Elsevier

Academic Radiology

Volume 18, Issue 2, February 2011, Pages 199-204
Academic Radiology

Original investigation
Socioeconomic Status is Positively Associated with Percent Emphysema on CT Scan: The MESA Lung Study

https://doi.org/10.1016/j.acra.2010.10.010Get rights and content

Rationale and Objectives

Higher socioeconomic status (SES) has been associated with lower respiratory mortality and better lung function, but whether a similar gradient exists for computed tomography (CT) measures of subclinical emphysema is unknown.

Materials and Methods

The Multi-Ethnic Study of Atherosclerosis (MESA) recruited African-American, Chinese, Hispanic, and white participants, ages 45 to 84 years, without clinical cardiovascular disease, from six US sites between 2000 and 2002. The MESA Lung Study assessed percent emphysema, defined based on the proportion of pixels below an attenuation threshold of 910 HU from lung windows of cardiac CT scans. Generalized linear models were adjusted for demographic characteristics, height, body mass index, history of respiratory illness, occupational and residential exposures, tobacco use, and CT scanner type.

Results

Among 3706 participants with a mean age of 61 (±10), the median value for percent emphysema was 18 (interquartile range = 20). Compared with those who did not complete high school, participants with a graduate degree had a higher percent emphysema (difference of 4; P < .001). Income and wealth were also positively associated with percent emphysema. In contrast, higher SES was associated with better lung function. Descriptive and subgroup analyses were used to explore potential explanations for divergent results, including the possibility that suboptimal inspiration during CT scanning would decrease percent emphysema, making the lungs appear healthier when effort is relatively poor.

Conclusion

Although SES indicators were positively associated with subclinical emphysema detectable on CT scan, this unexpected association may highlight potential bias because of effort dependence of both CT measures and spirometry.

Section snippets

Setting and Subjects

The Multi-Ethnic Study of Atherosclerosis (MESA) is a prospective cohort study designed to investigate prevalence, correlates and progression of subclinical cardiovascular disease (11). The study enrolled 6814 men and women from six communities in the United States: Forsyth County, NC; Northern Manhattan and the Bronx, NY; Baltimore City and Baltimore County, MD; St. Paul, MN; Chicago, IL; and Los Angeles, CA. Participants were between ages 45 and 84 when recruited between 2000 and 2002.

Results

The 3706 participants had an average age of 61; 25% were African-American, 17% were Chinese, 23% were Hispanic, and 36% were non-Hispanic whites (Table 1). As expected, FEV1/FVC ratio was negatively correlated with percent emphysema (r = −0.35).

Discussion

Contrary to our hypothesis, higher socioeconomic indicators were associated with more emphysema-like CT patterns. There are no prior studies with which to compare this result because epidemiologic studies that include CT measures of emphysema are, to date, few and almost all are case-control studies of chronic obstructive pulmonary disease (which may yield biased results for emphysema since they, by design, select on lung function). However, higher SES did have the expected association with

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    The authors thank the National Institutes of Health (R01 HL077612, HL075476, N01-HC95159-165, N01-HC95169) and the Robert Wood Johnson Foundation Health & Society Scholars Program for financial support.

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