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1.  Outcomes following chronic obstructive pulmonary disease presentations to emergency departments in Alberta: A population-based study 
Chronic obstructive pulmonary disease (COPD) is a complex, multisystem disorder that often results in exacerbations requiring emergency department (ED) management. Following an exacerbation and discharge from the ED, reassessment and management adjustment with a health care provider are recommended to re-establish control of the disease.
To describe outcomes of all COPD presentations to EDs made by adults in Alberta including the time spent in the ED and the physician visits following the ED visit.
Provincial administrative databases were used to obtain all ED encounters for COPD during six fiscal years (1999 to 2005). The information extracted included demographics, ED visit timing, and acute and subacute outcomes (physician visits up to 365 days after discharge for all 7302 discharged individuals during a one-year period). Data analysis included descriptive summaries and survival curves.
There were 85,330 ED visits for acute COPD, of which 67% were discharged from the ED. Median ED length of stay was longer in large urban areas (Calgary: 5 h 9 min; Edmonton: 4 h 58 min) than in other regions of Alberta (1 h 17 min). Admissions resulted from 32% of visits and varied among regions; however, few were admitted to the intensive care unit (1%) or died (0.1%). Following discharge, the median time to first follow-up with a physician was 13 days; however, only 40% of patients had follow-up visits in the first seven days. Repeat ED visits within seven days occurred in 5.7% of discharged patients, while 25.6% of discharged patients had repeat ED visits within 365 days of discharge.
More than 30% of COPD ED visits resulted in admission; regional variation was significant. Moreover, discharged patients experienced delayed follow-up and often required repeat ED visits. Interventions to improve reassessment and reduce COPD-related repeat ED visits should be explored.
PMCID: PMC3006153  PMID: 21165352
Chronic obstructive pulmonary disease; Databases; Emergency medicine; Epidemiology; Respiratory diseases
2.  Action plans in patients presenting to emergency departments with asthma exacerbations: Frequency of use and description of contents 
Written asthma action plans (AAPs) represent one of the key strategies for ambulatory asthma care and management. Despite the success of AAPs, however, they continue to be underused in asthma patients presenting with acute exacerbations. This study examined AAPs reported by patients presenting to three urban Canadian emergency departments, and explored knowledge and care gaps that may represent barriers to urgently needed effective uptake to reduce the burden of disease in at-risk populations.
Although underused, written asthma action plans (AAPs) are associated with reduced numbers of emergency department (ED) visits and hospitalizations.
To describe the frequency of use and contents of any AAPs reported by patients presenting with exacerbations to three urban Canadian EDs.
Prospective data were collected through ED interview and chart review. Descriptive analyses used proportions and medians with interquartile range; multivariable logistic regression was used for the adjusted analyses.
Among 176 enrolled patients, the median age was 27 years (interquartile range 23 to 39 years) and 97 (55%) were female. Few (n=42 [24%]) reported having AAPs at ED presentation and only six were written. Most (n=35 [75%]) patients with any AAP took action before the ED visit; none used a valid anti-inflammatory strategy. The first step of 27 plans was to increase asthma medication; no patients appropriately increased inhaled corticosteroids (ICS). In multivariable analyses, only the use of either ICS or ICS/long-acting β-agonist combination agents (31% had AAPs versus 12% did not have AAPs (adjusted OR 3.0 [95% CI 1.14 to 8.07]) and asthma education (47% had AAPs versus 21% did not have AAPs, adjusted OR 3.2 [95% CI 1.13 to 9.19]) were independently associated with AAP possession.
Possession of AAPs among patients presenting to the ED with acute asthma was low, and only one in 10 AAPs were written. Patients who reported having any AAP used ineffective strategies to abort or mitigate the severity of an ED visit. Increasing frequency of written AAPs and improving their contents holds immediate promise in improving outcomes related to asthma.
PMCID: PMC4266154  PMID: 25493590
Acute asthma; Asthma education; Care gaps; Prevention
3.  Congenital cytomegalovirus infection in Canada: Active surveillance for cases diagnosed by paediatricians 
Paediatrics & Child Health  2014;19(1):e1-e5.
To determine the rate of diagnosis; demographic, clinical and laboratory characteristics; and management of congenital cytomegalovirus (cCMV) cases identified by paediatricians in routine clinical practice in Canada.
National active monthly surveillance of all clinically practicing general and subspecialty paediatricians in Canada was performed for cCMV from March 1, 2005 to February 28, 2008, through the Canadian Paediatric Surveillance Program.
Forty-nine cases of cCMV infection were reported (4.5 per 100,000 births): 40.8% were born before 36 weeks’ gestation; 55.1% had a birth weight <2500 g; and 28.6% and 30.6% were below the third percentile for weight and head circumference, respectively. The median maternal age was 23 years, and 18.4% were <20 years of age. Eight mothers (16.3%) were Aboriginal (non-Aboriginal birth prevalence 3.9 per 100,000; Aboriginal birth prevalence 15.8 per 100,000; P<0.005). The most common laboratory abnormality was thrombocytopenia (53.1%). Thirty-three (67.3%) infants exhibited neurological manifestations; ganciclovir therapy was administered to 12 (36.4%) and was not administered to 21 (63.6%) of the infants with neurological manifestations.
Only a minority of the expected number of symptomatic cCMV-infected infants were reported in the present study. The majority of these severely affected infants, including those with neurological disease, are not being treated with ganciclovir. The present description of current diagnosis and practice highlights the need for more complete case identification in the population as well as the need for increased awareness of the optimal therapy for symptomatic cCMV.
PMCID: PMC3938223  PMID: 24627656
Aboriginal; Canada; Congenital infection; Cytomegalovirus; Surveillance
4.  Characteristics of Children and Youth Who Visit the Emergency Department for a Behavioural Disorder 
Relatively little is known about children who present to emergency departments (EDs) to stabilize acute emergencies related to behavioural disorders. This study describes patient and treatment characteristics of such children/youth.
We conducted a retrospective medical record review of consecutive ED presentations made by children/youth (10 to 17 years) between January 2009 and December 2011 for visits with a main discharge diagnosis of hyperkinetic disorder, mixed disorder of conduct and emotions, or conduct disorder. Socio-demographic and ED visit data were analyzed descriptively.
During the study period, 365 consecutive presentations made by 325 children/youth. The most common presenting complaints were related to depression/self-harm (45.8%) and violent behaviours (28.8%). Many children/youth had a previously diagnosed psychiatric disorder (59.4%) and identified being under the care of a child psychiatrist (42.2%). The majority of ED visits were triaged as urgent or emergent (51.5% and 41.1%, respectively) and included mood and suicidality assessments (84.7% and 80.8%, respectively). Follow-up with various services was made for all visits.
Children and youth presented to the ED for a behavioural disorder had urgent needs related to self-harm, depression and violent behaviours. These findings draw attention to the important role of the ED in managing physical safety and well-being concerns for families and recommending follow-up in the post-crisis period.
PMCID: PMC4032079  PMID: 24872826
behavioural disorders; mental health; emergency department; pediatrics; troubles de comportement; santé mentale; département d’urgence; pédiatrie
5.  Pharmacy study of natural health product adverse reactions (SONAR): a cross-sectional study using active surveillance in community pharmacies to detect adverse events associated with natural health products and assess causality 
BMJ Open  2014;4(3):e003431.
To investigate the rates and causality of adverse event(s) (AE) associated with natural health product (NHP) use, prescription drug use and concurrent NHP-drug use through active surveillance in community pharmacies.
Cross-sectional study of screened patients.
10 community pharmacies across Alberta and British Columbia, Canada from 14 January to 30 July 2011.
The participating pharmacy staff screened consecutive patients, or agents of patients, who were dropping or picking up prescription medications.
Primary outcome measures
Patients were screened to determine the proportions of them using prescription drugs and/or NHPs, as well as their respective AE rates. All AEs reported by the screened patients who took a NHP, consented to, and were available for, a detailed telephone interview (14%) were adjudicated fully to assess for causality.
Over a total of 105 pharmacy weeks and 1118 patients screened, 410 patients reported taking prescription drugs only (36.7%; 95% CI 33.9% to 39.5%), 37 reported taking NHPs only (3.3%; 95% CI 2.4% to 4.5%) and 657 reported taking prescription drugs and NHPs concurrently (58.8%; 95% CI 55.9% to 61.6%). In total, 54 patients reported an AE, representing 1.2% (95% CI 0.51% to 2.9%), 2.7% (95% CI 0.4% to 16.9%) and 7.3% (95% CI 5.6% to 9.6%) of each population, respectively. Compared with patients who reported using prescription drugs, the patients who reported using prescription drugs and NHPs concurrently were 6.4 times more likely to experience an AE (OR; 95% CI 2.52 to 16.17; p<0.001). Combined with data from Ontario, Canada, a national proportion was calculated, which found that 45.4% (95% CI 43.8% to 47.0%) of Canadians who visit community pharmacies take NHPs and prescription drugs concurrently, and of those, 7.4% (95% CI 6.3% to 8.8%) report an AE.
A substantial proportion of community pharmacy patients use prescription drugs and NHPs concurrently; these patients are at a greater risk of experiencing an AE. Active surveillance provides a means of detecting such AEs and collecting high-quality data on which causality assessment can be based.
PMCID: PMC3975764  PMID: 24682573
Complementary Medicine; Toxicology
6.  Time Trends in Suicide-Related Behaviours in Girls and Boys 
To examine the incidence and nature of emergency department (ED) presentations for nonfatal suicide-related behaviours (SRBs) over time, in boys and girls living in Ontario. We hypothesize declining rates (fiscal years [FYs] 2002/03 to 2006/07) ceased thereafter owing to renewed regulatory warnings against prescribing antidepressants and the economic recession.
We graphed and tested differences in ED SRB incidence rates for FYs 2002/03 to 2010/11. We estimated rate ratios and 95% confidence intervals using negative binomial regression controlling for changes in the underlying population (age, community size, and neighbourhood income quintile). We examined the nature of the incident (index) presentations over time in terms of the method(s) used and events occurring before and after the index event.
ED SRB incidence rates decreased by 30% in boys and girls from FYs 2002/03 to 2006/07, but not thereafter. This trend was most evident in girls who self-poisoned and in girls’ presentations to hospital with mental illness in the preceding year. Within a year of the index event, the proportion of girls with a repeat ED SRB presentation also declined by about one-third, but beyond FYs 2005/06 to 2009/10. However, the proportion admitted subsequent to the index event increased by about one-third. In boys, their patterns of presentations to hospital with mental illness and SRB repetition over time were similar to girls, but estimated with greater variability.
While the decline in ED SRB rates to FY 2006/07 is encouraging, the lack of decline thereafter and an increase in subsequent admissions merits ongoing monitoring and evaluation.
PMCID: PMC4079127  PMID: 24881164
attempted suicide; adolescent; incidence; time factors; sex distribution
7.  Children's Mental Health Visits to the Emergency Department: Factors Affecting Wait Times and Length of Stay 
Objective. This study explores the association of patient and emergency department (ED) mental health visit characteristics with wait time and length of stay (LOS). Methods. We examined data from 580 ED mental health visits made to two urban EDs by children aged ≤18 years from April 1, 2004, to March 31, 2006. Logistic regressions identified characteristics associated with wait time and LOS using hazard ratios (HR) with 95% confidence intervals (CIs). Results. Sex (male: HR = 1.48, 95% CI = 1.20–1.84), ED type (pediatric ED: HR = 5.91, 95% CI = 4.16–8.39), and triage level (Canadian Triage and Acuity Scale (CTAS) 2: HR = 3.62, 95% CI = 2.24–5.85) were statistically significant predictors of wait time. ED type (pediatric ED: HR = 1.71, 95% CI = 1.18–2.46), triage level (CTAS 5: HR = 2.00, 95% CI = 1.15–3.48), number of consultations (HR = 0.46, 95% CI = 0.31–0.69), and number of laboratory investigations (HR = 0.75, 95% CI = 0.66–0.85) predicted LOS. Conclusions. Based on our results, quality improvement initiatives to reduce ED waits and LOS for pediatric mental health visits may consider monitoring triage processes and the availability, access, and/or time to receipt of specialty consultations.
PMCID: PMC3915921  PMID: 24563785
8.  Study of Natural Health Product Adverse Reactions (SONAR): Active Surveillance of Adverse Events Following Concurrent Natural Health Product and Prescription Drug Use in Community Pharmacies 
PLoS ONE  2012;7(9):e45196.
Many consumers use natural health products (NHPs) concurrently with prescription medications. As NHP-related harms are under-reported through passive surveillance, the safety of concurrent NHP-drug use remains unknown. To conduct active surveillance in participating community pharmacies to identify adverse events related to concurrent NHP-prescription drug use.
Methodology/Principal Findings
Participating pharmacists asked individuals collecting prescription medications about (i) concurrent NHP/drug use in the previous three months and (ii) experiences of adverse events. If an adverse event was identified and if the patient provided written consent, a research pharmacist conducted a guided telephone interview to gather additional information after obtaining additional verbal consent and documenting so within the interview form. Over a total of 112 pharmacy weeks, 2615 patients were screened, of which 1037 (39.7%; 95% CI: 37.8% to 41.5%) reported concurrent NHP and prescription medication use. A total of 77 patients reported a possible AE (2.94%; 95% CI: 2.4% to 3.7%), which represents 7.4% of those using NHPs and prescription medications concurrently (95%CI: 6.0% to 9.2%). Of 15 patients available for an interview, 4 (26.7%: 95% CI: 4.3% to 49.0%) reported an AE that was determined to be “probably” due to NHP use.
Active surveillance markedly improves identification and reporting of adverse events associated with concurrent NHP-drug use. Although not without challenges, active surveillance is feasible and can generate adverse event data of sufficient quality to allow for meaningful adjudication to assess potential harms.
PMCID: PMC3461007  PMID: 23028841
9.  Emergency health care use and follow-up among sociodemographic groups of children who visit emergency departments for mental health crises 
Previous studies of differences in mental health care associated with children’s sociodemographic status have focused on access to community care. We examined differences associated with visits to the emergency department.
We conducted a 6-year population-based cohort analysis using administrative databases of visits (n = 30 656) by children aged less than 18 years (n = 20 956) in Alberta. We measured differences in the number of visits by socioeconomic and First Nations status using directly standardized rates. We examined time to return to the emergency department using a Cox regression model, and we evaluated time to follow-up with a physician by physician type using a competing risks model.
First Nations children aged 15–17 years had the highest rate of visits for girls (7047 per 100 000 children) and boys (5787 per 100 000 children); children in the same age group from families not receiving government subsidy had the lowest rates (girls: 2155 per 100 000 children; boys: 1323 per 100 000 children). First Nations children (hazard ratio [HR] 1.64; 95% confidence interval [CI] 1.30–2.05), and children from families receiving government subsidies (HR 1.60, 95% CI 1.30–1.98) had a higher risk of return to an emergency department for mental health care than other children. The longest median time to follow-up with a physician was among First Nations children (79 d; 95% CI 60–91 d); this status predicted longer time to a psychiatrist (HR 0.47, 95% CI 0.32–0.70). Age, sex, diagnosis and clinical acuity also explained post-crisis use of health care.
More visits to the emergency department for mental health crises were made by First Nations children and children from families receiving a subsidy. Sociodemographics predicted risk of return to the emergency department and follow-up care with a physician.
PMCID: PMC3447077  PMID: 22690003
10.  Parents as Agents of Change (PAC) in pediatric weight management: The protocol for the PAC randomized clinical trial 
BMC Pediatrics  2012;12:114.
There is an urgent need to develop and evaluate weight management interventions to address childhood obesity. Recent research suggests that interventions designed for parents exclusively, which have been named parents as agents of change (PAC) approaches, have yielded positive outcomes for managing pediatric obesity. To date, no research has combined a PAC intervention approach with cognitive behavioural therapy (CBT) to examine whether these combined elements enhance intervention effectiveness. This paper describes the protocol our team is using to examine two PAC-based interventions for pediatric weight management. We hypothesize that children with obesity whose parents complete a CBT-based PAC intervention will achieve greater reductions in adiposity and improvements in cardiometabolic risk factors, lifestyle behaviours, and psychosocial outcomes than children whose parents complete a psycho-education-based PAC intervention (PEP).
This study is a pragmatic, two-armed, parallel, single-blinded, superiority, randomized clinical trial. The primary objective is to examine the differential effects of a CBT-based PAC vs PEP-based PAC intervention on children’s BMI z-score (primary outcome). Secondary objectives are to assess intervention-mediated changes in cardiometabolic, lifestyle, and psychosocial variables in children and parents. Both interventions are similar in frequency of contact, session duration, group facilitation, lifestyle behaviour goals, and educational content. However, the interventions differ insofar as the CBT-based intervention incorporates theory-based concepts to help parents link their thoughts, feelings, and behaviours; these cognitive activities are enabled by group leaders who possess formal training in CBT. Mothers and fathers of children (8–12 years of age; BMI ≥85th percentile) are eligible to participate if they are proficient in English (written and spoken) and agree for at least one parent to attend group-based sessions on a weekly basis. Anthropometry, cardiometabolic risk factors, lifestyle behaviours, and psychosocial health of children and parents are assessed at pre-intervention, post-intervention, 6-, and 12-months follow-up.
This study is designed to extend findings from earlier efficacy studies and provide data on the effect of a CBT-based PAC intervention for managing pediatric obesity in a real-world, outpatient clinical setting.
Trial Registration identifier: NCT01267097
PMCID: PMC3469386  PMID: 22866998
Obesity; Pediatric; Treatment; Parents; Cognitive behavioral therapy; Canada
11.  Clinical Acuity of Repeat Pediatric Mental Health Presentations to the Emergency Department 
We examined whether clinical acuity changed in children and youth with repeated emergency department (ED) visits for mental illness. A secondary, exploratory objective was to examine characteristics associated with clinical acuity.
We conducted a four-year historical cohort study reviewing data from 1,033 ED presentations by 474 patients (≤17 years) for mood disorders, neurotic/stress-related disorders, and psychosis-related illnesses. We used a multivariable generalized linear mixed model to examine the relationship between clinical acuity (defined by triage level at presentation) and length of time since initial ED visit. Interactions between diagnosis group and age group, sex, and visiting timing were also examined. Explanatory variables (patient demography, diagnosis, disposition, institutional classification and location) were entered into the model to explore their relationship to clinical acuity.
Clinical acuity did not change between ED visits for children with mood disorders, neurotic/stress-related disorders, or psychosis-related illnesses. The median time to ED return was 7 days. Several characteristics were associated with a higher likelihood of increased clinical acuity at presentation: being male, presenting to the ED with a mood disorder, and attendance to an urban-based ED.
Repeat ED visits for several pediatric mental illnesses were not a result of destabilized conditions. Further investigation of the relationship between patient characteristics, available community services, and patterned mental health care use is needed to clarify ED utilization patterns.
PMCID: PMC3143697  PMID: 21804850
emergency service; repeat visits; pediatrics; illness severity; psychiatry; urgence; visites répétées; pédiatrie; gravité de la maladie; psychiatrie
12.  Congenital cytomegalovirus infection in high-risk Canadian infants: Report of a pilot screening study 
Congenital cytomegalovirus (cCMV) is the most common congenital infection; however, the epidemiology in Canada has not been recently examined. The present prospective study pilots tools for a population-based study of cCMV infection in Canada by determining the maternal seroprevalence and risk factors, the clinical characteristics and the incidence of cCMV using a variety of diagnostic tests in a cohort of high-risk infants in northern Alberta.
All infants born at the Royal Alexandra Hospital in Edmonton, Alberta, from June 1, 2003, to May 31, 2004, were screened for the study. Eligible infants were those with very low birth weights (VLBWs) or small for gestational age (SGA). Maternal CMV serostatus was determined, and chart review and parental interviews were completed. Neonatal urine and throat cultures, and polymerase chain reaction (PCR) were performed. Dried blood spots (DBS) were tested for CMV by PCR.
In total, 213 infants were eligible for the study. Of these, 137 entered the study (79 VLBW and 58 SGA). Some families were not contacted for participation in the study due to neonatal deaths or early discharge. The mean age of the mothers was 27.6 years; 68% of the mothers were Caucasian and 16% were Aboriginal. The maternal CMV seroprevalence was 55%. Seropositivity was significantly associated with ethnicity (First Nations [100%]; Caucasian [34%]) and country of birth (outside Canada [94%]; Canadian born [45%]). The rate of cCMV was two in 137 (1.5%), with a rate of one in 79 (1.3%) for the VLBW infants and one in 58 (1.7%) for the SGA infants. Both had positive throat or urine specimens, but only the symptomatic infant was positive on DBS.
A cCMV screening program should be universal and routine to successfully screen all newborns. Maternal CMV seropositivity varies widely within the Canadian population. In the present pilot study, DBS PCR was not a sensitive screening tool and throat swab was the best screening specimen.
PMCID: PMC2852289  PMID: 21358874
Congenital; Cytomegalovirus; High-risk infants; Maternal seropositivity
13.  An exact test to detect geographic aggregations of events 
Traditional approaches to statistical disease cluster detection focus on the identification of geographic areas with high numbers of incident or prevalent cases of disease. Events related to disease may be more appropriate for analysis than disease cases in some contexts. Multiple events related to disease may be possible for each disease case and the repeated nature of events needs to be incorporated in cluster detection tests.
We provide a new approach for the detection of aggregations of events by testing individual administrative areas that may be combined with their nearest neighbours. This approach is based on the exact probabilities for the numbers of events in a tested geographic area. The test is analogous to the cluster detection test given by Besag and Newell and does not require the distributional assumptions of a similar test proposed by Rosychuk et al. Our method incorporates diverse population sizes and population distributions that can differ by important strata. Monte Carlo simulations help assess the overall number of clusters identified. The population and events for each area as well as a nearest neighbour spatial relationship are required. We also provide an alternative test applicable to situations when only the aggregate number of events, and not the number of events per individual, are known. The methodology is illustrated on administrative data of presentations to emergency departments.
We provide a new method for the detection of aggregations of events that does not rely on distributional assumptions and performs well.
PMCID: PMC2898811  PMID: 20529286
14.  Plasma matrix metalloproteinases in neonates having surgery for congenital heart disease 
Heart International  2009;4(1):e4.
During cardiopulmonary-bypass matrix-metalloproteinases released may contribute to ventricular dysfunction. This study was to determine plasma matrix-metalloproteinases in neonates after cardiopulmonary-bypass and their relation to post-operative course. A prospective observational study included 18 neonates having cardiac surgery. Plasma matrix-metalloproteinases-2 and 9 activities were measured by gelatin-zymography pre-operatively, on starting cardiopulmonarybypass, 7–8 min after aortic cross-clamp release, and 1h, 4h, 24h, and 3d after cardiopulmonary-bypass. Plasma concentrations of their tissue inhibitors 1 and 2 were determined by enzyme-linked immunosorbent assay. Cardiac function was assessed by serial echocardiography. Paired t-tests and Wilcoxon tests were used to assess temporal changes, and linear correlation with simultaneous clinical and cardiac function parameters were assessed using Pearson's product-moment correlation coefficient. Plasma matrix-metalloproteinases activities and their tissue inhibitor concentrations decreased during cardiopulmonary-bypass. Matrix-metalloproteinase-2 plasma activity increased progressively starting 1h after cardiopulmonarybypass and returned to pre-operative levels at 24h. Matrix-metalloproteinase-9 plasma activity increased significantly after release of aortic cross-clamp, peaked 7–8min later, and returned to baseline at 24h. Plasma tissueinhibitor 1 and 2 concentrations increased 1h after cardiopulmonary-bypass. Cardiac function improved from 4h to 3d after surgery (p<0.05). There was no evidence of significant correlations between matrix-metalloproteinases or their inhibitors and cardiac function, inotrope scores, organ dysfunction scores, ventilation days, or hospital days. The temporal profile of plasma matrix-metalloproteinases and their inhibitors after cardiopulmonary-bypass in neonates are similar to adults. In neonates, further study should determine whether circulating matrix-metalloproteinases are useful biomarkers of disease activity locally within the myocardium, and hence of clinical outcomes.
PMCID: PMC3184692  PMID: 21977281
cardiopulmonary bypass; congenital heart disease; matrix metalloproteinases; neonate; pediatrics.
15.  Spatial event cluster detection using an approximate normal distribution 
In geographic surveillance of disease, areas with large numbers of disease cases are to be identified so that investigations of the causes of high disease rates can be pursued. Areas with high rates are called disease clusters and statistical cluster detection tests are used to identify geographic areas with higher disease rates than expected by chance alone. Typically cluster detection tests are applied to incident or prevalent cases of disease, but surveillance of disease-related events, where an individual may have multiple events, may also be of interest. Previously, a compound Poisson approach that detects clusters of events by testing individual areas that may be combined with their neighbours has been proposed. However, the relevant probabilities from the compound Poisson distribution are obtained from a recursion relation that can be cumbersome if the number of events are large or analyses by strata are performed. We propose a simpler approach that uses an approximate normal distribution. This method is very easy to implement and is applicable to situations where the population sizes are large and the population distribution by important strata may differ by area. We demonstrate the approach on pediatric self-inflicted injury presentations to emergency departments and compare the results for probabilities based on the recursion and the normal approach. We also implement a Monte Carlo simulation to study the performance of the proposed approach.
In a self-inflicted injury data example, the normal approach identifies twelve out of thirteen of the same clusters as the compound Poisson approach, noting that the compound Poisson method detects twelve significant clusters in total. Through simulation studies, the normal approach well approximates the compound Poisson approach for a variety of different population sizes and case and event thresholds.
A drawback of the compound Poisson approach is that the relevant probabilities must be determined through a recursion relation and such calculations can be computationally intensive if the cluster size is relatively large or if analyses are conducted with strata variables. On the other hand, the normal approach is very flexible, easily implemented, and hence, more appealing for users. Moreover, the concepts may be more easily conveyed to non-statisticians interested in understanding the methodology associated with cluster detection test results.
PMCID: PMC2632623  PMID: 19077271
16.  Medical Students and Pandemic Influenza 
Emerging Infectious Diseases  2007;13(11):1781-1783.
To assess knowledge of pandemic influenza, we administered a questionnaire to all medical students at the University of Alberta; 354 (69%) of 510 students responded. Data from questionnaires such as this could help determine the role of medical students during a public health emergency.
PMCID: PMC3375803  PMID: 18217571
Pandemic influenza; medical students; knowledge; volunteering; attitudes; penalties; dispatch
17.  Adaptations for finding irregularly shaped disease clusters 
Recent adaptations of the spatial scan approach to detecting disease clusters have addressed the problem of finding clusters that occur in non-compact and non-circular shapes – such as along roads or river networks. Some of these approaches may have difficulty defining cluster boundaries precisely, and tend to over-fit data with very irregular (and implausible) clusters shapes.
Results & Discussion
We describe two simple adaptations to these approaches that can be used to improve the effectiveness of irregular disease cluster detection. The first adaptation penalizes very irregular cluster shapes based on a measure of connectivity (non-connectivity penalty). The second adaptation prevents searches from combining smaller clusters into large super-clusters (depth limit). We conduct experiments with simulated data in order to observe the performance of these adaptations on a number of synthetic cluster shapes.
Our results suggest that the combination of these two adaptations may increase the ability of a cluster detection method to find irregular shapes without affecting its ability to find more regular (i.e., compact) shapes. The depth limit in particular is effective when it is deemed important to distinguish nearby clusters from each other. We suggest that these adaptations of adjacency-constrained spatial scans are particularly well suited to chronic disease and injury surveillance.
PMCID: PMC1939838  PMID: 17615077
18.  Identifying geographic areas with high disease rates: when do confidence intervals for rates and a disease cluster detection method agree? 
Geographic regions are often routinely monitored to identify areas with excess cases of disease. Further epidemiological investigations can be targeted to areas with higher disease rates than expected. Surveillance strategies typically include the calculation of sub-regional rates, and their associated confidence intervals, that are compared with the rate of the entire geographic region. More sophisticated approaches use disease cluster detection methods that require specialized software. These approaches are not the same but may lead to similar results in specific situations. A natural question arises as to when these different approaches lead to the same conclusions. We compare the Besag and Newell [1] cluster detection method, suitable for geographic areas with diverse population sizes, with confidence intervals for crude and directly standardized rates. The cluster detection method tests each area at a pre-specified cluster size. Conditions when these methods agree and disagree are provided. We use a dataset on self-inflicted injuries requiring medical attention as an illustration and give power comparisons for a variety of situations.
Three conditions must be satisfied for the confidence interval and cluster detection methods to both provide statistically significant higher rates for an individual administrative area. These criteria are based on observed and expected cases above specific thresholds. In our dataset, two areas are significant with both methods and one additional area is identified with the cluster detection method. Power comparisons for different scenarios suggest that the methods have similar power for detecting rates that are twice as large as the overall rate and when the overall rate and sample sizes are not too small. The cluster detection method has better power when the size of the cluster is relatively small.
The cluster size plays a key role in the comparability of methods. The cluster detection method is preferred when the cluster size exceeds the number of cases in an administrative area or when the expected number of cases exceeds a threshold.
PMCID: PMC1630694  PMID: 17049097
19.  Effectiveness of a home-based balance-training program in reducing sports-related injuries among healthy adolescents: a cluster randomized controlled trial 
Sport is the leading cause of injury requiring medical attention among adolescents. We studied the effectiveness of a home-based balance-training program using a wobble board in improving static and dynamic balance and reducing sports-related injuries among healthy adolescents.
In this cluster randomized controlled trial, we randomly selected 10 of 15 high schools in Calgary to participate in the fall of 2001. We then recruited students from physical education classes and randomly assigned them, by school, to either the intervention (n = 66) or the control (n = 61) group. Students in the intervention group participated in a daily 6-week and then a weekly 6-month home-based balance-training program using a wobble board. Students at the control schools received testing only. The primary outcome measures were timed static and dynamic balance, 20-m shuttle run and vertical jump, which were measured at baseline and biweekly for 6 weeks. Self-reported injury data were collected over the 6-month follow-up period.
At 6 weeks, improvements in static and dynamic balance were observed in the intervention group but not in the control group (difference in static balance 20.7 seconds, 95% confidence interval [CI] 10.8 to 30.6 seconds; difference in dynamic balance 2.3 seconds, 95% CI 0.7 to 4.0 seconds). There was evidence of a protective effect of balance training in over 6 months (relative risk of injury 0.2, 95% CI 0.05 to 0.88). The number needed to treat to avoid 1 injury over 6 months was 8 (95% CI 4 to 35).
Balance training using a wobble board is effective in improving static and dynamic balance and reducing sports-related injuries among healthy adolescents.
PMCID: PMC552888  PMID: 15767608

Results 1-19 (19)