Status report -- Childhood overweight and obesity in Canada: an integrative assessment. / Rapport d'étape -- Embonpoint et obésité chez les enfants au Canada : une évaluation globale.

INTRODUCTION: Obesity is a complex risk factor for chronic disease that is associated with a number of socioecological determinants. In this status report, we provide an overview of the socioecological framework that is now guiding our ongoing surveillance efforts in the area of childhood overweight and obesity. This framework considers individual risk and protective factors (sociodemographic, lifestyle, psychosocial and early-life) through the lens of the life stage, levels of influence and environments in which these factors play a role. METHODS: Using data from the Canadian Community Health Survey and the Canadian Health Measures Survey, univariate and bivariate analyses were used to report on behavioural, psychosocial, and early life factors associated with excess weight among Canadian children. RESULTS: Estimates of early-life (e.g. breastfeeding), behavioural (e.g. physical activity), and psychosocial factors (e.g. sense of community) are presented as they relate to age group, sex, income adequacy and weight status. CONCLUSION: Building upon our recent reporting on trends in and sociodemographic factors associated with childhood obesity in Canada, this work illustrates the remaining risk and protective factors shown in our surveillance framework. This analysis supports the shift towards a holistic appraisal of determinants related to healthy weights.

INTRODUCTION: L'obésité est un facteur de risque complexe des maladies chroniques associé à un certain nombre de déterminants socioécologiques. Ce rapport d'étape fournit un aperçu du cadre socioécologique qui guide actuellement nos efforts de suivi de l'embonpoint et de l'obésité chez les enfants. Ce cadre intègre différents facteurs de risque et de protection (facteurs sociodémographiques, liés au mode de vie, psychosociaux et en début de vie) et tient compte de l'étape de vie, des niveaux d'influence et de l'environnement au sein desquels ces facteurs jouent un rôle. MÉTHODOLOGIE: Nous avons effectué des analyses univariées et bivariées fondées sur les données de l'Enquête sur la santé dans les collectivités canadiennes et de l'Enquête canadienne sur les mesures de la santé pour rendre compte des facteurs comportementaux, des facteurs psychosociaux et des facteurs en début de vie associés à un surplus de poids chez les enfants canadiens. RÉSULTATS: Les estimations liées aux facteurs en début de vie (p. ex. l'allaitement), aux facteurs comportementaux (p. ex. l'activité physique) et aux facteurs psychosociaux (p. ex. le sentiment d'appartenance à la collectivité) sont présentées en fonction du groupe d'âge, du sexe, de la suffisance du revenu et du poids. CONCLUSION: Cette étude, qui s'appuie sur notre publication récente sur les tendances en matière d'obésité chez les enfants au Canada et les facteurs sociodémographiques qui y sont associés, présente les facteurs de risque et de protection intégrés à notre cadre de surveillance. D'après notre analyse, une évaluation plus globale des déterminants associés au maintien d'un poids santé est nécessaire.

Canadian Public Health Laboratory Network laboratory guidelines for the use of direct tests to detect syphilis in Canada.

Treponema pallidum subsp. pallidum and/or its nucleic acid can be detected by various methods such as microscopy, rabbit infectivity test or polymerase chain reaction (PCR) tests. The rabbit infectivity test for T. pallidum, although very sensitive, has been discontinued from most laboratories due to ethical issues related to the need for animal inoculation with live T. pallidum, the technically demanding procedure and long turnaround time for results, thus making it impractical for routine diagnostic use. Dark-field and phase-contrast microscopy are still useful at clinic- or hospital-based laboratories for near-bedside detection of T. pallidum in genital, skin or mucous lesions although their availability is decreasing. The lack of reliable and specific anti-T. pallidum antibodies and its inferior sensitivity to PCR may explain why the direct fluorescent antibody test for T. pallidum is not widely available for clinical use. Immunohistochemical staining for T. pallidum also depends on the availability of specific antibodies, and the method is only applicable for histopathological examination of biopsy and autopsy specimens necessitating an invasive specimen collection approach. With recent advances in molecular diagnostics, PCR is considered to be the most reliable, versatile and practical for laboratories to implement. In addition to being an objective and sensitive test for direct detection of Treponema pallidum subsp. pallidum DNA in skin and mucous membrane lesions, the resulting PCR amplicons from selected gene targets can be further characterized for antimicrobial (macrolide) susceptibility testing, strain typing and identification of T. pallidum subspecies.

Diverses méthodes, telles que la microscopie, le test d'infectivité du lapin et la réaction en chaîne de la polymérase (PCR), permettent de déceler le Treponema pallidum sous-espèce pallidum et/ou son acide nucléique. Même s'il est très sensible, le test d'infectivité du lapin n'est plus utilisé dans la plupart des laboratoires pour déceler le T. pallidum. En effet, des raisons éthiques liées à la nécessité d'inoculer le T. pallidum vivant à l'animal, l'intervention exigeante sur le plan technique et la longue attente avant d'obtenir les résultats le rendent peu pratique pour un usage diagnostique régulier. Dans les laboratoires des cliniques ou des hôpitaux, la microscopie à fond noir et la microscopie à contraste de phase contribuent toujours à déceler le T. pallidum dans les lésions génitales, cutanées ou muqueuses près du chevet du patient, mais elles sont de moins en moins offertes. Le test d'immunofluorescence directe est peu utilisé pour diagnostiquer le T. pallidum en milieu clinique, peut-être en raison de l'absence d'anticorps anti-T. pallidum fiables et spécifiques et de sa faible sensibilité par rapport au PCR. La coloration immunohistochimique du T. pallidum dépend également de la présence d'anticorps spécifiques, et la méthode est applicable seulement à l'examen histopathologique des prélèvements invasifs de biopsies et d'autopsies. Étant donné les progrès récents des diagnostics moléculaires, la PCR est considérée comme le test le plus fiable, le plus polyvalent et le plus pratique à utiliser en laboratoire. Le PCR est objectif et spécifique pour la détection directe de l'ADN du Treponema pallidum sous-espèce pallidum dans les lésions de la peau et des muqueuses ; ses amplicons provenant de cibles géniques précises peuvent être caractérisés en vue de tests de susceptibilité antimicrobienne (aux macrolides), du typage des souches et du dépistage des sousespèces de T. pallidum.

A Protocol for the secure linking of registries for HPV surveillance.

INTRODUCTION: In order to monitor the effectiveness of HPV vaccination in Canada the linkage of multiple data registries may be required. These registries may not always be managed by the same organization and, furthermore, privacy legislation or practices may restrict any data linkages of records that can actually be done among registries. The objective of this study was to develop a secure protocol for linking data from different registries and to allow on-going monitoring of HPV vaccine effectiveness. METHODS: A secure linking protocol, using commutative hash functions and secure multi-party computation techniques was developed. This protocol allows for the exact matching of records among registries and the computation of statistics on the linked data while meeting five practical requirements to ensure patient confidentiality and privacy. The statistics considered were: odds ratio and its confidence interval, chi-square test, and relative risk and its confidence interval. Additional statistics on contingency tables, such as other measures of association, can be added using the same principles presented. The computation time performance of this protocol was evaluated. RESULTS: The protocol has acceptable computation time and scales linearly with the size of the data set and the size of the contingency table. The worse case computation time for up to 100,000 patients returned by each query and a 16 cell contingency table is less than 4 hours for basic statistics, and the best case is under 3 hours. DISCUSSION: A computationally practical protocol for the secure linking of data from multiple registries has been demonstrated in the context of HPV vaccine initiative impact assessment. The basic protocol can be generalized to the surveillance of other conditions, diseases, or vaccination programs.

Acceptability of human papillomavirus vaccination and sexual experience prior to disclosure to health care providers among men who have sex with men in Vancouver, Canada: implications for targeted vaccination programs.

BACKGROUND: Men who have sex with men (MSM) may benefit from human papillomavirus (HPV) vaccine due to increased risk for HPV infection and related disease. We assessed HPV vaccine acceptability and sexual experience prior to disclosure to Health Care Providers (HCP) to understand implications of targeted vaccination strategies for MSM. METHODS: From July 2008 to February 2009, 1169 MSM aged ≥19 years were recruited at community venues in Vancouver. We assessed key variables from a self-administered questionnaire and independent predictors of HPV vaccine acceptability using multivariate logistic regression. RESULTS: Of 1041 respondents, 697 (67.0%) were willing to receive HPV vaccine and 71.3% had heard of HPV. Significant multivariate predictors of higher vaccine acceptability were (adjusted odds ratio [95% CI]): previous diagnosis of genital warts (1.7 [1.1, 2.6]), disclosure of sexual behavior to HCP (1.6 [1.1, 2.3]), annual income at least $20,000 (1.5 [1.1, 2.1]), previous hepatitis A or B vaccination (1.4 [1.0, 2.0]), and no recent recreational drug use (1.4 [1.0, 2.0]). Most MSM (78.7%) had disclosed sexual behavior to HCP and median time from first sexual contact with males to disclosure was 6.0 years (IQR 2-14 years); for men ≤26 years these were 72.0% and 3.0 years (IQR 1-8 years) respectively. CONCLUSIONS: Willingness to receive HPV vaccine was substantial among MSM in Vancouver; however, acceptability varied by demographics, risk, and health history. HPV vaccine programs delivered by HCP would offer limited benefit given the duration of time from sexual debut to disclosure to HCP.

Estimation of the burden of disease and costs of genital Chlamydia trachomatis infection in Canada.

BACKGROUND: Rates of Chlamydia trachomatis (CT) infection in Canada have been increasing since the mid-1990s. We sought to estimate the burden of CT in this population. METHODS: We developed an age- and sex-structured mathematical model parameterized to reproduce trends in CT prevalence between 1991 and 2009 in the Canadian population aged 10 to 39 years. Costs were identified, measured, and valued using a modified societal perspective and converted to year 2009 Canadian dollars. Cost-effectiveness of the implemented policy of enhanced screening for asymptomatic infections was estimated by comparison with model-projected trends in the absence of increased screening. Main outcome measures were current net cost and burden of illness attributable to CT infection, and incremental cost-effectiveness ratios. RESULTS: Under base case model assumptions, there was a trend of increasing detection of CT cases (due to increases in screening), despite an underlying stabilization of actual CT infections. Average estimated costs associated with CT infection over this period were $51.4 million per year. Costs of screening and treatment of asymptomatic infections as a proportion of total CT costs were estimated to have increased over time, whereas costs of long-term sequelae associated with untreated infections declined over the same period. Compared with no change in screening, enhanced screening was estimated to be highly cost-effective, with an incremental cost-effectiveness ratio of $2910 per quality-adjusted life year. CONCLUSIONS: Despite increases in screening, the economic burden of CT in Canada remains high. Further investigation of trends in chlamydia-associated complications is required to better understand the impact of screening on incidence.

Clinical utility of commercial enzyme immunoassays during the inaugural season of West Nile virus activity, Alberta, Canada.

West Nile virus (WNV) has spread rapidly across North America, creating a need for rapid and accurate laboratory diagnosis on a large scale. Immunoglobulin M (IgM) capture enzyme immunoassays (EIA) became commercially available in the summer of 2003, but limited data are available on their clinical performance. Consolidated human WNV diagnostic testing for the province of Alberta, Canada, at the public health laboratory permitted a large-scale evaluation of the assays, covering a wide clinical spectrum. Two thousand nine hundred sixty-nine sera were tested, from 2,553 Alberta residents, and 266 cases were identified. Sensitivities of the Focus assay and first-generation Panbio IgM capture EIA were 79 and 80%, respectively. During the first week of illness only 53 to 58% of cases were positive, but sensitivity was 96 to 97% after day 8. Sensitivity for neurological cases was 92% overall. Specificity was high for the Focus kit at 98.9%, but only 82.9% for the first Panbio kit. A positive Focus WNV IgG result with a twofold rise in IgG index was a reliable indicator of acute flavivirus infection (67/67 WNV). Agreement between the IgG test and hemagglutinin inhibition titers in paired sera was at least 82%. Commercial IgM and IgG EIA proved useful for WNV diagnosis, provided follow-up sera were collected after 8 days of illness.

Mandatory reporting of HIV infection and opt-out prenatal screening for HIV infection: effect on testing rates.

BACKGROUND: Mandatory reporting of HIV infection to public health authorities, although now common, may deter people from undergoing testing. We examined HIV testing frequency in Alberta before and after mandatory reporting was implemented. We also examined the effect on testing rates among pregnant women when Alberta adopted an opt-out approach to prenatal HIV screening. METHODS: Using data from the Provincial Laboratory for Public Health, we determined the number of HIV tests done between Jan. 1, 1993, and Dec. 31, 2000, for males and females in Alberta. We used data from the Canadian Blood Services laboratories to obtain the number of tests conducted as part of the opt-out prenatal HIV testing program. Reporting of HIV infection became mandatory on May 1, 1998, and opt-out prenatal HIV testing was introduced on Sept. 1, 1998. RESULTS: Among males, the average annual percent increase in the number of HIV tests was 4.0% for the period before mandatory testing, as compared with 4.3% for the period after mandatory reporting was implemented; the difference in yearly trend was significant (p < 0.001). Among females, the average annual percent increase in the number of HIV tests was 9.2% for the period before mandatory reporting. In the month immediately following the adoption of opt-out prenatal HIV testing, the rate increased by 28%. Between 1999 and 2000, the average annual percent increase in the number of HIV tests among females was 1.4%. INTERPRETATION: The introduction of mandatory reporting of HIV infection did not appear to have a deterrent effect on rates of HIV testing. The implementation of an opt-out prenatal HIV testing policy resulted in a dramatic increase in the number of females being tested for HIV infection.