According to a newly published Yale study, differences in smoking habits between whites and African-Americans may disadvantage the latter in terms of access to potentially lifesaving medical interventions.

The study, published last month in the journal Nicotine & Tobacco Research, was conducted by researchers at the Yale School of Public Health. The researchers used data from the National Health Interview Surveys, conducted from 1965 to 2012, to identify differences in tobacco-smoking habits between white and African-American smokers. The study analyzed smoking history patterns following the 1964 publication of the Surgeon General’s Report, which linked smoking with adverse health effects. The researchers found that African-Americans are less likely than whites to begin smoking at younger ages, but also less likely to quit as they get older. The study also found that African-American smokers smoke fewer cigarettes a day compared to whites.

“For young people, the smoking rates are initially higher for the white population, but then it reverses and the rates for the African-Americans take over,” said Theodore Holford, co-author of the study and a professor at the School of Public Health.

According to Holford, despite smoking fewer cigarettes a day, African-American males are at a higher risk of suffering from smoking-related diseases, particularly lung cancer. Holford said that this “somewhat contradictory result” could be attributed to the fact that African-Americans are more likely to continue smoking into their later years, when the health risks of smoking become most apparent. Holford added that certain biological differences might also play a role, explaining that the length of time it takes for nicotine to clear from the body is on average longer in African-Americans than in whites.

While male African-American smokers are more likely to suffer from life-threatening diseases than white males, Holford said that the “pack-years” measurement — a calculation made by multiplying the number of cigarette packs smoked per day by years of smoking — may underestimate the risk for African-Americans. The number of pack-years smoked determine a person’s eligibility for lung cancer screening. According to the Centers for Medicare and Medicaid Services, only those who have smoked a minimum of 30 pack-years are eligible for access to lung cancer screenings under the Medicare program.

Holford noted that because African-Americans end up smoking fewer cigarettes, they tend to have fewer average pack-years. David Levy, co-author of the study and a professor at the Georgetown University Medical Center, said this figure means that even though African-Americans may be more susceptible to smoking-related diseases, they often do not meet the pack-year benchmark required to access screening resources.

“African-Americans have less access to the health care system, and, as a result, are more prone to early deaths due to disease,” Levy said.

According to Jessica Ho, a research scientist at Duke University and the author of a 2013 study analyzing the contributions of smoking to black-white differences in U.S. mortality rates, the dangers of restricted access to medical screenings are made worse by several factors. Ho said that the tendency of tobacco companies to increasingly target and advertise in minority neighborhoods, as well as higher unemployment rates and stress among African-Americans, could contribute to higher uptake of smoking and difficulty quitting. African-Americans might also experience more difficulty in accessing smoking cessation support programs and investing in measures to help combat addiction, such as nicotine patches, Ho added. Ho also stated that perhaps factors other than pack-years should be taken into account when determining eligibility for lung cancer screenings.

“I do think that it is important to consider dimensions other than pack-years, because blacks clearly suffer from a higher burden of smoking related diseases and mortality,” Ho said.

Holford said that while the study suggests that the pack-years measure may need to be revised, further research is needed to determine how modifying the measure would affect the number of cases of smoking-related diseases in the population. Holford added that comparing the smoking history patterns of different socioeconomic groups could also yield important results.

According to the Centers for Disease Control and Prevention, in 2012, black men had the highest rate of lung cancer diagnosis, followed by white, Asian, American-Indian and Hispanic men.