Laura M. Kuyper

Characterization of airway plugging in fatal asthma

PURPOSE Case reports suggest that deaths due to asthma can occur without airway plugging. In this study, we examined the hypothesis that obstruction of the airway lumen by an exudate containing mucus and cells is a key feature of fatal asthma attacks. METHODS We quantified airway narrowing and lumenal content in 275 airways from 93 patients with fatal asthma aged 10 to 49 years (59 white subjects and 34 Polynesian subjects, including 19 children), compared with airways from control patients who died suddenly without pulmonary diseases. RESULTS The severity of lumenal occlusion ranged from 4% to 100% in these cases, but only five airways showed less than 20% occlusion. Compared with controls, patients with asthma had more lumenal occlusion (mean [+/- SD] open lumen, 42% +/- 23% vs. 93% +/- 8%), greater mucus occlusion (28% +/- 13% vs. 5% +/- 6%), and more occlusion by cells (30% +/- 17% vs. 3% +/- 2%, all P<0.0001). Airway narrowing was greater in larger airways (P<0.0001) and older patients (P = 0.009). Greater lumen content was associated with a higher proportion of cells (P = 0.003), and cells made up a higher proportion of the exudate in the small airways (P<0.0001). Lumenal mucus was greater in younger patients with asthma (P = 0.0007) and in Polynesian patients with asthma (P = 0.04). CONCLUSION Airway lumenal obstruction by an exudate composed of mucus and cells is a major contributing cause of fatal asthma in most patients.

Gender Differences in Hiv-1 Rna Rebound Attributed to Incomplete Antiretroviral Adherence Among Hiv-infected Patients in a Population-based Cohort

Background:There have been growing concerns about possible gender-related differences in rates of responses to highly active antiretroviral therapy (HAART). We therefore examined the association between gender and time to HIV-1 RNA rebound in antiretroviral-naive HIV-infected patients initiating HAART in a population-based setting. Methods:We evaluated all antiretroviral-naive HIV-infected men and women who achieved HIV-1 RNA suppression at least once (HIV RNA <500 copies/mL) after initiating HAART between August 1, 1996 and July 31, 2000 and who were followed until March 31, 2002 in a province-wide HIV treatment program. We evaluated time to HIV-1 RNA rebound (≥500 copies/mL) using Kaplan-Meier methods and Cox proportional hazards regression. Results:In total, 844 (87.0%) men and 126 (13.0%) women initiated HAART during the study period and achieved HIV-1 RNA suppression at least once. Overall rates of rebound were 47.4% and 34.0% for women and men, respectively (log-rank, P < 0.021). Women were less likely to be ≥95% adherent (P = 0.001) and more likely to have a history of injection drug use (P = 0.001). In multivariate analysis, incomplete adherence was found to be highly predictive of HIV-1 RNA rebound (adjusted relative hazard [ARH] = 4.00, 95% confidence interval [CI]: 3.33-5.00). Although female patients had higher rates of HIV-1 RNA rebound in univariate analysis (relative hazard [RH] = 1.39, 95% CI: 1.05-1.82), this was no longer statistically significant once other known confounders such as adherence and injection drug use were adjusted for (RH = 0.95, 95% CI: 0.71-1.28). When the analyses were stratified based on history of injection drug use, we found that rates of rebound were higher among injection drug-using women than among injection drug-using men (P = 0.048), whereas there was no gender difference among non-injection drug users with respect to rebound (P = 0.345). Conclusions:We found that higher rates of HIV-1 RNA rebound among women were primarily explained by incomplete adherence, which was more prevalent among women in this cohort. Our findings suggest that psychosocial factors such as drug use and incomplete adherence predict HIV-1 RNA rebound and that gender differences in time to rebound can be largely attributed to a disproportionate prevalence of these factors among women in this population.

Factors associated with sex trade involvement among male participants in a prospective study of injection drug users

Objectives: While much research to date has examined female sex trade work, little has been done to evaluate factors associated with male sex trade involvement or to assess their health service needs. This is particularly true for male sex trade workers who are also injection drug users (IDUs). Therefore, the present analyses were undertaken to evaluate factors associated with sex trade work in a prospective cohort study of male IDUs. Methods: We identified factors associated with sex trade involvement among male participants enrolled in the Vancouver Injection Drug Users Study (VIDUS). Since serial measures for each individual were available at semiannual intervals, variables potentially associated with sex trade involvement were evaluated with adjusted odds ratios (AOR) and 95% confidence intervals (CI) computed using generalised estimating equations (GEE). Results: Between 1996 and 2003, 995 male IDUs were enrolled into the VIDUS cohort among whom 108 (11%) reported being involved in the sex trade at enrolment and 102 (10%) individuals initiated sex trade involvement during the follow up period. In multivariate analyses, factors independently associated with sex trade involvement included HIV positive serostatus (AOR: 1.77 (95% CI: 1.44 to 2.17)), daily cocaine injection (AOR: 1.37 (95% CI: 1.11 to 1.70)), daily crack smoking (AOR: 1.36 (95% CI: 1.07 to 1.72)), borrowing syringes (AOR: 1.73 (95% CI: 1.32 to 2.25)), and inconsistent use of condoms with casual sexual partners (AOR 0.66, CI 0.53 to 0.82). We also found that male sex trade workers were more likely to report having sought but been unable to access substance abuse treatment (AOR: 1.28 (95% CI: 0.98 to 1.67); p = 0.076). Conclusions: Males involved in the sex trade in this setting have higher levels of HIV infection and engage in risky injection behaviours at an elevated rate. Since these behaviours have major implications for HIV acquisition and public health, prevention efforts and targeted provision of addiction treatment to this population should be expanded.

Predictors of Early Hospital Readmission in HIV‐infected Patients with Pneumonia

OBJECTIVE: Although hospitalization patterns have been studied, little is known about hospital readmission among HIV-infected patients in the era of highly active antiretroviral therapy. We explored the risk factors for early readmission to a tertiary care inner-city hospital among HIV-infected patients with pneumonia in Vancouver, Canada.DESIGN: Case-control study.SETTING: Tertiary care, university-affiliated, inner-city hospital.PARTICIPANTS: All HIV-infected patients who were hospitalized with Pneumocystis carinii pneumonia (PCP) or bacterial pneumonia (BP) between January 1997 and December 2000. Case patients included those who had early readmissions, defined as being readmitted within 2 weeks of discharge (N=131). Control patients were randomly selected HIV-infected patients admitted during the study period who were not readmitted within 2 weeks of discharge (N=131), matched to the cases by proportion of PCP to BP.MEASUREMENTS: Sociodemographic, HIV risk category, and clinical data were compared using x2 test for categorical variables, and the Wilcoxon rank-sum test was used for continuous variables. Multivariable logistic regression was performed to determine the factors independently associated with early readmission. We also reviewed the medical records of 132 patients admitted to the HIV/AIDS ward during the study period and collected more detailed clinical data for a subanalysis.MAIN RESULTS: Patients were at significantly increased odds of early readmission if they left the hospital against medical advice (AMA) (adjusted odds ratio [OR], 4.26; 95% confidence interval [95% CI], 2.13 to 8.55), lived in the poorest urban neighborhood (OR, 2.03; 95% CI, 1.09 to 3.77), were hospitalized in summer season (May though October, OR, 2.36; 95% CI, 1.36 to 4.10), or had been admitted in the preceding 6 months (OR, 2.55; 95% CI, 1.46 to 4.47). Gender, age, history of AIDS-defining illness, and injection drug use status were not significantly associated with early readmission.CONCLUSIONS: Predictors of early readmission of HIV-infected patients with pneumonia included: leaving hospital AMA, living in the poorest urban neighborhood, being hospitalized in the preceding 6 months and during the summer months. Interventions involving social work may address some of the underlying reasons why these patients leave hospital AMA and should be further studied.

Potential uptake and correlates of willingness to use a supervised smoking facility for noninjection illicit drug use.

Many cities are experiencing infectious disease epidemics and substantial community harms as a result of illicit drug use. Although medically supervised smoking facilities (SSFs) remain untested in North America, local health officials in Vancouver are considering to prepare a submission to Health Canada for an exemption to open Canada’s first SSF for evaluation. Reluctance of health policymakers to initiate a pilot study of SSFs may be due in part to outstanding questions regarding the potential uptake and community impacts of the intervention. This study was conducted to evaluate the prevalence and correlates of willingness to use an SSF among illicit drug smokers who are enrolled in the Vancouver Injection Drug Users Study. Participants who reported actively smoking cocaine, heroin, or methamphetamine who returned for follow-up between June 2002 and December 2002 were eligible for these analyses. Those who reported willingness to use an SSF were compared with those who were unwilling to use an SSF by using logistic regression analyses. Four hundred and forty-three participants were eligible for this study. Among respondents, 124 (27,99%) expressed willingness to attend an SSF. Variables that were independently associated with willingness to attend an SSF in multivariate analyses included sex-trade work (adjusted odds ratio [AOR]=1.85), crack pipe sharing (AOR=2.24), and residing in the city’s HIV epicentre (AOR=1.64). We found that participants who demonstrated a willingness to attend an SSF were more likely to be involved in the sex trade and share crack pipes. Although the impact of SSFs in North America can only be quantified by scientific evaluation, these data indicate a potential for public health and community benefits if SSFs were to become available.

Factors associated with sex-trade involvement among female injection drug users in a Canadian setting

Background: We undertook this study to evaluate the factors associated with sex-trade involvement among a cohort of female injection drug users (IDUs). Methods: We performed a prospective analysis of factors associated with sex-trade involvement among female participants enrolled in a prospective cohort study of Vancouver injection drug users. We examined HIV-status during follow-up and measured time updated social, sex- and drug-related variables relating to activities engaged in during the previous six months. Variables potentially associated with sex-trade involvement were evaluated using generalized estimating equations (GEE) with logit link for binary outcomes. Results: Between May 1, 1996 and November 30, 2003, 565 participants were recruited into the cohort of whom 336 (59%) reported being involved in the sex-trade at baseline. Factors associated with reporting sex-trade involvement among women in the adjusted model included incarceration, daily injected cocaine use, daily crack use, borrowing syringes, lending syringes, and having sought but been unable to access addiction treatment during the previous six months. Conclusions: Our study demonstrates significant risky sexual and injection behaviours as well as difficulties with access to addiction treatment among female IDUs involved in the sex-trade in Vancouver.

The cost of inaction on HIV transmission among injection drug users and the potential for effective interventions.

Estimated and potential medical costs of treating patients infected with human immunodeficiency virus (HIV) in urban areas of high HIV prevalence have not been well defined. We estimated the total medical cost of HIV disease among injection drug users in Vancouver, British Columbia, Canada, assuming stable and increasing HIV prevalence. Total medical costs were estimated by multiplying the average lifetime medical cost per person by the number of HIV-infected individuals. We assumed the cost of each HIV infection to be

The prevalence and incidence of sexually transmitted infections in a prospective cohort of injection drug users in Vancouver, British Columbia.

150,000 (Canadian), based on empirical data, and HIV prevalence estimates were derived from the Vancouver Injection Drug Users Study (VIDUS) and external data sources. By use of Monte Carlo simulation methodology, we performed sensitivity analyses to estimate total medical cost, assuming the HIV prevalence remained stable at 31% and under a scenario in which the prevalence rose to 50%. Expected medical expenditures based on current HIV prevalence levels were estimated as

Does initiation of HIV antiretroviral therapy influence patterns of syringe lending among injection drug users

215,852,613. If prevalence rises to 50% as reported in other urban centers, the median estimated medical cost would be approximately

Factors Associated With Buying and Selling Syringes Among Injection Drug Users in a Setting of One of North America's Largest Syringe Exchange Programs

348,935,865. This represents a difference in the total costs between the two scenarios of