Study Notes Growing Trends of COPD in Industries and Occupations Across the US

A new US study published in the American Journal of Preventative Medicine has examined the trends in prevalence of chronic obstructive pulmonary disease (COPD) in a number of industries. On top of a general rise in COPD rates, the study found data suggesting increases not tied to a past history of smoking in several occupations.

COPD is the fourth leading cause of death in the United States, with an estimated 3.4 million US workers currently experiencing the disease, including 2.2 million who have never smoked. An estimated 19% of COPD cases are attributable to workplace exposures in America. COPD occupational risk awareness efforts are needed to reduce prevalence among workers, especially in the at-risk industries examined, the study authors noted.

Between 2012 and 2018, an age-adjusted annual average of 4.1% of workers had chronic COPD. Prevalence varied by industry and occupation. COPD increased at an estimated annual average of 1.5% (P < .05).

Female workers, workers 65 years and older, non-Hispanic White workers, workers with a high school degree/GED or less, those lacking health insurance, and current smokers had significantly higher COPD prevalence. These trends were consistent with previous findings.

By the authors’ estimates, 40% of COPD cases were among workers who have never smoked. Their findings suggest that workplace exposures to environmental respiratory irritants like vapor, tobacco smoke, paper dust, photocopier fumes, paints, and glues could be leading to higher rates. Chronic bronchitis also played a role in the data, as it was reported 19 times more frequently than emphysema in nonsmokers, suggesting it is an overlapping contributor to the COPD rates.

Overall, trends increased notably across many fields, including in entertainment, the arts, recreation, financial specialists, food service workers, maintenance workers, personal care workers, office and administrative support workers, material moving workers, and motor-vehicle operators.

As a foundation for their work, the authors used data from the National Health Interview Survey, collecting from the years 2012-2018 from workers 18 years and older. The interviews used were analyzed in 2019. Response rates to the surveys varied from 61.2% in 2012 to 53.1% in 2018. Due to several small sample sizes (<45), industry and occupation groups were combined into 38 separate categories. In line with previous studies, the reference group to calculate the adjusted prevalence odds ratio (POR) consisted of real estate and rental/leasing workers and management, as they have a low reported likelihood of environmental exposure to COPD-causing agents.

A Poisson regression model was used to examine annual trends, with a multivariate logistic regression then applied to calculate adjusted PORs.

COPD cases that could be traced to work were 27.3% for all workers and 24.0% among those who never smoked.

PORs were significantly elevated among workers in the other office and administrative support (POR, 1.8) occupations. Next in prominence were the PORs among workers in food and beverage serving (POR, 1.6) occupations, then installation maintenance and repair (POR, 1.6) occupations, and finally motor-vehicle operators and material moving occupations (POR, 1.6) compared with those in the reference group.

The authors wrote, “Among those who never smoked, workers in 12 of the 38 occupation groups had a higher age-adjusted COPD prevalence than the national average (2.3%). The highest COPD prevalence was among workers in the other office and administrative support occupation (4.5%), and PORs were significantly elevated in the office and administrative support (POR=2.1) occupations, followed by the PORs among supervisors and those in other food services (POR=1.9) occupations.”

Some key limitations were present in the study. First, information on COPD was self-reported. This may have left out up to two-thirds of COPD patients with persistent airflow limitation. The authors’ findings were not validated by medical records or pulmonary function tests or medical records, which might have resulted in misclassification of status and underestimation of prevalence.

The previously mentioned small sample sizes may have contributed unreliable estimates. Among the never-smokers sampled, prevalence trends were not assessed by industry and occupation. This was also due to the small sample sizes in certain years of the data. Industry groups can include several occupations worth of workers. It is thus possible some of the industries with higher ORs may not represent the occupation categories with increased risks.

Additionally, while cumulative smoking intensity is notably associated with higher COPD risk, data on smoking intensity and duration for all workers were not available during the study. Current smoking rates were used to substitute. Temporal information on COPD onset and exposures in the workplace was not available from NHIS data, so it was not technically possible to find the direct association between work and COPD.

Of note, the authors pointed out that only workers employed at any point in the prior 12 months of the study were included. Some workers with COPD may have since left the fields in which workplace exposure led to COPD, altering the data. However, analyses of workers with COPD prevalence in the longest held jobs found similar rates of results.

Lastly, attributable case calculations can be sensitive to the chosen reference group. For this study, separate reference groups by industry and occupation were selected to calculate the POR. Based on lower COPD prevalence and workplace exposures, the findings show COPD cases attributable to work were higher for industry than occupation. Previous studies have developed similar findings.

Despite these limitations, the authors feel that the general rise in COPD prevalence tracked by their work is a meaningful addition to research that can be used to positively address COPD health and safety concerns in many key industries of the working world.

REFERENCE

Syamlal G, Doney B, Hendricks S, Mazurek JM. Chronic obstructive pulmonary disease and U.S. workers: prevalence, trends, and attributable cases associated with work. Am J Prev Med. 2021;61(3):e127-e137. doi:10.1016/j.amepre.2021.04.011