A Cohort Study Of Cancer Incidence Among Seattle And Tacoma Firefighters

Author : Ash M. Genaidy
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (612 download)

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Download or read book Cancer Risk Among Firefighters written by Ash M. Genaidy and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The work carried out in this research was initiated as a result of the inquiry of the State of Ohio Bureau of Worker's Compensation into the extent of cancer risk among firefighters. Because there is limited information on the availability of procedures for evaluation of the methodological qualities of observational studies, the goal of Part one was to develop and test a general purpose "Epidemiological Appraisal Instrument (EAI)" for evaluating existing studies using a critical appraisal system rooted in epidemiological principles. A pilot EAI version was developed and tested by a research team consisting of three epidemiologists, two physicians, and two biostatisticians. The EAI consisted of 43 questions grouped into six scales (reporting or study description, study execution, subject selection, measurement quality, data analysis, and generalization of results). The pilot version was further tested with respect to other raters with considerable and minimal background in epidemiology and biostatistics. A revised version was again developed and its criterion validity and reliability was examined. An assessor with basic background in epidemiology and biostatistics was shown to be able to correctly respond on four out of five questions. On average, the assessor performance improved with the quality of the article. The inter-rater degree of agreement was largely above 90% and the assessors resolved their differences in subsequent rounds. The preliminary application of EAI to meta-analysis suggests that the inclusion of the overall quality into the calculations may reduce heterogeneity and improve the meta-risk estimate. The EAI proved to be a valid (e.g., criterion validity between experienced epidemiologist and other assessors with considerable background in epidemiology and biostatistics) d reliable (e.g., inter-rater agreement) appraisal instrument that may be used in various applications, such as systematic reviews and meta-analyses. The goals of Part two were three-fold: (1) to systematically review and critically appraise studies on cancer risk among firefighters on the basis of sound epidemiological principles using the EAI, (2) to quantitatively determine the extent of cancer risk among firefighters using meta-analysis, and, (3) to assess the epidemiological evidence for causal relationship between working as a firefighter and excess cancer risks. A comprehensive search of electronic databases and bibliographies from identified articles was performed. The articles were critically evaluated through the use of the EAI. A meta-analysis was undertaken separately for mortality and morbidity studies, and for these studies combined. A fixed-effect model was adopted in the absence of heterogeneity; otherwise, a random-effects model was implemented. An assessment of epidemiological evidence for a causal relationship was conducted as a function of multiple criteria including pattern of meta-relative risk association, study quality, consistency among studies, risk factors (other than exposure), exposure-response relationships, and analogy (with respect to other occupational groups). The results of Part two indicated that retrospective cohort mortality and incidence studies were of similar quality, but proportionate mortality studies were of lower quality. There appear to be 'probable' likelihood of risk for multiple myeloma, and testicular and prostate cancers, and 'possible' likelihood of risk for cancers of the digestive system (i.e., stomach, colon, rectum), brain, and skin (including malignant melanoma), and non-Hodgkin lymphoma. In conclusion, the findings of this study indicate that firefighters may be at excess risk of cancer in selected sites. A prospective cohort study of firefighters from multiple geographic locations, with quantified risk factors for disease and job-related exposures, is needed to resolve these issues.