Total and Cause-Specific Mortality Risk Associated With Low-Level Exposure to Crystalline Silica: A 44-Year Cohort Study From China.

The association between low-level crystalline silica (silica) exposure and mortality risk is not well understood. We investigated a cohort of 44,807 Chinese workers who had worked in metal mines or pottery factories for at least 1 year from January 1, 1960, to December 31, 1974, and were followed through 2003. Low-level silica exposure was defined as having a lifetime highest annual mean silica exposure at or under a permissible exposure limit (PEL). We considered 3 widely used PELs, including 0.05 mg/m3, 0.10 mg/m3, and 0.35 mg/m3. Cumulative silica exposure was estimated by linking a job exposure matrix with each participant's work history. For the 0.10-mg/m3 exposure level, Cox proportional hazards models showed significantly increased risk of mortality from all diseases (for each 1-ln mg/m3-years increase in logged cumulative silica exposure, hazard ratio (HR) = 1.05, 95% confidence interval (CI): 1.03, 1.07), malignant neoplasms (HR = 1.06, 95% CI: 1.03, 1.09), lung cancer (HR = 1.08, 95% CI: 1.02, 1.14), ischemic heart disease (HR = 1.09, 95% CI: 1.02, 1.16), pulmonary heart disease (HR = 1.08, 95% CI: 1.00, 1.16), and respiratory disease (HR = 1.20, 95% CI: 1.14, 1.26). The 0.05-mg/m3 and 0.35-mg/m3 exposure levels yielded similar associations. Long-term exposure to low levels (PELs ≤0.05 mg/m3, ≤0.10 mg/m3, or ≤0.35 mg/m3) of silica is associated with increased total and certain cause-specific mortality risk. Control of ambient silica levels and use of personal protective equipment should be emphasized in practice.

Change in prevalence of restrictive lung impairment in the U.S. population and associated risk factors: the National Health and Nutrition Examination Survey (NHANES) 1988-1994 and 2007-2010.

BACKGROUND: Data for the U.S adult population from the National Health and Nutrition Examination Survey (NHANES) were used to evaluate risk factors for a restrictive pattern on spirometry and estimate the change in its prevalence from the 1988-1994 to 2007-2010 sampling periods. Several previous epidemiologic studies used the Global Initiative for Chronic Obstructive Lung Disease fixed forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) > 0.70 criteria for classifying restrictive pattern rather than the age-defined American Thoracic Society (ATS)/European Respiratory Society (ERS) lower limit of normal (LLN) criteria, which may lead to misclassification. METHODS: Spirometry measurements from NHANES data for the 1988-1994 and 2007-2010 periods were analyzed to estimate the age-standardized prevalence of a restrictive pattern on spirometry and the change in prevalence over time for adults aged 20-79. A restrictive pattern was defined based on ATS/ERS LLN criteria as FEV1/FVC > LLN and FVC < LLN, and a moderate to more severe restrictive pattern was further evaluated using FEV1 < 70% predicted. The associations between demographic and other individual risk factors for restrictive lung impairment were examined using multivariable logistic regression models for the two consecutive time periods. RESULTS: The overall age-standardized prevalence of restrictive pattern decreased significantly from 7.2% (1988-1994) to 5.4% (2007-2010) (p = 0.0013). The prevalence of moderate to more severe restrictive pattern also decreased significantly from 2.0% to 1.4% (p = 0.023). Factors positively associated with restrictive pattern on spirometry included age, female sex, white race, lower education, former and current smoking, and comorbidities including doctor-diagnosed cardiovascular disease, doctor-diagnosed diabetes, and abdominal obesity. CONCLUSIONS: The overall prevalence of restrictive pattern and moderate to more severe restrictive pattern decreased between the 1988-1994 and 2007-2010 survey periods despite a population increase in the proportion of comorbidities associated with restrictive pattern (i.e. diabetes and abdominal obesity). This suggests a decline in individual risk factors for restrictive pattern and a need for future research.

Prevalence of Airflow Obstruction in U.S. Adults Aged 40-79 Years: NHANES Data 1988-1994 and 2007-2010.

BACKGROUND: The study evaluated the change in the prevalence of airflow obstruction in the U.S. population 40-79 years of age from years 1988-1994 to 2007-2010. METHODS: Spirometry data from two representative samples of the U.S. population, the National Health and Nutrition Examination Surveys (NHANES) conducted in 1988-1994 and 2007-2010, were used. The American Thoracic Society/European Respiratory Society (ATS/ERS) criteria were used to define airflow obstruction. RESULTS: Based on ATS/ERS criteria, the overall age-adjusted prevalence of airflow obstruction among adults aged 40-79 years decreased from 16.6% to 14.5% (p < 0.05). Significant decreases were observed for the older age category 60-69 years (20.2% vs. 15.4%; p < 0.01), for males (19.0% vs. 15.4%; p < 0.01), and for Mexican American adults (12.7% vs. 8.4%; p < 0.001). The prevalence of moderate and more severe airflow obstruction decreased also (6.4% vs. 4.4%; p < 0.01). Based on ATS/ERS criteria, during 2007-2010, an estimated 18.3 million U.S. adults 40-79 years had airflow obstruction, 5.6 million had moderate or severe airflow obstruction and 1.4 million had severe airflow obstruction. CONCLUSIONS: The overall age-adjusted prevalence of airflow obstruction among U.S. adults aged 40-79 years decreased from 1988-1994 to 2007-2010, especially among older adults, Mexican Americans, and males.

Changes in prevalence of chronic obstructive pulmonary disease and asthma in the US population and associated risk factors.

Chronic lower airway diseases, including chronic obstructive pulmonary disease (COPD) and asthma, are currently the third leading cause of death in the United States. We aimed to evaluate changes in prevalence of and risk factors for COPD and asthma among the US adult population. We evaluated changes in prevalence of self-reported doctor-diagnosed COPD (i.e. chronic bronchitis and emphysema) and asthma and self-reported respiratory symptoms comparing data from the 1988-1994 and 2007-2010 National Health and Nutrition Examination Surveys. To investigate changes in the severity of each outcome over the two periods, we calculated changes in the proportions of spirometry-based airflow obstruction for each outcome. Prevalence of doctor-diagnosed chronic bronchitis and emphysema decreased significantly mainly among males, while asthma increased only among females. The self-reported disease and the respiratory symptoms were associated with increased prevalence of airflow obstruction for both periods. However, the prevalence of airflow obstruction decreased significantly in the second period among those with shortness of breath and doctor-diagnosed respiratory conditions (chronic bronchitis, emphysema, and asthma). COPD outcomes and asthma were associated with lower education, smoking, underweight and obesity, and occupational dusts and fumes exposure. Chronic lower airway diseases continue to be major public health problems. However, decreased prevalence of doctor-diagnosed chronic bronchitis and emphysema (in males) and decreased prevalence of airflow obstruction in those with respiratory symptoms and doctor-diagnosed respiratory diseases may indicate a declining trend and decrease in disease severity between the two periods. Continued focus on prevention of these diseases through public health interventions is prudent.

Prevalence of chronic obstructive pulmonary disease among US working adults aged 40 to 70 years. National Health Interview Survey data 2004 to 2011.

OBJECTIVE: To estimate the prevalence and prevalence odds ratios of chronic obstructive pulmonary disease (COPD) among US workers by major occupational groups. METHODS: The 2004 to 2011 National Health Interview Survey data for working adults 40 to 70 years old was analyzed to estimate the prevalence of COPD by major occupational groups. Logistic regression models were used to evaluate the associations between COPD (chronic bronchitis or emphysema) and occupations. RESULTS: The estimated overall COPD prevalence was 4.2% (95% CI, 4.0 to 4.3). The odds of COPD were highest among workers in health care support occupations (prevalence odds ratio, 1.64; 95% CI, 1.25 to 2.14) followed by food preparation and serving-related occupations (prevalence odds ratio, 1.57; 95% CI, 1.20 to 2.06). CONCLUSIONS: Prevalence varied by occupations, suggesting workplace exposures may contribute to COPD. Preventive measures such as interventions to reduce smoking may reduce the prevalence of COPD.

Occupational risk factors for COPD phenotypes in the Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study.

INTRODUCTION: The contribution of occupational exposure to the risk of chronic obstructive pulmonary disease COPD in population-based studies is of interest. We compared the performance of self-reported exposure to a newly developed JEM in exposure-response evaluation. METHODS: We used cross-sectional data from Multi-Ethnic Study of Atherosclerosis (MESA), a population-based sample of 45-84 year olds free of clinical cardiovascular disease at baseline. MESA ascertained the most recent job and employment, and the MESA Lung Study measured spirometry, and occupational exposures for 3686 participants. Associations between health outcomes (spirometry defined airflow limitation and Medical Research Council-defined chronic bronchitis) and occupational exposure [self-reported occupational exposure to vapor-gas, dust, or fumes (VGDF), severity of exposure, and a job-exposure matrix (JEM)-derived score] were evaluated using logistic regression models adjusted for non-occupational risk factors. RESULTS: The prevalence of airflow limitation was associated with self-reported exposure to vapor-gas (OR 2.6, 95%CI 1.1-2.3), severity of VGDF exposure (P-trend < 0.01), and JEM dust exposure (OR 2.4, 95%CI 1.1-5.0), and with organic dust exposure in females; these associations were generally of greater magnitude among never smokers. The prevalence of chronic bronchitis and wheeze was associated with exposure to VGDF. The association between airflow limitation and the combined effect of smoking and VGDF exposure showed an increasing trend. Self-reported vapor-gas, dust, fumes, years and severity of exposure were associated with increased prevalence of chronic bronchitis and wheeze (P < 0.001). CONCLUSIONS: Airflow limitation was associated with self-reported VGDF exposure, its severity, and JEM-ascertained dust exposure in smokers and never-smokers in this multiethnic study.

Estimating the U.S. prevalence of chronic obstructive pulmonary disease using pre- and post-bronchodilator spirometry: the National Health and Nutrition Examination Survey (NHANES) 2007-2010.

BACKGROUND: During 2007-2010, the National Health and Nutrition Examination Survey (NHANES) conducted a spirometry component which obtained pre-bronchodilator pulmonary lung function data on a nationally representative sample of US adults aged 6-79 years and post-bronchodilator pulmonary lung function data for the subset of adults with airflow limitation. The goals of this study were to 1) compute prevalence estimates of chronic obstructive pulmonary disease (COPD) using pre-bronchodilator and post-bronchodilator spirometry measurements and fixed ratio and lower limit of normal (LLN) diagnostic criteria and 2) examine the potential impact of nonresponse on the estimates. METHODS: This analysis was limited to those aged 40-79 years who were eligible for NHANES pre-bronchodilator spirometry (n=7,104). Examinees with likely airflow limitation were further eligible for post-bronchodilator testing (n=1,110). Persons were classified as having COPD based on FEV1/FVC < 70% (fixed ratio) or FEV1/FVC < lower limit of normal (LLN) based on person's age, sex, height, and race/ethnicity. Those without spirometry but self-reporting both daytime supplemental oxygen therapy plus emphysema and/or current chronic bronchitis were also classified as having COPD. The final analytic samples for pre-bronchodilator and post-bronchodilator analyses were 77.1% (n=5,477) and 50.8% (n=564) of those eligible, respectively. To account for non-response, NHANES examination weights were adjusted to the eligible pre-bronchodilator and post-bronchodilator subpopulations. RESULTS: In 2007-2010, using the fixed ratio criterion and pre-bronchodilator test results, COPD prevalence was 20.9% (SE 1.1) among US adults aged 40-79 years. Applying the same criterion to post-bronchodilator test results, prevalence was 14.0% (SE 1.0). Using the LLN criterion and pre-bronchodilator test results, the COPD prevalence was 15.4% (SE 0.8), while applying the same criterion to post-bronchodilator test results, prevalence was 10.2% (SE 0.8). CONCLUSIONS: The overall COPD prevalence among US adults aged 40-79 years varied from 10.2% to 20.9% based on whether pre- or post-bronchodilator values were used and which diagnostic criterion (fixed ratio or LLN) was applied. The overall prevalence decreased by approximately 33% when airflow limitation was based on post-bronchodilator as compared to pre-bronchodilator spirometry, regardless of which diagnostic criterion was used.

Exposure-response analysis and risk assessment for lung cancer in relationship to silica exposure: a 44-year cohort study of 34,018 workers.

Crystalline silica has been classified as a human carcinogen by the International Agency for Research on Cancer (Lyon, France); however, few previous studies have provided quantitative data on silica exposure, silicosis, and/or smoking. We investigated a cohort in China (in 1960-2003) of 34,018 workers without exposure to carcinogenic confounders. Cumulative silica exposure was estimated by linking a job-exposure matrix to work history. Cox proportional hazards model was used to conduct exposure-response analysis and risk assessment. During a mean 34.5-year follow-up, 546 lung cancer deaths were identified. Categorical analyses by quartiles of cumulative silica exposure (using a 25-year lag) yielded hazard ratios of 1.26, 1.54, 1.68, and 1.70, respectively, compared with the unexposed group. Monotonic exposure-response trends were observed among nonsilicotics (P for trend < 0.001). Analyses using splines showed similar trends. The joint effect of silica and smoking was more than additive and close to multiplicative. For workers exposed from ages 20 to 65 years at 0.1 mg/m(3) of silica exposure, the estimated excess lifetime risk (through age 75 years) was 0.51%. These findings confirm silica as a human carcinogen and suggest that current exposure limits in many countries might be insufficient to protect workers from lung cancer. They also indicate that smoking cessation could help reduce lung cancer risk for silica-exposed individuals.

COPD causation and workplace exposures: an assessment of agreement among expert clinical raters.

BACKGROUND: Although occupational exposure is a known risk factor for Chronic Obstructive Pulmonary Disease (COPD), it is difficult to identify specific occupational contributors to COPD at the individual level to guide COPD prevention or for compensation. The aim of this study was to gain an understanding of how different expert clinicians attribute likely causation in COPD. METHODS: Ten COPD experts and nine occupational lung disease experts assigned occupational contribution ratings to fifteen hypothetical cases of COPD with varying combinations of occupational and smoking exposures. Participants rated the cause of COPD as the percentage contribution to the overall attribution of disease for smoking, occupational exposures and other causes. RESULTS: Increasing pack-years of tobacco smoking was associated with significantly decreased proportional occupational causation ratings. Increasing weighted occupational exposure was associated with increased occupational causation ratings by 0.28% per unit change. Expert background also contributed significantly to the proportion of occupational causation rated, with COPD experts rating on average a 9.4% greater proportion of occupational causation per case. CONCLUSION: Our findings support the notion that respiratory physicians are able to assign attribution to different sources of causation in COPD, taking into account both smoking and occupational histories. The recommendations on whether to continue to work in the same job also differ, the COPD experts being more likely to recommend change of work rather than change of work practice.

Longitudinal decline in lung function in former asbestos exposed workers.

BACKGROUND: This study was designed to assess the effect of asbestos exposure on longitudinal lung function decline. METHODS: A group of 502 former asbestos-cement workers with at least two spirometry tests 4 years apart. Repeated evaluations included respiratory symptoms questionnaire, spirometry and chest imaging. Asbestos exposure was ascertained as years of exposure, an index of cumulative exposure and latency time. The mixed effects model was used to evaluate the effect of exposure on the level and rate of change in forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC). RESULTS: Mean age at entry was 51 (SD 9.9) years, mean latency time 25.6 (SD 10.0) years, mean follow-up time 9.1 (SD 2.8) years and mean number of spirometry tests 3.5. The FEV(1) level was significantly related to pack-years of smoking at entry and during the follow-up, the index of cumulative asbestos exposure at entry, and the presence of asbestosis at follow-up. The FVC level was significantly related to pack-years of smoking during the follow-up, cumulative asbestos exposure at entry, asbestosis and pleural thickening at follow-up, and body mass index at entry. Asbestos exposure was not associated with increasing rates of FEV(1) and FVC decline. However, FEV(1) regression slopes with age, estimated by terciles of cumulative exposure, showed significant differences. Combined effects of smoking and exposure conferred further acceleration in lung function decline. CONCLUSIONS: Occupational exposure in asbestos-cement industry was a risk factor for increased lung function decline. The effect seems to be mostly concentrated during the working period. Smoking and exposure had synergic effects.

Combined effect of lung function level and decline increases morbidity and mortality risks.

Lung function level and decline are each predictive of morbidity and mortality. Evaluation of the combined effect of these measurements may help further identify high-risk groups. Using Copenhagen City Heart Study longitudinal spirometry data (n = 10,457), 16-21 year risks of chronic obstructive pulmonary disease (COPD) morbidity, COPD or coronary heart disease mortality, and all-cause mortality were estimated from combined effects of level and decline in forced expiratory volume in one second (FEV(1)). Risks were evaluated using Cox proportional hazards models for individuals grouped by combinations of baseline predicted FEV(1) and quartiles of slope. Hazard ratios (HR) and 95 % confidence intervals (CI) were estimated using stratified analysis by gender, smoking status, and baseline age (≤45 and >45). For COPD morbidity, quartiles of increasing FEV(1) decline increased HRs (95 % CI) for individuals with FEV(1) at or above the lower limit of normal (LLN) but below 100 % predicted, reaching 5.11 (2.58-10.13) for males, 11.63 (4.75-28.46) for females, and 3.09 (0.88-10.86) for never smokers in the quartile of steepest decline. Significant increasing trends were also observed for mortality and in individuals with a baseline age ≤45. Groups with 'normal' lung function (FEV(1) at or above the LLN) but excessive declines (fourth quartile of FEV(1) slope) had significantly increased mortality risks, including never smokers and individuals with a baseline age ≤45.

The value of periodic spirometry for early recognition of long-term excessive lung function decline in individuals.

OBJECTIVE: To establish the value of workplace spirometry monitoring methods for early recognition of long-term excessive lung function decline in individuals. METHODS: Sensitivity, specificity, and positive likelihood ratio were calculated to determine the predictive value of the linear regression slope and limits of longitudinal decline for early prediction of long-term excessive forced expiratory volume in 1 second (FEV1) decline (> 90 mL/yr established over 9 to 11 years) in ongoing spirometry monitoring programs (firefighters and construction workers) and a historical program (paper-pulp mill workers). The longitudinal limits account for the expected FEV1 within-person variability. RESULTS: The longitudinal limits achieved clinical "usefulness" (positive likelihood ratio 10 or higher) from the fourth to fifth year of follow-up, whereas the linear regression slope was less useful. The usefulness depended on data precision and measurement frequency. CONCLUSION: The limits of longitudinal decline are more useful for early recognition of long-term excessive FEV1 decline than the linear regression slope.

Long-term exposure to silica dust and risk of total and cause-specific mortality in Chinese workers: a cohort study.

BACKGROUND: Human exposure to silica dust is very common in both working and living environments. However, the potential long-term health effects have not been well established across different exposure situations. METHODS AND FINDINGS: We studied 74,040 workers who worked at 29 metal mines and pottery factories in China for 1 y or more between January 1, 1960, and December 31, 1974, with follow-up until December 31, 2003 (median follow-up of 33 y). We estimated the cumulative silica dust exposure (CDE) for each worker by linking work history to a job-exposure matrix. We calculated standardized mortality ratios for underlying causes of death based on Chinese national mortality rates. Hazard ratios (HRs) for selected causes of death associated with CDE were estimated using the Cox proportional hazards model. The population attributable risks were estimated based on the prevalence of workers with silica dust exposure and HRs. The number of deaths attributable to silica dust exposure among Chinese workers was then calculated using the population attributable risk and the national mortality rate. We observed 19,516 deaths during 2,306,428 person-years of follow-up. Mortality from all causes was higher among workers exposed to silica dust than among non-exposed workers (993 versus 551 per 100,000 person-years). We observed significant positive exposure-response relationships between CDE (measured in milligrams/cubic meter-years, i.e., the sum of silica dust concentrations multiplied by the years of silica exposure) and mortality from all causes (HR 1.026, 95% confidence interval 1.023-1.029), respiratory diseases (1.069, 1.064-1.074), respiratory tuberculosis (1.065, 1.059-1.071), and cardiovascular disease (1.031, 1.025-1.036). Significantly elevated standardized mortality ratios were observed for all causes (1.06, 95% confidence interval 1.01-1.11), ischemic heart disease (1.65, 1.35-1.99), and pneumoconiosis (11.01, 7.67-14.95) among workers exposed to respirable silica concentrations equal to or lower than 0.1 mg/m(3). After adjustment for potential confounders, including smoking, silica dust exposure accounted for 15.2% of all deaths in this study. We estimated that 4.2% of deaths (231,104 cases) among Chinese workers were attributable to silica dust exposure. The limitations of this study included a lack of data on dietary patterns and leisure time physical activity, possible underestimation of silica dust exposure for individuals who worked at the mines/factories before 1950, and a small number of deaths (4.3%) where the cause of death was based on oral reports from relatives. CONCLUSIONS: Long-term silica dust exposure was associated with substantially increased mortality among Chinese workers. The increased risk was observed not only for deaths due to respiratory diseases and lung cancer, but also for deaths due to cardiovascular disease. Please see later in the article for the Editors' Summary.

Periodic spirometry in occupational setting: improving quality, accuracy, and precision.

OBJECTIVE: Effectiveness of periodic spirometry in medical monitoring depends on spirometry quality. We describe an intervention on spirometry quality and its impact on accuracy and precision of longitudinal measurements. METHODS: The intervention was conducted from 2005 to 2010 in a monitoring program involving approximately 2500 firefighters. Intervention supported adherence to 2005 American Thoracic Society/European Respiratory Society recommendations through monitoring of spirometry quality and longitudinal data precision, technician training, change of spirometer, and quality control. RESULTS: The percentage of forced vital capacity tests meeting the American Thoracic Society/European Respiratory Society criteria increased from 60% to 95% and the mean longitudinal forced expiratory volume in 1 second within-person variation decreased from 6% to 4%. The increased accuracy and precision of measurements and estimated rates of forced expiratory volume in 1 second decline were statistically significant. CONCLUSION: Monitoring of quality and data precision helped to recognize the need for intervention. The intervention improved accuracy and precision of spirometry measurements and their usefulness.

Health outcomes associated with lung function decline and respiratory symptoms and disease in a community cohort.

BACKGROUND: In workplace respiratory disease prevention, a thorough understanding is needed of the relative contributions of lung function loss and respiratory symptoms in predicting adverse health outcomes. METHODS: Copenhagen City Heart Study respiratory data collected at 4 examinations (1976-2003) and morbidity and mortality data were used to investigate these relationships. With 15 or more years of follow-up for a hospital diagnosis of chronic obstructive pulmonary disease (COPD) morbidity, COPD or coronary heart disease (CHD) mortality, and all-cause mortality, risks for these outcomes were estimated in relation to asthma, chronic bronchitis, shortness of breath, and lung function level at examination 2 (1981-1983) or lung function decline established from examinations 1 (1976-1978) to 2 using 4 measures (FEV(1) slope, FEV(1) relative slope, American College of Occupational and Environmental Medicine's Longitudinal Normal Limit [LNL], or a limit of 90 milliliters per year [ml/yr]). These risks were estimated by hazard ratios (HR) and 95% confidence intervals (CI) adjusted for age, height-adjusted baseline forced expiratory volume in 1 second (FEV(1)/height(2)), and height. RESULTS: For COPD morbidity, the increasing trend in the HR (95% CI) by quartiles of the FEV(1) slope reached a maximum of 3.77 (2.76-5.15) for males, 6.12 (4.63-8.10) for females, and 4.14 (1.57-10.90) for never-smokers. Significant increasing trends were also observed for mortality, with females at higher risk. CONCLUSION: Lung function decline was associated with increased risk of COPD morbidity and mortality emphasizing the need to monitor lung function change over time in at-risk occupational populations.

Worksite wellness program for respiratory disease prevention in heavy-construction workers.

OBJECTIVE: To describe a respiratory disease prevention program in a US heavy-construction company. METHODS: The program uses periodic spirometry and questionnaires and is integrated into a worksite wellness program involving individualized intervention. Spirometry Longitudinal Data Analysis (SPIROLA) technology is used to assist the physician with (i) management and evaluation of longitudinal spirometry and questionnaire data; (ii) designing, recoding, and implementing intervention; and (iii) evaluation of impact of the intervention. Preintervention data provide benchmark results. RESULTS: Preintervention results on 1224 workers with 5 or more years of follow-up showed that the mean rate of FEV1 decline was 47 mL/year. Age-stratified prevalence of moderate airflow obstruction was higher than that for the US population. CONCLUSION: Preintervention results indicate the need for respiratory disease prevention in this construction workforce and provide a benchmark for future evaluation of the intervention.

Evaluation of methods to determine excessive decline of forced expiratory volume in one second in workers exposed to diacetyl-containing flavorings.

OBJECTIVE: To evaluate methods for determining excessive short-term decline in forced expiratory volume in one second (FEV1) in diacetyl-exposed workers. METHODS: We evaluated five methods of determining excessive longitudinal FEV1 decline in diacetyl-exposed workers and workers from a comparative cohort: American Thoracic Society (ATS), ACOEM an 8% limit, and a relative and absolute longitudinal limit on the basis of spirometry data variability. Relative risk and incidence of excess decline were evaluated. RESULTS: Incidence of excessive FEV1 decline was 1% in the comparative cohort using ATS and ACOEM criteria, 4.1% using relative limit of longitudinal decline, 4.4% with absolute longitudinal limit of decline, and 5.6% by using the 8% limit. Relative risk of abnormal FEV1 decline in diacetyl-exposed workers was elevated in all evaluated methods. CONCLUSION: Alternative methods for respiratory surveillance in diacetyl-exposed workers may be preferable to ATS or ACOEM.

Spirometry Longitudinal Data Analysis Software (SPIROLA) for Analysis of Spirometry Data in Workplace Prevention or COPD Treatment.

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality. Periodic spirometry is often recommended for individuals with potential occupational exposure to respiratory hazards and in medical treatment of respiratory disease, to prevent COPD or improve treatment outcome. To achieve the full potential of spirometry monitoring in preserving lung function, it is important to maintain acceptable precision of the longitudinal measurements, apply interpretive strategies that identify individuals with abnormal test results or excessive loss of lung function in a timely manner, and use the results for intervention on respiratory disease prevention or treatment modification. We describe novel, easy-to-use visual and analytical software, Spirometry Longitudinal Data Analysis software (SPIROLA), designed to assist healthcare providers in the above aspects of spirometry monitoring. Software application in ongoing workplace spirometry-based medical monitoring programs helped to identify increased spirometry data variability due to deteriorating test quality and subsequent improvement following interventions, and helped to enhance identification of individuals with excessive decline in lung function.