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Work-Related Lung Disease Surveillance System (eWoRLD)

Methods: Morbidity

Prevalence (Asthma, Chronic Obstructive Pulmonary Disease, and Smoking)

The estimated prevalence of asthma, chronic obstructive pulmonary disease (COPD), and tobacco use was based on public-use National Health Interview Survey (NHIS) data from the National Center for Health Statistics (NCHS), (http://www.cdc.gov/nchs/nhis.htm).

Asthma was defined as a "yes" response to the question "Have you ever been told by a doctor or other health professional that you had asthma?" Current asthma was defined as positive response to having asthma and a “yes” response to “Do you still have asthma?” Asthma attack was defined as a "yes" response to the question "During the past 12 months, have you had an episode of asthma or an asthma attack?" COPD was defined as a "yes" response to one or both of the following questions: (1) "During the past 12 months, have you been told by a doctor or other health professional that you had chronic bronchitis?" or (2) "Have you ever been told by a doctor or other health professional that you had emphysema?"

Cigarette smoking status was classified in three groups: nonsmokers, former smokers, and current smokers. Nonsmokers were defined as those who smoked fewer than 100 cigarettes during their entire life. Former smokers were defined as those who smoked at least 100 cigarettes in their entire life and do not currently smoke. Current smokers were defined as those who smoked at least 100 cigarettes in their entire life and currently smoke every day or some days. Smokeless tobacco users were defined as adults who reported having ever used snuff or chewing tobacco and are currently using snuff or chewing tobacco every day or some days. Any tobacco users were defined as adults who reported having ever used snuff or chewing tobacco or a cigar or cigarettes and are currently using snuff, chewing tobacco or smoke cigars or smoke cigarettes every day or some days. Dual users were defined as current cigarette smokers who also reported current smokeless tobacco use.

Information on current industry and occupation was collected from all individuals who were employed during the week before the survey interview. The NCHS recodes all industry and occupation verbatim responses to a coding scheme based on 4-digit Census Industry and Occupation codes that are informed by the 2002 and 2007 North American Industry Classification System (NAICS) and the 2000 and 2010 Standard Occupational Classification (SOC), respectively. These codes are further collapsed into 79 distinct industry categories reflecting NAICS Sectors and Subsectors and 94 distinct occupation categories reflecting SOC Major Groups and Subgroups. The latter are used and can be accessed on the NCHS website at http://www.cdc.gov/nchs/nhis/quest_data_related_1997_forward.htm.

Estimated prevalences of asthma, COPD, smokeless tobacco use, any tobacco use, and cigarette smoking status by gender, current industry and occupation were calculated using sample weights and adjustment for non-responses. For asthma and COPD, estimated prevalences were also calculated by cigarette smoking status. Survey respondents with unknown or missing information were excluded from the denominator when calculating prevalences. SAS® software (SAS Institute Inc., Cary, NC) was used to analyze data and to calculate the estimated frequencies, variances, and prevalences with corresponding 95% confidence intervals.

Prevalence (Coal Workers' Pneumoconiosis)

Prevalence of coal workers' pneumoconiosis (CWP) is reported by tenure and time period. The Coal Workers' Health Surveillance Program (CWHSP) defines radiographic evidence of CWP in chest x-rays as the presence of either small opacities with a profusion category greater than or equal to International Labour Office (ILO) category 1/0, large opacities (i.e., larger than one centimeter in diameter), or both. Administrative and regulatory guidelines have varied over the life of the program. The prevalence of CWP is presented by underground coal mining tenure of miners who participated in the surveys. Tenure calculations were based upon the work histories reported by each miner at the time of the examination. For presentations by five-year periods, only the most recent examination in that period was used for miners with more than one radiograph.

Incidence (Occupational Respiratory Illnesses)

Estimated numbers of work-related respiratory illness (with days away from work) and incidence rates of occupational respiratory conditions due to toxic agents were generally abstracted from the Bureau Labor Statistics annual reports of occupational injuries and illnesses.

Association of Occupational and Environmental Clinics Diagnoses and Hazards

The frequency distributions of work-related respiratory conditions diagnosed in the Association of Occupational and Environmental Clinics (AOEC) and the respiratory hazards associated with these respiratory diagnoses were tabulated from summary reports prepared by AOEC. For hazards other than asbestos, only the top two are listed and the number in parentheses represents the number of diagnoses associated with that reported hazard. The list of the most frequently associated respiratory hazards (excluding asbestos) is a partial listing of all occupational hazards associated with the work-related respiratory conditions. All remaining occupational hazards are aggregated in an "All other" category.

Discharges from Short-Stay Non-federal Hospitals (Asbestosis, Coal Workers' Pneumoconiosis, Silicosis)

Estimated numbers of discharges from short-stay non-federal hospitals were tabulated from the National Hospital Discharge Survey (NHDS) data files provided by the National Center for Health Statistics. Estimated numbers were based on any mention of asbestosis, coal workers' pneumoconiosis, or silicosis from among the seven diagnosis codes provided in the data files for discharged patients who were of age 15 years and older.

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