Coal Workers’ Pneumoconiosis–Attributable Years of Potential Life Lost to Life Expectancy and Potential Life Lost Before Age 65 Years — United States, 1999–2016

Coal workers' pneumoconiosis (CWP) is a preventable occupational lung disease caused by inhaling coal mine dust that can lead to premature* death (1,2). To assess trends in premature mortality attributed to CWP (3), CDC analyzed underlying† causes of death data from 1999 to 2016, the most recent years for which complete data are available. Years of potential life lost to life expectancy (YPLL) and years of potential life lost before age 65 years (YPLL65)§ were calculated (4). During 1999-2016, a total of 38,358 YPLL (mean per decedent = 8.8 years) and 2,707 YPLL65 (mean per decedent = 7.3 years) were attributed to CWP. The CWP-attributable YPLL decreased from 3,300 in 1999 to 1,813 in 2007 (p<0.05). No significant change in YPLL occurred after 2007. During 1996-2016, however, the mean YPLL per decedent significantly increased from 8.1 to 12.6 per decedent (p<0.001). Overall, CWP-attributable YPLL65 did not change. The mean YPLL65 per decedent decreased from 6.5 in 1999 to 4.3 in 2002 (p<0.05), sharply increased to 8.9 in 2005, and then gradually decreased to 6.5 in 2016 (p<0.001). Increases in YPLL per decedent during 1999-2016 indicate that over time decedents aged ≥25 years with CWP lost more years of life relative to their life expectancies, suggesting increased CWP severity and rapid disease progression. This finding underscores the need for strengthening proven prevention measures to prevent premature CWP-associated mortality.

Coal workers' pneumoconiosis (CWP) is a preventable occupational lung disease caused by inhaling coal mine dust that can lead to premature* death (1,2). To assess trends in premature mortality attributed to CWP (3), CDC analyzed underlying † causes of death data from 1999 to 2016, the most recent years for which complete data are available. Years of potential life lost to life expectancy (YPLL) and years of potential life lost before age 65 years (YPLL 65 ) § were calculated (4). During 1999-2016, a total of 38,358 YPLL (mean per decedent = 8.8 years) and 2,707 YPLL 65 (mean per decedent = 7.3 years) were attributed to CWP. The CWPattributable YPLL decreased from 3,300 in 1999 to 1,813 in 2007 (p<0.05). No significant change in YPLL occurred after 2007. During 1996-2016, however, the mean YPLL per decedent significantly increased from 8.1 to 12.6 per decedent (p<0.001). Overall, CWP-attributable YPLL 65 did not change. The mean YPLL 65 per decedent decreased from 6.5 in 1999 to 4.3 in 2002 (p<0.05), sharply increased to 8.9 in 2005, and then gradually decreased to 6.5 in 2016 (p<0.001). Increases in YPLL per decedent during 1999-2016 indicate that over time decedents aged ≥25 years with CWP lost more years of life relative to their life expectancies, suggesting increased CWP severity and rapid disease progression. This finding underscores the need for strengthening proven prevention measures to prevent premature CWP-associated mortality.
The National Vital Statistics System's multiple cause-ofdeath data during 1999-2016 were analyzed to examine * Early pneumoconiosis (i.e., simple CWP) is often asymptomatic, but the disease can progress to more severe forms associated with substantial impairment, including progressive massive fibrosis. Progression can occur despite cessation of exposure. Progression might be more rapid after high levels of exposure to coal mine dust or if the dust has a high respirable crystalline silica content. There are no accepted specific therapies to prevent progression of CWP. † Underlying cause of death is defined as "the disease or injury which initiated the chain of morbid events leading directly to death, or the circumstances of the accident or violence which produced the fatal injury.    Industry and occupation data were available for 740 § § (94.6%) of 782 CWP deaths among U.S. residents aged ≥25 years that occurred in 26 states during 1999, 2003, 2004, and 2007-2012 (Table). By industry, three quarters of deaths occurred among residents who worked in the coal mining industry (560; 75.7%) accounting for 5,415 YPLL (mean per decedent = 9.7). By occupation, approximately two thirds of deaths occurred among mining machine operators (504; 68.1%) accounting for 4,822 YPLL (mean per decedent = 9.6). Remaining CWP deaths were associated with 68 other industries and 79 other occupations.

Discussion
CDC's National Institute for Occupational Safety and Health (NIOSH) examined information on CWP deaths reported during 1968-2006, which indicated that CWP deaths and annual YPLL 65 attributed to CWP have been decreasing § § For 42 residents of these 26 states, deaths occurred in states other than the state of residence that did not code the industry and occupation information.
(3). The findings in the current report indicate that CWP deaths among U.S. residents aged ≥65 years continued to decrease during 1999-2016; however, no significant changes in CWP deaths among persons aged 25-64 years and CWPattributable YPLL 65 were observed. Furthermore, there was a sharp increase in the mean YPLL 65 per decedent since 2002, with a peak (9.6 years) in 2004, followed by a continual, albeit slow, decline. Also, while there was a decline in YPLL during 1999-2016, the increase in the mean YPLL per decedent during this period indicates that each year, on average, decedents aged ≥25 years with CWP lost more years of life relative to their life expectancies. These premature deaths are consistent with observed increased severity and rapid progression of disease (6)(7)(8).
The decline in age-adjusted CWP death rates and CWPattributable YPLL might be explained, in part, by the decline in employment in the mining industry. The growing gap between each decedent's actual age at death from CWP and his or her life expectancy corroborates recent reports of increasing

Summary
What is already known about this topic?
Coal workers' pneumoconiosis (CWP) is a preventable occupational lung disease caused by inhaling coal mine dust; CWP can progress to respiratory failure and premature death.
What is added by this report?
During 1999-2016, the mean CWP-attributable years of potential life lost per decedent increased from 8.1 to 12.6 years, likely because of increased severity and rapid progression of CWP.
What are the implications for public health practice?
The continuing occurrence of premature deaths from CWP underscores the need for primary prevention by preventing hazardous exposures to coal mine dust, secondary prevention by early disease detection and prevention of further hazardous exposures, and tertiary prevention by providing appropriate medical care to persons with CWP.
prevalence and severity of CWP and of rapid disease progression among coal miners (6)(7)(8). In particular, an 8.6-fold increase in the prevalence of progressive massive fibrosis (PMF) from an annual average of 0.37% during 1994-1998 to 3.23% during 2008-2012, was identified among longer-tenured Kentucky, Virginia, and West Virginia underground coal miners participating in the Coal Workers' Health Surveillance Program (6,7). Most of the CWP deaths in this report (68%) occurred among mining machine operators. This finding is consistent with a report describing a cluster of PMF cases identified in coal miners at a clinic in Kentucky, which found that a high proportion (76%) of miners reported working as roof bolters or continuous miner operators (6). In addition, a recent study of 416 primarily former miners with PMF served by a network of three Black Lung Clinics in Southwest Virginia represents the largest known cluster of PMF reported in the scientific literature; one third of miners with CWP had indications of exceptionally severe and rapidly progressive disease (9). Moreover, an increase in lung transplants performed for patients with CWP has been reported during 2008-2014 (10). The findings in this report are subject to at least four limitations. First, CWP diagnosis as the underlying cause of death could not be validated. Some deaths from CWP might have been attributed to other interstitial lung diseases (e.g., idiopathic pulmonary fibrosis) or other chronic diseases (e.g., chronic obstructive pulmonary disease) occurring in coal miners. Second, there is no specific ICD-10 code for PMF to allow better identification of decedents with severe CWP. Third, complete work histories were not available for analyses. Finally, YPLL and YPLL 65 in this report did not account for reduced quality of life or work years lost attributed to disability from CWP. ¶ ¶ In 2014, a new Federal Rule*** on miners' occupational exposure to respirable coal mine dust was introduced. The rule decreased allowable exposure to respirable coal mine dust, made changes in dust monitoring, and directed NIOSH to expand medical monitoring for coal mine dust lung diseases. CDC provides information about diseases caused by coal mine dust and the Coal Workers' Health Surveillance Program. † † † The continuing occurrence of premature deaths from CWP underscores the need for primary prevention through prevention of exposures to hazardous levels of coal mine dust, secondary prevention through early disease detection and prevention of further hazardous exposures, and tertiary prevention through provision of appropriate medical care to persons with CWP.