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RATIONALE: Little is known about personal characteristics and systemic responses to particulate pollution in patients with COPD. OBJECTIVES: Assess whether diabetes, obesity, statins and non-steroidal anti-inflammatory medications (NSAIDs)) modify associations between indoor black carbon (BC) and fine particulate matter ≤2.5 μm in diameter (PM(2.5)) on systemic inflammation and endothelial activation. METHODS: 144 individuals with COPD without current smoking and without major in-home combustion sources were recruited at Veterans Affairs Boston Healthcare System. PM(2.5) and BC were measured in each participant’s home seasonally for a week (up to 4 times; 482 observations)and plasma biomarkers of systemic inflammation [C-reactive protein (CRP); interleukin-6 (IL-6)] and endothelial activation [soluble vascular adhesion molecule-1 (sVCAM-1)] measured. Linear mixed effects regression with a random intercept was used, and effect modification assessed with multiplicative interaction terms and stratum specific estimates. RESULTS: Median (25%ile,75%ile) indoor BC and PM(2.5) were 0.6 (0.5,0.7) μg/m(3) and 6.8 (4.8,10.4) μg/m(3), respectively. Although p-values for effect modification were not statistically significant, there were positive associations (%-increase/interquartile range; 95% CI) between CRP and BC greater among non-statin (18.4%; 3.14–36.0) than statin users (10.8%; 1.9–20.4). There were also positive associations greater among non-statin users between PM(2.5) and CRP. For IL-6, associations with BC and PM(2.5) were also greater among non-statin users. Associations between CRP and BC were greater (17.7%; 4.1–33.0) in persons with diabetes than without diabetes (10.0%; 0.43–20.4) with similar effects of PM(2.5). There were no consistent associations that differed based on obesity. Effect modification was not observed for NSAID use, or with any factor considered with sVCAM-1. CONCLUSIONS: Associations between indoor BC and PM(2.5) and CRP were greater in patients with diabetes and those not taking statins, and with IL-6 if not taking statins. These results suggest that these characteristics may modify the systemic response to indoor BC and PM(2.5) in persons with COPD. |
