Mortality Among Persons With Both Asthma and Chronic Obstructive Pulmonary Disease Aged ≥25 Years, by Industry and Occupation

United States, 1999-2016

Katelynn E. Dodd, MPH; John Wood, MS; Jacek M. Mazurek, MD, PhD

Disclosures

Morbidity and Mortality Weekly Report. 2020;69(22):670-679. 

In This Article

Discussion

Among persons aged ≥25 years, more women than men died from asthma-COPD overlap. A study using 2012 Behavioral Risk Factor Surveillance System data from South Carolina found that asthma-COPD overlap was more prevalent among women than among men.[2] The annual age-adjusted death rate per million for both men and women decreased from 1999 through 2016. When analyzed separately, the age-adjusted death rate for asthma similarly declined among men and women from 1999 to 2016.[3] The age-adjusted death rate for COPD among men declined from 1999 to 2011; however, among women, it increased from 2000 to 2011.[4] A 2016 Danish study of the long-term prognosis of persons with chronic airway disease found that the number of deaths from chronic respiratory disease were higher among persons with asthma-COPD overlap with late-onset asthma than among those with COPD only.[5]

The American Thoracic Society estimates that approximately 16% of asthma and 14% of COPD among adults is attributable to workplace exposures.[6] Several workplace exposures, (e.g., dusts, secondhand smoke, welding fumes, and isocyanates) are causative agents for both asthma and COPD.[7] An analysis of workplace exposures among U.S. adults using 2010 National Health Interview Survey data found that workers in industries and occupations similar to those identified in the current study had exposure to vapors, gas, dust, or fumes at work.[8] In that study, an estimated 52.9% of workers in agriculture, forestry, fishing, and hunting and 42.8% of workers in manufacturing industries, as well as 61.5% of production workers, 50.8% of farming, fishing, and forestry workers, and 16.5% of adults in food preparation and serving occupations had frequent exposure to vapors, gas, dust, or fumes at work.[8] Although cigarette smoking is the primary cause of COPD, 25% of U.S. adults with COPD have never smoked.*** Among nonsmoking adults in food preparation and serving occupations, an estimated 15.4% had frequent exposure to secondhand smoke at work.[8] Exposure to these agents might explain the increased prevalence of asthma-COPD overlap mortality among workers in certain industries and occupations and should be considered for targets for public health interventions.

Nonpaid workers, nonworkers, and persons working at home had significantly elevated asthma-COPD overlap PMRs among both men and women aged 25–64 years, suggesting that asthma-COPD overlap might be associated with substantial morbidity resulting in loss of employment. Previous reports have similarly found that patients with asthma-COPD overlap were observed to have worse health outcomes than those with asthma or COPD alone.[1,5] Moreover, persons with asthma caused or made worse by workplace exposures were similarly more likely to be unemployed and retire at a significantly younger mean age than were those with asthma that is not work-related.[9] Retired and unemployed persons might have left the workforce because of severe asthma or COPD; however, complete decedent work histories were unavailable to assess such changes in employment.

The findings in this report are subject to at least five limitations. First, a discrete diagnosis code for asthma-COPD overlap does not currently exist, and no information was available to validate asthma and COPD diagnoses, which might be subject to misdiagnosis. A 1991 study from the United States found that 37% of subjects with a history of physician-diagnosed airways obstructive disease had airways obstructive disease reported on their death certificate, suggesting the potential for underreporting.[10] In addition, it is possible that differences in patterns of asthma and COPD diagnosis regionally and over time might have affected how these diagnoses were recorded on death certificates. Second, discrete diagnosis codes for occupational asthma or COPD do not currently exist; therefore, determining whether the asthma or COPD diagnoses listed as underlying or contributing to death were caused by workplace exposures is not possible. Third, guidelines for reporting industry and occupation on death certificates††† instruct recorders to report decedent's "kind of business/industry" and "usual occupation" (i.e., "the type of job the individual was engaged in for most of his or her working life"). Therefore, if asthma and COPD were caused by workplace exposures, the industry and occupation reported on death certificates might not reflect those in which potential workplace exposures occurred. Workers might have changed jobs or held more than one job; however, information is not available to assess changes in employment. Fourth, no information was available to evaluate the smoking status of decedents, which might have caused or worsened the consequences of asthma or COPD. Finally, only selected states provided information on industry and occupation, and only for certain years; therefore, information by industry and occupation might not be nationally representative.

Among persons aged ≥25 years, deaths associated with asthma-COPD overlap were more frequent among women than among men. The association between asthma-COPD overlap mortality and nonworking status among adults of working age (25–64 years) suggests that asthma-COPD overlap might be associated with substantial morbidity resulting in loss of employment. Increased risk for asthma-COPD overlap mortality among adults in certain industries and occupations suggests targets for public health interventions (e.g., elimination or substitution of exposures, removing workers from exposures, engineering controls such as ventilation or enclosure of exposure generating processes, and workplace smoke-free policies) to prevent asthma and COPD in and out of the workplace. Continued surveillance for asthma-COPD overlap morbidity and mortality is essential to inform policy and intervention activities.

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