American adults who are uninsured or on Medicaid smoke at rates more than double those for adults with private health insurance or Medicare, according to a study published by the Centers for Disease Control and Prevention in today’s Morbidity and Mortality Weekly Report (MMWR).

Data from the 2014 National Health Interview Survey (NHIS) show that 27.9 percent of uninsured adults and 29.1 percent of Medicaid recipients currently smoke. By contrast, 12.9 percent of adults with private insurance and 12.5 percent of those on Medicare currently smoke.

“Smoking kills half a million Americans each year and costs more than $300 billion,” said CDC Director Tom Frieden, M.D., M.P.H. “This report shows real progress helping American smokers quit and that more progress is possible.”

The study reported that the prevalence of cigarette smoking among U.S. adults declined from 20.9 percent to 16.8 percent from 2005 to 2014, including a full percentage-point decline between 2013 and 2014 alone. The considerable drop in the overall adult smoking rate over time shows marked progress toward achieving the Healthy People 2020 goal of reducing the cigarette smoking rate to 12 percent or lower. Another major finding was that the average number of cigarettes smoked per day among daily smokers declined from 16.7 in 2005 to 13.8 in 2014 — driven by declines in the proportion of daily smokers who smoked 20 or more cigarettes per day.

The study found other differences in smoking rates consistent with previous studies. In 2014, prevalence of cigarette smoking was higher among these groups:

• Males (18.8 percent vs. 14.8 percent for females)
• Adults ages 25-44 years (20.0 percent)
• Multiracial (27.9 percent) or American Indian/Alaska Natives (29.2 percent)
• People with a General Education Development certificate (43.0 percent)
• People who live below the federal poverty level (26.3 percent)
• People who live in the Midwest (20.7 percent)
• People who have a disability/limitation (21.9 percent)
• People who are lesbian, gay, or bisexual (23.9 percent)