Parkinson's disease and occupation: differences in associations by case identification method suggest referral bias.

Methods: We used a population-based sample of 403 Parkinson's disease cases and 405 controls to examine risks by occupation. Results were compared to a previous clinic-based analysis.

Results: With censoring of jobs held within 10 years of diagnosis, the following had significantly or strongly increased risks: social science, law and library jobs (OR = 1.

Head injuries and Parkinson's disease in a case-control study.

Background: Head injury is a hypothesised risk factor for Parkinson's disease, but there is a knowledge gap concerning the potential effect of injury circumstances (eg, work-related injuries) on risk. The objective of this study is to address this gap while addressing issues of recall bias and potential for reverse causation by prediagnosis symptoms.

Methods: We conducted a population based case-control study of Parkinson's disease in British Columbia, Canada (403 cases, 405 controls).

Occupational exposure to whole-body vibration and Parkinson's disease: results from a population-based case-control study.

Mechanical stress producing head injury is associated with Parkinson's disease, suggesting that relations with other physical hazards such as whole-body vibration (WBV) should be tested. In this study, the authors evaluated the relation between occupational exposure to WBV and Parkinson's disease. A population-based case-control study with 403 cases and 405 controls was conducted in British Columbia, Canada, between 2001 and 2008.

Association of Parkinson's disease with infections and occupational exposure to possible vectors.

The ultimate causes of idiopathic Parkinson's disease (PD) are not fully known, but environmental and occupational causes are suspected. Postencephalitic parkinsonism has been linked to influenza, and other viral infections have also been suspected to relate to PD. We estimated the relationship between PD and both infections and possible vectors of infection (i.

Pesticide exposure and risk of Parkinson's disease--a population-based case-control study evaluating the potential for recall bias.

Objective: The aim of this study was to investigate whether pesticide exposure was associated with Parkinson's disease in a population-based case-control study in British Columbia, Canada.

Methods: Patients reimbursed for anti-parkinsonian agents were identified and screened for eligibility as cases. Controls were selected from the universal health insurance database, frequency-matched to the case sample on birth year, gender, and geographic region.

Public opinions about participating in health research.

Objectives: Privacy legislation has limited options for recruiting subjects to health studies. Policy changes are motivated by assumptions about public attitudes towards participation, yet surveys of attitudes have rarely been done. We investigated public willingness to participate in health research and how willingness was affected by various factors.

In-hospital death of critically ill patients who have congestive heart failure: does size of hospital matter?

Data from the British Columbia Linked Health Database were analyzed to determine if size of hospital is associated with in-hospital death of critically ill adults whose admitting diagnosis is congestive heart failure (CHF). Patients who were <19 years of age, transferred from or to other hospitals, or who developed CHF as a complication were excluded. In unadjusted logistic regression analysis of 2616 patients, the odds ratio (OR) for in-hospital death associated with a doubling of the number of hospital beds was 1.

The effect of patterns of infectiousness on epidemic size.

In the course of an infectious disease in a population, each infected individual presents a different pattern of progress through the disease, producing a corresponding pattern of infectiousness. We postulate a stochastic infectiousness process for each individual with an almost surely finite integral, or total infectiousness. Individuals also have different contact rates.

Bimodal epidemic size distributions for near-critical SIR with vaccination.

We introduce a recursive algorithm which enables the computation of the distribution of epidemic size in a stochastic SIR model for very large population sizes. In the important parameter region where the model is just slightly supercritical, the distribution of epidemic size is decidedly bimodal. We find close agreement between the distribution for large populations and the limiting case where the distribution is that of the time a Brownian motion hits a quadratic curve.

Participant-collected, mail-delivered oral fluid specimens can replace traditional serosurveys: a demonstration-of-feasibility survey of hepatitis A virus-specific antibodies in adults.

Background: Although population-based serosurveys offer an optimal measure of cumulative infection rates, they are seldom performed due to high cost and complex logistics. Use of participant self-collected oral fluid as a diagnostic specimen and mail for specimen delivery has the potential of generating reliable, population-representative data at limited cost.

Methods: A survey of oral fluid HAV-specific immunoglobulin G (an indicator of past HAV infection) was undertaken in a provincially representative sample of 20-39 year olds as a pilot study.

Mixed models and empirical bayes estimation for retrospective exposure assessment of dust exposures in Canadian sawmills.

Objectives: Data on job histories is commonly available from study subjects and worksites, therefore jobs are often used for assigning exposures in historical epidemiological studies. Exposure estimates are often derived by offering jobs as fixed effects in statistical models. An alternative approach would be to offer job as a random effect to obtain empirical Bayes estimates of exposure.

Enzyme immunoassay of Cryptosporidium-specific immunoglobulin G antibodies to assess longitudinal infection trends in six communities in British Columbia, Canada.

A newly developed enzyme-linked immunosorbent assay (ELISA) that detects immunoglobulin G antibodies to the 27-kDa Cryptosporidium parvum sporozoite surface antigen was used to test 4,097 sera collected from pregnant women in 6 communities in British Columbia, Canada, between January 1996, and December 1997. Waterborne outbreaks of cryptosporidiosis occurred in two of the study communities during the period of follow-up, and ELISA seropositivity was high in all six communities during the study period (77% positive to 92% positive). In the community with the largest outbreak, levels of antibody to the 27-kDa antigen increased rapidly and then decayed to background levels within 3-4 months of the peak of the epidemic curve.

Back to work: correlates of employment among persons receiving highly active antiretroviral therapy.

The aim of this study was to quantify the level of employment at one-year and to determine potential predictors of future employment among HIV-positive persons on highly active antiretroviral therapy (HAART) in the province of British Columbia. Of the 392 individuals that were initially unemployed at baseline 63 (16.1%) found a job over the subsequent year.

Are questions from the Italian National Health Survey adequate to measure prevalence of smoking among teens.

Objectives: Studies on the prevalence of smoking among Italian adolescents have generated inconsistent estimates. Notably, the Italian National Health Survey (INHS) generates relatively lower estimates than estimates reported in other studies. The INHS asks adults and adolescents if they are smokers or nonsmokers.

Estimating mortality rates: the role of proportional life expectancy.

The computation of long-term survival is usually based on adjustments to the conventional life table. Assessing the validity of different types of adjustments can be difficult, partly because of the need to allow for two age-related trends-the decline in the average (normal) life expectancy, as well as in the new (abnormal) estimate. In this paper, we illustrate the value of routinely expressing each new estimate as a percentage of normal at each age.

Reducing attenuation in exposure-response relationships by exposure modeling and grouping: the relationship between wood dust exposure and lung function.

Background: In a study of wood dust exposure and lung function, we tested the effect on the exposure-response relationship of six different exposure metrics using the mean measured exposure of each subject versus the mean exposure based on various methods of grouping subjects, including job-based groups and groups based on an empirical model of the determinants of exposure.

Methods: Multiple linear regression was used to examine the association between wood dust concentration and forced expiratory volume in 1s (FEV(1)), adjusting for age, sex, height, race, pediatric asthma, and smoking.

Results: Stronger point estimates of the exposure-response relationships were observed when exposures were based on increasing levels of aggregation, allowing the relationships to be found statistically significant in four of the six metrics.

Highly active antiretroviral therapy: physician experience and enhanced adherence to prescription refill.

Objective: To identify patient and physician characteristics that may act as determinants of adherence to prescription refill of triple combination antiretroviral therapy.

Methods: A population-based analysis of antiretroviral therapy-naive HIV-positive men and women in British Columbia, Canada, who initiated triple combination therapy between August 1 1996 and October 31 1998. Study participants were considered adherent if they were actually dispensed antiretrovirals > or = 95% over the first year of therapy.

How does direct-to-consumer advertising (DTCA) affect prescribing? A survey in primary care environments with and without legal DTCA.

Background: Direct-to-consumer advertising (DTCA) of prescription drugs has increased rapidly in the United States during the last decade, yet little is known about its effects on prescribing decisions in primary care. We compared prescribing decisions in a US setting with legal DTCA and a Canadian setting where DTCA of prescription drugs is illegal, but some cross-border exposure occurs.

Methods: We recruited primary care physicians working in Sacramento, California, and Vancouver, British Columbia, and their group practice partners to participate in the study.

Oculo-respiratory syndrome: a new influenza vaccine-associated adverse event?

During the 2000-2001 influenza immunization campaign in Canada, a new adverse event, oculo-respiratory syndrome (ORS), was noted in association with administration of vaccine supplied by one manufacturer. The original case definition for ORS specified bilateral conjunctivitis, facial edema, or respiratory symptoms beginning 2-24 h after influenza vaccination and resolving within 48 h after onset. To characterize the spectrum, severity, and impact of ORS, we contacted persons who had reported any influenza vaccine-associated adverse event in British Columbia, Canada, during the 2000-2001 vaccination campaign.

Clinical decision analysis in the treatment of acute otitis media in a child over 2 years of age.

Acute otitis media (AOM) is the most common infection diagnosed in children. In Canada and the United States, the standard of care for treatment of children over 2 years of age diagnosed with AOM is a course of antibiotics for 5 to 10 days. However, in other countries, treatment is primarily symptomatic, and antibiotics are prescribed only if symptoms fail to resolve.