Look Around Me: Environmental and Socio-Economic Factors Related to Community Participation for Children with Cerebral Palsy in Québec.

Aims: This study aimed at gaining a deeper understanding of the environmental and socio-economic factors affecting participation outcomes in community and leisure activities for children with disabilities, as well as the trajectories of participation for these children to promote their health and guarantee their rights are respected.Methods: A participatory action research (PAR) approach and linear regression analysis were employed to identify contextual factors associated with the community participation of children with cerebral palsy (CP) living in Quebec, Canada. Stakeholders engaged through the entire research process supported the development of questionnaires, data collection, analysis and interpretation of results.Results: Neighborhood outings were ranked among the most practiced activities by children with CP. Only in a few cases (9%) did children participate in more than two types of activities outside of school. Factors limiting children's participation were predominantly extrinsic in origin, including financial burden and lack of information about existing opportunities.Conclusions: There is a serious need for communities and local governments to inform parents about available resources, programs and policies that can support their child's participation. Rehabilitation professionals could partner with stakeholders to inform the development of public policies that target the identified barriers and promote children's integration and fulfillment.

Latency of tobacco smoking for head and neck cancer among HPV-positive and HPV-negative individuals.

Human papillomavirus (HPV) infection and tobacco smoking are well-known risk factors for head and neck cancers (HNC). Although an effect modification between oral HPV infection and tobacco smoking may exist, evidence is lacking on how they interact temporally. We investigated the latency and life course effects of tobacco smoking on risk of HNC among HPV-positive (HPV+ve ) and negative (HPV-ve ) individuals. We used data from 631 ever-smoker participants of a hospital-based case-control study conducted in four major hospitals in Montréal, Canada. Cases (n = 320), incident, histologically confirmed, primary squamous cell carcinomas, were frequency-matched to controls (n = 311) by age and sex. Sociodemographic and behavioral factors (e.g., tobacco and alcohol use and sexual history) were collected using a structured interview applying a life grid technique. Oral exfoliated cells were used for HPV DNA detection and genotyping. Latency effects were estimated flexibly using a Bayesian relevant exposure model and further extended with a life course approach. Retrospective smoking trajectories for HPV+ve cases and controls had similar shapes. Exposure to tobacco smoking even 40 years before diagnosis was associated with an increased HNC risk among both HPV+ve and HPV-ve participants. The effect of smoking before the start of sexual activity compared to afterwards was higher among HPV+ve individuals. This pattern of association was less profound among HPV-ve participants. Temporal interactions may exists between oral HPV infection and life course smoking trajectories in relation to HNC risk.

Bayesian Methods for Exposure Misclassification Adjustment in a Mediation Analysis: Hemoglobin and Malnutrition in the Association Between Ascaris and IQ.

BACKGROUND: Soil-transmitted helminth infections have been found to be associated with child development. The objective was to investigate hemoglobin levels and malnutrition as mediators of the association between Ascaris infection and intelligence quotient (IQ) scores in children. METHODS: We conducted a longitudinal cohort study in Iquitos, Peru, between September 2011 and July 2016. A total of 1760 children were recruited at 1 year of age and followed up annually to 5 years. We measured Ascaris infection and malnutrition at each study visit, and hemoglobin levels were measured as of age 3. The exposure was defined as the number of detected Ascaris infections between age 1 and 5. We measured IQ scores at age 5 and used Bayesian models to correct exposure misclassification. RESULTS: We included a sample of 781 children in the analysis. In results adjusted for Ascaris misclassification, mean hemoglobin levels mediated the association between Ascaris infection and IQ scores. The natural direct effects (not mediated by hemoglobin) (95% CrI) and natural indirect effects (mediated by hemoglobin) (95% CrI) were compared with no or one infection: -0.9 (-4.6, 2.8) and -4.3 (-6.9, -1.6) for the effect of two infections; -1.4 (-3.8, 1.0) and -1.2 (-2.0, -0.4) for three infections; and -0.4 (-3.2, 2.4) and -2.7 (-4.3, -1.0) for four or five infections. CONCLUSION: Our results are consistent with the hypothesis that hemoglobin levels mediate the association between Ascaris infection and IQ scores. Additional research investigating the effect of including iron supplements in STH control programs is warranted.

Bayesian consensus-based sample size criteria for binomial proportions.

Many sample size criteria exist. These include power calculations and methods based on confidence interval widths from a frequentist viewpoint, and Bayesian methods based on credible interval widths or decision theory. Bayesian methods account for the inherent uncertainty of inputs to sample size calculations through the use of prior information rather than the point estimates typically used by frequentist methods. However, the choice of prior density can be problematic because there will almost always be different appreciations of the past evidence. Such differences can be accommodated a priori by robust methods for Bayesian design, for example, using mixtures or ϵ-contaminated priors. This would then ensure that the prior class includes divergent opinions. However, one may prefer to report several posterior densities arising from a "community of priors," which cover the range of plausible prior densities, rather than forming a single class of priors. To date, however, there are no corresponding sample size methods that specifically account for a community of prior densities in the sense of ensuring a large-enough sample size for the data to sufficiently overwhelm the priors to ensure consensus across widely divergent prior views. In this paper, we develop methods that account for the variability in prior opinions by providing the sample size required to induce posterior agreement to a prespecified degree. Prototypic examples to one- and two-sample binomial outcomes are included. We compare sample sizes from criteria that consider a family of priors to those that would result from previous interval-based Bayesian criteria.

Pneumococcal pneumonia prevalence among adults with severe acute respiratory illness in Thailand - comparison of Bayesian latent class modeling and conventional analysis.

BACKGROUND: Determining the etiology of pneumonia is essential to guide public health interventions. Diagnostic test results, including from polymerase chain reaction (PCR) assays of upper respiratory tract specimens, have been used to estimate prevalence of pneumococcal pneumonia. However limitations in test sensitivity and specificity and the specimen types available make establishing a definitive diagnosis challenging. Prevalence estimates for pneumococcal pneumonia could be biased in the absence of a true gold standard reference test for detecting Streptococcus pneumoniae. METHODS: We conducted a case control study to identify etiologies of community acquired pneumonia (CAP) from April 2014 through August 2015 in Thailand. We estimated the prevalence of pneumococcal pneumonia among adults hospitalized for CAP using Bayesian latent class models (BLCMs) incorporating results of real-time polymerase chain reaction (qPCR) testing of upper respiratory tract specimens and a urine antigen test (UAT) from cases and controls. We compared the prevalence estimate to conventional analyses using only UAT as a reference test. RESULTS: The estimated prevalence of pneumococcal pneumonia was 8% (95% CI: 5-11%) by conventional analyses. By BLCM, we estimated the prevalence to be 10% (95% CrI: 7-16%) using binary qPCR and UAT results, and 11% (95% CrI: 7-17%) using binary UAT results and qPCR cycle threshold (Ct) values. CONCLUSIONS: BLCM suggests a > 25% higher prevalence of pneumococcal pneumonia than estimated by a conventional approach assuming UAT as a gold standard reference test. Higher quantities of pneumococcal DNA in the upper respiratory tract were associated with pneumococcal pneumonia in adults but the addition of a second specific pneumococcal test was required to accurately estimate disease status and prevalence. By incorporating the inherent uncertainty of diagnostic tests, BLCM can obtain more reliable estimates of disease status and improve understanding of underlying etiology.

An Unsupervised Smart App-Optimized HIV Self-Testing Program in Montreal, Canada: Cross-Sectional Study.

BACKGROUND: Although HIV self-testing strategies have been recommended by the World Health Organization, HIV self-tests are not yet approved in Canada. Currently approved HIV self-tests offer toll-free lines that are insufficient for initiating expedited linkages to counseling and care, accurate interpretation, and support during HIV self-testing. We developed an innovative, multilingual software app called HIVSmart! to plug these gaps. OBJECTIVE: This study aimed to test our app-optimized oral HIV self-testing strategy for feasibility in men who have sex with men (MSM) who presented to test at a large sexual health clinic (Clinique Médicale L'Actuel) in Montreal. METHODS: Between July 2016 and February 2017, we offered a strategy consisting of the OraQuick In-Home HIV Test (an investigational device) and a tablet installed with the HIVSmart! app to study participants, who presented at a private office in the clinic, mimicking an unsupervised home environment. We evaluated the strategy for its feasibility, acceptability, and preference. Using the HIVSmart! app, participants were guided through the self-testing process. We determined feasibility with a metric defined as the completion rate, which consisted of the following 3 steps: (1) self-test conduct; (2) self-test interpretation; and (3) linkages to care. Participants independently performed, interpreted, recorded their self-test and result, engaged in pre- and posttest counseling, and sought linkages to care. Laboratory tests (p24, Western Blot, and RNA), as per country algorithms, were expedited, and linkages based on the rapid test status were arranged. RESULTS: Mean age of the 451 participants enrolled was 34 (range, 18-73) years. Of all participants, 97.1% (438/451) completed and submitted the survey through the HIVSmart! app. In total, 84.7% (371/438) of the participants were well educated (beyond high school) and 52.5% (230/438) had been tested within the past 6 months. Of the 451, 11.5% (52/451) were on pre-exposure prophylaxis. Feasibility (completion rate), an average proportion of the 3 steps, was computed to be 96.6% (419/451). The acceptability of the strategy was high at 98.5% (451/458). A majority of the participants (448/451, 99.3%) were found to be self-tested and lab-confirmed negative and were counseled after self- and rapid tests. In total, 0.7% (3/451) of the participants who self-tested positive and were lab-confirmed positive were linked to a physician within the same day. Furthermore, 98.8% (417/422) of the participants found the app to be useful and 94.0% (424/451) were willing to recommend it to a friend or partner. CONCLUSIONS: The HIVSmart! app-optimized strategy was feasible, accepted, and preferred by an educated, urban MSM population of Montreal. With the app, participants were able to perform, interpret, store results, and get rapidly linked to care. The HIVSmart!-optimized, self-testing strategy could be adapted and contextualized to many at-risk populations within Canada and worldwide, thereby maximizing its public health impact.

The Risk of Recurrent Anaphylaxis.

OBJECTIVES: To determine the recurrence rate of anaphylaxis in children medically attended in an emergency department (ED), we performed a prospective cohort study to evaluate prehospital and ED management of children with recurrent anaphylaxis and to assess factors associated with recurrent anaphylaxis. STUDY DESIGN: As part of the Cross-Canada Anaphylaxis Registry, parents of children with anaphylaxis identified prospectively in 3 EDs and through an emergency medical response service were contacted annually after presentation and queried on subsequent reactions. Cox regression analysis determined factors associated with recurrence. RESULTS: Among 292 children who were registered as having had medical attended anaphylaxis, 68.5% completed annual follow-up questionnaires. Forty-seven patients experienced 65 episodes of anaphylaxis during 369 patient-years of follow-up. Food was the trigger in 84.6% of cases, and epinephrine was used in 66.2%. In 50.8%, epinephrine was used outside the health care facility, and 81.7% were brought to a health care facility for treatment. Asthma, reaction triggered by food, and use of epinephrine during the index episode increased the odds of recurrent reaction. Patients whose initial reaction was triggered by peanut were less likely to have a recurrent reaction. CONCLUSIONS: We report a yearly anaphylaxis recurrence rate of 17.6% in children. There is substantial underuse of epinephrine in cases of anaphylaxis. Educational programs that promote effective avoidance strategies and prompt use of epinephrine are required.

Biomass Burning as a Source of Ambient Fine Particulate Air Pollution and Acute Myocardial Infarction.

BACKGROUND: Biomass burning is an important source of ambient fine particulate air pollution (PM2.5) in many regions of the world. METHODS: We conducted a time-stratified case-crossover study of ambient PM2.5 and hospital admissions for myocardial infarction (MI) in three regions of British Columbia, Canada. Daily hospital admission data were collected between 2008 and 2015 and PM2.5 data were collected from fixed site monitors. We used conditional logistic regression models to estimate odds ratios (ORs) describing the association between PM2.5 and the risk of hospital admission for MI. We used stratified analyses to evaluate effect modification by biomass burning as a source of ambient PM2.5 using the ratio of levoglucosan/PM2.5 mass concentrations. RESULTS: Each 5 µg/m increase in 3-day mean PM2.5 was associated with an increased risk of MI among elderly subjects (≥65 years; OR = 1.06, 95% CI: 1.03, 1.08); risk was not increased among younger subjects. Among the elderly, the strongest association occurred during colder periods (<6.44°C); when we stratified analyses by tertiles of monthly mean biomass contributions to PM2.5 during cold periods, ORs of 1.19 (95% CI: 1.04, 1.36), 1.08 (95% CI: 1.06, 1.09), and 1.04 (95% CI: 1.03, 1.06) were observed in the upper, middle, and lower tertiles (Ptrend = 0.003), respectively. CONCLUSION: Short-term changes in ambient PM2.5 were associated with an increased risk of MI among elderly subjects. During cold periods, increased biomass burning contributions to PM2.5 may modify its association with MI.

Defining optimal activated clotting time for percutaneous coronary intervention: A systematic review and Bayesian meta-regression.

BACKGROUND: Guidelines recommend routine monitoring of unfractionated heparin (UFH) with activated clotting time (ACT) during percutaneous coronary intervention (PCI). However, the optimal ACT for patients undergoing PCI is unclear. METHODS: We sought to determine the association of peak ACT during PCI with 30-day major adverse cardiac events (MACE; all-cause mortality, myocardial infarction, and revascularization) and bleeding events. We searched the Cochrane Central Register of Controlled Trials, EMBASE, and Medline for randomized controlled trials (RCTs) evaluating UFH through May 2015. Only patients randomized to UFH alone or to UFH with a glycoprotein IIb/IIIa inhibitor (GPI) were analyzed using Bayesian meta-regression. RESULTS: Among 13 included RCTs (n = 17455), eight (n = 5521) included study arms of UFH alone and 12 (n = 11934) included arms of UFH with a GPI. Peak ACT ranged from 201 to 460 sec for UFH alone and 248-317 sec for UFH with a GPI. With UFH alone, the probability of MACE was 7.0% (95% credible interval [CrI] 1.5, 31.5) for a peak ACT of 200 sec and 5.8% (95% CrI 2.6, 12.0) for 300 sec. Among UFH with a GPI, the probability of MACE was 2.8% (95% CrI 0.8, 6.8) for a peak ACT of 200 sec and 7.2% (95% CrI 5.4, 9.7) for 300 sec. CONCLUSION: Among individual RCTs, the probability of MACE and major bleeding events associated with low versus high values of peak ACT is inconsistent. Our meta-regression results are inconclusive, emphasizing the need for RCTs comparing low versus high doses of UFH. © 2016 Wiley Periodicals, Inc.

Physician step prescription and monitoring to improve ARTERial health (SMARTER): A randomized controlled trial in patients with type 2 diabetes and hypertension.

AIMS: There are few proven strategies to enhance physical activity and cardiometabolic profiles in patients with type 2 diabetes and hypertension. We examined the effects of physician-delivered step count prescriptions and monitoring. METHODS: Participants randomized to the active arm were provided with pedometers and they recorded step counts. Over a 1-year period, their physicians reviewed their records and provided a written step count prescription at each clinic visit. The overall goal was a 3000 steps/day increase over 1 year (individualized rate of increase). Control arm participants were advised to engage in physical activity 30 to 60 min/day. We evaluated effects on step counts, carotid femoral pulse wave velocity (cfPWV, primary) and other cardiometabolic indicators including haemoglobin A1c in diabetes (henceforth abbreviated as A1c) and Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) in participants not receiving insulin therapy. RESULTS: A total of 79% completed final evaluations (275/347; mean age, 60 years; SD, 11). Over 66% of participants had type 2 diabetes and over 90% had hypertension. There was a net 20% increase in steps/day in active vs control arm participants (1190; 95% CI, 550-1840). Changes in cfPWV were inconclusive; active vs control arm participants with type 2 diabetes experienced a decrease in A1c (-0.38%; 95% CI, -0.69 to -0.06). HOMA-IR also declined in the active arm vs the control arm (ie, assessed in all participants not treated with insulin; -0.96; 95% CI, -1.72 to -0.21). CONCLUSIONS: A simple physician-delivered step count prescription strategy incorporated into routine clinical practice led to a net 20% increase in step counts; however, this was below the 3000 steps/day targeted increment. While conclusive effects on cfPWV were not observed, there were improvements in both A1c and insulin sensitivity. Future studies will evaluate an amplified intervention to increase impact.

Understanding the effects of conditional dependence in research studies involving imperfect diagnostic tests.

When two imperfect diagnostic tests are carried out on the same subject, their results may be correlated even after conditioning on the true disease status. While past work has focused on the consequences of ignoring conditional dependence, the degree to which conditional dependence can be induced has not been systematically studied. We examine this issue in detail by introducing a hypothetical missing covariate that affects the sensitivities of two imperfect dichotomous tests. We consider four forms for this covariate, normal, uniform, dichotomous and trichotomous. In the case of a dichotomous covariate, we derive an expression showing that the conditional covariance is a function of the product of the changes in test sensitivities (or specificities) between the subgroups defined by the covariate. The maximum possible covariance is induced by a dichotomous covariate with a very strong effect on both tests. Through simulations, we evaluate the extent to which fitting a latent class model ignoring each type of covariate but including a general covariance term can adjust for the correlation induced by the covariate. We compare the results to when the conditional dependence is ignored. We find that the bias because of ignoring conditional dependence is generally small even for moderate covariate effects, and when bias is present, a model including a covariance term works well. We illustrate our methods by analyzing data from a childhood tuberculosis study. Copyright © 2016 John Wiley & Sons, Ltd.

Modeling conditional dependence among multiple diagnostic tests.

When multiple imperfect dichotomous diagnostic tests are applied to an individual, it is possible that some or all of their results remain dependent even after conditioning on the true disease status. The estimates could be biased if this conditional dependence is ignored when using the test results to infer about the prevalence of a disease or the accuracies of the diagnostic tests. However, statistical methods correcting for this bias by modelling higher-order conditional dependence terms between multiple diagnostic tests are not well addressed in the literature. This paper extends a Bayesian fixed effects model for 2 diagnostic tests with pairwise correlation to cases with 3 or more diagnostic tests with higher order correlations. Simulation results show that the proposed fixed effects model works well both in the case when the tests are highly correlated and in the case when the tests are truly conditionally independent, provided adequate external information is available in the form of fixed constraints or prior distributions. A data set on the diagnosis of childhood pulmonary tuberculosis is used to illustrate the proposed model.

Industrial air emissions, and proximity to major industrial emitters, are associated with anti-citrullinated protein antibodies.

OBJECTIVE: To determine the association of anti-citrullinated antibodies (ACPA) with the ambient air pollutants fine particulate matter (PM2.5) and sulfur dioxide (SO2). METHODS: The CARTaGENE first-wave cohort includes 20,000 general population subjects from Quebec (Canada). On a sample of unselected 1586 subjects, we determined serum, ACPA and performed multivariable logistic regression, for the outcome of positive ACPA, assessing for independent effects of our air pollution variables, adjusting for age, sex, smoking, and French Canadian origin. Two models assessed distance to main industrial emitters of PM2.5, and of SO2, and two models assessed tons of SO2 and of PM2.5 annual emissions. We also assessed associations with PM2.5 regional ambient concentrations estimated with satellite imagery. RESULTS: Adjusted analyses suggested a positive association between annual industrial PM2.5 and SO2 emissions and the presence of ACPA antibodies (OR: 1.02, 95%CI 1.00-1.04 per 10t of PM2.5 and 100t of SO2). The data were also consistent with a negative association between the presence of ACPA, and distance to a major industrial emitter of both PM2.5 and SO2. We found no association with PM2.5 estimates of ambient levels. CONCLUSIONS: These analyses suggest that exposure to industrial emissions of air pollutants is related to ACPA positivity.

Tryptase levels in children presenting with anaphylaxis: Temporal trends and associated factors.

BACKGROUND: The diagnosis of anaphylaxis currently relies on suggestive clinical history after exposure to a potential triggering factor because no reliable diagnostic marker is available to confirm the diagnosis. OBJECTIVES: We aimed to evaluate tryptase levels in children with anaphylaxis and to examine predictors of elevated tryptase level (defined as ≥11.4 µg/L during reaction and for those with a baseline level, defined as a reaction level of at least 2 ng/mL + 1.2 × [postreaction tryptase level]). METHODS: Children presenting with anaphylaxis to the Montreal Children's Hospital were recruited over a 4-year period. Symptoms, triggers, and management of anaphylaxis were documented. Levels during the reaction and approximately 9 months after the reaction were compared on the basis of paired means using the t distribution. Multivariate linear and logistic regressions were used to evaluate the association between tryptase levels and risk factors. RESULTS: Over a 4-year period, 203 children had serum tryptase levels measured. Among these, 39 children (19.2%; 95% CI, 14.1%-25.4%) had elevated levels. Only severe reactions were associated with reaction levels of 11.4 µg/L or more (odds ratio, 6.5; 95% CI, 2.2-19.0). Milk-induced anaphylaxis and severe reactions were more likely associated with increased tryptase levels (beta-adjusted, 4.0; 95% CI, 0.95-7.0, and 7.5; 95% CI, 4.8-10.3, respectively). Reaction levels exceeding the threshold level of 2 ng/mL + 1.2 × (postreaction tryptase level) detected most of the anaphylactic reactions, particularly if baseline levels were taken within 2 months of the reaction. CONCLUSIONS: Tryptase levels are particularly useful for the diagnosis of severe and/or milk-induced anaphylaxis. Assessing the difference between reaction and postreaction tryptase levels may improve diagnostic sensitivity.

Diagnostic Test Accuracy in Childhood Pulmonary Tuberculosis: A Bayesian Latent Class Analysis.

Evaluation of tests for the diagnosis of childhood pulmonary tuberculosis (CPTB) is complicated by the absence of an accurate reference test. We present a Bayesian latent class analysis in which we evaluated the accuracy of 5 diagnostic tests for CPTB. We used data from a study of 749 hospitalized South African children suspected to have CPTB from 2009 to 2014. The following tests were used: mycobacterial culture, smear microscopy, Xpert MTB/RIF (Cepheid Inc.), tuberculin skin test (TST), and chest radiography. We estimated the prevalence of CPTB to be 27% (95% credible interval (CrI): 21, 35). The sensitivities of culture, Xpert, and smear microscopy were estimated to be 60% (95% CrI: 46, 76), 49% (95% CrI: 38, 62), and 22% (95% CrI: 16, 30), respectively; specificities of these tests were estimated in accordance with prior information and were close to 100%. Chest radiography was estimated to have a sensitivity of 64% (95% CrI: 55, 73) and a specificity of 78% (95% CrI: 73, 83). Sensitivity of the TST was estimated to be 75% (95% CrI: 61, 84), and it decreased substantially among children who were malnourished and infected with human immunodeficiency virus (56%). The specificity of the TST was 69% (95% CrI: 63%, 76%). Furthermore, it was estimated that 46% (95% CrI: 42, 49) of CPTB-negative cases and 93% (95% CrI: 82; 98) of CPTB-positive cases received antituberculosis treatment, which indicates substantial overtreatment and limited undertreatment.

Cessation treatment adherence and smoking abstinence in patients after acute myocardial infarction.

BACKGROUND: Previous trials examining the use of bupropion for smoking cessation therapy after myocardial infarction (MI) have been inconclusive. To understand better the observed lack of effectiveness of bupropion in this population, we examined abstinence rates by level of adherence across treatment groups. METHODS: We used data from a randomized, double-blind, placebo-controlled trial of bupropion in smokers (n = 388) hospitalized with MI to study the association of interest. Patients were classified as being fully adherent if they reported taking 2 pills/d; partially adherent if they reported 0, 1, and/or 2 pills/d; and nonadherent if they reported 0 and/or 1 pill/d throughout the 9-week treatment period. Abstinence was assessed by 7-day biochemically validated self-report at 4 and 9 weeks and 6 and 12 months. RESULTS: A total of 156 patients were fully adherent to the study medication (66 bupropion and 90 placebo), 149 were partially adherent (76 and 73, respectively), and 83 were nonadherent (46 and 37, respectively). Regardless of treatment group, patients who were fully or partially adherent reported greater abstinence than did nonadherent patients. Among partially adherent patients, bupropion conferred an important benefit at 12 months (% difference 13.3, 95% CI 1.3-25.3). At 12 months, patients who were fully adherent were more likely to be abstinent compared with those who were nonadherent (adjusted odds ratio 7.6, 95% CI 3.2-17.6). CONCLUSIONS: Adherence to study medication, regardless of assigned treatment, is associated with a substantial increase in abstinence. Patients who are motivated to quit smoking should be targeted for smoking cessation treatment after MI.

Fine particulate air pollution and systemic autoimmune rheumatic disease in two Canadian provinces.

OBJECTIVE: To estimate the degree to which fine particulate (PM2.5) air pollution is associated with systemic autoimmune rheumatic diseases (SARDs). METHODS: We used population-based administrative data from Alberta (1993-2007) and Quebec (1989-2011). SARD algorithms included ≥2 physician billing codes, or ≥1 rheumatology billing code, or ≥1 hospitalization diagnostic code (for systemic lupus, Sjogren's Syndrome, scleroderma, polymyositis, dermatomyositis, or undifferentiated connective tissue disease). Bayesian hierarchical latent class regression models estimated the probability that any given resident was a SARD case, based on the algorithms. Mean 2001-2006 residential ambient PM2.5 levels were assigned using satellite-derived data for dissemination area regions in Alberta and CLSC regions in Quebec. The sum of individual level probabilities provided the estimated total cases per region in each province, according to age, sex, urban-versus-rural residence, income, and PM2.5 levels. In Alberta, we ran separate models for First-Nations (FN) and non-First Nations subgroups. Bayesian logistic regression modeling generated odds ratio (OR) estimates for being a SARD case, accounting concurrently for demographics, as well as an interaction term between age and sex. RESULTS: Our data suggested that the probability of being a SARD case was higher among females versus males and for residents aged >45 versus younger, with the highest ORs for older females. Independently, the odds of being a SARDs case increased with PM2.5 levels in both provinces. CONCLUSION: Our data suggest that PM2.5 exposure may be associated with an increased risk of SARDs.

Health-selective migration among patients with rheumatoid arthritis in Québec: a cohort study using administrative data.

Little is known about how rheumatoid arthritis (RA) affects an individual's ability to relocate. The current literature suggests the relationship between health and migration is often disease-specific. We sought to estimate the impact of RA diagnosis on migration within a Canadian province, comparing migration rates in residents before and after RA diagnosis. We identified a cohort of 81,181 individuals diagnosed with RA between 1998 and 2009 using Québec administrative databases. A migration was defined as a change in the first three characters of the postal code. We categorized migrations as urban or rural depending upon an individual's origin and destination. We estimated the association between RA diagnosis and migration by fitting marginal models using a generalized estimating equations approach, adjusting for age, sex, and population level socioeconomic status indicators. The vast majority of moves after RA diagnosis were within urban areas. RA diagnosis was associated with increased migration except for people around age 50 moving within urban areas. Although RA was associated with increased inter-urban migration in many demographic groups, the net result did not translate to higher rates of rural-to-urban migration after RA diagnosis. Our results suggest fairly complex associations between RA diagnosis and migration. Both age and location (urban or rural) modify this effect. Overall, we did not see a greater movement from rural-to-urban areas after RA diagnosis. This is of interest for studies of regional environmental effects on chronic disease patterns.

Neighbourhood walkability and home neighbourhood-based physical activity: an observational study of adults with type 2 diabetes.

BACKGROUND: Converging international evidence suggests that diabetes incidence is lower among adults living in more walkable neighbourhoods. The association between walkability and physical activity (PA), the presumed mediator of this relationship, has not been carefully examined in adults with type 2 diabetes. We investigated the associations of walkability with total PA occurring within home neighbourhoods and overall PA, irrespective of location. METHODS: Participants (n = 97; 59.5 ± 10.5 years) were recruited through clinics in Montreal (QC, Canada) and wore a GPS-accelerometer device for 7 days. Total PA was expressed as the total Vector of the Dynamic Body Acceleration. PA location was determined using a Global Positioning System (GPS) device (SIRF IV chip). Walkability (street connectivity, land use mix, population density) was assessed using Geographical Information Systems software. The cross-sectional associations between walkability and location-based PA were estimated using robust linear regressions adjusted for age, body mass index, sex, university education, season, car access, residential self-selection, and wear-time. RESULTS: A one standard deviation (SD) increment in walkability was associated with 10.4 % of a SD increment in neighbourhood-based PA (95 % confidence interval (CI) 1.2, 19.7) - equivalent to 165 more steps/day (95 % 19, 312). Car access emerged as an important predictor of neighbourhood-based PA (Not having car access: 38.6 % of a SD increment in neighbourhood-based PA, 95 % CI 17.9, 59.3). Neither walkability nor car access were conclusively associated with overall PA. CONCLUSIONS: Higher neighbourhood walkability is associated with higher home neighbourhood-based PA but not with higher overall PA. Other factors will need to be leveraged to facilitate meaningful increases in overall PA among adults with type 2 diabetes.

MDS research criteria for prodromal Parkinson's disease.

This article describes research criteria and probability methodology for the diagnosis of prodromal PD. Prodromal disease refers to the stage wherein early symptoms or signs of PD neurodegeneration are present, but classic clinical diagnosis based on fully evolved motor parkinsonism is not yet possible. Given the lack of clear neuroprotective/disease-modifying therapy for prodromal PD, these criteria were developed for research purposes only. The criteria are based upon the likelihood of prodromal disease being present with probable prodromal PD defined as ≥80% certainty. Certainty estimates rely upon calculation of an individual's risk of having prodromal PD, using a Bayesian naïve classifier. In this methodology, a previous probability of prodromal disease is delineated based upon age. Then, the probability of prodromal PD is calculated by adding diagnostic information, expressed as likelihood ratios. This diagnostic information combines estimates of background risk (from environmental risk factors and genetic findings) and results of diagnostic marker testing. In order to be included, diagnostic markers had to have prospective evidence documenting ability to predict clinical PD. They include motor and nonmotor clinical symptoms, clinical signs, and ancillary diagnostic tests. These criteria represent a first step in the formal delineation of early stages of PD and will require constant updating as more information becomes available.