A comparison of exposure assessment approaches: lung cancer and occupational asbestos exposure in a population-based case-control study.

OBJECTIVES: In attempts to overcome the limitations of self-reported data in occupational health research, job-exposure matrices, which assign exposure by occupation, have emerged as an objective approach for assessing occupational exposures. On the basis of a lung cancer case-control study conducted in the Greater Toronto Area, 1997-2002, assessment of occupational exposure to asbestos was compared using self-reports and a general population job-exposure matrix (DOM-JEM). METHODS: Cases and frequency matched controls provided life-time job histories and self-reported exposures to potential lung carcinogens including asbestos through a detailed questionnaire. Exposure to asbestos was also assigned to each job by linking occupational histories with DOM-JEM. Agreement in classification of exposed and unexposed jobs according to self-reports and DOM-JEM was evaluated using Cohen's κ. Risks for lung cancer were estimated using unconditional logistic regression for each exposure assessment approach. RESULTS: The prevalence of occupational asbestos exposure was greater when based on DOM-JEM than when based on self-reports. Agreement in classifying exposure to jobs between the two assessment approaches was poor. The risk of lung cancer was not elevated among workers who self-reported asbestos exposure, whereas workers considered exposed on the basis of DOM-JEM were almost twice as likely as unexposed workers to be diagnosed with lung cancer (OR 1.9, 95% CI 1.3 to 2.7). CONCLUSIONS: It is generally assumed by epidemiologists that self-reported exposure assessments result in inflated risk estimates. In this study, self-reports found no association with a well-established risk factor, whereas a high-quality job-exposure matrix revealed relative risk estimates that are more consistent with previous findings.

The accuracy of self-reported smoking: a systematic review of the relationship between self-reported and cotinine-assessed smoking status.

INTRODUCTION: Smoking is a leading cause of premature mortality and preventable morbidity. Surveillance is most often based on self-reported data, but studies have shown that self-reports tend to underestimate smoking status. METHODS: This study systematically reviewed the literature to measure the concordance between self-reported smoking status and smoking status determined through measures of cotinine in biological fluids. Four electronic databases were searched to identify observational and experimental studies on adult populations over the age of 18 years. RESULTS: Searching identified 67 studies that met the eligibility criteria and examined the relationship between self-reported smoking and smoking confirmed by cotinine measurement. Overall, the data show trends of underestimation when smoking prevalence is based on self-report and varying sensitivity levels for self-reported estimates depending on the population studied and the medium in which the biological sample is measured. Sensitivity values were consistently higher when cotinine was measured in saliva instead of urine or blood. Meta-analysis was not appropriate because of the substantial heterogeneity among the cutpoints used to define smokers and the poor reporting on outcomes of interest. DISCUSSION: Further research in this field would benefit from the standardization of cutpoints to define current smokers and the implementation of standard reporting guidelines to enhance comparability across studies. Accurate estimation of smoking status is important as data from population studies such as those included in this review are used to generate regional and national estimates of smoking status and in turn are used to allocate resources and set health priorities.

A comparison of direct versus self-report measures for assessing physical activity in adults: a systematic review.

BACKGROUND: Accurate assessment is required to assess current and changing physical activity levels, and to evaluate the effectiveness of interventions designed to increase activity levels. This study systematically reviewed the literature to determine the extent of agreement between subjectively (self-report e.g. questionnaire, diary) and objectively (directly measured; e.g. accelerometry, doubly labeled water) assessed physical activity in adults. METHODS: Eight electronic databases were searched to identify observational and experimental studies of adult populations. Searching identified 4,463 potential articles. Initial screening found that 293 examined the relationship between self-reported and directly measured physical activity and met the eligibility criteria. Data abstraction was completed for 187 articles, which described comparable data and/or comparisons, while 76 articles lacked comparable data or comparisons, and a further 30 did not meet the review's eligibility requirements. A risk of bias assessment was conducted for all articles from which data was abstracted. RESULTS: Correlations between self-report and direct measures were generally low-to-moderate and ranged from -0.71 to 0.96. No clear pattern emerged for the mean differences between self-report and direct measures of physical activity. Trends differed by measure of physical activity employed, level of physical activity measured, and the gender of participants. Results of the risk of bias assessment indicated that 38% of the studies had lower quality scores. CONCLUSION: The findings suggest that the measurement method may have a significant impact on the observed levels of physical activity. Self-report measures of physical activity were both higher and lower than directly measured levels of physical activity, which poses a problem for both reliance on self-report measures and for attempts to correct for self-report - direct measure differences. This review reveals the need for valid, accurate and reliable measures of physical activity in evaluating current and changing physical activity levels, physical activity interventions, and the relationships between physical activity and health outcomes.

Are we ready? Evidence of support mechanisms for Canadian health care workers in multi-jurisdictional emergency planning.

BACKGROUND: Federal, provincial and municipal leaders in Canada have adopted a culture of preparedness with the development and update of emergency plans in anticipation of different types of disasters. As evident during the 2003 global outbreak of Severe Acute Respiratory Syndrome (SARS), it is important to provide support for health care workers (HCWs) who are vulnerable during infectious outbreak scenarios. Here we focus on the identification and evaluation of existing support mechanisms incorporated within emergency plans across various jurisdictional levels. METHODS: Qualitative content analysis of 12 emergency plans from national, provincial and municipal levels were conducted using NVIVO software. The plans were scanned and coded according to 1) informational, 2) instrumental, and 3) emotional support mechanisms for HCWs and other first responders. RESULTS: Emergency plans were comprised of a predominance of informational and instrumental supports, yet few emotional or social support mechanisms. All the plans lacked gender-based analysis of how infectious disease outbreaks impact male and female HCWs differently. Acknowledgement of the need for emotional supports was evident at higher jurisdictional levels, but recommended for implementation locally. CONCLUSIONS: While support mechanisms for HCWs are included in this sample of emergency plans, content analysis revealed few emotional or social supports planned for critical personnel; particularly for those who will be required to work in extremely stressful conditions under significant personal risk. The implications of transferring responsibilities for support to local and institutional jurisdictions are discussed.