Lung function predicts survival in a cohort of asbestos cement workers

Diminished pulmonary function in long-term workers exposed to cotton dust determined in a cross-sectional study in small Pakistani enterprises

PURPOSE

While large cotton industry plants producing for the foreign market have undergone improvements of occupational hygiene lately, working conditions in power looms producing mainly for the local market are still poor. The respiratory health in workers of power looms has not been studied so far.

METHODS

In a cross-sectional study, 51 male cotton workers from power looms, 58 from large cotton factories and 52 controls were investigated by spirometry and a symptoms questionnaire. Spirometric measurements and respiratory symptoms were related to exposure duration in large and small factories by multivariate linear regression and logistic regression, respectively, with smoking, age and anthropometric parameters considered as confounders.

RESULTS

Work duration in power looms was associated with declines in forced expiratory volume in 1 s, peak flow, maximum midexpiratory flow and forced expiratory flow 75 and an increased risk of obstruction (OR 1.09/year; 95% CI: 1.002 to 1.18) by applying the Global Lung Initiative equations. Except cough that was only associated with smoking, all respiratory symptoms (chest tightness, shortness of breath, fever) increased as a function of duration of exposure in power looms but not in large factories.

CONCLUSIONS

Despite limitations inherent in the cross-sectional approach, there is evidence for workers in small weaving factories to face an increased risk of pulmonary function loss and respiratory symptoms. Industrial hygiene measures in these small enterprises should be encouraged. Failure to detect adverse respiratory outcomes from occupation in large factories could be due to a 'survivor' (healthy worker) effect.

Prediction models and risk assessment for silicosis using a retrospective cohort study among workers exposed to silica in China

This study aims to develop a prognostic risk prediction model for the development of silicosis among workers exposed to silica dust in China. The prediction model was performed by using retrospective cohort of 3,492 workers exposed to silica in an iron ore, with 33 years of follow-up. We developed a risk score system using a linear combination of the predictors weighted by the LASSO penalized Cox regression coefficients. The model's predictive accuracy was evaluated using time-dependent ROC curves. Six predictors were selected into the final prediction model (age at entry of the cohort, mean concentration of respirable silica, net years of dust exposure, smoking, illiteracy, and no. of jobs). We classified workers into three risk groups according to the quartile (Q1, Q3) of risk score; 203 (23.28%) incident silicosis cases were derived from the high risk group (risk score ≥ 5.91), whilst only 4 (0.46%) cases were from the low risk group (risk score < 3.97). The score system was regarded as accurate given the range of AUCs (83-96%). This study developed a unique score system with a good internal validity, which provides scientific guidance to the clinicians to identify high-risk workers, thus has important cost efficient implications.

Lung Function Profiles among Individuals with Nonmalignant Asbestos-related Disorders

Background

Inhalation of asbestos fibers can lead to adverse health effects on the lungs. This study describes lung function profiles among individuals with nonmalignant asbestos-related disorders (ARDs).

Methods

The study population was from the Workers' Compensation (Dust Diseases) Board of New South Wales, Sydney, Australia. Lung function measurements were conducted in males with asbestosis (n = 26), diffuse pleural thickening (DPT; n = 129), asbestosis and DPT (n = 14), pleural plaques only (n = 160) and also apparently healthy individuals with a history of asbestos exposure (n = 248). Standardized spirometric and single-breath diffusing capacity for carbon monoxide (DL_CO) measurements were used.

Results

Mean age [standard deviation (SD)] was 66.7 (10.3) years for all participants. Current and ex-smokers among all participants comprised about 9.0% and 54.8%, respectively. Median pack-years (SD) of smoking for ex- and current-smokers were 22.7 (19.9). Overall 222 participants (38.6%) and 139 participants (24.2%) had forced expiratory volume in 1 second (FEV₁) and forced vital capacity (FVC) measurements < 80% predicted, and 217 participants (37.7%) had FEV₁/FVC results < 70%. A total of 249 individuals (43.8%) had DLco values < 80% predicted and only 75 (13.2%) had DLco/VA results < 80% predicted. A total of 147 participants (25.6%) had peak expiratory flow (PEF) measurements < 80% predicted. The presence of ARDs lowered the lung function measurements compared to those of healthy individuals exposed to asbestos.

Conclusion

Lung function measurement differs in individuals with different ARDs. Monitoring of lung function among asbestos-exposed populations is a simple means of facilitating earlier interventions.

Lung function predicts mortality: 10-year follow-up after lung cancer screening among asbestos-exposed workers

PURPOSE

To assess the predictive value of lung function impairment on mortality among asbestos-exposed workers.

METHODS

A total of 590 workers originally screened for occupational lung disease including spirometry and pulmonary diffusing capacity measurements were followed up for mortality data (ICD-10 classification). The mean follow-up time was 10.5 years. Associations of different lung function parameters with mortality from all causes and from cardiovascular (I00-I99) and non-malignant respiratory diseases (J00-J99) were analysed. Factor analysis was used to create obstructive and restrictive factors.

RESULTS

A total of 191 deaths were found altogether. Most measured lung function variables were associated with increased mortality when studied separately. Both decreased forced expiratory flow in one second (hazard ratio/measurement unit = 0.977, 95 % CI 0.969-0.988, p < 0.001) and impaired diffusing capacity (0.973, 0.965-0.981, p < 0.001) were independently associated with mortality from all causes, as well as from cardiovascular and non-malignant respiratory diseases. Both obstructive factor alone and the sum of obstructive and restrictive factors were associated with all studied mortality categories. The restrictive factor alone was associated with all-cause and respiratory mortality.

CONCLUSIONS

Deteriorated lung function predicts deaths. The reasons for impaired lung function should be medically explored to enable restoring measures aiming thus to prevent premature deaths.

Lung function in asbestos-exposed workers, a systematic review and meta-analysis

BACKGROUND

A continuing controversy exists about whether, asbestos exposure is associated with significant lung function impairments when major radiological abnormalities are lacking. We conducted a systematic review and meta-analysis in order to assess whether asbestos exposure is related to impairment of lung function parameters independently of the radiological findings.

METHODS

MEDLINE was searched from its inception up to April 2010. We included studies that assessed lung function parameters in asbestos exposed workers and stratified subjects according to radiological findings. Estimates of VC, FEV1 and FEV1/VC with their dispersion measures were extracted and pooled.

RESULTS

Our meta-analysis with data from 9,921 workers exposed to asbestos demonstrates a statistically significant reduction in VC, FEV1 and FEV1/VC, even in those workers without radiological changes. Less severe lung function impairments are detected if the diagnoses are based on (high resolution) computed tomography rather than the less sensitive X-ray images. The degree of lung function impairment was partly related to the proportion of smokers included in the studies.

CONCLUSIONS

Asbestos exposure is related to restrictive and obstructive lung function impairment. Even in the absence of radiological evidence of parenchymal or pleural diseases there is a trend for functional impairment.