Chronic Obstructive Pulmonary Disease and U.S. Workers: Prevalence, Trends, and Attributable Cases Associated With Work

Abstract

Introduction:

Chronic obstructive pulmonary disease is the fourth leading cause of death in the U.S. Workplace exposures are important modifiable contributors to the burden of chronic obstructive pulmonary disease. Among U.S. workers, 19% of chronic obstructive pulmonary disease cases are attributable to workplace exposures. This study examines the trends in chronic obstructive pulmonary disease prevalence during 2012–2018 among workers and assesses the population attributable fraction for chronic obstructive pulmonary disease associated with work by smoking status, industry, and occupation.

Methods:

The 2012–2018 National Health Interview Survey data for workers aged ≥18 years employed during the 12 months before the interview were analyzed in 2019. Annual trends were examined using the Poisson regression model. Multivariate logistic regression was used to calculate adjusted prevalence ORs.

Results:

During 2012–2018, an estimated age-adjusted annual average of 4.1% of workers had chronic obstructive pulmonary disease, and prevalence varied by industry and occupation. Overall, chronic obstructive pulmonary disease prevalence increased by an estimated annual average of 1.5% (p<0.05). The prevalence trends increased significantly among workers in the merchant wholesale nondurable and the arts, entertainment, and recreation industries and among financial specialists; supervisors, other food services workers; supervisors, building grounds workers, and maintenance workers; personal care and services workers; supervisors and office and administrative support workers; and motor-vehicle operators and material moving workers. The proportion of chronic obstructive pulmonary disease cases attributable to work was 27.3% among all workers and 24.0% among never smokers.

Conclusions:

Public health efforts to increase the awareness and understanding of chronic obstructive pulmonary disease associated with occupational risk factors are needed to prevent chronic obstructive pulmonary disease among workers, especially among those employed in industries and occupations with increasing prevalence trends.

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) refers to progressive lung diseases that are non-reversible and often associated with emphysema and chronic bronchitis.¹ It is one of the major causes of morbidity and the fourth leading cause of death in the U.S.^2,3 In 2013, an estimated 15.7 million U.S. adults had COPD.⁴ Among U.S. workers, an estimated 3.4 million (6%) currently have COPD, including 2.2 million workers who have never smoked.⁵ Among workers with COPD, half had activity limitations, and a quarter were unable to work.³ In addition, COPD is associated with increased healthcare utilization, including increased frequency of emergency room visits, physician office visits, and hospitalizations,^4,6 with an estimated $32 billion in expenditures attributable to COPD among U.S. adults.⁶ Among U.S. workers, the direct medical expenditures associated with treated COPD were estimated at $5 billion, and the highest expenditures were for prescription medications.⁷

Cigarette smoking is the most important preventable risk factor for developing COPD. However, an estimated 30% of adults with COPD are never smokers,¹ indicating that other risk factors, such as environmental and occupational exposures to substances, can irritate and damage the lungs. For example, occupational exposures to dusts, gases, minerals (coal, silica), metals (vanadium, cadmium), and welding fumes have been associated with COPD.^8–16 According to the American Thoracic Society, 14% of COPD in the general population is attributable to occupational exposures.¹ Among U.S. workers, the population attributable fraction (PAF) for COPD associated with work was estimated at 19.2%, and the proportion was even higher (31.0%) among workers who never smoked.¹⁷

The objectives of the current are to (1) assess the current trends in COPD prevalence from 2012 to 2018 among workers aged ≥18 years who were employed during the 12 months before the survey interview and (2) to estimate the age-adjusted prevalence, prevalence OR (POR), and the PAF for COPD associated with work by smoking status, industry, and occupation.

METHODS

Study Sample

For this study, the 2012–2018 National Health Interview Survey (NHIS) data were used. The NHIS is a personal household interview survey of the U.S. civilian non-institutionalized population conducted annually by the National Center for Health Statistics. The survey response rates during the study period ranged from 53.1% in 2018 to 61.2% in 2012. The 2012–2018 NHIS was approved by the Research Ethics Review Board of the National Center for Health Statistics. For this study, a secondary data analysis, publicly available NHIS data were used, and National Institute for Occupational Safety and Health IRB approval was not needed.

Measures

Currently, employed adults were respondents aged ≥18 years who reported working at a job or business, with a job or business but not at work, or working, but not for pay, at a family-owned job or business during the 12 months before the survey interview. Information on participants’ current occupation and industry available in the NHIS data are grouped into 79 industry groups and 94 occupation groups. For this analysis, industry and occupation groups were further combined because of small sample sizes (<45), resulting in 38 industry and 38 occupation groups as defined in Appendix Table 1 (available online).

Current smokers were those who smoked ≥100 cigarettes during their entire life and currently smoke. Former smokers were those who smoked ≥100 cigarettes during their entire life and currently do not smoke. Never smokers were those who reported that they had never smoked or smoked <100 cigarettes during their entire life. Participants with COPD were identified using a yes response to any of the following 3 questions: During the past 12 months, have you been told by a doctor or other health professional that you had chronic bronchitis? Have you ever been told by a doctor or other health professional that you had emphysema? Have you ever been told by a doctor or other health professional that you had COPD?

Statistical Analysis

For this study, the 2012–2018 NHIS data were combined to improve the reliability of the estimates. Data were weighted to produce nationally representative estimates using sample weights.¹⁸ The data were analyzed in 2019. Variance estimates were calculated to account for the clustered and stratified survey design. A 7-year (2012–2018) COPD prevalence trend was examined, adjusting for serial correlation using the autoregressive option.¹⁹ Annual trend in age-adjusted COPD prevalence (annual percentage change) was examined using a Poisson regression model. Multivariate logistic regression was used to calculate the adjusted PORs. All multivariate models were simultaneously adjusted for age (continuous), sex, race/ethnicity, and smoking status. For calculating the adjusted POR, the reference group used for industry and for occupation was real estate and rental and leasing workers and management workers, respectively. Workers in these occupations/industry groups have been selected in previous studies as reference groups and have reported a low likelihood of workplace exposure to agents (including dusts, vapors, gas, and fumes) that could contribute to COPD.^20–22

Joinpoint, version 4.7.0.0,¹⁹ and SAS, version 9.4, were used to examine the trends and for data analysis.

Estimates with a relative SE (SE of the estimate divided by the estimate) ≥30% were not reported. PAFs for COPD among all workers and among workers who never smoked, controlling for age, sex, race, and smoking status, were estimated. Education and income were not included in the analysis because they are considered determinants and consequences of occupational status, respectively, and are therefore on the causal pathway between occupation and COPD (rather than functioning as confounders).²² The PAF for COPD is the fraction of cases with COPD associated with occupational exposure and was calculated according to the following formula^14,17:

$$\begin{array}{c}k\\ \text{PAF}=\sum {\text{P}}_{ci}\left({\text{POR}}_i-1\right)/{\text{POR}}_i\\ i=1,\end{array}$$

where k=number of industry or occupation (38 groups); P_ci=−cases/total cases, cases represent the estimated number of COPD cases in the i^th industry or occupation group, and total cases represent the total estimated number of COPD cases summed across industry/occupation groups; and POR_i=the adjusted POR for COPD estimated in the i^th occupation or industry.

Attributable cases (ACs) are cases attributable to employment in the i^th industry group/i^th occupation group.

ACs were calculated according to the following formula:

$$\text{AC}=N_i*P_i\left({\text{POR}}_i-1\right)/{\text{POR}}_i,$$

where N_i=estimated respondents in the i^th industry or occupation group; and P_i=estimated age-adjusted prevalence in the ith industry or occupation.

RESULTS

During 2012–2018, the estimated annual age-adjusted average COPD prevalence among all workers was 4.1% (crude prevalence=3.6%), and the highest odds of having COPD was among workers aged ≥65 years (POR=4.1), among non-Hispanic Whites (POR=2.0), and among current cigarette smokers (POR=3.8) than among workers aged 18–34 years, among other race/ethnicity groups, and among never smokers, respectively (Table 1).

Table 1.

COPD P, Trends, and PORs Among Workers by Selected Characteristics and Smoking Status

Characteristics	All workers				Never smokers
	Estimated workers (1,000s)	Age-adjusted P (95% CI)	POR (95% CI)	AAPC	Estimated workers (1,000s)	Age-adjusted P (95% CI)	POR (95% CI)	AAPC
Total (100%)	164,296	4.1 (4.0, 4.3)		1.5	106,193	2.3 (2.2, 2.4)		−0.6
Age group, years
18–34	22,239	2.3 (1.9, 2.6)	1.0	−6.6	17,623	1.6 (1.2, 1.9)	1.0	−5.3
35–44	70,247	2.4 (2.2, 2.5)	1.0 (0.9, 1.2)	0.6	46,016	1.6 (1.5, 1.8)	1.0 (0.8, 1.3)	1.7
45–64	61,829	4.7 (1.5, 4.9)	2.1 (1.8, 2.5)	1.3	37,354	2.9 (1.5, 3.1)	1.9 (1.5, 2.3)	−0.7
≥65	9,982	7.7 (7.1, 8.2)	4.1 (3.4, 4.9)	2.4	5,199	4.3 (3.7, 5.0)	2.8 (2.1, 3.7)	−3.0
Sex
Male	86,127	2.8 (2.7, 3.0)	1.0	1.0	52,143	1.5 (1.4, 1.7)	1.0	−1.0
Female	78,169	4.3 (4.2, 4.5)	1.7 (1.6, 1.8)	0.2	54,050	2.8 (2.6, 3.0)	1.9 (1.6, 2.1)	0.2
Race/ethnicity
Hispanic	26,737	2.2 (2.0, 2.5)	1.2 (1.0, 1.5)	0.4	19,859	1.8 (1.5, 2.1)	1.5 (1.1, 2.1)	3.7
Non-Hispanic White	106,914	4.0 (3.8, 4.2)	2.0 (1.6, 2.4)	0.6	63,666	2.4 (2.2, 2.6)	2.1 (1.6, 2.7)	−0.6
Non-Hispanic Black	19,425	3.6 (3.3, 4.0)	1.8 (1.4, 2.3)	−2.4	14,250	2.5 (2.2, 2.8)	2.1 (1.5, 2.8)	−2.9
Other	11,221	1.9 (1.6, 2.3)	1.0	6.6	8,417	1.2 (0.9, 1.6)	1.0	2.5
Education
≤High school/GED	51,948	4.5 (4.2, 4.7)	1.3 (1.2, 1.4)	1.3	28,969	2.3 (2.1, 2.6)	1.1 (1.0, 1.2)	−1.6
>High school	111,756	4.0 (3.0, 3.3)	1.0	0.0	76,889	2.2 (2.0, 2.3)	1.0	−0.9
Unknown	593	2.3 (1.3, 4.1)	—a		335	0.8 (0.3, 2.8)	—
Income, $
<35,000	34,120	5.3 (5.0, 5.6)	1.7 (1.5, 1.8)	0.1	20,468	2.7 (2.5, 3.0)	1.5 (1.3, 1.7)	−0.7
35,000–75,000	46,837	4.0 (3.9, 4.4)	1.5 (1.3, 1.6)	2.2	28,911	2.7 (2.5, 3.0)	1.5 (1.3, 1.7)	0.1
≥75,000	71,380	2.6 (2.4, 2.7)	1.0	2.3	48,699	1.8 (1.6, 2.0)	1.0	0.2
Unknown	11,960	2.9 (2.5, 3.4)	1.1 (0.9, 1.3)		8,115	1.8 (1.5, 2.3)	1.0 (0.8, 1.3)	−3.7
Health insurance
Not insured	22,551	4.2 (3.8, 4.6)	1.0 (0.9, 1.2)	−3.8	12,762	2.2 (1.8, 2.6)	1.0 (0.8, 1.2)	−0.9
Insured	140,855	3.5 (3.4, 3.6)	1.0	1.3	92,826	2.2 (2.1, 2.3)	1.0	−0.6
Unknown	890	—	—		605	—	—
U.S. Census regionb
Northeast	29,240	3.3 (3.0, 3.6)	1.1 (1.0, 1.2)	0.6	18,839	1.9 (1.6, 2.2)	0.9 (0.8, 1.2)	−1.1
Midwest	38,100	4.0 (3.7, 4.3)	1.3 (1.1, 1.4)	2.9	23,157	2.5 (2.2, 2.8)	1.3 (1.1, 1.5)	−1.3
South	58,496	3.9 (3.7, 4.1)	1.3 (1.2, 1.4)	−1.5	37,922	2.3 (2.1, 2.5)	1.2 (1.0, 1.4)	−2.7
West	38,461	2.9 (2.7, 3.1)	1.0	0.6	26,275	2.0 (1.8, 2.2)	1.0	3.8
Smoking status
Current	25,915	7.7 (7.2, 8.1)	3.8 (3.5, 4.1)	2.4	—	—
Former	31,564	4.3 (4.0, 4.6)	2.0 (1.9, 2.2)	4.3	—	—
Never	106,193	2.3 (2.2, 2.4)	1.0	−0.9	106,193	2.3 (2.2, 2.4)		−0.6
Unknown	625	—	—	—	—	—	—	—

Note: Boldface indicates statistical significance (p<0.05).

The overall totals may not add up owing to rounding. Age-adjusted COPD P was defined as a positive response to any of the 3 questions: (1) Have you ever been told by a doctor or other health professional that you had chronic obstructive pulmonary disease, also called COPD? or (2) Have you ever been told by a doctor or other health professional that you had emphysema? or (3) During the past 12 months, have you been told by a doctor or other health professional that you had chronic bronchitis? (total COPD cases for all workers N=5,841,696 and for never smokers n=558,596). For trends, AAPC is in age-adjusted COPD P during 2012–2018 (annual average trends). Workers included adults who reported working at a job or business; with a job or business but not at work; or working, but not for pay, at a family-owned job or business during the last 12 months of the survey interview. Estimates are weighted to provide national estimates for current employment and are presented in thousands.

^aEstimates suppressed because relative SE for the estimate was ≥30%.

^bhttps://www2.census.gov/geo/pdfs/maps-data/maps/reference/us_regdiv.pdf.

AAPC, annual average percentage change; COPD, chronic obstructive pulmonary disease: P, prevalence; POR, prevalence OR.

Age-adjusted COPD prevalence among those who never smoked was 2.3%, and the highest odds of having COPD was among workers aged ≥65 years (POR= 2.8) and among non-Hispanic Whites and non-Hispanic Blacks (POR=2.1) than among workers aged 18–34 years and other race/ethnicity groups (including American Indian and Alaska Native, Asian, multiple race) (Table 1). Ever smokers reporting emphysema, chronic bronchitis, or COPD were 1.1%, 3.8%, 2.6%, respectively. Never smokers reporting emphysema, chronic bronchitis, or COPD were 0.1%, 1.9%, and 0.4%.

Overall, among all workers, estimated age-adjusted COPD prevalence increased annually by 1.5% (p<0.05) from 2012 to 2018. Significant (p<0.05) increases in COPD prevalence over time were observed among male participants (1.0%), Hispanics (0.4%), other race/ethnicity groups (6.6%; American Indian and Alaska Native, Asian, multiple race), workers aged ≥65 years (2.4%), workers with a high-school degree/GED or less (1.3%), workers with a combined family income of ≥$75,000 (2.3%), workers with health insurance (1.3%), and workers living in the Midwest (2.9%) (Table 1).

Workers in 14 of the 38 industry groups had age-adjusted COPD prevalence higher than the national average (4.1%), with the highest prevalence among workers in the clothing and clothing accessories stores (8.4%), followed by that in the nursing and residential care facilities (5.5%). From 2012 to 2018, a significant (p<0.05) increase in annual average percentage change in age-adjusted COPD prevalence was observed among workers in the merchant wholesale nondurable (24.1%) and arts, entertainment, and recreation industries (10.3%) (Table 2). PORs were significantly elevated among workers in the clothing and clothing accessories stores (POR=2.7), followed by that in the credit intermediation and related activities (POR=1.9) industry compared with that among workers in the reference group (workers in the insurance, real estate, and other finance industry).

Table 2.

COPD P, Trends, POR, and PAF Among Workers by Industry and Smoking Status

Industries	All workers						Never smokers
	Estimated workers (1,000s)	Age-adjusted P (95% CI)	POR (95% CI)	AAPC	ACa (1,000s)	PAF	Workers (1,000s)	Age-adjusted P (95% CI)	POR (95% CI)	ACa (1,000s)	PAF (%)
Agriculture	23,757	2.8 (2.2, 3.6)	1.2 (0.8, 1.7)	−3.3	10	0.2	15,517	2.1 (1.3, 2.8)	1.3 (0.7, 2.3)	7	0.3
Mining	9,313	4.0 (2.7, 5.8)	1.7 (1.0, 2.8)	−9.7	15	0.3	5,066	3.7 (1.4, 6.1)	2.7 (1.2, 5.7)	12	0.5
Utilities	13,737	3.2 (2.2, 4.7)	1.4 (0.9, 2.3)	−8.9	13	0.2	8,406	1.8 (0.7, 2.9)	1.1 (0.5, 2.4)	2	0.1
Construction	106,618	3.4 (3.0, 3.9)	1.4 (1.0, 1.9)	2.0	101	1.7	54,711	1.7 (1.2, 2.2)	1.2 (0.7, 2.1)	18	0.8
Manufacturing	162,019	3.1 (2.7, 3.4)	1.2 (0.9, 1.6)	−3.9	81	1.4	94,636	1.9 (1.5, 2.4)	1.2 (0.7, 1.9)	30	1.3
Merchant wholesale durable	18,920	2.9 (2.0, 4.0)	1.1 (0.7, 1.8)	8.2	7	0.1	11,011	2.0 (1.0, 3.0)	1.3 (0.7, 2.5)	5	0.2
Merchant wholesale nondurable	19,398	3.2 (2.3, 4.4)	1.3 (0.8, 2.0)	24.1	13	0.2	11,889	2.8 (1.5, 4.0)	1.8 (1.0, 3.3)	14	0.6
Motor-vehicle part dealers	18,550	1.9 (1.3, 2.7)	0.7 (0.4, 1.1)	2.2	0	0.0	10,414	0.5 (0.1, 1.0)	0.4 (0.1, 1.0)	0	0
Building material and garden equipment and supplies dealer	13,478	4.2 (2.9, 6.1)	1.6 (1.0, 2.6)	5.8	22	0.4	7,866	1.0 (0.2, 1.8)	0.6 (0.3, 1.6)	0	0
Food and beverage stores	32,488	4.2 (3.2, 5.4)	1.4 (1.0, 2.0)	−5.4	40	0.6	20,574	1.1 (0.6, 1.6)	0.7 (0.4, 1.3)	0	0
Health and personal care gasoline stations	12,798	3.0 (2.1, 4.3)	1.1 (0.7, 1.8)	5.9	5	0.1	9,480	1.6 (0.7, 2.6)	1.0 (0.5, 2.0)	0	0
Clothing and clothing accessories stores	5,889	8.4 (5.9, 11.8)	2.7 (1.7, 4.1)	−0.9	31	0.4	3,021	2.6 (0.1, 5.2)	1.7 (0.6, 5.0)	3	0.1
Clothing and general merchandise stores	44,355	5.2 (4.3, 6.3)	1.8 (1.3, 2.5)	−3.4	102	1.5	30,773	2.4 (1.6, 3.2)	1.5 (0.9, 2.5)	24	1.0
Miscellaneous, nonstore, and nonspecified retailers	23,625	4.3 (3.2, 5.7)	1.6 (1.0, 2.4)	−3.2	37	0.6	15,210	2.6 (1.3, 3.9)	1.5 (0.8, 3.0)	14	0.6
Transportation (including support activities for transportation)	54,138	4.4 (3.7, 5.2)	1.8 (1.3, 2.4)	5.3	104	1.9	29,838	2.4 (1.5, 3.3)	1.6 (0.9, 2.8)	26	1.1
Postal service, couriers, and messengers	14,951	3.9 (2.9, 5.4)	1.6 (1.0, 2.4)	−4.2	22	0.4	9,253	2.9 (1.5, 4.3)	1.9 (1.0, 3.5)	13	0.5
Information	33,314	4.2 (3.3, 5.3)	1.7 (1.2, 2.4)	8.7	58	1.0	21,523	3.0 (1.9, 4.2)	1.9 (1.1, 3.3)	31	1.3
Monetary authorities	20,893	2.7 (1.9, 3.6)	1.0 (0.7, 1.5)	−4.9	0	0.0	15,098	1.9 (1.1, 2.7)	1.0 (0.6, 1.9)	1	<0.1
Credit intermediation and related activities	12,457	4.8 (3.3, 7.1)	1.9 (1.1, 3.1)	−1.2	28	0.4	8,860	3.4 (1.7, 5.1)	2.0 (1.1, 3.9)	15	0.7
Security, commodity contract, and other financial investments and related activities	12,199	1.9 (1.2, 2.9)	0.8 (0.5, 1.4)	−15.5	0	0.0	8,925	1.6 (0.6, 2.5)	0.9 (0.5, 2.0)	0	0
Insurance carriers and related activities	27,621	4.1 (3.2, 5.2)	1.6 (1.1, 2.2)	2.6	40	0.7	18,828	3.3 (2.1, 4.5)	1.8 (1.0, 3.2)	28	1.2
Real estate and rental and leasing	32,419	2.7 (2.1, 3.4)	Ref	−11.7	0	0.0	19,463	1.9 (1.1, 2.6)	Ref	0	0
Professional, scientific, and technical service industries	123,046	2.8 (2.4, 3.2)	1.2 (0.9, 1.6)	2.4	46	0.8	87,042	1.9 (1.6, 2.3)	1.2 (0.7, 1.9)	27	1.2
Administrative and support and waste management and remediation services	73,490	4.3 (3.7, 4.9)	1.5 (1.1, 2.1)	−0.4	110	1.8	42,585	2.3 (1.7, 2.8)	1.4 (0.9, 2.3)	29	1.2
Education services	156,484	3.1 (2.8, 3.5)	1.2 (0.9, 1.6)	−0.6	84	1.5	118,887	2.7 (2.3, 3.1)	1.4 (0.9, 2.2)	92	3.9
Ambulatory healthcare services	85,047	3.4 (3.0, 3.9)	1.2 (0.9, 1.6)	4.2	43	0.7	59,019	2.1 (1.7, 2.6)	1.1 (0.7, 1.7)	6	0.3
Hospital	70,926	3.0 (2.5, 3.5)	1.1 (0.8, 1.5)	−5.1	13	0.2	51,456	2.3 (1.7, 2.9)	1.2 (0.7, 1.9)	16	0.7
Nursing and residential care facilities	29,361	5.5 (4.5, 6.7)	1.7 (1.2, 2.3)	6.0	64	1.1	17,785	3.0 (1.9, 4.1)	1.5 (0.8, 2.6)	17	0.7
Social assistance	35,808	5.2 (4.2, 6.4)	1.7 (1.2, 2.4)	4.7	77	1.3	24,738	3.5 (2.4, 4.7)	1.7 (1.0, 2.9)	36	1.5
Arts, entertainment, and recreations	35,913	3.8 (3.0, 4.8)	1.5 (1.1, 2.2)	10.3	46	0.7	24,902	2.0 (1.3, 2.8)	1.3 (0.8, 2.4)	13	0.6
Accommodation	16,840	4.2 (3.2, 5.5)	1.4 (1.0, 2.1)	−5.5	21	0.3	10,419	2.7 (1.6, 3.8)	1.5 (0.8, 2.7)	9	0.4
Food services and drinking places	95,835	5.0 (4.3, 5.8)	1.7 (1.2, 2.3)	3.1	194	2.4	58,524	1.6 (1.2, 2.1)	1.2 (0.7, 2.0)	15	0.7
Repair and maintenance	22,043	3.8 (2.5, 5.8)	1.5 (0.9, 2.6)	−0.3	29	0.5	11,688	1.0 (0.3, 1.8)	0.8 (0.3, 1.8)	0	0
Personal services (barber shops, beauty salons, nail salons, laundry, funeral homes, and cemeteries)	23,355	3.5 (2.8, 4.5)	1.2 (0.8, 1.7)	−0.7	12	0.2	14,196	1.7 (1.0, 2.5)	0.9 (0.5, 1.7)	0	0
Religious, grantmaking, civic labor, professional, and similar organizations	25,086	3.1 (2.5, 4.0)	1.2 (0.9, 1.7)	−0.6	14	0.3	17,467	3.0 (2.0, 3.9)	1.5 (0.9, 2.6)	18	0.8
Private households	9,652	5.0 (3.5, 7.0)	1.5 (1.0, 2.4)	2.3	17	0.3	6,997	2.7 (1.3, 4.0)	1.2 (0.6, 2.4)	3	0.1
Public administration	79,456	3.6 (3.1, 4.1)	1.4 (1.1, 1.9)	8.8	86	1.6	52,623	2.3 (1.8, 2.8)	1.3 (0.8, 2.1)	27	1.2
All others	22,572	2.8 (2.1, 3.9)	1.1 (0.7, 1.7)	−1.5	7	0.1	14,834	2.0 (1.0, 3.0)	1.3 (0.7, 2.6)	7	0.3
Unknown	25,113	2.5 (1.8, 3.5)	1.0 (0.7, 1.6)	−2.2	1	0.0	18,402	1.2 (0.6, 1.9)	0.7 (0.4, 1.4)	0	0
Total	164,296	4.1 (4.0, 4.3)		1.5	1,595	27.3	106,193	2.3 (2.2, 2.4)		559	24.0

Note: Boldface indicates statistical significance (p<0.05).

The overall totals may not add up owing to rounding. By industry groups, P trends among those who never smoked were not calculated owing to unreliable data within groups by year.

Age-adjusted COPD P was defined as a positive response to any of the 3 questions: (1) Have you ever been told by a doctor or other health professional that you had chronic obstructive pulmonary disease, also called COPD? or (2) Have you ever been told by a doctor or other health professional that you had emphysema? or (3) During the past 12 months, have you been told by a doctor or other health professional that you had chronic bronchitis? (total COPD cases for all workers n=5,841,696 and for never smokers n=558,596). For trends, AAPC was in age-adjusted COPD P during 2012–2018. PAF included the proportion of COPD cases attributable to work in percentage. Workers included adults who reported working at a job or business; with a job or business but not at work; or working, but not for pay, at a family-owned job or business during the last 12 months of the survey interview. Estimates are weighted to provide national estimates for current employment and are presented in thousands.

^aNumber of COPD cases in thousands attributable to work.

AAPC, annual average percentage change; AC, attributable cases; COPD, chronic obstructive pulmonary disease; P, prevalence; PAF, population attributable fraction; POR, prevalence OR.

Among workers who never smoked, those in 16 of the 38 industry groups had a higher age-adjusted COPD prevalence than the national average (2.3%). The highest COPD prevalence was among workers in the mining industry (3.7%), and the PORs were significantly elevated among workers in mining (POR=2.7) followed by the PORs among those in the credit intermediation and related activities (POR=2.0) industry, compared with the PORs among workers in the reference group (workers in the insurance, real estate, and other finance industry).

Workers in 11 of the 38 occupation groups had COPD prevalence higher than the national average (4.1%), with the highest prevalence among workers in the food and beverage serving occupation (5.9%). From 2012 to 2018, a significant (p<0.05) increase in annual average percentage change in age-adjusted COPD prevalence was observed among financial specialists (16.1%); supervisors and other food services workers (15.1%); supervisors, building grounds workers, and maintenance workers (17.0%); personal care and service workers (10.6%); supervisors and office and administrative support workers (18.3%); and motor-vehicle operators and material moving workers (7.5%) (Table 3). PORs were significantly elevated among workers in the other office and administrative support (POR=1.8) occupations, followed by the PORs among workers in food and beverage serving (POR=1.6) occupations, installation maintenance and repair (POR=1.6) occupations, and motor-vehicle operators and material moving occupations (POR=1.6) compared with the PORs among those in the reference group.

Table 3.

COPD P, Trends, POR, and PAF Among Workers by Occupation and Smoking Status

Occupations	All workers						Never smokers
	Workers (1,000s)	Age-adjusted P (95% CI)	POR (95% CI)	AAPC	ACa (1,000s)	PAF, %	Workers (1,000s)	Age-adjusted P (95% CI)	POR (95% CI)	ACa (1,000s)	PAF, %
Management	15,943	2.8 (2.5, 3.1)	ref	−2.2			10,189	2.0 (1.6, 2.3)	ref	—	—
Business operation specialists	4,538	3.2 (2.6, 4.0)	1.1 (0.8, 1.4)	−1.1	11	0.2	3,050	1.9 (1.3, 2.6)	1.0 (0.6, 1.4)	0	0
Financial specialists	3,771	3.1 (2.4, 3.9)	1.1 (0.8, 1.4)	16.1	9	0.2	2,723	2.7 (1.8, 3.6)	1.3 (0.9, 2.0)	19	0.8
Computer and mathematical and architecture engineers	9,001	2.2 (1.8, 2.6)	0.9 (0.7, 1.1)	1.5	0	0	6,645	1.6 (1.1, 2.0)	1.0 (0.7, 1.4)	2	0.1
Life, physical, and social science	1,753	2.6 (1.8, 3.7)	1.0 (0.6, 1.4)	−8.0	18	0.3	1,308	2.0 (1.0, 3.0)	1.1 (0.6, 1.9)	2	0.1
Community and social services	3,017	3.6 (2.9, 4.5)	1.2 (0.9, 1.6)	−5.0	7	0.1	2,145	2.8 (1.9, 3.6)	1.3 (0.9, 1.9)	14	0.6
Postsecondary, primary, secondary, special education, and other teachers and instructors	8,943	3.0 (2.6, 3.5)	1.0 (0.8, 1.3)	2.4	0	0	6,962	2.9 (2.4, 3.4)	1.3 (1.0, 1.8)	52	2.2
Arts design entertainment, sports, and media	3,630	2.2 (1.7, 2.9)	0.8 (0.6, 1.1)	2.5	0	0	2,516	1.5 (0.9, 2.0)	0.8 (0.5, 1.2)	0	0
Health diagnosing and treating practitioners	6,363	2.3 (1.8, 2.8)	0.7 (0.6, 1.0)	−0.1	0	0	4,801	1.6 (1.1, 2.2)	0.7 (0.5, 1.1)	0	0
Healthcare technologist and technicians and other health care	2,877	3.4 (2.7, 4.4)	1.0 (0.8, 1.4)	−6.7	1	0.1	1,945	1.8 (1.0, 2.7)	0.9 (0.5, 1.4)	0	0
Nursing, psychiatric, and home health aids	2,186	5.3 (4.3, 6.6)	1.4 (1.1, 1.9)	4.4	34	0.6	1,430	3.6 (2.3, 4.9)	1.6 (1.1, 2.4)	19	0.8
Occupational and physical therapist assistants and aides and other healthcare support	1,693	3.3 (2.3, 4.8)	0.9 (0.6, 1.4)	8.1	0	0	1,156	2.0 (0.9, 3.1)	1.0 (0.5, 1.8)	0	0
Protective services	3,391	3.6 (2.8, 4.5)	1.3 (1.0, 1.8)	−2.3	30	0.5	2,242	2.3 (1.4, 3.1)	1.5 (1.0, 2.4)	17	0.8
Cooks and food preparation workers	3,346	4.8 (3.7, 6.1)	1.4 (1.0, 1.9)	−7.0	46	0.6	2,073	1.6 (0.9, 2.2)	0.9 (0.6, 1.5)	0	0
Food and beverage serving	3,560	5.9 (4.7, 7.4)	1.6 (1.2, 2.1)	−2.1	77	0.9	2,137	2.2 (1.1, 3.3)	1.4 (0.8, 2.5)	14	0.6
Supervisors and other food services	1,879	4.1 (3.0, 5.4)	1.2 (0.9, 1.7)	15.1	15	0.2	1,186	3.0 (1.7, 4.2)	1.9 (1.2, 3.0)	16	0.7
Building and grounds cleaning and pest control	4,480	5.0 (4.3, 5.8)	1.5 (1.2, 1.8)	−2.7	74	1.4	2,704	2.5 (1.8, 3.2)	1.2 (0.8, 1.6)	9	0.4
Supervisors and building grounds and maintenance workers	1,920	2.9 (2.1, 3.9)	1.0 (0.7, 1.5)	17.0	2	<0.1	1,054	1.1 (0.2, 1.9)	0.7 (0.3, 1.6)	15	0.6
Personal care and services	5,849	4.7 (4.0, 5.5)	1.4 (1.1, 1.7)	10.6	71	1.2	3,958	2.5 (1.9, 3.1)	1.2 (0.9, 1.6)	0	0
Supervisors sales	3,991	3.4 (2.7, 4.3)	1.1 (0.8, 1.4)	4.3	9	0.1	2,356	1.8 (1.0, 2.5)	1.0 (0.6, 1.5)	0	0
Retail sales workers	7,174	4.6 (4.0, 5.4)	1.4 (1.1, 1.7)	−3.0	97	1.4	4,971	2.0 (1.4, 2.5)	1.1 (0.8, 1.6)	13	0.5
Sales representatives and other sales related	4,962	2.6 (2.1, 3.2)	0.9 (0.7, 1.2)	−4.8	0	0	3,189	1.5 (1.0, 2.0)	0.8 (0.5, 1.1)	0	0
Supervisors and office and administrative support	1,269	3.9 (2.8, 5.5)	1.2 (0.8, 1.7)	18.3	7	0.1	709	1.7 (0.7, 2.8)	0.8 (0.4, 1.5)	0	0
Financial clerks	2,817	4.2 (3.3, 5.2)	1.2 (0.9, 1.5)	2.6	17	0.3	1,831	2.3 (1.5, 3.2)	1.0 (0.6, 1.5)	0	0
Information and records clerks	5,478	5.2 (4.4, 6.2)	1.5 (1.2, 1.9)	3.2	99	1.6	3,666	3.3 (2.4, 4.2)	1.7 (1.2, 2.3)	48	2.1
Material recording, scheduling, dispatching, and distributing	4,100	4.0 (3.3, 4.9)	1.3 (1.0,1.7)	2.4	41	0.7	2,525	2.3 (1.6, 3.1)	1.4 (1.0, 2.0)	16	0.7
Secretaries and administrative assistants	2,992	3.8 (3.1, 4.7)	1.0 (0.8, 1.4)	−12.2	554	0.1	1,937	3.4 (2.4, 4.4)	1.3 (0.9, 1.9)	15	0.6
Other office and administrative support	3,382	5.8 (4.9, 7.0)	1.8 (1.4, 2.3)	6.6	89	1.6	2,371	4.5 (3.4, 5.6)	2.1 (1.5, 2.9)	55	2.4
Farming, fishing, and forestry	1,329	2.6 (1.8, 3.7)	0.9 (0.6, 1.3)	4.1	0		913	1.7 (0.7, 2.7)	1.0 (0.5, 1.9)	1	0.1
Construction trade and extraction workers	6,915	3.3 (2.7, 3.9)	1.2 (0.9, 1.5)	−3.8	33	0.5	3,399	1.4 (0.9, 1.9)	1.0 (0.7, 1.6)	1	0.1
Other construction and extraction	1,347	3.2 (2.2, 4.5)	1.2 (0.8, 1.9)	14.9	7	0.1	676	2.6 (1.0, 4.3)	1.8 (0.9, 3.6)	8	0.4
Installation maintenance and repair	5,309	4.2 (3.3, 5.2)	1.6 (1.2, 2.1)	2.3	82	1.4	2,646	2.2 (1.1, 3.3)	1.5 (0.9, 2.7)	204	0.9
Assemblers and fabricators	1,431	3.9 (2.8, 5.3)	1.2 (0.9, 1.8)	2.8	10	0.2	834	1.5 (0.4, 2.5)	0.8 (0.4, 1.8)	0	0
Metal and plastic workers	1,867	3.0 (2.3, 4.0)	1.1 (0.8, 1.4)	4.5	3	0.1	911	1.1 (0.4, 1.8)	0.7 (0.4, 1.4)	0	0
Food processing, printing, textile, apparel and furnishing, wood workers, and plant and system operators	2,113	3.6 (2.5, 5.1)	1.1 (0.8, 1.7)	−7.8	10	0.2	1,256	2.3 (0.4, 4.2)	1.2 (0.5, 2.8)	4	0.2
Supervisors and other production	3,993	3.7 (2.9, 4.6)	1.2 (0.9, 1.6)	−0.2	21	0.4	2,138	2.7 (1.5, 3.9)	1.5 (0.9, 2.5)	19	0.8
Motor-vehicle operators and material moving workers	8,648	4.5 (3.9, 5.2)	1.6 (1.3, 1.9)	7.5	143	2.5	4,663	2.3 (1.7, 2.9)	1.5 (1.1, 2.1)	35	1.5
All other workers	2,500	2.8 (2.0, 3.9)	1.0 (0.8, 1.3)	0.1	0	0	1,830	2.1 (1.5, 2.8)	1.0 (0.7, 1.5)	1	0.0
Unknown	4,540	2.9 (2.3, 3.5)	1.0 (0.7, 1.4)	−11.5	0	0	3,145	1.4 (0.7, 2.1)	0.7 (0.4, 1.3)
Total	164,296	4.1 (4.0, 4.3)		1.5	1,070	17.4	106,193	2.3 (2.2, 2.4)		414	17.8

Note: Boldface indicates statistical significance (p<0.05).

The overall totals may not add up owing to rounding. By industry groups, P trends among those who never smoked were not calculated owing to unreliable data within groups by year. Age-adjusted COPD P was defined as a positive response to any of the 3 questions: (1) Have you ever been told by a doctor or other health professional that you had chronic obstructive pulmonary disease, also called COPD? or (2) Have you ever been told by a doctor or other health professional that you had emphysema? or (3) During the past 12 months, have you been told by a doctor or other health professional that you had chronic bronchitis? (total COPD cases for all workers n=5,841,696 and for never smokers n=558,596). AAPC in age-adjusted COPD P during 2012–2018. PAF included the proportion of COPD cases attributable to work in percentage. Workers included adults who reported working at a job or business; with a job or business but not at work;or working, but not for pay, at a family-owned job or business during the last 12 months of the survey interview. Estimates are weighted to provide national estimates for current employment and are presented in thousands.

^aNumber of COPD cases in thousands attributable to work.

AAPC, annual average percentage change; AC, attributable case; COPD, chronic obstructive pulmonary disease; PAF, population attributable fraction; P, prevalence; POR, prevalence OR.

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 (Table 3).

By industry, among an estimated 5.8 million workers with COPD, an estimated 1.6 million COPD cases were attributable to work (PAF=27.3%, 95% CI=6.0, 41.3) (Table 2). The highest PAF for COPD was among workers in the food services and drinking places industry (PAF=2.4%). Among the 2.3 million workers with COPD who never smoked, an estimated 559,000 COPD cases were attributable to work (PAF=24.0%) (Table 3), and the highest PAF for COPD was among workers in the education services industry (PAF=3.9%) (Table 2). By occupation, among 5.8 million workers with COPD, an estimated 1.1 million COPD cases were attributable to work (PAF=17.4%, 95% CI=9.2, 24.3). The highest PAF for COPD was among workers in the motor-vehicle operators and material moving occupations (PAF=2.5%) (Table 3). Among 2.3 million workers with COPD who never smoked, an estimated 414,000 cases were attributable to work (PAF=17.8%) (Table 3), and the highest PAF for COPD was among workers in the office and administrative support (PAF=2.4%) occupations (Table 3).

DISCUSSION

During 2012–2018, an estimated 5.8 million U.S. workers had COPD, and the COPD prevalence varied by sociodemographic characteristics, industry, and occupations. Consistent with previous findings, female workers, those aged ≥65 years, those with a high-school degree/GED or less, those with no health insurance, and current smokers had significantly higher COPD prevalence.²² Although there has been a recent decline in the smoking prevalence among U.S. workers,²³ COPD prevalence in certain groups has remained intractably high, possibly reflecting the lingering burden of tobacco use from past decades and the long lag period between the first exposure and the development of COPD or associated with other risk factors.¹⁵ An estimated 40% of the overall COPD cases were among workers who have never smoked, and the proportions varied by industry and occupation, indicating that other risk factors, including workplace exposures, may be associated with higher prevalence among these groups.⁵ In this study, although similar responses were observed for all the 3 COPD-related questions by smoking status, chronic bronchitis was 19 times more frequently reported than emphysema among never smokers, compared with 3.5 times among ever smokers. These findings are similar to those previously reported that a substantial proportion of COPD among the nonsmokers might be explained by chronic bronchitis.^5,24

During 2012–2018, a significant increase in the estimated annual average percentage change in age-adjusted COPD prevalence was observed among all U.S. workers and among certain subpopulations, including workers in certain industry and occupations. Although the exact cause of the increasing COPD trends is unknown, some of these increases could be explained in part by higher tobacco smoking prevalence, environmental exposures, and workplace exposures among these workers.^{8,16,22,25,26} In addition, employment duration and the type of job held have been associated with increased COPD risk among workers in specific occupations.²⁷ Calvert et al.²⁵ found that an estimated 30% of the workers in the wholesale trade and arts entertainment industry worked outdoors and that of these, >21% were exposed to vapor, dust, gas, and fumes, and ≥14% were exposed to secondhand smoke. Similarly, workers in building grounds (47%), those in personal care service (27%), and those in material moving occupations (48%) were exposed to vapor, dust, gas, and fumes.²⁵ In addition, 17%–31% of workers in these industries and occupations also used some form of tobacco products, suggesting that some COPD cases may be due to the synergistic effect of tobacco smoking and occupational exposure.^23,26

Tobacco smoking as a causative factor for COPD is well established. Approximately 8 of 10 COPD-related deaths are associated with cigarette smoking; however, 1 in 4 U.S. adults with COPD are never smokers.²⁸ Previous studies have reported that a substantial proportion of COPD cases may be associated with outdoor pollution, secondhand smoke exposure, biomass smoke, dietary factors, and occupational exposures.^8–11,29 Current findings show that among workers with COPD, an estimated 17.4%–27.3% of all cases and 17.8%–24.0% of cases among those who never smoked were attributable to workplace exposures. Although these findings were higher than the 14% PAF on the basis of the American Thoracic Society report, similar findings were observed among all U.S. adults.^2,8,9,17 Current findings indicate that the fraction of COPD cases attributable to work ranged from 1.1 million to 1.6 million and that the proportion varied by industries and occupations. Workers in the food services and drinking places industry and motor-vehicle operators and material moving occupations had the highest proportions of cases attributable to work. Workers in these groups are exposed to certain chemicals; dusts; fumes; and vapors, including silica, fiberglass, sawdust, solvents, secondhand smoke, and welding fumes.^25,28–30 These exposures have been previously associated with COPD.^9–12 Among never smokers, the highest PAFs were observed in the education industry and administrative support occupations. These workers are exposed to environmental tobacco smoke; vapors; fumes; and other known respiratory irritants, including exposure to paper dust and fumes from photocopiers, chemicals, oil-based ink, paints, and glues, all of which have been associated with bronchitis, emphysema, and COPD.^5,24,25

Limitations

The findings in this report are subject to some limitations. Information on COPD was self-reported, which may have identified only a third of the patients with COPD with persistent airflow limitation.³¹ In addition, the findings were not validated by medical records or pulmonary function tests, which could have resulted in misclassification of COPD status and may have caused an underestimation of COPD prevalence.³² Cumulative smoking intensity is significantly associated with increased COPD risk; however, data on smoking intensity and duration for all workers were not available for this study, and therefore current smoking was adjusted for in this study. Temporal information on COPD onset and detailed information on exposures at workplace were not available in the NHIS data; therefore, it was not possible to directly determine COPD association with work. In this study, only workers employed at some time in the past 12 months of the survey were included. Those with severe COPD might have left employment in industries/occupations with workplace exposures, and thus industry or occupation groups listed may not accurately identify workers’ occupation where exposures occurred. However, additional analyses examined longest-held job and COPD prevalence and found similar results (i.e., high COPD prevalence among workers reporting longest-held jobs in the clothing and clothing accessories industry and food and beverage serving occupations).

The calculation of ACs can be sensitive to the selection of the reference group. For this study, separate reference groups were selected for industry and occupation for calculating the POR, on the basis of lower COPD prevalence and workplace exposures, and PAF findings indicate that COPD cases attributable to work were higher for industry than for occupation. However, previous study findings using the same reference group (office workers) for both industry and occupation had similar findings (1.5 million cases by industry and 1.1 million cases by occupation were attributable to work) to this study results.¹⁷ An industry group can include workers from several occupations.¹⁷ Therefore, it is also possible that some of the industry groups with higher ORs may not represent the occupational categories with increased risk.¹⁷ In addition, small sample sizes for some groups resulted in unreliable estimates. Finally, among those who never smoked, prevalence trends were not assessed by industry and occupations owing to the small sample size in certain years of data.

CONCLUSIONS

Among an estimated 5.8 million workers with COPD, 40% (2.3 million) of cases were among those who never smoked. The overall increase in the estimated annual average COPD prevalence and findings of a high proportion of COPD cases attributable to work among workers in certain industries and occupations add further evidence that workplace exposures may be associated with an increased burden of COPD. Targeted intervention strategies addressing both tobacco smoking and workplace exposures are needed to reduce the burden of COPD among workers, especially among groups with higher prevalence.