The longitudinal impact of diet, physical activity, sleep, and screen time on Canadian adolescents' academic achievement: An analysis from the COMPASS study.

Adequate amounts of physical activity, sleep, and screen time along with a healthy diet have been demonstrated to have positive associations with academic achievement. No longitudinal study has investigated the simultaneous relationship between all of these behaviours and academic achievement. Data from 11,016 adolescent participants of the COMPASS study in Alberta and Ontario were analysed. Students self-reported their adherence to Canadian recommendations for health behaviours and academic achievement in Math and English on school-based surveys administered in the 2015/16 and 2016/17 waves of COMPASS. Multinomial generalized estimating equations were used to evaluate the association between longitudinal changes in adherence to recommendations and academic achievement at follow-up. Models were adjusted for self-reported sociodemographic information, body weight status, and baseline academic achievement. Students who adhered to a greater number of recommendations performed better than students who adhered to fewer recommendations. Meeting recommendations for Meat and Alternatives (protein-rich foods) and screen time were consistently associated with higher academic achievement compared to students who did not meet these recommendations. A change from not meeting recommendations for Vegetables and Fruit to meeting the recommendation in the following year was associated with higher achievement in both subjects. There was no association between sleep behaviours or physical activity and academic achievement. Results indicate that adherence to recommendations for protein-rich foods, screen time, and vegetables and fruit show promise as behavioural targets for higher academic achievement among youth. Further study using objectives measurements of behaviours and further consideration of socioeconomic variables is merited.

Vigorous physical activity and longitudinal associations with cardiometabolic risk factors in youth.

OBJECTIVE: To examine the longitudinal associations between different physical activity (PA) intensities and cardiometabolic risk factors among a sample of Canadian youth. METHODS: The findings are based on a 2-year prospective cohort study in a convenience sample of 315 youth aged 9-15 years at baseline from rural and urban schools in Alberta, Canada. Different intensities (light, moderate and vigorous) of PA were objectively assessed with Actical accelerometers. The main outcome measures were body mass index (BMI) z-score, waist circumference, cardiorespiratory fitness and systolic blood pressure at 2-year-follow-up and conditional BMI z-score velocity. A series of linear regression models were conducted to investigate the associations after adjusting for potential confounders. RESULTS: At follow-up, cardiorespiratory fitness increased (quartile 1 vs quartile 4=43.3 vs 50.2; P(trend)<0.01) and waist circumference decreased (quartile 1 vs quartile 4=79.0 vs 72.6; P(trend)=0.04; boys only) in a dose-response manner across quartiles of baseline vigorous-intensity PA. A similar trend was observed for systolic blood pressure (quartile 1 vs quartile 4=121.8 vs 115.3; P(trend)=0.07; boys only). Compared with quartile 1 of vigorous-intensity PA, BMI z-score at follow-up and conditional BMI z-score velocity were significantly lower in the quartile 2 and 3 (P<0.05). Waist circumference at follow-up also decreased (quartile 1 vs quartile 4=75.3 vs 73.8; P(trend)=0.04) across quartiles of baseline moderate-intensity PA. CONCLUSIONS: Time spent in vigorous-intensity PA was associated with several positive health outcomes 2 years later. These findings suggest that high-intensity activities in youth help to reduce the risk for several chronic diseases.

Assessment of children's own health status using visual analogue scale and descriptive system of the EQ-5D-Y: linkage between two systems.

OBJECTIVES: The objective of the study is to derive a scoring system for the EQ-5D child-friendly version (EQ-5D-Y) from a population-based sample of children based on their own health state assessments on the descriptive system and the visual analogue scale (VAS). METHODS: We used data from the 2008 and 2010 Raising Healthy Eating and Active Living Kids in Alberta surveys of grade five students aged primarily 10-11 years and their parents in the Canadian province of Alberta. We applied a random split sample approach. Two-thirds of the sample (modeling sample) was used for the estimation of the EQ-5D-Y VAS. The remaining one-third sample (validation sample) was used for the examination of the prediction accuracy of the estimation model. Multilevel linear regression was used to estimate EQ-5D-Y VAS score and produce EQ-5D-Y index values from the children's self-rated states described in the EQ-5D-Y and the accompanying VAS values. RESULTS: The mean EQ-5D-Y VAS-based index value was 0.891 (SD 0.133) in the modeling sample and 0.885 (SD 0.134) in the validation sample. The own VAS-based index generally showed logical consistency, with lower values for health states that were logically worse. There was no statistically significant difference between the observed and the predicted VAS values in this sample. CONCLUSIONS: This study elicited a value set for health states defined by the EQ-5D-Y that is based on respondents' own VAS ratings from a large representative sample of Canadian children. Future study is needed to validate this type of value set among different age groups of children.

Vitamin D and health-related quality of life in a community sample of older Canadians.

PURPOSE: To assess how vitamin D status is associated with health-related quality of life (HRQOL) among older residents of Canada. DESIGN: We analysed baseline data of 1,493 Canadians aged 50 years and over in Alberta on HRQOL (EQ-5D-5L) and serum 25-hydroxyvitamin D (25(OH)D) as a measure of vitamin D status. We applied multivariable regression methods to examine the association between vitamin D status and each of the five dimensions and the summary index of the EQ-5D-5L. RESULTS: Participants with higher serum 25(OH)D levels were significantly less likely to report problems with mobility, usual activities, and depression and anxiety. Specifically, age- and gender-adjusted odds ratios for reporting problems with mobility, usual activities, and depression and anxiety were 0.58 (95 % confidence interval 0.44-0.78), 0.67 (0.50-0.89), and 0.67 (0.51-0.88) per 100 nmol/L increase in 25(OH)D, respectively. No significant associations were observed for problems with self-care and with pain and discomfort. HRQOL scores combining the responses of each of the five dimensions increased significantly with increasing serum 25(OH)D levels. CONCLUSIONS: This is the first study to reveal the importance of vitamin D for the five dimensions of HRQOL in a community-based sample. The observed associations of vitamin D and HRQOL call for intervention studies to strengthen the evidence of the potential benefits of vitamin D supplementation for HRQOL among older adults.

Vitamin D status of Canadians employed in northern latitudes.

BACKGROUND: Vitamin D deficiency and insufficiency are prevalent worldwide, but relatively few studies have examined vitamin D status in working populations. AIMS: To assess the prevalence of vitamin D deficiency and insufficiency in Canadian workers and investigate risk factors in this population. METHODS: A cross-sectional study using data from a health programme enrolling workers mostly from Northern Alberta, Canada. As part of the programme, volunteers were invited to complete a lifestyle questionnaire. Blood was taken to determine plasma 25-hydroxyvitamin D (25(OH)D) levels. Logistic and linear regressions were used to investigate the relationships between individual characteristics and vitamin D status. RESULTS: Between October 2007 and December 2012, 6101 eligible workers enrolled in the health programme. The prevalence of vitamin D deficiency (plasma 25(OH)D, levels <27.5 nmol/l) and insufficiency (<37.5 nmol/l) were 3 and 8%, respectively. Male employees were significantly more likely to be vitamin D deficient and insufficient than females. Residing at a more northern latitude increased the likelihood of vitamin D deficiency and insufficiency. Age, assessments made in summer, better general health and physical activity and use of vitamin D supplementation were all related to lower likelihood of deficiency and insufficiency. CONCLUSIONS: Vitamin D deficiency and insufficiency are a concern in this sample of Canadian workers. Vitamin D supplementation is recommended to reduce the prevalence of deficiency and insufficiency in this group.

Glucose-lowering agents and cancer mortality rates in type 2 diabetes: assessing effects of time-varying exposure.

AIMS/HYPOTHESIS: We explored the relationship between glucose-lowering agents and cancer mortality rates in type 2 diabetes patients, hypothesising a decreased risk of cancer mortality with metformin use and a dose-risk gradient for insulin therapy. METHODS: This was a population-based cohort study using administrative data from Saskatchewan Health, Canada. We identified new users of metformin or sulfonylureas from 1 January 1991 to 31 December 1996, with follow-up until death, departure from the province or 31 December 1999. Cox regression analyses were used to estimate the HR of death from cancer, accounting for time-varying exposure to metformin, sulfonylurea, and exogenous insulin therapy. RESULTS: We identified 10,309 new users of metformin or sulfonylurea. The average follow-up was 5.4 (1.9) years, during which 407 (4.0%) cancer deaths occurred. Adjusting for age, sex and chronic disease score, the adjusted HR for metformin use was 0.80 (95% CI 0.65-0.98) compared with sulfonylurea monotherapy users. Adjusted HRs for subsequent insulin use were 2.22 (0.99-5.00), 3.33 (2.26-4.89) and 6.40 (4.69-8.73) for <3, 3 to 11 and > or = 12 insulin dispensations/year, respectively, compared with patients not on insulin. We observed a similar risk gradient among the sub-cohort of new insulin users. CONCLUSIONS/INTERPRETATION: Our results support previous reports of a decreased risk of cancer outcomes associated with metformin use relative to sulfonylurea monotherapy. We also provide new evidence of a gradient of cumulative insulin dispensations and cancer mortality rates.

Sociodemographic and neighbourhood determinants of health-related quality of life among grade-five students in Canada.

OBJECTIVES: To describe the health-related quality of life (HRQOL) of grade-five students in Alberta, Canada, and to assess how this correlates with sociodemographic and neighbourhood characteristics. METHODS: In 2008, we conducted a comprehensive population-based survey among 3,421 grade-five students aged primarily 10-11 years from 148 schools and their parents that included questions on sociodemographic and neighbourhood factors. The HRQOL of the students was assessed using the EQ-5D Canadian English child version (EQ-5D-Y). We applied multilevel multivariable linear regression to examine the independent importance of sociodemographic and neighbourhood factors for the EQ-5D-Y index and EQ-5D-Y Visual Analogue Scale (VAS) score. RESULTS: In five EQ-5D-Y dimensions, problems with 'walking', 'looking after myself', 'usual activities', 'pain or discomfort' and 'worried, sad or unhappy' were reported by 8.1% (n = 288), 6.5% (n = 215), 11.8% (n = 431), 46.0% (n = 1600), and 37.7% (n = 1292) of students, respectively. Their mean EQ-5D-Y index was 0.86 and mean EQ-5D-Y VAS was 80.4. Children from families reporting higher educational attainment reported higher HRQOL both in terms of a higher EQ-5D-Y index and in terms of a higher EQ-5D-Y VAS. Also, children residing in neighbourhood characterized as providing good satisfaction and facilities reported higher HRQOL. CONCLUSIONS: Public health initiatives to improve HRQOL among children are suggested to take into account the influence of different sociodemographic and neighbourhood characteristics such that priority is given to those residing in towns, rural areas and dissatisfying neighbourhoods with poor access to recreational facilities and stores for fresh products.

Disease progression among multiple sclerosis patients before and during a disease-modifying drug program: a longitudinal population-based evaluation.

Randomized controlled trials have demonstrated the efficacy of disease-modifying drugs (DMDs) in persons with relapsing-remitting multiple sclerosis (MS) and secondary progressive MS with superimposed relapses. However, these brief studies of selected patients have focused mainly on reducing attacks and must be complemented by evaluations in 'realworld' clinical settings to establish the effectiveness of DMD programs in slowing disease progression and to inform health policy and program decision-making. We assessed the effectiveness of DMDs as administered in a comprehensive publicly funded drug insurance program that provides DMDs to a geographically defined population of MS patients who meet specific eligibility criteria. Data from 1752 MS patients (10,312 assessments) seen between 1980 and 2004 at a regional MS Clinic serving the entire population of Nova Scotia, Canada were analysed. Using survival methods we observed a statistically significant reduction in disease progression to specific Expanded Disability Status Scale endpoints following the introduction of this program. Subgroup analyses of patients eligible for treatment using hierarchical linear regression methods also suggested that disease progression was slowed in patients treated with the first DMD prescribed. These findings provide evidence supporting DMD program effectiveness that can be used to inform the broader implementation of such programs.

Fourteen years of surveillance of HIV-1 prevalence among pregnant women attending antenatal care clinics in western Uganda.

This study monitored long-term temporal trends in HIV-1 prevalence in antenatal clinic attendees living in western Uganda. Semi-annual data collection was done from 1991 to 2004. For each woman the following data were recorded: HIV-1 status, age, educational status, marital status, occupation and parity. The results show that the overall HIV-1 prevalence was 15.3% during the entire time period (urban 21.3%, semi-urban 12.7% and rural 7.1%). Between 1991 and 2004, we observed a gradual decline in the HIV-1 prevalence. The decline was most pronounced in urban women aged 15-19 years old and least pronounced in rural women aged 20-24 years. Women above 25 years of age did not show any decline in HIV-1 prevalence over time. The declining HIV-1 prevalence in the younger age groups (15-24 years) likely represents a declining risk for acquiring HIV infection as we have previously shown in the urban sub-sample of this data set.

Comparison of progression and non-progression in injecting drug users and homosexual men with documented dates of HIV-1 seroconversion. European Seroconverter Study and the Tricontinental Seroconverter Study.

OBJECTIVE: To compare the progression and non-progression of HIV infection among 418 injecting drug users (IDU) and 422 homosexual men with documented dates of HIV seroconversion from 12 cohorts. METHODS: Seroconversion dates were calculated for each subject using a cohort-specific estimate of the cumulative HIV seroincidence over calendar time. In survival analysis, we studied the progression from seroconversion to AIDS and death by risk group. We compared non-progression between both risk groups by evaluating annual CD4 decline over the 7 years following seroconversion among AIDS-free subjects. RESULTS: The relative hazard (RH) of AIDS for homosexual men compared with IDU was 1.54 before, and 1.21 after, adjusting for age at seroconversion and year of seroconversion. The risk of death from any cause for homosexual men compared with IDU increased over time since seroconversion. Fifty IDU died prior to AIDS, compared with seven homosexual men (unadjusted RH for homosexual men 0.10). Ignoring this pre-AIDS mortality, the crude RH of death for homosexual men compared with IDU was 2.05. Alter adjusting for age at seroconversion and year of seroconversion in multivariate analysis, the RH became 1.42. No differences in progression between subgroups aged 24 years or older could be demonstrated, but subjects < 24 years were found to be at a decreased risk. Proportions of non-progressors based on CD4 slope > or = 0 at 7 years following seroconversion were higher for IDU than for homosexual men. No differences were found in the proportion (approximately 5%) classified as non-progressors by criteria of both slope > or = 0 and absolute CD4 counts > 500 cells x 10(6)/l, even if pre-AIDS deaths and losses to follow-up were included. CONCLUSIONS: We found little evidence for an effect of risk group on progression and non-progression. Pre-AIDS mortality was much higher among IDU than homosexual men. Pre-AIDS mortality and a nonlinear age effect should be considered in planning interventions as well as studies comparing risk groups and modelling the epidemic.

The epidemiology of HIV-associated Kaposi's sarcoma: the unraveling mystery.

Unraveling the mysteries associated with the etiology of KS is of tremendous public health significance. Whereas the introduction of prophylaxis has led to a decreased incidence of Pneumocystis carinii pneumonia, the incidence of KS has remained relatively stable and treatment of the HIV-infected KS patient remains a challenge. The last year has brought forth significant breakthroughs in KS research. Although KSHV has only recently been described, rapid progress is being made in understanding the role of this virus in the pathophysiology of the various forms of KS. It is too early to conclude whether KSHV is the elusive 'KS cofactor' or if all forms of KS share a common etiology, but it appears to be the single most plausible agent to be identified to date. Since all cancers are multifactorial in origin, it is likely that other host, environmental and possibly other viral cofactors could influence the risk of developing KS. The search for such cofactors must continue. Even if KSHV plays a central role, the exact mechanisms by which HIV and KSHV may interact to induce KS lesions, the tendency for KS to occur among homosexual men relative to other HIV transmission groups, and the reasons for the aggressive course of this neoplasm in HIV-infected persons remain to be determined. If a causal association can be established, KSHV could provide a model for the understanding of virus-induced neoplasia, like its cousin EBV. Although important questions regarding the specificity and temporality of KSHV and KS remain unanswered, the development and application of a sensitive serodiagnostic tool in longitudinal studies will be a crucial next step.

Increasing age is associated with faster progression to neoplasms but not opportunistic infections in HIV-infected homosexual men.

OBJECTIVE: To characterize the associations of age and progression rates to AIDS-defining neoplasms and opportunistic infections (OI) in HIV-infected homosexual men. METHODS: Data from 407 homosexual men with documented dates of HIV seroconversion participating in cohort studies from four geographic locations were merged. Kaplan-Meier and Cox proportional hazards analyses were conducted with respect to the association of age with time from seroconversion to the first AIDS-defining neoplasm and OI. RESULTS: Among the 407 participants, 139 (34%) were diagnosed with AIDS; 45 (11%) with neoplasms and 90 (22%) with OI. Older age at seroconversion was significantly associated with faster progression to neoplasms, but not to OI. For each 10-year increase in age the risk for neoplasms increased 1.65-fold [95% confidence interval (CI), 1.12-2.43], after adjustment for clinical treatments. For OI this risk estimate was 0.98 (95% CI, 0.72-1.34). CONCLUSIONS: Increasing age is associated with faster progression to AIDS-defining neoplasms, but not with progression to OI. This has not been previously reported and may explain conflicting results in other studies among homosexual men that considered AIDS as a single entity. Our findings suggest that age and AIDS manifestations should be considered, particularly in the context of natural history studies, clinical trials and mathematical modelling.

Lack of consistency between five definitions of nonprogression in cohorts of HIV-infected seroconverters.

OBJECTIVE: To identify appropriate criteria for characterizing HIV-infected nonprogressors. DESIGN: Five definitions were compared as follows: (1) last CD4 count > 500 x 10(6)/l; (2) two most recent CD4 counts > 500 x 10(6)/l; (3) calculated CD4 count based on linear regression > 500 x 10(6)/l; (4) CD4 slope > or = 0 with no antiretroviral use; (5) all CD4 counts > 500 x 10(6)/l, decline in CD4 slope < 5 cells per year, no antiretroviral use. PARTICIPANTS: Five prospective cohorts of homosexual men with documented dates of HIV-1 seroconversion. MAIN OUTCOME MEASURES: Proportions of nonprogressors were calculated 7, 8, 9 and 10 years following seroconversion (n = 285). Definitions were evaluated with respect to consistency over time and across sites. Subjects lacking CD4 counts within 3 years preceding end of follow-up were excluded. RESULTS: Across sites, proportions of nonprogressors ranged from 1% (definition 5) to 17.5% (definition 1) 10 years after seroconversion. Definitions based on absolute CD4 counts (definitions 1-3) had higher proportions and were less consistent than those based on stable slopes (definitions 4 and 5). For each definition, proportions decreased as follow-up increased, but were most stable for definition 4 (3%). Site differences decreased as follow-up increased, but remained nearly threefold for definitions 1-3. None of the definitions classified the same subjects as nonprogressors at any timepoint. CONCLUSIONS: Observations regarding nonprogression are highly dependent on the definition and the duration of follow-up. Our findings highlight methodological challenges which will need to be overcome in natural history studies of nonprogression.

Is AIDS a floating point between HIV seroconversion and death? Insights from the Tricontinental Seroconverter Study.

OBJECTIVE: To investigate the significance of the time from seroconversion to AIDS (incubation time) and other covariates for survival from AIDS to death. METHODS: In survival analysis, survival from AIDS to death was compared for different categories of length of incubation time adjusted and unadjusted for other covariates, and significant predictors for survival from AIDS to death were investigated. RESULTS: Survival after AIDS was not affected by the incubation time in univariate as well as in multivariate analyses. Predictive factors for progression from AIDS to death were age at seroconversion, type of AIDS diagnosis, and CD4 cell count at AIDS. The relative hazard for age at seroconversion increased 1.38-fold over 10 years. Men with a CD4 cell count at AIDS of <130 x 10(6)/l had a twofold higher risk in progression to death than men with higher CD4 cell counts. Persons diagnosed with lymphoma had a sixfold higher risk of progression to death than persons with Kaposi's sarcoma or opportunistic infections. CONCLUSIONS: The incubation time as well as other factors before AIDS did not affect survival after AIDS. Survival from AIDS to death can be predicted by data obtained at the time of AIDS diagnosis, such as type of diagnosis, age and CD4 cell count. AIDS seems to be a significant point in progression to death, and not just a floating point between infection and death affected by prior factors for persons who did not receive effective therapy and did not have long incubation times.

Early and late HIV-1 RNA level and its association with other markers and disease progression in long-term AIDS-free homosexual men.

OBJECTIVE: To study the association between virological markers and clinical progression in individuals with long-term AIDS-free HIV infection. DESIGN: Seventy-seven HIV-infected participants in the Amsterdam cohort study who remained AIDS-free for at least 8 years were prospectively followed during that time and during a subsequent period in which 15 developed AIDS. METHODS: Serum HIV-1 RNA levels were evaluated at 1 and 8 years after study entry. Progression to AIDS following the 8 AIDS-free years was studied using Kaplan-Meier estimates and Cox proportional hazard analysis. RESULTS: HIV-1 RNA increased over time in a large proportion of these long-term AIDS-free men. Most subjects showed progressive immune system damage and/or clinical manifestations of HIV disease at year 8. High RNA levels at year 8 were significantly associated with symptomatic HIV Infection, low CD4+ T-cell count, p24 antigenaemia, low T-cell reactivity at year 8 as well as rapid annual CD4+ T-cell decline. High RNA level at year 1 was associated with high RNA levels at year 8 and low CD4+ T-cell count at year 1. In univariate analysis, RNA was associated with progression to AIDS after 8 years. In multivariate analysis, only the CD4+ T-cell count at year 8 remained significantly associated with progression to AIDS. CONCLUSIONS: In later stages of HIV infection, measures of immune deficiency may be more powerful prognostic markers than serum HIV-1 RNA level, indicating that optimal staging of the HIV-infected patient requires the combined use of RNA levels, CD4+ T-cell counts, and T-cell reactivity instead of RNA levels alone.

Differences in time from HIV seroconversion to CD4+ lymphocyte end-points and AIDS in cohorts of homosexual men.

OBJECTIVE: To evaluate the decline in CD4+ counts in relation to the incidence of AIDS in different cohorts of homosexual men and to quantify possible consequences of laboratory variation in CD4+ measurement. METHODS: Our study includes 403 men with well documented dates of HIV seroconversion originating from five cohort studies among homosexual men. Differences in time from HIV seroconversion to the first CD4+ count dropping < 500 or 200 x 10(6)/l and to AIDS were evaluated using Kaplan-Meier survival analyses. RESULTS: We found considerable differences between cohorts in CD4+ depletion, but not in the incidence of AIDS (1987 definition). CONCLUSIONS: Variation in CD4+ depletion appears to be mainly the result of laboratory differences. Policy recommendations on a basis of CD4+ counts probably requires a calibration of measurement. The 1993 AIDS case definition leads to a site-specific shortening of the incubation time, which complicates the study of the natural history of HIV infection and of trends in the AIDS epidemic.

An outbreak of hepatitis A among homosexual men in Amsterdam, 1991-1993.

BACKGROUND: When in August 1992 it became evident that an outbreak of hepatitis A virus infections (HAV) was taking place in the male homosexual community in Amsterdam a case-control study was conducted to validate the assumption that the outbreak was associated with sexual practices involving oro-anal and digital-anal contact and frequent visits to gay saunas and darkrooms. METHODS: In all, 37 cases reported to the Amsterdam Municipal Health Service (AMHS) in the period December 1991 to March 1993 and 68 anti-HAV negative controls completed an anonymous questionnaire concerning the practice of different sexual techniques and the number of visits to gay saunas and darkrooms in the 2 months preceding the onset of illness or date of interview. Controls were recruited from healthy homosexual men participating in a prospective study on HIV/AIDS conducted by the AMHS. RESULTS: In univariate analysis a statistically significant association was found between visits to gay saunas and darkrooms, the number of visits to these locations (OR = 8.2) and HAV infection. In the logistic regression analysis the association for visits to saunas and darkrooms remained significant (OR = 10) whereas high-risk sexual techniques could not be included in the model. CONCLUSIONS: These results indicate that to prevent future outbreaks of HAV in male homosexuals in Amsterdam there is a need to stress in the 'safe sex' campaigns, directed at the prevention of HIV infection or in additional campaigns, the prevention of other sexually transmitted disease including HAV infection with emphasis on routes associated with certain sexual techniques and on visits to gay saunas and darkrooms.

Secular trends in the survival of HIV-infected homosexual men in Amsterdam and Vancouver estimated from a death-included CD4-staged Markov model.

BACKGROUND: The purpose of this study was to investigate secular trends in waiting times in CD4-based stages of human immunodeficiency virus (HIV) disease progression in two cohorts of homosexual men, one in Vancouver and one in Amsterdam. All HIV-positive men with two or more CD4 counts in their AIDS-free period between 1 January 1985 and 1 January 1997 were included in this study. Data regarding clinical AIDS diagnoses (using the 1987 Centers for Disease Control and Prevention [CDC] AIDS case definition) and death were collected through active follow-up, review of hospital records, and municipal/national registries. The Vancouver Lymphadenopathy-AIDS Study (VLAS), was started in November 1982 and had enrollment until December 1984. Both HIV-negative and HIV-positive men were followed at intervals of 3-6 months until 1986 and annually thereafter. The Amsterdam cohort study on HIV and AIDS (ACS) started in December 1984, has ongoing enrollment and follow-up of both HIV-negative and HIV-positive homosexual men. The HIV-positive men were followed at intervals of 3 months. METHODS: The CD4-based stage of an individual at each visit was determined using smoothed data. For each cohort and in each calendar time period, a CD4-based Markov model with death as the absorbing stage was fitted to the data. The parameters in this model were estimated using the method of maximum likelihood and confidence intervals were calculated using bootstrap methods. RESULTS: A total of 509 homosexual men participating in the VLAS were included in this study, providing 5356 visits. Some 292 men developed AIDS before 1 January 1997 and 239 died before this date. In all, 232 of the 239 deaths were AIDS related. Thirty-seven per cent of all visits were related to treatment. A total of 543 homosexual men participating in the ACS were included in this study, providing 10 043 visits; 277 men developed AIDS before 1 January 1997 and 250 died before this date. The date of AIDS diagnosis was known for 225 of the 250 deaths. Twenty per cent of all visits were related to treatment. We found that in both cohort studies the stage-specific waiting times were longer in the low CD4-based stages (stages 4, 5 and 6: i.e. CD4 count <500 cells per mm(3)) after March 1990 compared to waiting times before March 1990. The increase in mean waiting time in these stages with low CD4 count was 21%, 33% and 53%, respectively in the ACS and 20%, 2% and 29% in the VLAS. Because waiting times alone are not exclusive for progression in a reversible model we also calculated the stage-specific median incubation periods till death. Men spent considerably longer in these CD4-based stages after March 1990 compared to before March 1990. CONCLUSIONS: Data from these population-based cohort studies showed that HIV disease progression in the calendar period where treatment was administered was slower for individuals in stages with low CD4 counts. We found no evidence for shortening of the incubation period that may have appeared from increasing virulence of the HIV in the population.

Socioeconomic disparities in health care use: Does universal coverage reduce inequalities in health?

BACKGROUND: Despite enormous public sector expenditures, the effectiveness of universal coverage for health care in reducing socioeconomic disparities in health has received little attention. STUDY OBJECTIVE: s: To evaluate whether universal coverage for health care reduces socioeconomic disparities in health. DESIGN: Information on participants of the 1990 Nova Scotia Nutrition Survey was linked with eight years of administrative health services data and mortality. The authors first examined whether lower socioeconomic groups use more health services, as would be expected given their poorer health status. They then investigated to what extent differential use of health services modifies socioeconomic disparities in mortality. Finally, the authors evaluated health services use in the last years of life when health is poor regardless of a person's socioeconomic background. SETTING: The Canadian province of Nova Scotia, which provides universal health care coverage to all residents. PARTICIPANTS: 1816 non-institutionalised adults, aged 18-75 years, from a two stage cluster sample stratified by age, gender, and region. MAIN RESULTS: People with lower socioeconomic background used comparatively more family physician and hospital services, in such a way as to ameliorate the socioeconomic differences in mortality. In contrast, specialist services were comparatively underused by people in lower socioeconomic groups. In the last three years of life, use of specialist services was significantly higher in the highest income group. CONCLUSIONS: Universal coverage of family physician and hospital services ameliorate the socioeconomic differences in mortality. However, specialist services are underused in lower socioeconomic groups, bearing the potential to widen the socioeconomic gap in health.

Inequalities in health. Analytic approaches based on life expectancy and suitable for small area comparisons.

STUDY OBJECTIVE: Simple measures of inequalities in health are proposed to facilitate the work of health policy makers and to build on the understanding of health differences between populations. In addition, it is aimed to make these measures applicable for comparisons of small populations and subgroups. METHODS: Inequalities in health or health deficiencies were quantified as the difference between the life expectancy of the subgroup of interest and that of the national population. Health deficiencies were divided into disease specific components by partial application of cause eliminated life table methods. To manage small numbers and to depict time trends, locally weighted regression smoothing was applied. Confidence intervals were constructed through Monte Carlo simulations. APPLICATIONS AND COMPARISONS: The proposed approaches were applied to the health situation in Cape Breton County, Nova Scotia, Canada, and disclosed the significance of different diseases and distinct patterns between communities. The proposed measures were also compared with the traditionally used standardised mortality rates and ratios. Here, the proposed measures appeared beneficial in that they are easier to comprehend and that they provide time trends and more robust estimates. CONCLUSIONS: The above advantages make the proposed approaches beneficial to health policy makers and epidemiologists. The approaches may also be incorporated in economic evaluations as well as in more sophisticated public health models.