Could something as obvious as smoking explain immigrants’ and Hispanics’ life expectancy advantage in the U.S.? This is the theory that Fenelon and I set out to test. In 2009 and 2010 we conducted two analyses of National Vital Statistics System and Census Bureau data from 2000: one to compare Hispanics with non-Hispanic whites (with no regard to birthplace) and a second to compare immigrants with native-born Americans (with no regard to ethnicity). Regrettably, we could not specifically compare immigrant and native Hispanics; there are not enough data about older U.S.-born Hispanics to generate statistically valid estimates of total life expectancy for the purposes of comparison. In each analysis, we estimated the number of deaths attributable to smoking for each group we were comparing and then checked how much of the difference in total death rates could be explained by smoking. We used death from lung cancer as a marker for smoking-related death because lung cancer is the condition most strongly tied to smoking. We then used death from lung cancer to extrapolate death from all smoking-related conditions.
The strength of the results, published this year in the International Journal of Epidemiology, surprised even us. We found that smoking is the single best explanation of the Hispanic paradox and the general immigrant advantage, at least among adults. Our results show that in 2000 smoking explained more than 75 percent of the difference in life expectancy at age 50 between Hispanic and non-Hispanic white men and roughly 75 percent among women. It also accounted for more than 50 percent of the difference in life expectancy at age 50 between foreign- and native-born men and more than 70 percent of the difference among women. We cannot know from these estimates whether less smoking means that foreign-born Hispanics live longer than their U.S.-born Hispanic counterparts, because we did not estimate death rates separately for these groups. But recent data are not inconsistent with that idea: Fenelon has found that foreign-born Hispanics do smoke substantially less than U.S.-born Hispanics do.
People ask me how it is that no one noticed the role of smoking before. Of course, people did know that smoking is bad for health. But the extent of its role in health disparities between ethnic groups was not much recognized, perhaps because most studies of health habits in different populations have been based on large-scale surveys, which typically do not include tremendous detail about smoking and thus do not reveal differences in smoking habits between groups.
Consider, for example, a typical health survey, which somewhat resembles the health history form you often fill out when you visit a new doctor. The form will probably ask whether you smoke now and whether you used to smoke. But smokers and former smokers are rarely asked precisely how long they smoked and how many cigarettes a day they consumed at every point in their lives. Even if the questions were asked, people might misremember exactly how much they smoked several decades ago.
Nevertheless, a number of studies based on survey data have picked up some ethnic differences in smoking prevalence (whether or not people smoke)—and this was exactly the kind of information that inspired Fenelon and me to determine whether smoking was the key factor in the Hispanic paradox. But those surveys have generally failed to notice ethnic differences in smoking intensity and duration or how much smokers are smoking. At least one set of data, however, does address such details. The National Health Interview Survey, an annual questionnaire that asks fairly detailed questions about tobacco use, has shown that Hispanics are not only less likely to be smokers or former smokers but that the smokers among them are also less likely to smoke heavily. In 2009, for instance, only 9 percent of Hispanic women were current smokers, compared with 21 percent of non-Hispanic white women; 18 percent of Hispanic men smoked, compared with 25 percent of non-Hispanic white men. Among smokers, Hispanics also consumed far fewer cigarettes on average.