Дисертації з теми "Workers' exposure model"

Occupational exposures of healthcare workers tend to occur because of inconsistent compliance with standard precautions. Also, incidence of occupational exposure is underreported among operating room personnel. The purpose of this project was to develop national estimates for compliance with standard precautions and occupational exposure reporting practices among operating room nurses in Australia. Data was obtained utilizing a 96-item self-report survey. The Standard Precautions and Occupational Exposure Reporting survey was distributed anonymously to 500 members of the Australian College of Operating Room Nurses. The Health Belief Model was the theoretical framework used to guide the analysis of data. Data was analysed to examine relationships between specific constructs of the Health Belief Model to identify factors that might influence the operating room nurse to undertake particular health behaviours to comply with standard precautions and occupational exposure reporting. Results of the study revealed compliance rates of 55.6% with double gloving, 59.1% with announcing sharps transfers, 71.9% with using a hands-free sharps pass technique, 81.9% with no needle recapping and 92.0% with adequate eye protection. Although 31.6% of respondents indicated receiving an occupational exposure in the past 12 months, only 82.6% of them reported their exposures. The results of this study provide national estimates of compliance with standard precautions and occupational exposure reporting among operating room nurses in Australia. These estimates can now be used as support for the development and implementation of measures to improve practices in order to reduce occupational exposures and, ultimately, disease transmission rates among this high-risk group.

Many workers are daily exposed to chemical risks in their work place that has to be assessed and controlled. Due to exposure variability, repeated and random measurements should be conducted for valid estimates of the average exposure. Traditionally, experts such as safety engineers, work environment inspectors, and occupational hygienists, have performed the measurements. In self assessment of exposure (SAE), the workers perform unsupervised exposure measurements of chemical agents. This thesis studies a prerequisite for SAE, i.e. the workers’ mental models of chemical exposure. Further, the workers’ mental models are contrasted with experts’ reasons and decision criteria for measurement. Both qualitative and quantitative data generated from three studies (Paper I, II, and III) were used to describe the workers’ mental model of chemical exposure. SAE was introduced to workers in three different industries; transports (benzene), sawmill industry (monoterpenes), and reinforced plastic industry (styrene). By interviews, qualitative data were collected on the workers’ interpretation of measurement results and preventive actions. To evaluate the validity of worker measurement, the measurements were compared with expert measurements. The association between each worker’s number of performed measurement and mean level and variability in exposure concentrations was calculated. Mean absolute percent/forecast error (MAPE) was used to assess whether the workers’ decision models were in accordance with a coherence or correspondence model. In Paper IV, experts (safety engineers, work environment inspectors, and occupational hygienists) were interviewed to elucidate their mental models about the triggers and decision criteria for exposure measurements. The results indicate that the workers’ measurement results were in agreement with experts’. However, the measurement results were not a strong enough signal to induce workers to take preventive actions and sustained exposure measurements even if the measurement result were close to the occupational exposure limit. The fit was best for the median model, indicating that the workers’ mental models for interpretation of measurement data can best be described by the coherence theory rather than by the correspondence theory. The workers seemed to mentally reduce the variation in the exposure to a measure of central tendency (the median), and underestimated the average exposure level. The experts were found to directly take preventive actions instead of performing exposure measurements. When they performed exposure measurements, a worst case sampling strategy was most common. An important trigger for measurement for the experts was “request from the employer” (safety engineers), “legal demands” (work environment inspectors), and “symptoms among workers” (occupational hygienists). When there was a trigger, all experts mentioned expectations of high exposure level as a decision criterion for measurements. In conclusion, the studies suggest that workers’ mental interpretation model is best described in terms of a coherence model rather than a model of correspondence. The workers reduced the variation mentally in favor of an estimate of average exposure (median), which may imply that they underestimate short-term, high exposure health risks. A consequence is that interpretation of measurements such as SAE cannot be given to the individual worker without some support, e.g. from an expert. However, experts often chose to directly take preventive actions, without measuring the exposure. The results indicate that also the experts need support e.g. from the legal system if exposure measurements are to be done.

Background: Prenatal exposure to perfluoroalkyl substances (PFAS) has been associated with lower birth weight in epidemiologic studies. This association could be attributable to glomerular filtration rate (GFR), which is related to PFAS concentration and birth weight. Objectives: We used a physiologically based pharmacokinetic (PBPK) model of pregnancy to assess how much of the PFAS–birth weight association observed in epidemiologic studies might be attributable to GFR. Methods: We modified a PBPK model to reflect the association of GFR with birth weight (estimated from three studies of GFR and birth weight) and used it to simulate PFAS concentrations in maternal and cord plasma. The model was run 250,000 times, with variation in parameters, to simulate a population. Simulated data were analyzed to evaluate the association between PFAS levels and birth weight due to GFR. We compared simulated estimates with those from a meta-analysis of epidemiologic data. Results: The reduction in birth weight for each 1-ng/mL increase in simulated cord plasma for perfluorooctane sulfonate (PFOS) was 2.72 g (95% CI: –3.40, –2.04), and for perfluorooctanoic acid (PFOA) was 7.13 g (95% CI: –8.46, –5.80); results based on maternal plasma at term were similar. Results were sensitive to variations in PFAS level distributions and the strength of the GFR–birth weight association. In comparison, our meta-analysis of epidemiologic studies suggested that each 1-ng/mL increase in prenatal PFOS and PFOA levels was associated with 5.00 g (95% CI: –21.66, –7.78) and 14.72 g (95% CI: –8.92, –1.09) reductions in birth weight, respectively. Conclusion: Results of our simulations suggest that a substantial proportion of the association between prenatal PFAS and birth weight may be attributable to confounding by GFR and that confounding by GFR may be more important in studies with sample collection later in pregnancy.

Les troubles musculo-squelettiques (TMS) sont une des questions les plus préoccupantes en santé au travail. Ils témoignent de l’intensification des conditions de travail qui affecte un nombre croissant de travailleurs. L’objectif de cette thèse était d’étudier les relations complexes entre les facteurs professionnels, notamment organisationnels, et les TMS de l’épaule.Trois populations salariées ont été étudiées : la cohorte Cosali et deux entreprises automobile et pharmaceutique. L’étude des caractéristiques organisationnelles des situations de travail par classifications ascendantes hiérarchiques des variables et des individus de la cohorte Cosali a identifié une classe d’organisation de type taylorien. Chez ces salariés, les douleurs et TMS de l’épaule étaient plus fréquents. Des modèles à équations structurelles ont montré que les facteurs organisationnels étaient des déterminants distaux des TMS en influençant l’exposition aux facteurs psychosociaux et physiques, alors que l’exposition aux facteurs physiques influençait à son tour les douleurs de l’épaule. L’application de la méthodologie aux deux populations des entreprises automobile et pharmaceutique a confirmé la pertinence du modèle issu de Cosali. En conclusion, les facteurs organisationnels sont des déterminants clés de la survenue des TMS de l’épaule en influençant en cascade les conditions d'exposition aux facteurs psychosociaux et physiques auxquels les travailleurs doivent faire face. Ces connaissances épidémiologiques originales améliorent la compréhension de la chaîne de déterminants des TMS et contribueront au ciblage des interventions de prévention sur les déterminants professionnels modifiables
Musculoskeletal disorders (MSDs) represent one of the most worrying issues in occupational health. They bear witness to the intensification of working conditions which affects an increasing number of workers. The aim of this thesis was to study the complex relationships between occupational factors and shoulder disorders, with attention paid to organizational factors. Three working populations were studied : the Cosali cohort, one automobile company and one pharmaceutical company. The study of the organizational characteristics of work situations by ascendant hierarchical clustering of variables and individuals of the Cosali cohort identified a Taylorist form of work organization. Among these employees, shoulder disorders were more frequent. Structural equation modeling has shown that organizational factors are distal determinants of MSDs by influencing exposure to psychosocial and physical factors, while exposure to physical factors in turn influences shoulder pain. The application of the methodology to the two populations of automotive and pharmaceutical companies confirmed the relevance of the Cosali model. In conclusion, organizational factors are key determinants of the onset of shoulder disorders by cascading the conditions of exposure to the psychosocial and physical factors that workers face. This original epidemiological knowledge improves understanding of the chain of determinants of MSDs and will contribute to the targeting of prevention interventions on modifiable occupational determinants

L'importance des facteurs de risque professionnels dans l'asthme est bien établie, mais le rôle de certains agents doit être clarifié. Les objectifs de la thèse sont d'évaluer les liens entre les expositions aux produits de nettoyage et l'asthme, et d'étudier l'impact et la prise en compte du biais du travailleur sain, dans l'étude Epidémiologique des facteurs Génétiques et Environnementaux de l'Asthme (EGEA, 2047 sujets dont 1477 adultes avec des données professionnelles). L'exposition aux produits de nettoyage a été estimée par une expertise et une matrice emploi-exposition. Chez les femmes, l'asthme actuel était associé à l'exposition aux détartrants (OR=2.4 (1.1-5.3)), et aux sprays (2.9 (1.0-8.1)) et à l'ammoniac (3.1 (1.2-7.8)) chez les aides-soignantes. Les détartrants et l'ammoniac sont des irritants. L'exposition aux produits de nettoyage était associée à l'asthme sévère et sans sensibilisation allergique. Deux analyses ont souligné l'importance du biais du travailleur sain dans l'asthme. Un biais de sélection à l'embauche a été observé chez des sujets avec un asthme sévère dans l'enfance. Un modèle marginal structural a permis de prendre en compte le biais du travailleur sain dans l'étude de l'effet des expositions professionnelles sur l'expression clinique de l'asthme au cours de la vie. En plus du rôle d'asthmogènes connus, le rôle d'agents moins bien établis, comprenant des irritants (1.6 (1.0-2.4)) était suggéré. Les résultats sont cohérents avec un rôle des irritants dans l'asthme lié au travail. Ils soutiennent une utilisation plus large d'approches d'analyse causale pour contrôler le biais du travailleur sain dans les études des risques professionnels.

碩士
高雄醫學大學
職業安全衛生研究所
101
Background: In Taiwan, there are many kinds of Ionizing Radiation-related workplaces, including Nuclear Power Plants, Medical Careers, Nuclear Engineering, Radiation Detection and etc. Hundreds of thousands employees are engaged in radiation-related works. According to Article 14 of Labor Health Protection Rules (LHPRs), amendment on January 21, 2011, enterprises with labors engage in operations with special health hazards (e.g. ionizing radiation) from Article 2 of LHPRs, must establish health data manager system, and implement the classifications of health manger system. We would like to analyze cancer risk of those workers who might be possible exposed to ionizing radiation in their past working history with Poisson Regression Model. Materials and Methods: Our objects are cancer cases in enterprises and with radiation exposure in Taiwan from year 1992 to 2010. Totally, we collected 84 cancer cases, and 34,404 person years. The collected data of 84 cancer employees included gender, exposure time and working areas. We grouped these workers into northern and southern areas by their working areas. Considering the latency period of radiation induced cancers, we set up criteria to exclude those workers whose exposure time is less than 5 years and working time is less than 10 years. We also excluded 3 female cases, because the case number is too few. Finally, 62 male workers’ data are suitable to input Poisson Regression Model. For the 62 workers, we grouped them into 1 year, 5 years and 10 years groups, to explore the cancer risk between different eras. Results: Our study results show that in groups of 1 year, cancer risk of northern working area is higher 0.14 time than southern, which is not statistically significant. In groups of 5 years, cancer risk of northern working area is 0.14 time than southern, and is not statistically significant. In groups of 10 years, cancer risk of northern working area is 0.14 time than southern, which is not statistically significant. Conclusions: In the Poisson Regression Model cancer risk analysis shows that in groups of 1 year, the cancer risk is not statistically significant. In groups of 10 years, cancer risk of the group 1992~1999 is 0.12 time higher than group 2000~2010, this trend is similar to the atomic bomb survivors’ Life Span Study (LSS) cohort in Japan, that is, cancer risk is higher when exposed at younger ages.

博士
國立中央大學
環境工程研究所
98
The exposure occurs when a person comes into contact with a pollutant at a particulate instant of time if the pollutant and the person are present at the same location. The exposure becomes the intersection, or joint occurrence, of two events: the person is present, and the pollutant is present as well. Hence, the exposure assessment depends on a complete record of the duration of exposure to assist in tracking the exposure source. The Task-Based Exposure Assessment Model (T-BEAM) stresses the identification of all hazards that may be associated with a particular work task. The Task-Based Exposure Assessment is a very powerful tool to collect data that can be utilized not only for exposure dose inclusion but also for source identification, validation of process improvements, determining retrofit control priorities and providing a strong supported dataset. This approach is be especially suitable for mobile or itinerant workers. The purpose of this study is to development an Auto Task-Based Exposure Assessment monitoring strategy based on an active radio frequency identification (active RFID) technology suitable for tracking and identifying workers’ locations in indoor workplaces. Called radio frequency identification exposure monitoring system (RFEMS), the system could also synchronously indicate the surrounding conditions using various sensors. Location and exposure data were transferred to data analysis software for visualization and tabular analysis in real-time. The RFEMS instruments provided adequate range for locating (typically ca. 6–45 m in each zone), allowing us to locate subjects within distinct microenvironments and to distinguish between the activities of a variety of workers, the average time activity pattern (TAP) recording deviation for both human observations and RFEMS was ca. 0.21–1.57%. A pilot field test indicated that the RFEMS offers a new level of accuracy for direct quantification of time activity patterns in exposure assessments of indoor workers over long periods of time. Additionally, in the field study, The RFEMS and sound level meter are mounted on the vests of workers to carry out on-site field test by monitoring the time activity pattern (TAP), and the noise dose level exposed by the workers. The results obtained using these three devices are well correlated with the results monitored by using a PND (personal noise dosimetry) with correlation coefficients (R2) of 0.915, 0.779 and 0.873, respectively. The errors of noise dose expressed in TWA (time weight average) for these three methods are 0.81, 1.57 and 1.23 dBA, respectively; they are well within the general errors of the average dosimetries. These observations indicate that the RFEMS developed in this research is applicable for conducting tasked-based measurements of indoor noise. The findings will assist in studying the source of long-term exposed by workers, and hence this devise is a valuable exposure monitoring strategy for tracing and automatic monitoring long-term exposure with reduced manpower requirement.

碩士
國立成功大學
環境醫學研究所
104
The purpose of this study is to develop a method which combines charcoal tube organic solvent sampling results, direct-reading instrument (Photo Ionization Detector, PID) total volatile organic compounds (TVOCs) sampling results, and biological monitoring (urinary acetone) results, with a long-term database of TVOCs measured values, via the use of the Bayesian decision analysis (BDA) technique, for assessing workers’ long-term organic solvent exposures in acetone manufacturing and using industries. One acetone manufacturing industry, one quartz wafer manufacturing industry, one semiconductor component cleaning industry, and one ink production industry were selected for conducting samplings. Results show that high correlations were found (R²=0.86~0.99) between estimated acetone exposures (obtained from the area charcoal sampling results and workers’ time/activity pattern) and actual acetone exposures (using personal charcoal tube sampling results) of the designated similar exposure groups (SEGs). Workers long-term exposures estimated based BDA show that organic solvent (acetone, MEK, DMF) exposure levels for all SEGs were consistently less than 0.5 permissible exposure limit (PEL). High correlations were also found between urinary acetone exposures and workers’ personal acetone exposures (i.e., for those who wore flat activated carbon (AC) masks (R²=0.74), and AC canisters (R²=0.55), respectively). Through the use of BDA, results show all investigated SEGs’ long-term urinary acetone exposures were consistently falling between 10%~250% PEL for acetone. In conclusion, the method combined the corrected models of personal organic solvents exposures and long-term TVOCs values in the workplaces was applicable to conduct and manage long-term exposure risk for workers in acetone manufacturing and using industries.

碩士
國立成功大學
環境醫學研究所
86
Occupational exposure to heat stresses has been already known to be dangerous to workers. To date, although more advanced techniques have been widely adopted by industries, however, workers might still suffer to heat exposures in some specific environments. To protect workers from ill-health effects caused by heat stresses, the government in Taiwan has promulgate the PELs in 1974, which was mainly modified from the ACGIH TLVs. However, the modification did not have any physiological basis at that time. Considering the existence of differences in race (Asian versus Caucasian) and living environment (humid and hot versus dry and cool), the feasibility of the current PELs for heat stress required further evaluations, especially on a reasonable physiological basis. In this study we have tried to build up heat exposure assessment predictive models which mainly based on the Taiwanese measured physiological data. The obtained predictive models were also used to compare with and evaluate the predictive models published by ISO on the document of ISO-7933.In this study, we found the predictive values of Cres and Eres obtained from ISO-7933 suggested models were significantly different from the theoretical values, which might mainly due to the existence of racial difference between Taiwanese and Caucasian. For this reason, two experimental predictive models for Cres and Eres were developed in this study, which were directly developed based on the measured physiological data. Due to the predictive model for skin temperature proposed by ISO was limited to specific environmental conditions, the predicted values were also found to be significantly different from the measured skin temperatures obtained from workers under wider environmental situations ( including temperature, wind velocity, and humidity, etc. ). Through multiple regression analysis, a proposed predictive model with 5 independent variables was proposed in this study for skin temperature predictions in the future. For metabolic predictions, the predictive model suggested by ISO shows that the predicted values which based on heart rate measurements did not consistent with the measured values. The relationship between heart rates and metabolic rates was further analyzed directed based on the measured values in this study, the obtained relationship not only has a higher R2, but also shows a more consistent trend. Finally, this study also shows that the predicted allowable exposure time suggested by ISO-7933 might lead to under-estimated situations as compared to the theoretical values, however, the predicted values obtained from modified predictive models do show a batter trend as used to predict allowable exposure time. It should noted here that the trend mentioned above doesn''''t have a good correlation with the experimental data, it might be due to the existence of experimental outliers because of experimental errors or intrinsic variations of tested subjects. Considering the residuals of the regression results, it is recommended in the future that the weighted-least-squares could be adopted for regression analysis to eliminate the effects caused by outliers in the future.

目的：本研究主要目的是建立預測模型來判定矽肺發生的累積風險從而推薦適宜的胸片照射年限並從而評估常規監測和推薦監測策略的成本效益。此外，本研究還評價了常規診斷和驗證性診斷的符合度以及在驗證性診斷中邀請的三位專家之間的符合度。
方法：總計有3492男性接塵工人在1964年1月1日到1974年12月31日期間進入本隊列並隨訪至2008年12月31日。不同閱片專家根據中國最新塵肺病診斷標準 （GBZ70-2009））分別閱片總計9084張。對專家之間閱片結果的兩兩比較和兩種診斷結果的比較均采用Cohen’s Kappa檢驗。應用三種篩選方法（強制所有變量同時進入模型，後退逐步篩選，以及Least Absolute Shrinkage and Selection Operator (LASSO)篩選。LASSO模型作為最優模型，以分數量表的方式來表達。根據分數，把工人分成高、中、低危險組，並估計這三組不同危險水平工人的累積危險度。運用0.1% 累積危險度來判定不同危险的工人及不同期別的矽肺病人的射線照射年限。多狀態Markov模型用於計算矽塵暴露工人不同狀態的年轉移概率，並應用Markov成本效益分析方法來估計每獲得一個生命年的成本效益。
結果：截至2008年底，本矽塵暴露隊列共計發現298例矽肺病人（累計發病率為8.53%），死亡1347例（死亡比例為38.57%）。本研究發現常規診斷和驗證性診斷有很好的符合度 （Kappa值為0.89， 95%可信區間為0.88-0.91）。基於LASSO模型的分數量表具有很好的診斷識別能力 （ROC曲線下面積為0.83， 95%可信區間為0.81-0.86）。根據0.1%累積危險度標準，我們判定低危險組工人第一次射線照射的時間為第11年，推薦每兩年隨訪一次；中等危險組工人和高危險組工人的第一次射線照射時間分別為第11年和第5年，推薦每年隨訪一次。矽肺病人未晉級到三期以前均一年隨訪一次。矽塵暴露工人的年轉移概率為：從健康狀態向疑似病例轉移的概率為0.0198，從疑似病例向一期矽肺轉移的概率為0.038，從一期矽肺向二期矽肺轉移的概率為0.0516，從二期矽肺向三期矽肺轉移的概率為0.059，從三期矽肺向死亡轉移的概率為0.18。在1964到2008年間，診斷一例矽肺病例平均花費醫療成本為21853.11美元，非醫療成本為5993.30美元。模擬10,000矽塵暴露工人在未來40年按照當前的狀態轉移概率，應用常規的職業健康檢查為手段獲得一個生命年的成本效益為43.60美元，應用推薦的職業健康檢查為手段獲得一個生命年的成本效益為46.99美元。
結論：本研究在最優預測模型的基礎上為不同矽肺危險度的矽塵暴露工人首次提供了科學的證據來判定射線照射的適宜年限，亦為未來矽塵暴露工人的職業健康監測提供了科學理論依據，雖然本研究推薦的監測策略獲得同常規策略相類似的成本和效益。
Objectives: The primary objective was to develop prediction models for determining the optimal intervals of chest radiographic surveillance for workers exposed to silica dust; the second primary objective is to assess the cost per case identification and compare the cost per life year gained under routine medical surveillance program with that under the recommended program for workers exposed to silica dust in China. In addition, the inter-rater agreement amongst three invited radiologists on rereading the chest radiographs and the agreement between the original diagnoses of silicosis (from routine reports) and the verified diagnoses reassessed by the three experts were also evaluated.
Methods: A total of 3492 male workers exposed to silica dust in an iron ore during the period 1964 - 1974 were recruited into this retrospective cohort study. All cohort members were followed up through the end of 2008 to observe the occurrence of silicosis and overall profile of mortality. All 9084 chest X-ray films were reread by three radiologists who had been qualified as experts at the national level according to the Chinese National Diagnostic Criteria of Pneumoconiosis (GBZ70-2009). The diagnosis of silicosis made by the panel of these three invited experts was referred to the “verified diagnosis“. Cohen’s Kappa test was used to test inter-rater agreements of three invited readers on chest radiographs and the agreement on the diagnosis of silicosis obtained from routine medical surveillance (i.e., the original routine diagnosis) was compared with those verified by the 3 qualified readers (i.e., the verified diagnosis). The multivariate Cox’s proportional hazard regression models were developed to predict the silicosis occurrence based on three selection approaches entry of all predictors at the same time, backward stepwise selection, and Least Absolute Shrinkage and Selection Operator (LASSO) selection. The LASSO model showed the best model fit which was thus regarded as the final model for predicting a score chart.
Based on this practically used score chart, we then classified workers into three groups of different risk levels of silicosis (low, moderate, and high). We estimated the cumulative risk of silicosis over years of follow-up for these three groups of workers at different risk levels. We used 1 per thousand of cumulative risk for developing silicosis as a “benchmark“ to determine the intervals of radiologic surveillance for workers with different risks of silicosis. Multi-state Markov model was used to calculate the transition probabilities of different states of silicosis and the analysis on cost and effectiveness was performed.
Results: By the end of 2008, the cumulative incidence rate of silicosis was 8.53% (298 silicosis cases) and a total of 1347 deaths (38.57%) were observed.
Good inter-rater agreements were observed amongst three invited radiologists for rereading all the chest films. Kappa value for the agreement between the original diagnoses and the verified diagnoses was 0.89 (95% confidence interval [95%CI], 0.88-0.91).
The model with the best fit was LASSO Cox model which showed a good discrimination with an area of 0.83 (95%CI, 0.81-0.86) under the receiver operating characteristic (ROC) curve. We classified workers into 3 risk groups according to the score chart obtained from the LASSO Cox model, and found the observed probabilities matched well to the predictions. According to 1 per thousand “benchmark“, we can determine that the initial interval of radiographic surveillance for workers in the low risk group was 11 years and a subsequent biyearly examination was recommended. The initial examination interval was 11 years and 5 years respectively for workers in the middle and high risk group, and then a yearly examination was recommended. For patients with silicosis, an annual radiological surveillance program was recommended regardless of the stage of pneumoconiosis.
According to results from multi-state model, we estimated that the yearly transition probability was 0.0198 for silica dust exposed workers from healthy state to the suspected silicosis cases (sojourn time = 47 years), 0.0338 from suspected silicosis cases to silicosis stage one (sojourn time = 23 years), 0.0516 from silicosis stage one to stage two (sojourn time = 9 years), 0.059 from silicosis stage two to stage three (sojourn time = 6 years), and 0.18 from silicosis stage three to death (sojourn time = 5 years).
During the period 1964 to 2008, the average direct medical cost spent on identifying one silicosis case was US$ 21853.11 and the non-medical cost for identifying one case was US$ 5993.30 per case. The estimated medical cost regarding per life year gained was US$ 43.60 under the routine medical surveillance program and it would be US$ 46.99 if the newly recommended surveillance program is adopted.
Conclusion: This study is the first to provide scientific evidence on determining the optimal intervals of radiographic surveillance for workers at different risk levels of silicosis based on the ‘best’ prediction model. Although our study revealed similar cost and effectiveness for using the recommended occupational health examination strategy compared with the routine program, this study is the first to provide scientific theory for guiding evidence-based occupational medical surveillance on workers exposed to silica dust in the world.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Chen, Minghui.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2012.
Includes bibliographical references (leaves 195-210).
Abstract also in Chinese.
Abstract (English) --- p.i
Abstract (Chinese) --- p.v
Acknowledgements --- p.vii
List of contents --- p.ix
List of tables --- p.xv
List of figures --- p.xviii
List of main abbreviations --- p.xx
Chapter Section I --- Introduction and Literature Review --- p.1
Chapter Chapter 1 --- Introduction --- p.2
Chapter Chapter 2 --- Literature Review of Medical Examination, Prediction model and Economic Evaluation in Silicosis --- p.7
Chapter 2.1 --- The aims of this literature review --- p.7
Chapter 2.2 --- Search strategies and selection criteria --- p.7
Chapter 2.3 --- Searching results --- p.8
Chapter 2.4 --- Critical appraisal criteria and quality of selected studies --- p.9
Chapter 2.4.1 --- Critical appraisal criteria --- p.9
Chapter 2.4.2 --- Quality of selected studies --- p.10
Chapter 2.5 --- Overview of effectiveness of chest radiography in medical surveillance of silicosis for workers exposed to silica dust --- p.15
Chapter 2.5.1 --- Occupational medical surveillance for workers exposed to silica dust --- p.15
Chapter 2.5.2 --- Comparison of CT or HRCT and chest radiography --- p.16
Chapter 2.5.3 --- Comparison of digital radiography (DR) and chest radiography --- p.17
Chapter 2.5.4 --- Other tests to be relevant to silicosis diagnosis --- p.23
Chapter 2.5.5 --- The effectiveness of chest radiography in medical surveillance and diagnosis of silicosis --- p.24
Chapter 2.5.6 --- Comparison between the ILO Classification and the Chinese Diagnostic criteria of pneumoconiosis --- p.25
Chapter 2.6 --- Overview of application of prediction model in silicosis and a review on methodology in prediction model --- p.32
Chapter 2.6.1 --- Application of prediction model in occupational diseases --- p.32
Chapter 2.6.2 --- Overview of application of predicting model in pneumoconiosis including silicosis in China in recent 10 years --- p.34
Chapter 2.6.3 --- Development of prediction model and the applications from practical perspectives --- p.35
Chapter 2.7 --- A review on economic evaluation in occupational diseases and the screening interval analyses --- p.42
Chapter 2.7.1 --- An overview on economic evaluation in pneumoconiosis --- p.42
Chapter 2.7.2 --- Overview of economic evaluation in occupational health and safety and screening interval analyses --- p.44
Chapter 2.7.3 --- Overview for methodology of performing CEA --- p.45
Chapter 2.8 --- Research gaps were found from this literature review --- p.52
Chapter Section II --- Objectives and Methods --- p.53
Chapter Chapter 3 --- General aims and objectives --- p.54
Chapter 3.1 --- General aims --- p.54
Chapter 3.2 --- Primary objectives --- p.54
Chapter 3.3 --- Secondary objective --- p.54
Chapter Chapter 4 --- Methodology and Research Plans --- p.55
Chapter 4.1 --- Study Design --- p.55
Chapter 4.2 --- The cohort --- p.55
Chapter 4.3 --- Follow-up --- p.58
Chapter 4.4 --- Data Collection --- p.58
Chapter 4.4.1 --- Baseline information --- p.58
Chapter 4.4.2 --- Diagnosis of silicosis and the verification --- p.59
Chapter 4.4.3 --- Occupational hygiene monitoring data --- p.60
Chapter 4.4.4 --- Cost data of medical examination --- p.61
Chapter 4.5 --- Data Entry and Data Analyses --- p.62
Chapter Section III --- Results and Discussions --- p.65
Chapter Chapter 5 --- Description of the cohort --- p.66
Chapter 5.1 --- Cohort recruitment --- p.66
Chapter 5.2 --- Baseline characteristics --- p.69
Chapter 5.3 --- Change of respirable silica dust concentration over time --- p.71
Chapter 5.5 --- Occurrence of silicosis --- p.73
Chapter 5.5.1 --- Basic characteristics of silicosis patients --- p.73
Chapter 5.5.2 --- Trend of silicosis occurrence with calendar year --- p.78
Chapter 5.5.3 --- Trend of silicosis occurrence with age of entering the cohort --- p.78
Chapter 5.5.4 --- Trend of silicosis occurrence with cumulative exposure to respirable silica dust --- p.78
Chapter 5.6 --- Survival distribution at different respirable silica dust exposure levels --- p.79
Chapter 5.7 --- A summary of the results in Chapter 5 --- p.82
Chapter Chapter 6 --- Agreement between the routine diagnosis of silicosis and the verified ‘new panel’ diagnosis --- p.83
Chapter [Summary] --- p.83
Chapter 6.1 --- Background --- p.85
Chapter 6.2 --- Methodology --- p.86
Chapter 6.2.1 --- The routine and the verified diagnosis of silicosis --- p.86
Chapter 6.2.2 --- Inter-rater agreement --- p.87
Chapter 6.3 --- Results --- p.89
Chapter 6.3.1 --- Technical quality of chest X-ray films --- p.89
Chapter 6.3.2 --- Inter-rater agreement amongst readers --- p.89
Chapter 6.3.3 --- Agreement between the routine and the verified diagnosis of silicosis --- p.93
Chapter 6.3.4 --- Agreement of the progression of silicosis between the routine and verified diagnosis --- p.95
Chapter 6.4 --- Discussion --- p.97
Chapter Chapter 7 --- Developing prediction model for determining the optimal intervals of chest radiographic examinations for workers at different risks of silicosis --- p.100
Chapter [Summary] --- p.100
Chapter 7.1 --- Background --- p.102
Chapter 7.2 --- Methods --- p.104
Chapter 7.2.1 --- The cohort and outcome determination --- p.104
Chapter 7.2.2 --- Developing prediction models for silicosis --- p.107
Chapter 7.2.3 --- Coding of Predictors --- p.113
Chapter 7.3 --- Results --- p.118
Chapter 7.3.1 --- Model Specifications --- p.118
Chapter 7.3.2 --- Stepwise Selection and LASSO selection --- p.119
Chapter 7.3.3 --- Model Validations: Stability and Optimism --- p.119
Chapter 7.3.4 --- Model Presentations --- p.126
Chapter 7.3.5 --- Cut-off point of follow up year for determining examination intervals --- p.130
Chapter 7.4 --- Discussions --- p.136
Chapter Chapter 8 --- Transition probabilities of multi-states for workers with silica dust exposure --- p.141
Chapter [Summary] --- p.141
Chapter 8.1 --- Background --- p.143
Chapter 8.2 --- Methodology of multi-state model --- p.145
Chapter 8.2.1 --- Survival data and multi-state model --- p.145
Chapter 8.2.2 --- Markov model and transition states --- p.151
Chapter 8.2.3 --- Model assessment --- p.153
Chapter 8.3 --- Results --- p.154
Chapter 8.3.1 --- Initial values specification and estimates of intensity matrix --- p.154
Chapter 8.3.2 --- Transition probability matrix, mean sojourn times, and survival situation --- p.159
Chapter 8.3.3 --- Observed and expected prevalence of each state for Model assessment --- p.163
Chapter 8.4 --- Discussion --- p.165
Chapter Chapter 9 --- Cost effectiveness analysis of occupational medical surveillance for workers exposed to silica dust --- p.168
Chapter [Summary] --- p.168
Chapter 9.1 --- Background --- p.170
Chapter 9.2 --- Methodologies --- p.171
Chapter 9.2.1 --- Costs and effectiveness --- p.171
Chapter 9.2.2 --- Cost per silicosis identification estimation in the iron ore during 1964 to 2008 --- p.172
Chapter 9.2.3 --- Cost effectiveness analysis in the Markov model --- p.173
Chapter 9.3 --- Results --- p.176
Chapter 9.3.1 --- Cost estimation and cost per silicosis identification in the iron ore cohort --- p.176
Chapter 9.3.2 --- Cost effectiveness analysis in the Markov model --- p.181
Chapter 9.4 --- Discussion --- p.187
Chapter Section IV --- Conclusions and Implications --- p.191
Chapter Chapter 10 --- Conclusions, implications, and recommendations --- p.192
Chapter 10.1 --- Conclusions --- p.192
Chapter 10.2 --- Implications and recommendations --- p.193
Reference list --- p.195
Chapter Appendix I --- Chest Radiographic Imaging of Different Diagnostic Criteria for Pneumoconiosis in China --- p.211
Chapter Appendix II --- Diagnosis Stages among Different Diagnostic Criteria for Pneumoconiosis in China --- p.212
Chapter Appendix III --- Publications in journals and international conferences during the PhD study --- p.213
Chapter Supplement I --- Syntax for test proportionality of Cox model in R survival package and LASSO model in R penalized package --- p.215
Chapter Supplement II --- Guideline of applying the prediction model in practice --- p.216
Chapter Supplement III --- Syntax for multi-state model in R msm package --- p.221
Chapter Supplement IV --- An example for cost estimation of adjusting inflation and exchanging --- p.222
Chapter Supplement V --- Cost estimation of workers, suspected silicosis cases and silicosis patients in the iron ore during 1964 - 2008 --- p.223
Chapter Supplement V (Continued) --- Cost estimation of workers, suspected silicosis cases and silicosis patients in the iron ore during 1964 - 2008 --- p.224
Chapter Supplement VI --- Number of deaths for all cause of death in the iron ore cohort until 2008 --- p.225
Chapter Supplement VII --- Decision tree of Markov model in the study --- p.226
Chapter Supplement VII (Continued) --- Decision tree of Markov model in the study --- p.227