Abstract
RATIONALE: Ambient air pollution exposure is associated with respiratory morbidity among individuals with chronic obstructive pulmonary disease (COPD), particularly among those with concomitant obesity. Although people with COPD report high incidence of poor sleep quality, no studies have evaluated the association between air pollution exposure, obesity, and sleep disturbances in COPD. METHODS: We analyzed data collected from current and former smokers with COPD enrolled in the Subpopulations and Intermediate Outcome Measures in COPD -Air Pollution ancillary study (SPIROMICS AIR). Socio-demographics and anthropometric measurements were collected, and 1-year mean historical ambient particulate matter (PM(2.5)) and ozone concentrations at participants' residences were estimated by cohort-specific spatiotemporal modeling. Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI), and regression models were constructed to determine the association of 1-year PM(2.5) (1Yr-PM(2.5)) and 1-year ozone (1Yr-ozone) with the PSQI score, and whether obesity modified the association. RESULTS: In 1308 participants (age: 65.8±7.8 years, 42% women), results of regression analyses suggest that each 10µg/m(3) increase in 1Yr-PM(2.5) was associated with a 2.1-point increase in PSQI (P=0.03). Obesity modified the association between 1Yr-PM(2.5) and PSQI (P=0.03). In obese and overweight participants, a 10µg/m(3) increase in 1Yr-PM(2.5) was associated with a higher PSQI (4.0 points, P<0.01, and 3.4 points, P<0.01, respectively); but no association in lean-normal weight participants (P=0.51). There was no association between 1 Yr-ozone and PSQI. CONCLUSIONS: Overweight and obese individuals with COPD appear to be susceptible to the effects of ambient PM(2.5) on sleep quality. In COPD, weight and ambient PM(2.5) may be modifiable risk factors to improve sleep quality.