Combining respondent-driven sampling with a community-based participatory action study of people who smoke drugs in two cities in British Columbia, Canada.

BACKGROUND: The smoking of illicit drugs presents a serious social and economic burden in Canada. People who smoke drugs (PWSD) are at increased risk of contracting multiple infections through risky drug practices. Peer-led harm reduction activities, and the resulting social networks that form around them, can potentially minimize the dangers associated with the smoking illicit drugs. GOAL: The goals of this study were to pilot test the combined approaches of respondent driven sampling with community based participatory action research in these settings and compare the attributes and social networks of PWSD in two British Columbia cities with different harm reduction programs. METHODS: Using community-based participatory action research (CBPAR) and respondent-driven sampling (RDS), individuals with lived drug experiences were employed from communities in Abbotsford and Vancouver as peer researchers to interview ten contacts from their social networks. Contacts completed a questionnaire about their harm reduction behaviours and interactions. RESULTS: We found that PWSD residing in Abbotsford were more likely to report engaging in harm-promoting behaviours, such as sharing, reusing, or borrowing crack pipes. However, PWSD in the Downtown East side Community of Vancouver were more likely to report engaging in harm-reducing activities, such as being trained in naloxone use and CPR. We found no differences in network sizes between the two communities, despite the population differences and harm reduction programs CONCLUSION: The high participation rates and interactions between researchers, and peer researchers enriched the study implementation and successfully informed our results. The fact that there were no differences in network size suggests that people have similar support in Vancouver as in Abbotsford, and that drug use practices differ mainly due to availability of harm reduction programming and resources.

Social network support and harm reduction activities in a peer researcher-led pilot study, British Columbia, Canada.

BACKGROUND: People who smoke drugs (PWSD) are at high risk of both infectious disease and overdose. Harm reduction activities organized by their peers in the community can reduce risk by providing education, safer smoking supplies, and facilitate access to other services. Peers also provide a network of people who provide social support to PWSD which may reinforce harm reducing behaviors. We evaluated the numbers of supportive network members and the relationships between received support and participants' harm-reducing activities. METHODS: Initial peer-researchers with past or current lived drug use experience were employed from communities in Abbotsford and Vancouver to interview ten friends from their social networks who use illegal drugs mainly through smoking. Contacts completed a questionnaire about people in their own harm reduction networks and their relationships with each other. We categorized social support into informational, emotional, and tangible aspects, and harm reduction into being trained in the use of, or carrying naloxone, assisting peers with overdoses, using brass screens to smoke, obtaining pipes from service organizations and being trained in CPR. RESULTS: Fifteen initial peer researchers interviewed 149 participants who provided information on up to 10 people who were friends or contacts and the relationships between them. People who smoked drugs in public were 1.46 (95% CI, 1.13-1.78) more likely to assist others with possible overdoses if they received tangible support; women who received tangible support were 1.24 (95% CI; 1.02-1.45) more likely to carry and be trained in the use of naloxone. There was no relationship between number of supportive network members and harm reduction behaviors. CONCLUSIONS: In this pilot study, PWSD who received tangible support were more likely to assist peers in possible overdoses and be trained in the use of and/or carry naloxone, than those who did not receive tangible support. Future work on the social relationships of PWSD may prove valuable in the search for credible and effective interventions.

Factors associated with human West Nile virus infection in Ontario: a generalized linear mixed modelling approach.

BACKGROUND: West Nile Virus (WNV) is a mosquito-borne pathogen that has become established in North America. Risk for human infection varies geographically in accordance with climate and population factors. Though often asymptomatic, human WNV infection can cause febrile illness or, rarely, neurologic disease. WNV has become a public health concern in Canada since its introduction in 2001. METHODS: To identify predictors of human WNV incidence at the public health unit (PHU) level in Ontario, Canada, we combined data on environmental and population characteristics of PHUs with historical mosquito and human surveillance records from 2002 to 2013. We examined the associations between annual WNV incidence and monthly climate indices (e.g. minimum and maximum temperature, average precipitation), land cover (e.g. deciduous forest, water), population structure (e.g. age and sex composition) and the annual percentage of WNV-positive mosquito pools from 2002 to 2013. We then developed a generalized linear mixed model with a Poisson distribution adjusting for spatial autocorrelation and repeat measures. Further to this, to examine potential 'early season' predictors of WNV incidence in a given year, we developed a model based on winter and spring monthly climate indices. RESULTS: Several climate indices, including mean minimum temperature (o C) in February (RR = 1.58, CI: [1.42, 1.75]), and the annual percentage of WNV-positive mosquito pools (RR = 1.07, CI: [1.04, 1.11]) were significantly associated with human WNV incidence at the PHU level. Higher winter minimum temperatures were also strongly associated with annual WNV incidence in the 'early season' model (e.g. February minimum temperature (RR = 1.91, CI: [1.73, 2.12]). CONCLUSIONS: Our study demonstrates that early season temperature and precipitation indices, in addition to the percentage of WNV-positive mosquito pools in a given area, may assist in predicting the likelihood of a more severe human WNV season in southern regions of Ontario, where WNV epidemics occur sporadically.

Can Social Network Analysis Help Address the High Rates of Bacterial Sexually Transmitted Infections in Saskatchewan?

BACKGROUND: Saskatchewan has one of the highest rates of gonorrhea among the Canadian provinces-more than double the national rate. In light of these high rates, and the growing threat of untreatable infections, improved understanding of gonorrhea transmission dynamics in the province and evaluation of the current system and tools for disease control are important. METHODS: We extracted data from a cross-sectional sample of laboratory-confirmed gonorrhea cases between 2003 and 2012 from the notifiable disease files of the Regina Qu'Appelle Health Region. The database was stratified by calendar year, and social network analysis combined with statistical modeling was used to identify associations between measures of connection within the network and the odds of repeat gonorrhea and risk of coinfection with chlamydia at the time of diagnosis. RESULTS: Networks were highly fragmented. Younger age and component size were positively associated with being coinfected with chlamydia. Being coinfected, reporting sex trade involvement, and component size were all positively associated with repeat infection. CONCLUSIONS: This is the first study to apply social network analysis to gonorrhea transmission in Saskatchewan and contributes important information about the relationship of network connections to gonorrhea/chlamydia coinfection and repeat gonorrhea. This study also suggests several areas for change of systems-related factors that could greatly increase understanding of social networks and enhance the potential for bacterial sexually transmitted infection control in Saskatchewan.

Female partner notification is a promising prevention strategy for controlling sexually transmitted infections in Shanghai: demographic and behavioral data from a Shanghai clinic.

We identified predictors of partner presentation and condom use among male gonorrhea patients in Shanghai, China. Stable relationships, intercourse in the preceding week, and longer duration of symptoms were associated with partner presentation. Men were more likely to use condoms with their spouse and if they were 35 years or younger.

Understanding recruitment: outcomes associated with alternate methods for seed selection in respondent driven sampling.

BACKGROUND: Respondent driven sampling (RDS) was designed for sampling "hidden" populations and intended as a means of generating unbiased population estimates. Its widespread use has been accompanied by increasing scrutiny as researchers attempt to understand the extent to which the population estimates produced by RDS are, in fact, generalizable to the actual population of interest. In this study we compare two different methods of seed selection to determine whether this may influence recruitment and RDS measures. METHODS: Two seed groups were established. One group was selected as per a standard RDS approach of study staff purposefully selecting a small number of individuals to initiate recruitment chains. The second group consisted of individuals self-presenting to study staff during the time of data collection. Recruitment was allowed to unfold from each group and RDS estimates were compared between the groups. A comparison of variables associated with HIV was also completed. RESULTS: Three analytic groups were used for the majority of the analyses-RDS recruits originating from study staff-selected seeds (n = 196); self-presenting seeds (n = 118); and recruits of self-presenting seeds (n = 264). Multinomial logistic regression demonstrated significant differences between the three groups across six of ten sociodemographic and risk behaviours examined. Examination of homophily values also revealed differences in recruitment from the two seed groups (e.g. in one arm of the study sex workers and solvent users tended not to recruit others like themselves, while the opposite was true in the second arm of the study). RDS estimates of population proportions were also different between the two recruitment arms; in some cases corresponding confidence intervals between the two recruitment arms did not overlap. Further differences were revealed when comparisons of HIV prevalence were carried out. CONCLUSIONS: RDS is a cost-effective tool for data collection, however, seed selection has the potential to influence which subgroups within a population are accessed. Our findings indicate that using multiple methods for seed selection may improve access to hidden populations. Our results further highlight the need for a greater understanding of RDS to ensure appropriate, accurate and representative estimates of a population can be obtained from an RDS sample.

Families' healthcare experiences for children with inherited metabolic diseases: protocol for a mixed methods cohort study.

INTRODUCTION: Children with inherited metabolic diseases (IMDs) often have complex and intensive healthcare needs and their families face challenges in receiving high-quality, family centred health services. Improvement in care requires complex interventions involving multiple components and stakeholders, customised to specific care contexts. This study aims to comprehensively understand the healthcare experiences of children with IMDs and their families across Canada. METHODS AND ANALYSIS: A two-stage explanatory sequential mixed methods design will be used. Stage 1: quantitative data on healthcare networks and encounter experiences will be collected from 100 parent/guardians through a care map, 2 baseline questionnaires and 17 weekly diaries over 5-7 months. Care networks will be analysed using social network analysis. Relationships between demographic or clinical variables and ratings of healthcare experiences across a range of family centred care dimensions will be analysed using generalised linear regression. Other quantitative data related to family experiences and healthcare experiences will be summarised descriptively. Ongoing analysis of quantitative data and purposive, maximum variation sampling will inform sample selection for stage 2: a subset of stage 1 participants will participate in one-on-one videoconference interviews to elaborate on the quantitative data regarding care networks and healthcare experiences. Interview data will be analysed thematically. Qualitative and quantitative data will be merged during analysis to arrive at an enhanced understanding of care experiences. Quantitative and qualitative data will be combined and presented narratively using a weaving approach (jointly on a theme-by-theme basis) and visually in a side-by-side joint display. ETHICS AND DISSEMINATION: The study protocol and procedures were approved by the Children's Hospital of Eastern Ontario's Research Ethics Board, the University of Ottawa Research Ethics Board and the research ethics boards of each participating study centre. Findings will be published in peer-reviewed journals and presented at scientific conferences.

A network view of the transmission of sexually transmitted infections in Manitoba, Canada.

Diez Roux has used the concept of complex systems to describe approaches for the incorporation of social factors into health research. These systems consist of heterogeneous interdependent units that also exhibit emergent properties. The latter embodies the concept that the interdependent units interact with and affect each other such that the resulting properties are not simple aggregates of the individual-level properties. This paper reviews research from Manitoba with a view towards conceptualising and phrasing the observed patterns within a complex system framework. A review of the temporal and spatial patterns seen within two large sexual network databases from Manitoba was undertaken and framed against the overlying patterns of sexually transmitted infection (STI) transmission within Manitoba. The review includes a summation of STI epidemiological patterns in Manitoba over a 5-year time frame, a comparison of temporal sexual network patterns, and an analysis of network patterns in relation to disparity in STI rates. Hypotheses are generated that focus on how individual-level behaviours and interactions create the observed complex system (network) patterns.

Increased risk for hepatitis C associated with solvent use among Canadian Aboriginal injection drug users.

BACKGROUND: Solvent abuse is a particularly serious issue affecting Aboriginal people. Here we examine the association between solvent use and socio-demographic variables, drug-related risk factors, and pathogen prevalence in Aboriginal injection drug users (IDU) in Manitoba, Canada. METHODS: Data originated from a cross-sectional survey of IDU from December 2003 to September 2004. Associations between solvent use and variables of interest were assessed by multiple logistic regression. RESULTS: A total of 266 Aboriginal IDU were included in the analysis of which 44 self-reported recent solvent use. Hepatitis C infection was 81% in solvent-users, compared to 55% in those reporting no solvent use. In multivariable models, solvent-users were younger and more likely to be infected with hepatitis C (AOR: 3.5; 95%CI: 1.3,14.7), to have shared needles in the last six months (AOR: 2.6; 95%CI:1.0,6.8), and to have injected talwin & Ritalin (AOR: 10.0; 95%CI: 3.8,26.3). INTERPRETATION: High hepatitis C prevalence, even after controlling for risky injection practices, suggests that solvent users may form closed networks of higher risk even amongst an already high-risk IDU population. Understanding the social-epidemiological context of initiation and maintenance of solvent use is necessary to address the inherent inequalities encountered by this subpopulation of substance users, and may inform prevention strategies for other marginalized populations.

The development of respondent-driven sampling (RDS) inference: A systematic review of the population mean and variance estimates.

BACKGROUND: Respondent-driven sampling (RDS) is a successful data collection method used in hard-to-reach populations, like those experiencing or at high risk of drug dependence. Since its introduction in 1997, identifying appropriate methods for estimating population means and sampling variances has been challenging and numerous approaches have been developed for making inferences about these quantities. To guide researchers and practitioners in deciding which approach to use, this article reviews the literature on these methodological developments. METHODS: A systematic review using four electronic databases was conducted in order to summarize the progress of RDS inference over the last 20 years and to provide insight to researchers on using the appropriate estimators in analyzing RDS data. Two independent reviewers selected the relevant abstracts and articles; thirty-two studies were included. The content of the studies was further categorized into developing and evaluating RDS mean and variance estimators. RESULTS: The population mean estimator RDSIEGO and the sampling variance estimators associated with tree boot strapping were identified as promising methods as the most robust population mean and variance estimate, respectively; as these estimators rely on a fewer assumptions. CONCLUSIONS: RDS holds substantial promise as a sampling method for understanding populations at high risk. The varied approaches to inference with RDS data each rely on different assumptions, but some require fewer assumptions than others and provide more robust and accurate inferences, when their corresponding assumptions are met.

Environmentally-induced parental or developmental conditioning influences coral offspring ecological performance.

The persistence of reef building corals is threatened by human-induced environmental change. Maintaining coral reefs into the future requires not only the survival of adults, but also the influx of recruits to promote genetic diversity and retain cover following adult mortality. Few studies examine the linkages among multiple life stages of corals, despite a growing knowledge of carryover effects in other systems. We provide a novel test of coral parental conditioning to ocean acidification (OA) and tracking of offspring for 6 months post-release to better understand parental or developmental priming impacts on the processes of offspring recruitment and growth. Coral planulation was tracked for 3 months following adult exposure to high pCO2 and offspring from the second month were reciprocally exposed to ambient and high pCO2 for an additional 6 months. Offspring of parents exposed to high pCO2 had greater settlement and survivorship immediately following release, retained survivorship benefits during 1 and 6 months of continued exposure, and further displayed growth benefits to at least 1 month post release. Enhanced performance of offspring from parents exposed to high conditions was maintained despite the survivorship in both treatments declining in continued exposure to OA. Conditioning of the adults while they brood their larvae, or developmental acclimation of the larvae inside the adult polyps, may provide a form of hormetic conditioning, or environmental priming that elicits stimulatory effects. Defining mechanisms of positive acclimatization, with potential implications for carry over effects, cross-generational plasticity, and multi-generational plasticity, is critical to better understanding ecological and evolutionary dynamics of corals under regimes of increasing environmental disturbance. Considering environmentally-induced parental or developmental legacies in ecological and evolutionary projections may better account for coral reef response to the chronic stress regimes characteristic of climate change.

Comparison of Neisseria gonorrhoeae multiantigen sequence typing and porB sequence analysis for identification of clusters of N. gonorrhoeae isolates.

porB DNA sequence analysis and Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST) methods were compared for their abilities to discriminate strains and to identify epidemiologically congruent pairs of N. gonorrhoeae. Both methods provided high-level discrimination of strains. NG-MAST further differentiated large porB-based clusters. However, considerations of cost suggest that porB DNA sequence analysis is a useful tool for preliminary molecular analysis of the epidemiology of N. gonorrhoeae.

Network analysis of cases with methicillin-resistant Staphylococcus aureus and controls in a large tertiary care facility.

BACKGROUND: Despite increased awareness of infection control precautions, methicillin-resistant Staphylococcus aureus (MRSA) still spreads through patients and contaminated objects, causing a substantial burden of illness and cost. Our objective was to define risk factors for contracting MRSA in a tertiary health care facility using a historic case-control study and to validate health care network changes during pre-outbreak and outbreak periods. METHODS: We conducted a case-control study using secondary data on hospitalizations where infected or colonized cases were compared with matched controls who tested negative by age, sex, and campus over 1 year. Social networks of all cases and controls were built from links joining patients to rooms, roommates, and health care providers over time. RESULTS: Matched controls were similar to cases in comorbidity, lengths of stay, mortality, and number of roommates, rooms, and health care providers. As expected, the number of rooms and roommates increased in the outbreak by more than 50%. A timed animation of the network at one campus identified potential source patients linked to 2 rooms and many roommates, after which cases connected to those same rooms proliferated. CONCLUSIONS: Only the network animation over time revealed possible transmission of MRSA through the network, rather than attributes measured in the traditional case control study.

Clusters of circulating Neisseria gonorrhoeae strains and association with antimicrobial resistance in Shanghai.

OBJECTIVES: (i) To distinguish Neisseria gonorrhoeae isolates in Shanghai by porB typing; (ii) to ascertain the congruence of porB DNA sequence typing with cases linked epidemiologically; (iii) to determine the association of specific PorB mutations with antimicrobial resistance to penicillin or tetracycline. METHODS: porB DNA sequences of 174 N. gonorrhoeae isolates, collected from 143 male patients and 31 female sexual partners in Shanghai were determined. Phylogenetic analysis was used to determine sequence associations and concordance with epidemiologically linked cases. PorB protein sequences were compared with the wild-type sequence to identify mutations associated with antimicrobial resistance to penicillin and tetracycline. RESULTS: porB1a genotypes comprised 27.0% of the isolates and included 15 distinct DNA sequences, while 73.0% of the isolates carried porB1b genotypes with 63 distinct DNA sequences. porB DNA sequence typing was congruent with patient-reported sexual contacts. In addition, porB DNA sequence analysis revealed a number of strains with identical DNA sequences not identified through traditional epidemiological methods. The porB1b isolates had a significantly higher percentage of chromosomally mediated resistance to tetracycline and higher MIC50s to penicillin and ciprofloxacin. G120K/A121D mutations were observed in 71.1% of PIB isolates and were associated with resistance to penicillin and/or tetracycline. The majority of the PIA isolates (82.1%) also carried G120D/A121G double mutations. The index of discrimination for porB DNA sequence analysis was 95%. CONCLUSIONS: The porB1b genotype was found to be predominant in Shanghai. porB DNA sequence typing was sufficiently discriminatory for differentiating N. gonorrhoeae isolates and was congruent with epidemiological linkages. Novel porB sequences of N. gonorrhoeae and novel mutations of PorB proteins were identified.

Identifying heterogeneity among injection drug users: a cluster analysis approach.

OBJECTIVES: We used cluster analysis to subdivide a population of injection drug users and identify previously unknown behavioral heterogeneity within that population. METHODS: We applied cluster analysis techniques to data collected in a cross-sectional survey of injection drug users in Winnipeg, Manitoba. The clustering variables we used were based on receptive syringe sharing, ethnicity, and types of drugs injected. RESULTS: Seven clusters were identified for both male and female injection drug users. Some relationships previously revealed in our study setting, such as the known relationship between Talwin (pentazocine) and Ritalin (methylphenidate) use, injection in hotels, and hepatitis C virus prevalence, were confirmed through our cluster analysis approach. Also, relationships between drug use and infection risk not previously observed in our study setting were identified, an example being a cluster of female crystal methamphetamine users who exhibited high-risk behaviors but an absence or low prevalence of blood-borne pathogens. CONCLUSIONS: Cluster analysis was useful in both confirming relationships previously identified and identifying new ones relevant to public health research and interventions.

The importance of social networks in their association to drug equipment sharing among injection drug users: a review.

AIM: To examine the scientific evidence regarding the association between characteristics of social networks of injection drug users (IDUs) and the sharing of drug injection equipment. METHODS: A search was performed on MEDLINE, EMBASE, BIOSIS, Current Contents, PsycINFO databases and other sources to identify published studies on social networks of IDUs. Papers were selected based on their examination of social network factors in relation to the sharing of syringes and drug preparation equipment (e.g. containers, filters, water). Additional relevant papers were found from the reference list of identified articles. RESULTS: Network correlates of drug equipment sharing are multi-factorial and include structural factors (network size, density, position, turnover), compositional factors (network member characteristics, role and quality of relationships with members) and behavioural factors (injecting norms, patterns of drug use, severity of drug addiction). Factors appear to be related differentially to equipment sharing. CONCLUSIONS: Social network characteristics are associated with drug injection risk behaviours and should be considered alongside personal risk behaviours in prevention programmes. Recommendations for future research into the social networks of IDUs are proposed.

Determinants of injection drug user (IDU) syringe sharing: the relationship between availability of syringes and risk network member characteristics in Winnipeg, Canada.

AIMS: Despite the establishment of syringe exchange programmes, syringe-sharing behaviour remains common among some injection drug users (IDU). Previous studies have identified several individual- and social network-level variables associated with syringe sharing. We examine the extent to which each of these variables is related independently to this behaviour within a diverse study population. DESIGN, SETTING AND PARTICIPANTS: A cross-sectional survey of 435 IDU conducted between December 2003 and September 2004 in Winnipeg, Canada. MEASUREMENTS: Individual and social-network variables were obtained from a survey instrument administered through a personal interview. Syringe sharing was defined as receptive syringe sharing in the last 6 months. Logistic regression analysis with generalized estimating equations was used to determine simultaneously the role of individual-level and risk network member-level variables on the odds of syringe sharing. FINDINGS: Individuals' relationship to a risk network member (sex partner, OR: 15.3 95% CI: 7.6-30.8; family member, OR: 3.4 95% CI: 1.3-9.0) and difficulty of access to syringes (OR: 3.6 95% CI: 1.3-9.9) were predictive of syringe sharing. Dyads who 'often' pooled resources to obtain drugs were at 4.9 times (95% CI: 2.1-11.6) the odds of syringe sharing, while those who 'sometimes' pooled resources were at 2.8 times (95% CI: 1.1-6.7) the odds, compared to those who 'never' pooled resources together. CONCLUSIONS: Syringe sharing in this population depended on both the availability of clean syringes and social network relationships. Adopting interventions that take into account relationships and behaviours that shape social norms present in networks/dyads would be a necessary prevention strategy alongside the provision of clean syringes.

Incorporating geographic settings into a social network analysis of injection drug use and bloodborne pathogen prevalence.

Using social network analysis, we investigated how communal meeting places can link injection drug user (IDU) populations and create opportunities for the transmission of bloodborne pathogens. In our locale, specific hotels played a key role in the injection drug scene. Within this hotel network some IDU injected at only one hotel while others injected at multiple hotels; this latter group potentially acted as spatial bridges linking relatively distinct hotel networks. Pathogen prevalence showed a gradation with the highest prevalence occurring at the centre of the network. Consistent with pathogen prevalence, people most central to the network were more likely to engage in risky injection practices. Incorporating geographic place into analyses involving IDU can contribute to an understanding of pathogen transmission patterns in an area and assist public health efforts to develop targeted intervention programs.

Demographic, risk behaviour and personal network variables associated with prevalent hepatitis C, hepatitis B, and HIV infection in injection drug users in Winnipeg, Canada.

BACKGROUND: Previous studies have used social network variables to improve our understanding of HIV transmission. Similar analytic approaches have not been undertaken for hepatitis C (HCV) or B (HBV), nor used to conduct comparative studies on these pathogens within a single setting. METHODS: A cross-sectional survey consisting of a questionnaire and blood sample was conducted on injection drug users in Winnipeg between December 2003 and September 2004. Logistic regression analyses were used to correlate respondent and personal network data with HCV, HBV and HIV prevalence. RESULTS: At the multivariate level, pathogen prevalence was correlated with both respondent and IDU risk network variables. Pathogen transmission was associated with several distinct types of high-risk networks formed around specific venues (shooting galleries, hotels) or within users who are linked by their drug use preferences. Smaller, isolated pockets of IDUs also appear to exist within the larger population where behavioural patterns pose a lesser risk, unless or until, a given pathogen enters those networks. CONCLUSION: The findings suggest that consideration of both respondent and personal network variables can assist in understanding the transmission patterns of HCV, HBV, and HIV. It is important to assess these effects for multiple pathogens within one setting as the associations identified and the direction of those associations can differ between pathogens.