic reviews and meta-analyses of incidence and prevalence studies in neuroepidemiology.

BACKGROUND: Systematic reviews and meta-analyses on the incidence and prevalence of neurological conditions are important methods of quantifying the burden and risk of disease. METHODS: The rigorous methodology required in order to minimize publication bias, account for study heterogeneity, and variation in study quality are described. When appropriate, a meta-analysis is a powerful statistical tool that can help synthesize a vast literature quantitatively, taking into account study heterogeneity. As the epidemiology of neurological conditions continue to be widely studied internationally, systematic reviews and meta-analyses have become essential. RESULTS: If not conducted carefully, systematic reviews and meta-analyses in neuroepidemiology may lead to erroneous conclusions. It is important to consider various methodological, clinical and statistical factors at all stages of the review and analysis process. Detailed documentation should be kept to assist in the reporting process. CONCLUSIONS: Published reporting standards should be consulted when conducting systematic reviews and meta-analyses of the incidence and prevalence of neurological conditions, though reporting standards specific to neuroepidemiology are urgently needed.

Spatio-temporal scan statistics for the detection of outbreaks involving common molecular subtypes: using human cases of Escherichia coli O157:H7 provincial PFGE pattern 8 (National Designation ECXAI.0001) in Alberta as an example.

Molecular typing methods have become a common part of the surveillance of foodborne pathogens. In particular, pulsed-field gel electrophoresis (PFGE) has been used successfully to identify outbreaks of Escherichia coli O157:H7 in humans from a variety of food and environmental sources. However, some PFGE patterns appear commonly in surveillance systems, making it more difficult to distinguish between outbreak and sporadic cases based on molecular data alone. In addition, it is unknown whether these common patterns might have unique epidemiological characteristics reflected in their spatial and temporal distributions. Using E. coli O157:H7 surveillance data from Alberta, collected from 2000 to 2002, we investigated whether E. coli O157:H7 with provincial PFGE pattern 8 (national designation ECXAI.0001) clustered in space, time and space-time relative to other PFGE patterns using the spatial scan statistic. Based on our purely spatial and temporal scans using a Bernoulli model, there did not appear to be strong evidence that isolates of E. coli O157:H7 with provincial PFGE pattern 8 are distributed differently from other PFGE patterns. However, we did identify space-time clusters of isolates with PFGE pattern 8, using a Bernoulli model and a space-time permutation model, which included known outbreaks and potentially unrecognized outbreaks or additional outbreak cases. There were differences between the two models in the space-time clusters identified, which suggests that the use of both models could increase the sensitivity of a quantitative surveillance system for identifying outbreaks involving isolates sharing a common PFGE pattern.

Prevalence of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) in food samples associated with foodborne illness in Alberta, Canada from 2007 to 2010.

Consumption of foods containing Staphylococcus aureus can cause severe gastro-intestinal illness. Given the fact that over the past decade, Canada has seen increasing rates of methicillin-resistant S. aureus (MRSA) carriage and infection, the objective of this study was to investigate the impact of methicillin-susceptible S. aureus (MSSA) and MRSA on foodborne illness in Alberta, Canada. Between January 2007 and December 2010, there were 693 food samples associated with foodborne investigations submitted to the Alberta Provincial Laboratory for Public Health (ProvLab). These foods were screened for: Bacillus cereus, Clostridium perfringens, S. aureus, Aeromonas spp., Campylobacter spp., Escherichia coli O157:H7, Salmonella, Shigella spp., and Yersinia spp. S. aureus was identified in 10.5% (73/693) of samples, and of these, 59% (43/73) were co-contaminated with at least one other organism on the screening panel. The S. aureus positive samples included 29 meat, 20 prepared foods containing meat, 11 prepared foods not containing meat, 10 dairy, and three produce. Methicillin-resistance was not detected in any isolates tested. These findings indicate that the presence of S. aureus in food associated with foodborne investigations is a cause for concern, and although MRSA was not found, the potential for outbreaks exists, and ongoing surveillance should be sustained.

Long-term mortality associated with community-onset bloodstream infection.

PURPOSE: Although bloodstream infection is widely recognized as an important cause of acute morbidity and mortality, long-term mortality outcomes are less well defined. The objective of this study was to define the early (≤28 days) and late (>28 days) mortality and assess determinants of late death following community-onset bloodstream infection. METHODS: All adult residents of the Calgary Zone who had community-onset bloodstream infections during the period 1 January 2003 and 31 December 2007 were included. The mortality outcome was assessed through to 31 December 2008. RESULTS: A total of 4,553 cases were identified, of which 2,105 (46%) were healthcare-associated and 2,448 (54%) were community-acquired. The 28-day, 90-day, and 365-day all-cause case-fatality rates were 561/4,553 (12%), 780/4,553 (17%), and 1,131 (25%), respectively. Within the first 28 days, the median time to death was 4 (interquartile range [IQR] 1-12) days, with 158 (28%) and 212 (38%) of early (≤28-day) deaths occurring by days 1 and 2, respectively. Among survivors to 28 days (n = 3,992), 570 (14%) suffered late 1-year mortality (i.e., death occurred between 29 and 365 days postinception). The most common causes of death in this cohort as listed by the vital statistics data were malignancy in 220 (39%), cardiovascular in 135 (24%), and infection-related in 37 (7%). Older age, higher Charlson score, prolonged initial admission duration, and healthcare-associated and polymicrobial infections were independently associated with late 1-year mortality. CONCLUSIONS: Community-onset bloodstream infection is associated with major early and late mortality.

Changing epidemiology of methicillin-resistant Staphylococcus aureus in Alberta, Canada: population-based surveillance, 2005-2008.

SUMMARYIncreasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has been reported in Canada. We report the results of a prospective surveillance of MRSA infections in Alberta over a consecutive 3-year period. A total of 8910 unique clinical MRSA isolates was analysed from July 2005 to June 2008. The incidence of MRSA infection increased over the study period and was highest in males, age group ⩾85 years, and the Calgary Area. CMRSA10 (USA300) and CMRSA2 (USA100/800) were the most common PFGE strain types, representing 53·0% and 27·9% of all isolates, respectively. Significant differences were noted between MRSA strains in the source of infection and antimicrobial susceptibility. The incidence of MRSA infection in Alberta has nearly doubled in the last 3 years; this is attributed to the emergence of CMRSA10 as the predominant strain.

Achalasia: incidence, prevalence and survival. A population-based study.

BACKGROUND: Studies of achalasia epidemiology are important as they often yield new insights into disease etiology. In this study, our objective was to carry out the first North American population-based study of achalasia epidemiology using a governmental administrative database. METHODS: All residents in the province of Alberta, Canada receive universal healthcare coverage as a benefit. The provincial health ministry, Alberta Health and Wellness, maintains a central stakeholder database of patient demographic information and physician billing claims. We defined an achalasia case as a billing claim submitted for the years 1996-2007 with an ICD-9-CM code of 530.0 or 530 and a Canadian Classification of Procedure treatment code of 54.92A (endoscopic balloon dilation) or 54.6 (esophagomyotomy). A preliminary validation study of the case definition demonstrated a sensitivity of 85% and specificity of 99% for known cases and controls. KEY RESULTS: A total of 463 achalasia cases were identified from 1995 to 2008 (59.6% males). Mean age at diagnosis was 53.1 years. In 2007, the achalasia incidence was 1.63/100,000 (95% CI 1.20, 2.06) and the prevalence was 10.82/100,000 (95% CI 9.70, 11.93). We observed a steady increase in the overall prevalence rate from 2.51/100,000 in 1996 to 10.82/100,000 in 2007. Survival of achalasia cases was significantly less than age-sex matched population controls (P < 0.0001). CONCLUSIONS & INFERENCES: Using a population-based approach, the incidence and prevalence of treated achalasia is 1.63/100,000 and 10.82/100,000, respectively. The disease appears to have a stable incidence but a rising prevalence. Survival of achalasia cases is significantly less than age-matched healthy controls.

Using administrative data to understand the geography of case ascertainment.

We examined the geographic variability of information generated from different case definitions of childhood asthma derived from administrative health data used in Alberta, Canada. Our objective was to determine if analyses based on different case ascertainment algorithms identify geographic clusters in the same region of the study area. Our study group was based on a closed cohort of asthmatic children born in 1988. We used a spatial scan statistic to identify variations in the approximate location of geographic clusters of asthma based on different case definitions. Our results indicate that the geographic patterns are not greatly affected by the case ascertainment algorithm or the source of data. For example, asthmatics identified from medical claims data showed similar clustering to asthmatics defined through hospitalization and emergency department data. However, estimates of prevalence and incidence require careful consideration and validation against other data sources.

Increasing incidence and prevalence with limited survival gains among rural Albertans with diabetes: a retrospective cohort study, 1995-2006.

OBJECTIVE: To compare recent trends of diabetes prevalence, incidence and mortality between men and women living in urban and rural Alberta, Canada. METHODS: We tracked population trends in diabetes in adults based on diagnostic codes from provincial administrative health records from 1995 to 2006. Location of residence was defined by registered postal codes. Sex-stratified logistic regression with interactions was used to compare increases in rates over the past decade by location of residence, adjusting for age. RESULTS: Men in rural residences had the greatest increases in prevalence, at 61%, from 3.6 per 100 in 1995 to 5.8 per 100 in 2006, compared with a 55% increase in urban men, from 3.9 per 100 in 1995 to 6.0 per 100 in 2006 (P < 0.001). Diabetes incidence in rural men increased 61% while urban men had a similar increase of 59% (P = 0.177). Incidence was lower in women in both urban and rural locations, at 5.6 and 5.3 per 1000 in 2006. Overall, mortality rates decreased by 34% for urban men and 8% for rural men with diabetes (P = 0.006). Women with diabetes in rural areas had no decline in overall mortality, compared with a 28% reduction in urban women (P < 0.001). CONCLUSIONS: Diabetes prevalence remains highest in men, with the greatest increases seen in men living in rural residences. While mortality rates have declined substantially over the past decade for those people with diabetes living in urban settings, declines in mortality in rural areas have been much more modest (for men) or non-existent (for women).

Differences between notifiable and administrative health information in the spatial-temporal surveillance of enteric infections.

PURPOSE: The purpose of this study is to compare the spatial and temporal information generated from two distinct health data sources available for the surveillance of intestinal infections associated with Escherichia coli O157:H7. METHODS: Our study area is the province of Alberta, Canada. Data are from two sources: a fee-for-service administrative health data system and a notifiable disease data reporting system. The study period is between 1999 and 2005. We compare the systems by observing correlations in the infections over time, the variability in the overall distribution of cases (as measured by a geographic dissimilarity index), and the relative locations of spatial-temporal clusters of infection. RESULTS: Our results indicate considerable variability in information generated from these two systems. The geographic distribution of cases varies considerably, with annual indices of dissimilarity suggesting considerable variation in the geographic distribution of cases throughout the study period (D=0.445). The temporal patterns identified by these two sources of information are negatively correlated (-0.40, p<0.001). Notifiable disease clusters occur in the summer in southern regions of the province, whereas cases identified from administrative health data system cluster in the winter season, and further to the north. CONCLUSIONS: Notifiable disease data may suffer from selection bias; administrative health data may be insufficiently precise without laboratory confirmation. Our results illustrate differences in the spatial and temporal information generated from these two systems of case identification. Future surveillance of gastrointestinal illness of infectious origin may benefit from case ascertainment algorithms based on both sources of data.

A multi-level approach for investigating socio-economic and agricultural risk factors associated with rates of reported cases of Escherichia coli O157 in humans in Alberta, Canada.

Using negative binomial and multi-level Poisson models, the authors determined the statistical significance of agricultural and socio-economic risk factors for rates of reported disease associated with Escherichia coli O157 in census subdivisions (CSDs) in Alberta, Canada, 2000-2002. Variables relating to population stability, aboriginal composition of the CSDs, and the economic relationship between CSDs and urban centres were significant risk factors. The percentage of individuals living in low-income households was not a statistically significant risk factor for rates of disease. The statistical significance of cattle density, recorded at a higher geographical level, depended on the method used to correct for overdispersion, the number of levels included in the multi-level models, and the choice of using all reported cases or only sporadic cases. Our results highlight the importance of local socio-economic risk factors in determining rates of disease associated with E. coli O157, but their relationship with individual risk factors requires further evaluation.

Contribution of incidence to increasing prevalence of multiple sclerosis in Alberta, Canada.

Alberta Health Care Insurance Plan (AHCIP) data were used to calculate prevalence and incidence rates for multiple sclerosis (MS) in the general population of Alberta from 1990 to 2004. Multiple sclerosis prevalence rose steadily each year over this time period, from 217.6/100,000 individuals in 1990 to 357.6/100,000 in 2004. Multiple sclerosis incidence fluctuated with a slight increase from 1990 to 2004, at 20.9/100,000 and 23.9/100,000, respectively. Age-specific prevalence rates were higher between ages 30 and 60 in 2004 than in 1990. The pattern of age-specific incidence rates was similar in 1990 and 2004, with a slight shift toward diagnosis in younger years. Gender-specific prevalence rates were higher for females in both 1990 and 2004, with a greater increase in females (43%) than males (29%). Gender-specific incidence rates were higher for females than males in both years, but there was no differential increase in incidence by gender from 1990 to 2004. The 2004 Alberta MS prevalence rate remains among the highest reported worldwide. Both increasing incidence and longer duration have likely contributed to increasing MS prevalence in the province.

Health disparities in chickenpox or shingles in Alberta?

OBJECTIVE: Exploring for evidence of socio-economic health disparities in chickenpox and shingles in Alberta, Canada. METHODS: Chickenpox and shingles cases were identified from administrative data from Alberta's universal health care insurance system for 1994-2002. Incident cases were those with the earliest dated utilization of a health service (chickenpox: ICD9-CM 052/ICD10-CA B01; shingles: ICD9-CM 053/ ICD10-CA B02). Crude and age-specific rates were estimated for each year by an indicator of socio-demographic status based upon the nature of the payer and eligibility for health care premium subsidy (SES-proxy) for the provincial health care insurance system. RESULTS: Among young children there is a gradient of disparity in chickenpox rates prior to the year in which publicly funded vaccination programs were implemented. After this point, disparities decline but less so for First Nations children than for others. There was no evidence of disparity by SES-proxy for shingles. CONCLUSION: Publicly funded vaccination programs may effectively contribute to reduction in disease disparities for vaccine-preventable diseases. Further study is required to ascertain why disparities continue for First Nations children.

Incidence of Guillain-Barré syndrome in Alberta, Canada: an administrative data study.

BACKGROUND: To examine the epidemiology of Guillain-Barré syndrome (GBS) in Alberta between 1994 and 2004 with data derived from hospital administration procedures. METHODS: Data from 3,959,857 individuals (1,956,841 females and 2,003,016 males) aged 1-110 years and residing in Alberta, Canada, were included in the analysis. A Poisson regression analysis was performed to determine the predictors of GBS events. RESULTS: After age and sex standardisation to the 2001 Canadian census population, incidence rates ranged from 0.97 to 2.32 per 100,000 over the course of the 11-year period, with a mean incidence of 1.6 per 100,000. Significant effects of gender, age group and year were found. Males were found to be 1.5 times more likely to acquire GBS than females. Relative to those in their first decade, the risk of acquiring GBS increased with advancing age, whereby the incidence in males peaked in the 7th decade of life and in females in the 8th decade of life. The incidence fluctuated over the 11-year period, with a minimum in 1998 and a maximum in 2004. CONCLUSIONS: The incidence of GBS in Alberta between 1994 and 2004 fluctuated within a narrow range, was similar to that previously reported worldwide, demonstrated a male preponderance and increased in elderly patients.

Epidemiological characteristics of reported sporadic and outbreak cases of E. coli O157 in people from Alberta, Canada (2000-2002): methodological challenges of comparing clustered to unclustered data.

Using multivariable models, we compared whether there were significant differences between reported outbreak and sporadic cases in terms of their sex, age, and mode and site of disease transmission. We also determined the potential role of administrative, temporal, and spatial factors within these models. We compared a variety of approaches to account for clustering of cases in outbreaks including weighted logistic regression, random effects models, general estimating equations, robust variance estimates, and the random selection of one case from each outbreak. Age and mode of transmission were the only epidemiologically and statistically significant covariates in our final models using the above approaches. Weighing observations in a logistic regression model by the inverse of their outbreak size appeared to be a relatively robust and valid means for modelling these data. Some analytical techniques, designed to account for clustering, had difficulty converging or producing realistic measures of association.

The use of randomization tests to assess the degree of similarity in PFGE patterns of E. coli O157 isolates from known outbreaks and statistical space-time clusters.

Using isolates from reported cases of Escherichia coli O157 from Alberta, Canada in 2002, we applied randomization tests to determine if cases associated with an outbreak or statistical space-time cluster had more similar pulsed-field gel electrophoresis patterns, based on Dice coefficients, than expected by chance alone. Within each outbreak and space-time cluster, we assessed the mean, median, 25th percentile, 75th percentile, standard deviation, coefficient of variation, and interquartile range of the Dice coefficients of each pairwise comparison among the isolates. To assess the statistical significance of measures of location (e.g. mean) and variation (e.g. standard deviation) we created randomization distributions using all isolates or only isolates from sporadic cases. We determined that randomization tests are an appropriate tool for evaluating the similarity among isolates from cases that have been linked epidemiologically or statistically. We found little difference between using all cases or only sporadic cases when creating our randomization distributions.

The use of outbreak information in the interpretation of clustering of reported cases of Escherichia coli O157 in space and time in Alberta, Canada, 2000-2002.

We obtained a list of all reported cases of Escherichia coli O157 in Alberta during the 2000-2002 period, and using scan statistics we identified yearly temporal and spatial clusters of reported cases of E. coli O157 during the summer and in southern Alberta. However, the location of the spatial cluster in the south was variable among years. The impact of using both outbreak and sporadic data or only sporadic data on the identification of spatial and temporal clusters was small when analysing individual years, but the difference between spatial clusters was pronounced when scanning the entire study period. We also identified space-time clusters that incorporated known outbreaks, and clusters that were suggestive of undetected outbreaks that we attempted to validate with molecular data. Our results suggest that scan statistics, based on a space-time permutation model, may have a role in outbreak investigation and surveillance programmes by identifying previously undetected outbreaks.