Endotoxin as a determinant of asthma and wheeze among rural dwelling children and adolescents: a case-control study.

BACKGROUND: The association between endotoxin exposure and asthma is complex and has been associated with rural living. We examined the relationship between domestic endotoxin and asthma or wheeze among rural school-aged children (6-18 years) and assessed the interaction between endotoxin and other characteristics with these outcomes. METHODS: Between 2005 and 2007 we conducted a case-control study of children 6-18 years in the rural region of Humboldt, Canada. Cases (n = 102) reported doctor-diagnosed asthma or wheeze in the past year. Controls (n = 208) were randomly selected from children without asthma or wheeze. Data were collected to ascertain symptoms, asthma history and indoor environmental exposures (questionnaire), endotoxin (dust collection from the play area floor and child's mattress), and tobacco smoke exposure (saliva collection). Statistical testing was completed using multiple logistic regression to account for potential confounders and to assess interaction between risk factors. A stratified analysis was also completed to examine the effect of personal history of allergy. RESULTS: Among children aged 6-12 years, mattress endotoxin concentration (EU/mg) and load (EU/m2) were inversely associated with being a case [odds ratio (OR) = 0.44, 95% confidence interval (CI) = 0.20-0.98; and OR = 0.38, 95% CI = 0.20-0.75, respectively]. These associations were not observed in older children or with play area endotoxin. CONCLUSIONS: Our results suggest that endotoxin exposure might be protective for asthma or wheeze. The protective effect is found in younger school-aged, non-allergic children. These results may help explain the inconsistencies in previous studies and suggest that the protective effects of endotoxin in the prevention of atopy and asthma or wheeze are most effective earlier in life.

Increased glutamate levels in the medial prefrontal cortex in patients with postpartum depression.

The medial prefrontal cortex (MPFC) is a key brain area in depressive symptomatology; specifically, glutamate (Glu) has been reported to play a significant role in major depression (MD) in this area. MPFC Glu levels are sensitive to ovarian hormone fluctuations and pregnancy and the postpartum period are associated with the most substantial physiological alterations of female hormones. It is therefore logical to measure MPFC Glu levels in women with postpartum depression (PPD). Using in vivo magnetic resonance spectroscopy (MRS) at a field strength of 3 T, we acquired single-voxel spectra from the MPFC of 12 women with PPD and 12 healthy controls (HCs) matched for postpartum scan timing. Water-referenced MPFC Glu levels were measured using a MRS technique that allowed us to be specific for Glu with very little glutamine contamination. The concentrations of other water-quantified brain metabolites such as glycerophosphorylcholine plus phosphorylcholine, N-acetylaspartate (NAA), and creatine plus phosphocreatine were measured in the same MR spectra. MPFC Glu levels were higher in women with PPD (7.21±1.20) compared to matched HCs (6.04±1.21). There were no differences between groups for other brain metabolites measured. These findings suggest an association between Glu dysregulation in the MPFC and PPD. Whether the pathophysiology of PPD differs from the pathophysiology of MD remains to be determined. Further investigations are needed to determine the chronological associations between the occurrence of symptoms of PPD and the onset of changes in MPFC Glu levels.

Hepatitis C virus co-infection increases neurocognitive impairment severity and risk of death in treated HIV/AIDS.

Previous studies have reported that hepatitis C virus (HCV) co-infection worsens neurocognitive status among individuals with human immunodeficiency virus (HIV)-1 infection. We assessed the prevalence of neurologic disorders and the severity of HIV-associated neurocognitive impairment among HIV-infected individuals in two centralized HIV clinics in Alberta, Canada from 1998 to 2010 based on their HCV serostatus. Of 456 HIV-infected persons without concurrent substance abuse, 91 (20.0%) were HCV seropositive. Of 58 neurologic disorders identified in the cohort, HIV/HCV co-infected individuals exhibited a higher prevalence of multiple neurologic disorders compared to HIV-infected individuals (60.4% vs. 46.6%, p<0.05) and a higher frequency of seizures (28.6% vs. 17.8%, p<0.05). Unlike HIV mono-infected persons, the risk of seizures was independent of immune status in HIV/HCV co-infected individuals (p<0.05). Symptomatic HIV-associated neurocognitive disorders (sHAND) were more severe among HIV/HCV co-infected persons (p<0.05). HCV co-infection was associated with an increased mortality rate (24.2% vs. 14.5%, p<0.05) with a mortality hazard ratio of 2.38 after adjusting for demographic and clinical variables. Our results indicate that the presence of HCV co-infection among HIV-infected individuals increased neurologic disease burden and risk of death, underscoring HCV's capacity to affect the nervous system and survival of HIV-infected persons.

The association between endotoxin and lung function among children and adolescents living in a rural area.

UNLABELLED: BACKGROUND/ OBJECTIVES: Knowledge of the effects of domestic endotoxin on children's lung function is limited. The association between domestic endotoxin and asthma or wheeze and lung function among school-age children (six to 18 years of age) was examined. The interaction between endotoxin and other personal and environmental characteristics and lung function was also assessed. METHODS: A case-control study was conducted in and around the rural community of Humboldt, Saskatchewan, between 2005 and 2007. Parents of cases reported either doctor-diagnosed asthma or wheeze in the previous year. Controls were randomly selected from those not reporting these conditions. Data were collected by questionnaire to ascertain symptoms and conditions, while spirometry was used to measure lung function including forced vital capacity and forced expiratory volume in 1 s. Dust collected from the child's play area floor and the child's mattress was used to quantify endotoxin, and saliva was collected to quantify cotinine levels and assess tobacco smoke exposure. RESULTS: There were 102 cases and 207 controls included in the present study. Lower forced expiratory volume in 1 s was associated with higher mattress endotoxin load among female cases (beta=-0.25, SE=0.07 [P<0.01]). There was a trend toward lower forced vital capacity, which was associated with higher play area endotoxin load among cases with high tobacco smoke exposure (beta=-0.17, SE=0.09 [P<0.10]). CONCLUSIONS: Findings indicated that high endotoxin levels present in common household areas of rural children with asthma or wheeze may also affect their lung function. These associations may be potentiated by tobacco smoke exposure and female sex.

Relationship of endotoxin and tobacco smoke exposure to wheeze and diurnal peak expiratory flow variability in children and adolescents.

BACKGROUND AND OBJECTIVE: The relationship between endotoxin exposure and asthma severity (wheeze and airways obstruction) is not well described. The effects of endotoxin and tobacco smoke exposure on self-reported wheeze and diurnal PEF variability (DV-PEF) were examined in children aged 6-18 years with asthma or wheeze. METHODS: A cross-sectional study was performed in a rural area. From this study, children who reported wheeze in the previous 12 months or a physician diagnosis of asthma (n = 98) were selected for a case-control study. These subjects, who were the basis for the present analysis, completed: (i) a home environmental assessment, including dust collection to measure endotoxin levels: (ii) a clinic visit, including saliva collection to measure cotinine levels; and (iii) 2 week monitoring of twice daily symptom records, including wheeze, and PEF to calculate DV-PEF. RESULTS: Among these children, 22.4% reported wheeze during the monitoring period. Greater DV-PEF was associated with higher endotoxin loads in play areas (P < 0.05). The association between salivary cotinine levels and high DV-PEF was modified by gender. In females, higher cotinine levels were associated with an increased risk of high DV-PEF compared with lower cotinine levels (P < 0.05), but this was not observed among males. CONCLUSIONS: Higher endotoxin exposure was associated with greater DV-PEF among children with asthma or wheeze. While previous studies have suggested that endotoxin exposure protects against the development of asthma, individuals with the disease should avoid high exposure levels to limit exacerbations. The effect of tobacco smoke exposure on lung health may differ between male and female children.

Improving reliability of the assessment of the life course of schizophrenia.

OBJECTIVE: Life course studies of schizophrenia that have used a 3-phase model (onset, course, and outcome) have had their use restricted owing to differences in definition and methodology. The purpose of this investigation was to describe life course data in mathematical terms and to compare the results with the findings from other life course studies. METHOD: The study population was comprised of 128 of 137 people who were first admitted for schizophrenia to 1 of the 2 mental hospitals in Alberta in 1963 and followed until 1997 or death. Patient evaluations were based on retrospective and contemporaneous information collected from the patients and hospital files, treatment records, and family members. Mathematically derived ratings were formulated for course, outcome, and onset (pre-admission years). The distribution of the resulting 8 life course types was compared with profiles drawn from other such studies reported in the literature. RESULTS: The use of mathematical descriptions of onset, course, and outcome produced profiles that did not closely match the results of other investigations, largely owing to inconsistency across studies. Further, the present approach to outcome measurement produced results that were less favourable than those found in other studies. CONCLUSIONS: Studies on the life course of schizophrenia could be made more comparable by specifying mathematically expressed operational definitions of onset, course, and outcome. Nonetheless, the use of the term outcome can be questioned as it implies an assessment at a specific time rather than providing a summary statement of the quality of a life.

Relationship between indoor environment and asthma and wheeze severity among rural children and adolescents.

Few studies have examined the associations between environmental characteristics and asthma severity among children in a rural setting. The authors studied these associations using a number of asthma severity indicators. They conducted a case-control study of 6- to 18-year-old children and adolescents in Humboldt, Saskatchewan, and the surrounding area. Only cases representing subjects reporting wheeze in the past 12 months or doctor-diagnosed asthma were used for the present analysis (n = 98). Data were collected by questionnaire, while vacuumed dust (mattress and play area floor) was used for the quantification of endotoxin exposure, and saliva was used for the measurement of cotinine to assess tobacco smoke exposure. Severity indicators included wheeze frequency, breathing medication use, sleep disruption from wheeze, and school absenteeism, all in the past 12 months. A majority of cases were male (62.3%). Wheezing 1 to 3 times was reported by 40.8% of cases, whereas 17.3% wheezed 4 or more times in the past 12 months. Short-acting beta agonist medications or inhaled corticosteroids alone were used by 24.5% of the cases, whereas 33.7% of the cases used multiple or additional breathing medications. Sleep disruption was reported by 28.6% of the cases, whereas 12.2% reported at least one school absence. High tobacco smoke exposure was associated with increased wheeze frequency. There was an inverse association between play area endotoxin concentration and school absenteeism, with some indication of interaction with tobacco smoke exposure. House-cleaning behaviors and changes in health behaviors resulting from the child's respiratory condition were different between those with and without report of sleep disruption due to wheeze. Several environmental variables were associated with severity indicators. However, the associations were not consistent between indicators, suggesting that other factors or changes in behavior resulting from the disease should be considered when assessing these associations.

A population-based family study of minor depression.

BACKGROUND: There is a paucity of research on whether minor depression is a familial disorder. METHODS: We conducted a population-based family study of minor depression in which subjects were interviewed using the Diagnostic Interview Schedule (DIS). Minor depression only (MDO) was diagnosed if there was a lifetime history of what the DIS refers to as a depressive "spell" and no lifetime history of either Diagnostic and Statistical Manual of Mental Disorders, Third Edition, major depression or dysthymia. There were 71 probands with a lifetime history of MDO; 577 controls with no lifetime history of MDO, major depression, or dysthymia; and 1,539 first-degree relatives (FDRs). Logistic regression was performed with the presence/absence of MDO in a proband/control as the "exposure" and MDO in an FDR as the "outcome". RESULTS: The odds ratio for the association between MDO in a proband and MDO in an FDR, after adjusting for age and sex of the FDR, was 1.55 (95% confidence interval: 0.93-2.58; P=.093). The study had 80% power to detect an odds ratio as small as 1.97, which is in the range of odds ratios seen for the familial aggregation of major depression. CONCLUSIONS: MDO does not appear to be a familial disorder, raising questions about the validity of "minor depression" as a distinct psychiatric syndrome.

Trends in antidepressant prescriptions among the elderly in Alberta during 1997 to 2004.

OBJECTIVE: To analyze trends in antidepressant (AD) prescription rates among the elderly (aged 65 years and older) in Alberta during 1997 to 2004. METHOD: Numerical data on AD prescriptions were obtained from Alberta Blue Cross. Age-standardized prescription rates were calculated according to type of AD. RESULTS: The prescription rate for all ADs combined increased by 59% for men and 55% for women. This change was due entirely to serotonin reuptake inhibitors (SSRIs) and other recently-introduced ADs, that by 2004 accounted for 72% of AD prescriptions for men and 69% for women. For each year and type of AD, the prescription rate for women was almost double that for men. CONCLUSIONS: In the elderly in Alberta, prescription rates for ADs increased markedly during 1997 to 2004, especially for SSRIs and other recently introduced ADs.

Case-control study of unemployment and parasuicide.

OBJECTIVE: The objective of the study was to estimate the odds ratio for the association between unemployment and parasuicide, controlling for potential confounding variables. METHODS: A case-control study was conducted involving 507 cases of parasuicide and 200 age- and sex-matched controls presenting to emergency departments in Edmonton, Canada. Subjects were interviewed using an extensive questionnaire developed for a World Health Organization study of parasuicide. The data were analyzed using conditional logistic regression. RESULTS: In a crude analysis, the odds ratio for the association between unemployment and parasuicide was 12.0 (95% confidence interval, 6.0-23.9). After controlling for sociodemographic factors, lifetime prevalence of several Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition, disorders, previous parasuicide, hopelessness, childhood experiences, and emotional support from family and friends, the odds ratio was 5.2 (95% confidence interval, 2.3-11.4). CONCLUSIONS: Those who are unemployed have an increased risk of parasuicide, and this association persists after accounting for a wide range of potential confounders.

The association between pathological gambling and attempted suicide: findings from a national survey in Canada.

OBJECTIVE: To examine the association between pathological gambling (PG) and attempted suicide in a nationally representative sample of Canadians. METHODS: Data came from the Canadian Community Health Survey, Cycle 1.2, conducted in 2002, in which 36 984 subjects, aged 15 years or older, were interviewed. Logistic regression was performed with attempted suicide (in the past year) as the dependent variable. The independent variables were PG, major depression, alcohol dependence, drug dependence, and mental health care (in the past year), as well as a range of sociodemographic variables. Survey weights and bootstrap methods were used to account for the complex survey design. RESULTS: In the final logistic regression model, which included terms for PG, major depression, alcohol dependence, and mental health care, as well as age, sex, education, and income, the odds ratio for PG and attempted suicide was 3.43 (95% confidence interval, 1.37 to 8.60). CONCLUSIONS: PG (in the past year) and attempted suicide (in the past year) are associated in a nationally representative sample of Canadians. However, it is not possible to say from these data whether this represents a causal relation.

Type 2 diabetes does not increase risk of depression.

BACKGROUND: Although diabetes mellitus has a strong association with the presence of depression, it is unclear whether diabetes itself increases the risk of developing depression. The objective of our study was to evaluate whether people with diabetes have a greater incidence of depression than those without diabetes. METHODS: We conducted a population-based retrospective cohort study using the administrative databases of Saskatchewan Health from 1989 to 2001. People older than 20 years with newly identified type 2 diabetes were identified by means of diagnostic codes and prescription records and compared with a nondiabetic cohort. Depression was ascertained via diagnostic codes and prescriptions for antidepressants. Cox regression analysis was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) after adjusting for age, sex, frequency of visits to physicians and presence of comorbidities. RESULTS: We identified 31 635 people with diabetes and 57 141 without. Those with diabetes were older (61.4 v. 46.8 yr; p < 0.001), were more likely to be male (55.4% v. 49.8%; p < 0.001) and had more physician visits during the year after their index date (mean 14.5 v. 5.9; p < 0.001). The incidence of new-onset depression was similar in both groups (6.5 v. 6.6 per 1000 person-years among people with and without diabetes, respectively). Similarity of risk persisted after controlling for age, sex, number of physician visits and presence of prespecified comorbidities (adjusted HR 1.04, 95% CI 0.94- 1.15). Other chronic conditions such as arthritis (HR 1.18) and stroke (HR 1.73) were associated with the onset of depression. INTERPRETATION: Using a large, population-based administrative cohort, we found little evidence that type 2 diabetes increases the risk of depression once comorbid diseases and the burden of diabetes complications were accounted for.

A population-based family study of DSM-III generalized anxiety disorder.

BACKGROUND: A recent meta-analysis provides evidence that generalized anxiety disorder (GAD) is familial. However, two of the key studies relied on subjects who were self-selected or recruited from the clinic setting, thereby limiting generalizability. METHOD: We conducted a family study of GAD in which probands and controls came from a community sample originally enrolled in a prevalence study in Edmonton, Canada. One hundred and sixty probands, 764 controls and 2386 first-degree relatives (FDRs) were interviewed using the Diagnostic Interview Schedule (DIS); lifetime diagnoses were made according to DSM-III criteria without exclusions. Logistic regression analysis was performed with GAD (in a proband) as the 'exposure', and GAD in an FDR as the 'outcome'. Several analytic strategies were used to control for potential confounding by major depressive disorder (MDD) and several anxiety disorders (panic disorder, phobic disorders, obsessive-compulsive disorder, and post-traumatic stress disorder). RESULTS: The odds ratios for the association between GAD in a proband and GAD in an FDR were in the range 1.4-1.8 when the entire FDR sample was analysed, and in the range 2.1-2.8 when we restricted to FDRs who were children of probands and controls. CONCLUSION: In the community setting, GAD exhibits mild to moderate familial aggregation.

Causal analysis of case-control data.

In a series of papers, Robins and colleagues describe inverse probability of treatment weighted (IPTW) estimation in marginal structural models (MSMs), a method of causal analysis of longitudinal data based on counterfactual principles. This family of statistical techniques is similar in concept to weighting of survey data, except that the weights are estimated using study data rather than defined so as to reflect sampling design and post-stratification to an external population. Several decades ago Miettinen described an elementary method of causal analysis of case-control data based on indirect standardization. In this paper we extend the Miettinen approach using ideas closely related to IPTW estimation in MSMs. The technique is illustrated using data from a case-control study of oral contraceptives and myocardial infarction.

Alteration of decreased plasma NO metabolites and platelet NO synthase activity by paroxetine in depressed patients.

Although major depression (MD) and cardiovascular disease (CVD) have been conclusively linked in the literature, the mechanism associating MD and CVD is yet undetermined. The purpose of this paper is to further investigate a potential mechanism involving nitric oxide (NO) and to examine the effect of the selective serotonin reuptake inhibitor paroxetine on NO production by both platelets and the endothelium. In total, 17 subjects with MD and 12 healthy controls (HCs) with no known history of cardiovascular illness completed the study. Paroxetine was administered to both the MD patients and HCs over an 8-week period, and then medication was discontinued. Blood samples were taken at various times throughout paroxetine treatment and after discontinuation. Plasma NO metabolite (NOx) levels were measured by a chemiluminescence method. Platelet endothelial NO synthase (eNOS) activity was examined through the conversion of L-[14C]arginine to L-[(14)C]citrulline. Data were analyzed using t-tests and a linear mixed effects model. Baseline levels of both plasma NOx and platelet NOS activity were significantly lower in subjects with MD compared to HCs. Throughout paroxetine treatment, plasma NOx levels increased in both HCs and MD patients. However, platelet eNOS activity decreased in HCs, while no statistically significant change was evidenced in MD patients. These data suggest that, in MD patients, decreased peripheral production of NO, a potential contributor to increased cardiovascular risk, is modified by administration of the antidepressant paroxetine.

An ecologic study of parasuicide in Edmonton and Calgary.

OBJECTIVE: From 1986 to 1999, the suicide rate in the Edmonton Regional Health Authority (RHA) was greater than that in the Calgary RHA (mean rate ratio 1.4). We conducted a study to determine whether a similar relation holds for parasuicide, and if so, whether the pattern can be explained at the ecologic level by sociodemographic factors. METHODS: The Edmonton and Calgary RHAs provided data on emergency department visits for nonfatal intentional self-injury for 1997. We obtained sociodemographic data from the 1996 national census for the Edmonton and Calgary census metropolitan areas (CMAs) from Statistics Canada's public-use files. In each CMA, which is nearly coterminous with the corresponding RHA, we created 10 geographic areas based on average income. We analyzed the data at the ecologic level, using linear regression and multilevel Poisson regression. RESULTS: The parasuicide rate in the Edmonton CMA was greater than that in the Calgary CMA (rate ratio 1.3). In both CMAs, the parasuicide rate decreased as average income increased. In the final regression models, the only independent variables were average income, CMA, and their interaction term (linear regression model R2 = 0.82). CONCLUSIONS: The parasuicide rate in the Edmonton CMA is elevated, compared with that in the Calgary CMA. At the ecologic level, much of the variation in rates can be explained by average income and CMA. The high degree of correlation among the sociodemographic variables suggests that it may not be low income per se that is affecting the parasuicide rate but, rather, the consequences of belonging to a socially disadvantaged stratum of society.

History of depression increases risk of type 2 diabetes in younger adults.

OBJECTIVE: The purpose of this study was to assess the history of previous depression in people with incident diabetes compared with people without diabetes. RESEARCH DESIGN AND METHODS: We conducted a population-based nested case-control study using the administrative databases of Saskatchewan Health to assess the study objective. We identified cases of type 2 diabetes based on diagnostics codes and prescription records for individuals over the age of 20 years. For each case subject, two control subjects were randomly selected from the nondiabetic population during the same index year. History of depression, based on diagnostic codes and antidepressant prescription, was ascertained up to 3 years before index date. Simple and multivariate logistic regression analysis was used to estimate the odds ratio (OR) and 95% CIs, after adjusting for age, sex, and frequency of physician visits. RESULTS: Individuals with newly diagnosed diabetes (1,622 of 33,257; 4.9%) were 30% more likely to have had a previous history of depression compared with people without diabetes (2,279 of 59,420; 3.8%). This increased risk remained after controlling for sex and number of physician visits but was limited to subjects 20-50 years of age (adjusted OR 1.23 [95% CI 1.10-1.37]) and not in those aged > or =51 years (0.92 [0.84-1.00]). CONCLUSIONS: Depression appears to increase the risk of developing diabetes by approximately 23% in younger adults. This provides information regarding the temporality of the relationship between diabetes and depression.

Prevalence and predictors of depression in elderly Canadians: The Canadian Study of Health and Aging.

Depression in elderly Canadians is an important but often unrecognized public health problem. Numerous studies have examined depression in the general community, but studies of depression in the elderly have generally been small and limited. The Canadian Study of Health and Aging (CSHA) includes a large and national representation of both the cognitively intact and the cognitively impaired elderly. The current analyses of 2,341 participants from the CSHA who completed a clinical rating scale for depression have two objectives: 1) to determine the prevalence of minor and major depression and 2) to examine the importance of several risk factors. The prevalences of major and minor depression were 2.6 percent and 4.0 percent, respectively, and were higher for females, specifically those in institutions, those who reported that their health problems limited activities, and those with chronic health conditions. Women were more likely to exhibit depression (OR = 3.5; 95% CI: 1.4-8.8) than men, and those with dementia more likely to exhibit depression than those without (OR = 2.4; 95% CI: 0.9-3.1). Depression is a significant mental health problem among elderly Canadians, particularly among women and those with physical limitations. More attention should be paid to the detection and treatment of depression in the elderly, particularly among those most at risk.

Test-retest and case-control study of psychological symptoms and social adjustment following parasuicide.

Numerous studies have been conducted in which cases of parasuicide have been followed for repeat parasuicide. By comparison, there have been relatively few studies of other morbidity endpoints. Over a 1-year period, 507 cases of parasuicide and 200 controls were recruited from emergency departments in Edmonton, Canada and interviewed using the Beck Hopelessness Scale, Beck Depression Inventory, State Anger Scale, Trait Anger Scale, Self-Esteem Scale, and Social Adjustment Scale. Over the ensuing 1 to 2 years, 414 cases were reinterviewed using the same questionnaires. Mean symptom scores on all questionnaires improved over the course of follow-up, but did not reach control levels. The pattern of improvement varied according to questionnaire. Only half of cases received treatment for the parasuicide from a psychiatrist, psychologist, or other health care provider during the 3 months following the emergency department visit.

Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) in a Northern Alberta population.

OBJECTIVE: To describe the demographics and estimate the prevalence of hepatitis C virus (HCV) in a cohort of Human Immunodeficiency Virus (HIV) positive patients in Northern Alberta. METHODS: A cross-sectional (prevalence) study was performed on a cohort of HIV-positive patients. HCV testing was not widely available until December 1989, and the more sensitive, second generation immunoassay was not available until 1992. To reduce the effect of testing bias, we restricted consideration of HCV status to patients first seen January 1, 1992 onward. RESULTS: Forty-four percent of patients in the whole cohort were tested for HCV (564/1,276) and 62% (505/809) of patients entered since January 1, 1992 were tested for HCV. During the period January 1, 1992-December 31, 1999, the prevalence of HCV in our cohort of northern Alberta HIV-positive patients was at least 37.9% (307/809) and was 60.8% (307/505) among those who were tested for HCV in 1992 or later. The mean age of the co-infected group was 33.6 years, 66.1% were male, 91.2% were injection drug users (IDUs), 56.8% were Caucasian, and 40.0% were Aboriginal. A statistically significant difference was found between the HCV-negative cohort, the HCV co-infected cohort, and the HCV-untested cohort for the following variables: risk behaviour, gender, ethnic status, death, occurrence of an AIDS-defining illness (p < 00.0001), and mean baseline CD4 cell count (p = 0.002). CONCLUSION: A high proportion of the HIV-infected IDUs was co-infected with HCV. Compared to the HCV-negative group, the co-infected group appears to have had less advanced HIV disease. This is likely a reflection of more recent HIV infection in the HCV co-infected group.