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By the numbers: Asthma-COPD overlap deaths



Death rates for combined asthma and chronic obstructive pulmonary disease declined during 1999-2016, but the risk remains higher among women, compared with men, and in certain occupations, according to a recent report from the Centers for Disease Control and Prevention.

Occupations with significantly high asthma-COPD overlap by sex, age

There is also an association between mortality and nonworking status among adults aged 25-64 years, which “suggests that asthma-COPD overlap might be associated with substantial morbidity,” Katelynn E. Dodd, MPH, and associates at the CDC’s National Institute for Occupational Safety and Health said in the Morbidity and Mortality Weekly Report. “These patients have been reported to have worse health outcomes than do those with asthma or COPD alone.”

For females with asthma-COPD overlap, the age-adjusted death rate among adults aged 25 years and older dropped from 7.71 per million in 1999 to 4.01 in 2016, with corresponding rates of 6.70 and 3.01 per million for males, they reported.

In 1999-2016, a total of 18,766 U.S. decedents aged ≥25 years had both asthma and COPD assigned as the underlying or contributing cause of death (12,028 women and 6,738 men), for an overall death rate of 5.03 per million persons (women, 5.59; men, 4.30), data from the National Vital Statistics System show.

Additional analysis, based on the calculation of proportionate mortality ratios (PMRs), also showed that mortality varied by occupational status and age for both males and females, the investigators said, noting that workplace exposures, such as dusts and secondhand smoke, are known to cause both asthma and COPD.

The PMR represents the observed number of deaths from asthma-COPD overlap in a specified industry or occupation, divided by the expected number of deaths, so a value over 1.0 indicates that there were more deaths associated with the condition than expected, Ms. Dodd and her associates explained.

Among female decedents, the occupation with the highest PMR that was statistically significant was bartending at 3.28. For men, the highest significant PMR, 5.64, occurred in logging workers. Those rates, however, only applied to one of the two age groups: 25-64 years in women and ≥65 in men, based on data from the National Occupational Mortality Surveillance, which included information from 26 states for the years 1999, 2003, 2004, and 2007-2014.

Occupationally speaking, the one area of common ground between males and females was lack of occupation. PMRs for those aged 25-64 years “were significantly elevated among men (1.98) and women (1.79) who were unemployed, never worked, or were disabled workers,” they said. PMRs were elevated for nonworking older males and females but were not significant.

The elevated PMRs suggest “that asthma-COPD overlap might be associated with substantial morbidity resulting in loss of employment [because] retired and unemployed persons might have left the workforce because of severe asthma or COPD,” the investigators wrote.

SOURCE: Dodd KE et al. MMWR. 2020 Jun 5. 69(22):670-9.

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