Association of Life’s Simple 7 lifestyle metric with cardiometabolic disease-free life expectancy in older British men
The current study aimed to quantify the number of years of life gained without CMD attributable to adherence to the LS7 lifestyle metric in older adults and investigated whether social class modified the association. Our results revealed that, for older British men living an ideal composite lifestyle as recommended by the AHA LS7 lifestyle metrics (i.e., maintaining healthy BMI, BP, blood glucose, and total cholesterol levels, and regularly participating in physical activity, eating a healthy diet, and not smoking), at the age of 60, they could potentially gain more than 4 years of life without CMD, compared to those reporting a poor LS7 adherence. And this health benefit was consistent across social class groups. Notably, among LS7 lifestyle metrics, we found that having a moderate to vigorous physical activity level improved the CMD-free life expectancy the most, with an estimated of 4.84 years of life gain compared to participants who were physically inactive.
Findings of the current study are consistent with previous studies, which suggest that a composite healthier lifestyle is associated with a longer life expectancy without chronic diseases17,18,19,20. Specifically, a prior study that involved 12 European cohorts computed a composite lifestyle score based on BMI, smoking, physical activity, and alcohol consumption17. The study found that individuals with the best composite lifestyle score had an average of 9.9 additional years of life without chronic diseases for men and 9.4 additional years for women between ages 40 and 75 years, compared to those with the worst lifestyle score. Another prior study including two large cohorts in the UK and USA showed that people could gain up to 12 years of life without chronic diseases at the age of 50 if having no behavioral risk factors (i.e., having a less than 30 kg/m2 BMI, not smoking, being physically active, and consuming alcohol less than 5 days a week)20. Variations in the estimated years of life gained across prior studies and between ours could be mainly due to the differences in the definitions of ideal healthy lifestyles, cohort population characteristics, and chronic conditions included in the analyses. Results of the current study were most comparable to the findings of a recent UK cohort study using LS7 measures42. Following 341,331 participants for a median of 11.4 years, the previous study estimated that UK males without CMD at baseline would gain 4.55 additional years of life at age 45 comparing those with an ideal LS7 profile to those with a poor LS7 profile. Our estimates were a bit smaller mainly because our study involved an older cohort and considered the survival benefits free of CMD. Therefore, while results of the current study kept with conclusions of prior studies, we extended previous work by quantifying the amount of survival years gained without CMD in older adults, through assessing lifestyles comprehensively with LS7 metric and including the three leading cardiometabolic conditions in combination in the analyses. Our study showed that the CMD-free survival benefit of living an overall healthier life defined by LS7 was quite large for British men at the age of 60, hence confirmed the importance of pursuing a composite healthy lifestyle to live healthier and longer for UK males even at an older age.
It has been well-documented that manual workers have higher risk of CMD, higher mortality risk, and lower disease-free life expectancy23,24,43. Our study also observed a notable discrepancy in CMD-free life expectancy between manual and non-manual workers. Irrespective of LS7 adherence level, manual workers had ~3 fewer years of CMD-free life compared to non-manual workers (Supplementary Table 7). Potential explanations of the health disparity between manual and non-manual workers are that manual workers may have less favorable working conditions, limited healthcare access, and higher stress levels44. This social class difference in healthy life expectancy warrants further clinical and public health consideration. However, although manual workers were estimated to have fewer years of CMD-free life expectancy, they could potentially gain similar or even slightly more years of CMD-free life if adopting a healthy lifestyle. These results, while highlighted the existing health disparities across social class groups, further demonstrated the importance of targeted healthy lifestyle promotions and interventions for manual workers. Such interventions have the potential to help this socially vulnerable group of people live a longer and healthier life.
Our study also examined the effects of individual LS7 metrics on CMD-free life expectancy, and we observed different impacts. We found that maintaining a usual pattern of moderate to vigorous physical activity, which indicated an ideal physical activity level, could potentially provide the largest CMD-free survival benefit of all components of the LS7 score. An ideal smoking status (i.e., never smoking or having given up smoking for more than 5 years) provided the second largest number of years life gained without CMD, followed by ideal BP, diet, and BMI levels. Achieving ideal blood glucose and total cholesterol levels did not yield CMD-free survival benefits in the current study. Several prior studies also suggested that among lifestyle metrics, physical activity, and smoking provided larger life expectancy benefits with or without chronic conditions17,20,41,45,46. Additionally, though having an ideal smoking status provided a large CMD-free life expectancy benefit, our study suggested that having an intermediate smoking status at baseline, which was defined as giving up smoking for no more than 5 years in our study, did not show CMD-free survival benefit compared to current smoking. But for other individual LS7 metrics that exerted survival benefits, including BMI, BP, physical activity, and diet, gradient benefits were found for intermediate and ideal levels compared to poor levels. Our results, along with previous evidence, further emphasized the importance of engaging in more physical activities and quitting smoking as early as possible.
Our study used a modified LS7 measure, with specific modifications made to the subjective LS7 factors, including diet, physical activity, and smoking status. These modifications aimed to more precisely capture the characteristics and lifestyle impacts on cardiovascular health in the BRHS. Previous BRHS reports have demonstrated associations between the modified LS7 factors and markers or risk of cardiovascular diseases28,29,33. The diet measure EDI has been shown to be associated with the risk of CHD in the BRHS28, and physical activity and smoking status have been found to be related to the markers of cardiovascular diseases in the BRHS29,33.
Since the introduction of LS7, the AHA has updated and introduced a new Life’s Essential 8 (LE8) construct, which added in a new component, sleep health, to the metric47. The current study has focused on the LS7 metric as we did not record information on sleep health. Though the LE8 score captures more inter-individual variations, LS7 and LE8 scores were highly correlated in a cross-sectional study of US adult men and women (\(\rho\) = 0.88, P < 0.0001)48. A recent prospective study also suggested that there was no distinguishable difference in between the two metrics in their associations with the risk of CVD and that LS7 maybe a more practical lifestyle index due to its ease of data collection and calculation49. Our current study, focusing on the simpler metric LS7, showed an association with increased life expectancy free of CMD in older adults. Further studies are warranted to investigate if the LE8 and the addition of sleep health would benefit CMD-free life expectancy even further.
The current study, to the best of our knowledge, is the first to investigate and quantify the effects of LS7 lifestyle metric on life expectancy free of CMD specifically in older adults. Key strengths of the study include a long follow-up term, detailed lifestyle measurements, and precise outcome ascertainments from record reviews. In addition, flexible parametric model used in the analyses enabled us to adjust for several covariates when estimating CMD-free life expectancy, which reduced the potential for confounding bias.
Several limitations of our study need to be considered. First, as in many large prospective studies, several lifestyle measures, including physical activity, smoking, and diet, were quantified through self-reported questionnaires, and this may lead to reporting bias. Second, LS7 measurements were obtained only once at baseline in the study, and potential changes over time were not accounted for. Lifestyle trajectory may be important in affecting disease-free life expectancy as suggested by prior studies50. Third, our study only included British men who were mostly from European ethnic origin. The impacts of lifestyle on the CMD-free life expectancy for women and other ethnic groups may be different. Fourth, since our study is an observational study, we did not evaluate if lifestyle intervention, particularly on smoking or physical activity, would provide a longer healthier life free of CMD for older adults as suggested in the current study. Lastly, although analyses were adjusted for known possible sources of bias, due to the study’s observational nature, there still could be unmeasured or residual confounding factors.
In conclusion, the current study quantified the likely benefits of adhering to the AHA LS7 lifestyle by estimating the years of life gained free of CMD in British men at the age of 60. We found that achieving 4 or more LS7 ideal levels was associated with a potential gain of 4.37 years of CMD-free life for older British men, and these benefits appeared to be consistent across social class groups. Our study also suggested that among LS7 lifestyle factors, maintaining a usual pattern of moderate to vigorous physical activity level and never smoking or having stopped smoking for more than 5 years may convey the largest gains in CMD-free life expectancy.
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