Smoking is a major worldwide public health concern, specifically as a risk factor for stroke. However, the association of secondhand smoke (SHS) exposure and stroke has not been sufficiently established to date. The goal of a current study led by Dr. Leslie A. McClure, professor in the department of biostatistics at the University of Alabama at Birmingham (UAB), and Dr. Angela M. Malek, research associate at the Medical University of South Carolina (MUSC) — in collaboration with Dr. George Howard, professor in UAB’s department of biostatistics; Dr. Mary Cushman, professor at the University of Vermont College of Medicine; and Dr. Daniel T. Lackland, professor at MUSC — was to analyze the relationship between SHS exposure and stroke risk among nonsmokers.
The researchers compared demographic and clinical characteristics by SHS exposure status for African American and White nonsmoking REasons for Geographic and Racial Differences in Stroke (REGARDS) study participants who were aged 45 years and older. Using Cox proportional hazards models, hazard ratios (HRs) and corresponding 95 percent confidence intervals (CIs) were calculated to evaluate the relationship between SHS exposure and stroke risk.
Of the 21,743 participants — of which 38 percent were African American and 45 percent were male — SHS exposure in the previous year was reported by 23 percent. Compared with those enrollees without SHS exposure, the team noted that “exposed participants were more likely to be female, white, younger, and reside with a smoker.” After adjustment for other stroke risk factors, from the total of 428 incident strokes observed from April 2003 to March 2012 (during a mean follow-up of 5.6 years), the overall risk of stroke was increased by 30 percent among participants with SHS exposure, compared to those with no SHS exposure, a relationship that appears to be driven by ischemic strokes.
The investigators concluded that SHS exposure is independently associated with a heightened risk of stroke and recommend that future studies be conducted to confirm the findings of this study, as well as to examine potential long-term effects of SHS exposure on stroke outcomes.
“Secondhand Smoke Exposure and Stroke: The REasons for Geographic and Racial Differences in Stroke (REGARDS) Study” was published in July in the American Journal of Preventive Medicine.
Journal article: http://www.ajpmonline.org/article/S0749-3797(15)00198-1/abstract