Socioeconomic disparities in pulmonary health persist over time

Over the past 6 decades, despite improvements in air quality and tobacco use, socioeconomic disparities in pulmonary disease prevalence, respiratory symptoms and lung function persisted and, in some cases, worsened, according to new data.

“Few studies of socioeconomic disparities in lung health have spanned the period that saw landmark policy changes affecting smoking, air quality, occupational exposures and health care access,” Adam W. Gaffney, MD, MPH, pulmonary specialist at Cambridge Health Alliance in Massachusetts and Harvard Medical School, and colleagues wrote in JAMA Internal Medicine. “Moreover, because reduced lung function is associated with elevated all-cause mortality (through mechanisms not fully understood), increased socioeconomic disparities in lung function may contribute to the widening gap in life expectancy between poorer and wealthier Americans in the 21st century.”

Researchers conducted a repeated cross-sectional analysis of the National Health and Nutrition Examination Surveys and predecessor surveys conducted from 1959 to 2018 to describe the long-term trends in socioeconomic disparities in respiratory health.

The analysis included 215,399 participants who were surveyed from 1959 to 2018.

Rates of smoking decreased from 1971 to 2018 among all adults aged 25 to 74 years, but the researchers observed an increase in income- and education-based disparities in smoking prevalence. From 1971 to 1975, 62.5% of adults who were current/former smokers were in the highest-income quintile compared with 56.3% in the lowest-income quintile, but from 2017 to 2018 34.2% of current/former smokers were in the highest-income quintile vs. 57.9% in the lowest-income quintile.

In addition, socioeconomic disparities in respiratory symptoms persisted or worsened over time, with 44.5% of individuals in the lowest-income quintile reporting dyspnea on exertion vs. 26.4% in the highest-income quintile from 1971 to 1975, compared with 48.3% and 27.9%, respectively, from 2017 to 2018.

The researchers also reported steady increases in disparities in cough and wheeze over time, with cough reported by 14% of individuals in the lowest-income quintile vs. 8.6% in the highest-income quintile in 1988 to 1994, which rose to 16.5% vs. 5.8% in 2011 to 2012.

There was also an increase in asthma prevalence among all children after 1980, with higher increases among children in lower-income quintiles compared with the highest-income quintile by 2017 to 2018 (14.8% vs. 6.8%). For COPD, researchers observed increases in income-based disparities over time, from 4.5 percentage points in 1971 to 11.3 percentage points from 2013 to 2018.

From 1971 to 1975, age- and height-adjusted FEV₁ in men in the lowest-income quintile was 203.6 mL lower compared with those in the highest quintile; this socioeconomic disparity in FEV₁ widened to 248.5 mL (95% CI, –328 to –169) from 2007 to 2012. Among women, the gap in FEV₁ increased from 154.5 mL from 1971 to 1975 to 191 mL from 2007 to 2012.

“The persistent and, in many instances, apparently growing socioeconomic disparities in respiratory health we observed over a 6-decade period suggest that inequality is a possible fundamental determinant of respiratory health and illness,” the researchers wrote.