Epidemiological evidence suggests that exposure to ozone increases cardiovascular morbidity. However, the specific biological mechanisms mediating ozone-associated cardiovascular effects are unknown. To determine whether short-term exposure to ambient levels of ozone causes changes in biomarkers of cardiovascular disease including heart rate variability (HRV), systemic inflammation, and coagulability, 26 subjects were exposed to 0, 100, and 200 ppb ozone in random order for 4 h with intermittent exercise. HRV was measured and blood samples were obtained immediately before (0 h), immediately after (4 h), and 20 h after (24 h) each exposure. Bronchoscopy with bronchoalveolar lavage (BAL) was performed 20 h after exposure. Regression modeling was used to examine dose-response trends between the endpoints and ozone exposure. Inhalation of ozone induced dose-dependent adverse changes in the frequency domains of HRV across exposures consistent with increased sympathetic tone [increase of (parameter estimate ± SE) 0.4 ± 0.2 and 0.3 ± 0.1 in low- to high-frequency domain HRV ratio per 100 ppb increase in ozone at 4 h and 24 h, respectively (P = 0.02 and P = 0.01)] and a dose-dependent increase in serum C-reactive protein (CRP) across exposures at 24 h [increase of 0.61 ± 0.24 mg/l in CRP per 100 ppb increase in ozone (P = 0.01)]. Changes in HRV and CRP did not correlate with ozone-induced local lung inflammatory responses (BAL granulocytes, IL-6, or IL-8), but changes in HRV and CRP were associated with each other after adjustment for age and ozone level. Inhalation of ozone causes adverse systemic inflammatory and cardiac autonomic effects that may contribute to the cardiovascular mortality associated with short-term exposure.

OBJECTIVE

The concurrent use of multiple health care systems may duplicate or fragment care. We assessed the characteristics of veterans who were dually enrolled in both the Veterans Affairs (VA) health care system and a Medicare Advantage (MA) plan, and compared intermediate quality outcomes among those exclusively receiving care in the VA with those receiving care in both systems.

DATA SOURCES/STUDY SETTING

VA and MA quality and administrative data from 2008 to 2009.

STUDY DESIGN

We used propensity score methods to test the association between dual use and five intermediate outcome quality measures. Outcomes included control of cholesterol, blood pressure, and glycosylated hemoglobin among persons with coronary heart disease (CHD), hypertension, and diabetes.

DATA COLLECTION/EXTRACTION METHODS

VA and MA data were merged to identify VA-only users (n = 1,637) and dual-system users (n = 5,006).

PRINCIPAL FINDINGS

We found no significant differences in intermediate outcomes between VA-only and dual-user populations. Differences ranged from a 3.2 percentage point (95 percent CI: -1.8 to 8.2) greater rate of controlled cholesterol among VA-only users with CHD to a 2.2 percentage point (95 percent CI: -2.4 to 6.6) greater rate of controlled blood pressure among dual users with diabetes.

CONCLUSIONS

For the five measures studied, we did not find evidence that veterans with dual use of VA and MA care experienced improved or worsened outcomes as compared with veterans who exclusively used VA care.