Cement dust and chronic obstructive pulmonary disease: a nested case-control study among plant workers

---------------------------------------------------------------------------------2 Background information ---------------------------------------------------------------3 Methods-------------------------------------------------------------------------------------7 Potential confounders--------------------------------------------------------9 Sample size--------------------------------------------------------------------9 Data Collection-----------------------------------------------------------------9 Ethical considerations------------------------------------------------------------------11 Study limitations-----------------------------------------------------------------------11 Data analysis-----------------------------------------------------------------------------12 Time frame for the Project------------------------------------------------------------12 Budget--------------------------------------------------------------------------------------13 Acknowledgements----------------------------------------------------------------------14 References---------------------------------------------------------------------------------15 Appendices--------------------------------------------------------------------------------17 Abstract Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. It results in a substantial and increasing economic and social burden for individuals, families, health care organizations, and society. Cement plant workers are at increased risk for COPD. According to data obtained from the head doctor of Ararat polyclinic, the prevalence rate of COPD was 128 per 1,000 in this occupational group during 1999-2000. To assess the relationship between cement dust exposure and COPD and to conduct dose-response analysis, a nested case-control study among “Ararat cement” plant workers will be conducted. Cases are defined as cement plant employees with a clinical diagnosis of COPD who worked in the plant during 1995-2000. Controls are cement plant employees who worked in the plant during 1995-2000 and have not been diagnosed with COPD by the general practitioner. The required sample size is 78 for each group. The selection of cases and controls will be done by simple random sampling and systematic sampling techniques using the polyclinic’s rosters of workers. Ascertainment of cases and controls will occur during face-to face interviews using a standardized questionnaire with specific questions about COPD-related symptoms (American Thoracic Society Adult Questionnaire-78). During interviews, information about potential confounders will also be gathered. Information about work history of cases and controls will be obtained from work employee records and interviews. The exposed workers will be divided according to the duration of work in an exposed job, to determine if increased duration led to increased risk of COPD (dose-response analysis). Logistic regression will be used for analysis to estimate a summary odds ratio after adjustment for confounders and to evaluate interactions between variables. The total budget is about $17,538.Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. It results in a substantial and increasing economic and social burden for individuals, families, health care organizations, and society. Cement plant workers are at increased risk for COPD. According to data obtained from the head doctor of Ararat polyclinic, the prevalence rate of COPD was 128 per 1,000 in this occupational group during 1999-2000. To assess the relationship between cement dust exposure and COPD and to conduct dose-response analysis, a nested case-control study among “Ararat cement” plant workers will be conducted. Cases are defined as cement plant employees with a clinical diagnosis of COPD who worked in the plant during 1995-2000. Controls are cement plant employees who worked in the plant during 1995-2000 and have not been diagnosed with COPD by the general practitioner. The required sample size is 78 for each group. The selection of cases and controls will be done by simple random sampling and systematic sampling techniques using the polyclinic’s rosters of workers. Ascertainment of cases and controls will occur during face-to face interviews using a standardized questionnaire with specific questions about COPD-related symptoms (American Thoracic Society Adult Questionnaire-78). During interviews, information about potential confounders will also be gathered. Information about work history of cases and controls will be obtained from work employee records and interviews. The exposed workers will be divided according to the duration of work in an exposed job, to determine if increased duration led to increased risk of COPD (dose-response analysis). Logistic regression will be used for analysis to estimate a summary odds ratio after adjustment for confounders and to evaluate interactions between variables. The total budget is about $17,538. Background information Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide and results in a substantial and increasing economic and social burden for individuals, families, health care organizations, and society. There are several lung diseases collectively known as COPD, including asthmatic bronchitis, chronic bronchitis, chronic obstructive bronchitis, emphysema and asthma. According to WHO, COPDs account each year for the deaths of almost 3 million people. The World Bank Global Burden of Disease Study estimated the worldwide prevalence of COPD at 9.34/1,000 in men and 7.33/1,000 in women. However, this study included all ages and grossly underestimated the true prevalence of this disease in the adult population, because COPD usually becomes clinically apparent after age 40. Recent estimates from surveys in European countries suggest that the prevalence of COPD may be closer to 80-100/1,000 in areas where the prevalence of smoking is very high. Cross-country comparisons made by the Global Burden of Disease Study also showed that the prevalence of COPD is highest in countries where cigarette smoking is very common, while the prevalence is lowest in countries where smoking is less common. According to data obtained from the Ministry of Health of Armenia more than threeforth of adult males in Yerevan are smokers. Among other groups, the rate of smoking is as follows: about 40% of adult women, 37% of adolescents (half of whom are girls). Even though there is no reliable data regarding prevalence of COPD in Armenia, considering the high rate of smoking among Armenian population, COPD is an important Public Health problem. Moreover, morbidity data on COPD probably greatly underestimate the total burden of the disease because COPD is not usually recognized and diagnosed until it is clinically apparent and moderately advanced. Mortality data also underestimate COPD as a cause of death because the disease is more likely to be cited as a contributory than as an underlying cause of death, or may not be cited at all. Because COPD can be severely disabling, medical expenditures for treating COPD and the indirect costs of morbidity can represent a substantial economic and social burden for society. In 1998, the annual economic burden for COPD in the US was estimated to be $23.9 billion, including $14.7 billion in direct expenditures for medical care services, $4.7 billion in indirect morbidity costs and $4.5 billion in costs related to premature mortality. Based on a prevalence of 15.7 million cases, the estimated impact of COPD is $1,522 per patient per year. According to the projections of the World Bank Global Burden of Disease Study, COPD will rank 5th in 2020, responsible for 4.1% of total DALYs (Disability-Adjusted Life Year) lost. Only ischemic heart disease, major depression, traffic accidents, and cerebrovascular disease will cause a greater burden. In Armenia, disabled individuals usually do not receive long-term supportive care services; therefore, COPD may force two individuals to leave the workplace the affected individual and a family member who must now stay home to care for the disabled relative. Thus, in terms of productivity lost, COPD may be doubly burdensome for Armenia. The factor common to all known environmental causes of COPD is prolonged exposure to small airborne particles, whether in cigarette smoke, ambient air, or the workplace environment. Tobacco use is a major risk factor for COPD. Data from the third National Health and Nutrition Examination Survey (NHANES 3), a large national survey carried out in the US between 1988 and 1994, reinforce the view that smoking status is the most important determinant of COPD prevalence in developed countries. Among white males, airflow limitation was present in 14.2 % of current smokers, 6.9 % of ex-smokers, and 3.3 % of never smokers. Among white females, the prevalence of airflow limitation was 13.6 % in smokers, 6.8 % in exsmokers and 3.1 % in never smokers. Recent studies of chronic obstructive pulmonary disease have raised interest in its relation to nutrition. Data from the Third National Health and Nutrition Examination Survey showed that higher levels of antioxidant nutrients are associated with better lung function. In particular, a diet rich in fresh fruit and fish is associated with a salutary effect on lung health. Reduced intake of fresh fruit and vegetables was linked with poorer lung function in a study of more than 9,000 adults in the United Kingdom. 13 However, the role of deficiency of antioxidant nutrients as a risk factor for COPD is putative. 13,14 Until recently, virtually all population-based studies in developed countries showed a marked male preponderance of COPD prevalence and mortality. A different pattern has been reported from developing countries, where a slightly higher prevalence in women than men is reported. The patterns seen in developing c