Save on tobacco – you will live longer

Smoking has overtaken the financial situation in terms of the impact on life expectancy

Maria Azarova, Naked Science

Smoking was in first place among 57 other economic, behavioral, social and psychological factors affecting life expectancy, a study by scientists from Georgetown and the University of California (USA) showed. The results of their work are presented in the journal JAMA Network (Glei et al., Assessment of Mortality Disparities by Wealth Relative to Other Measures of Socio-Economic Status Among US Adults).

In general, the authors of the study studied how much accumulated money affects longevity. This question remains controversial: as doctors often assume, wealth contributes to an increase in life expectancy, at the same time, many economists believe that, on the contrary, the level of income depends on health. For example, a serious illness can interfere with financial success, and bills for the provision of medical services hit the pocket. 

The researchers examined data from the Midlife in the United States (MIDUS) study, which involved English—speaking residents of the United States from 20 to 75 years old: the average age was 46.9 years, 36% were under 40 and younger, 3318 (52.5%) were women, 5,709 (90.3%) were white. The analysis began in 1995-1996, then until the end of the spring of 2013, we observed the mortality of respondents. More than seven thousand people took a telephone survey, 6325 (89%) also filled out questionnaires by mail. 

Income was estimated based on the net assets of the respondent and his spouse or partner. Other indicators studied included the level of education, professional socio-economic index, age, gender, race, marital status, chronic diseases and smoking status.

"There was no evidence that wealth inequality depends on age, but we identified disproportionate risks for many other indicators of socio-economic status. Therefore, we evaluated the remaining models separately for mortality before and after 65 years. Within these age intervals, there were no disproportionate risks for any of the covariates. Based on two models of mortality under the age of 65 and over, we have plotted the probability of survival from 25 to 65 years and from 65 to 85 years, respectively. In the final set, all potential distorting factors were corrected," the authors write.

By May 31, 2013, 1,000 participants (15.8%) had died. Although the mortality rate decreased as accumulated assets grew, the relationship was non-linear. The first 50 thousand dollars lowered the death rate by 22%, while the next 50 thousand correlated with a decrease of 17%, and another 50 thousand — with 5%. 

"We did not see significant differences between groups with a fortune of $50,000 to $299,999. However, those who had 300-499 thousand dollars, the mortality rate was 41% lower than the participants who had only 200,000 to 299,999 dollars. More than 500 thousand dollars of wealth did not bring "dividends" in the death rate (that is, the differences between the top three categories of the rich, including all those who had at least 300,000 dollars, were insignificant)," the scientists said. As a result, they brought out four groups of financial situation: debts or lack of assets, up to 50 thousand dollars, from 50 thousand to 300 thousand dollars, as well as from 300 thousand.

The probability of living to 25-75 years was 20% lower for those who had no savings (66%) than for participants with a fortune of at least 300 thousand dollars (86%). Scientists also found a 31% difference in the chances of living to 65-85 years between those who had no assets (40%) and those who had at least 300 thousand dollars (71%).

Although wealth clearly mattered, the association of smoking with life expectancy was stronger than for any indicator studied. Thus, the mortality rate adjusted for demographic data among smokers was more than three times higher after 65 years compared with those who had never had this bad habit (up to 65 years — 2.02 times).

"Up to the age of 65, the differences in survival depending on the presence of smoking in the anamnesis were only slightly more significant than the differences in income, but at an older age the difference became much more noticeable. So, the difference in the probability of living to 65-85 years between current smokers (probability — 24%) and never smokers (66%) was 42%, while between the poorest and richest categories — 31% (40% vs. 71%)," the researchers said. By the way, respondents who smoked had less money.

Scientists also confirmed that a serious illness destroys wealth: hospitalization over the past year correlated with increased mortality, and expensive hospitalization negatively affected the well-being of the respondent. In addition, the relationship between financial status and life expectancy could be explained by other factors: married people, as a rule, were richer and showed lower mortality than those who were not married.

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