Longitudinal Associations of Smoke-Free Policies and Incident Cardiovascular Disease: CARDIA Study

Abstract

Background: Smoke-free legislation has been associated with lower rates of cardiovascular disease hospital admissions in ecological studies. However, prior studies lacked detailed information on individual-level factors (eg, sociodemographic and clinical characteristics) that could potentially confound associations. Our objective was to estimate associations of smoke-free policies with incident cardiovascular disease in a longitudinal cohort after controlling for sociodemographics, cardiovascular disease risk factors, and policy covariates.

Methods: Longitudinal data from 3783 black and white adults in the CARDIA study (Coronary Artery Risk Development in Young Adults; 1995-2015) were linked to state, county, and local 100% smoke-free policies in bars, restaurants, and nonhospitality workplaces by Census tract. Extended Cox regression estimated hazard ratios (HRs) of incident cardiovascular disease associated with time-dependent smoke-free policy exposures. Models were adjusted for sociodemographic characteristics, cardiovascular disease risk factors, state cigarette tax, participant-reported presence of a smoking ban at their workplace, field center, and metropolitan statistical area poverty.

Results: During a median follow-up of 20 years (68 332 total person-years), 172 participants had an incident cardiovascular disease event (2.5 per 1000 person-years). Over the follow-up period, 80% of participants lived in areas with smoke-free policies in restaurants, 67% in bars, and 65% in nonhospitality workplaces. In fully adjusted models, participants living in an area with a restaurant, bar, or workplace smoke-free policy had a lower risk of incident cardiovascular disease compared with those in areas without smoke-free policies (HR, 0.75, 95% confidence interval, 0.49-1.15; HR, 0.76, 95% confidence interval, 0.47-1.24; HR, 0.54, 95% confidence interval, 0.34-0.86, respectively; HR, 0.58, 95% confidence interval, 0.33-1.00 for living in an area with all 3 types of policies compared with none). The estimated preventive fraction was 25% for restaurant policies, 24% for bar policies, and 46% for workplace policies.

Conclusions: Consistent with prior ecological studies, these individual-based data add to the evidence that 100% smoke-free policies are associated with lower risk of cardiovascular disease among middle-aged adults.

Keywords: cardiovascular diseases; epidemiology; health policy; risk factors; smoking.

Figure 1

Study Exclusions and Timing of Incident Cardiovascular Disease Events and Loss to Follow-up, CARDIA, United States, 1995-2015 (N=3,783)

Figure 2

Proportion of the study population living in areas with smoke-free policies in restaurants, bars, and other workplaces during follow-up, CARDIA, United States, 1995-2015 (N=3,783)