Abstract
Americans have a shorter life expectancy compared to almost all other high-income countries. We aim to estimate the impact of lifestyle factors on premature mortality and life expectancy in the US population. Based on the Nurses’ Health Study (1980–2014, n=78,865) and the Health Professionals Follow-up Study (1986–2014, n=44,354), we defined five low-risk lifestyle factors as fulfilling either: never smoking, body mass index (BMI) 18.5–24.9 kg/m2, 30+ minutes/day moderate to vigorous physical activity, moderate alcohol intake, and a high diet quality score (upper 40%) and estimated hazard ratios (HRs) for the association of total lifestyle score (0–5 scale) with mortality. We used data from the NHANES (2013–2014) to estimate the distribution of the lifestyle score, and the US CDC WONDER database to derive the age-specific death rates of Americans. We applied life table method to estimate life expectancy by levels of the lifestyle score.
Generated Summary
This research article, based on the Nurses’ Health Study (1980–2014, n=78,865) and the Health Professionals Follow-up Study (1986–2014, n=44,354), investigates the impact of lifestyle factors on life expectancies within the US population. The study defined five low-risk lifestyle factors: never smoking, a body mass index (BMI) between 18.5–24.9 kg/m², at least 30 minutes/day of moderate to vigorous physical activity, moderate alcohol intake, and a high diet quality score (upper 40%). The researchers utilized estimated hazard ratios (HRs) for the association of total lifestyle score (0–5 scale) with mortality. Data from the NHANES (2013–2014) was used to estimate the distribution of lifestyle scores, and the US CDC WONDER database was used to derive age-specific death rates of Americans. The life table method was applied to estimate life expectancy across different levels of lifestyle scores.
Key Findings & Statistics
- The multivariable-adjusted HRs for mortality in adults with five compared with zero low-risk factors were: 0.26 (95% CI: 0.22–0.31) for all-cause mortality, 0.35 (95% CI: 0.27–0.45) for cancer mortality, and 0.18 (95% CI: 0.12–0.26) for CVD mortality.
- The population-attributable-risk of non-adherence to five low-risk factors was: 60.7% (95% CI: 53.6%-66.7%) for all-cause mortality, 51.7% (95% CI: 37.1%-62.9%) for cancer mortality, and 71.7% (58.1%-81.0%) for CVD mortality.
- Life expectancy at age 50 for females adopting zero low-risk lifestyle factors: 29.0 years (95% CI: 28.3–29.8).
- Life expectancy at age 50 for males adopting zero low-risk lifestyle factors: 25.5 years (95% CI: 24.7–26.2).
- Life expectancy at age 50 for females adopting all five low-risk factors: 43.1 years (95% CI: 41.3–44.9).
- Life expectancy at age 50 for males adopting all five low-risk factors: 37.6 years (95% CI: 35.8–39.4).
- The projected life expectancy at age 50 was on average 14.0 (95% CI: 11.8–16.2) years longer among female Americans with five low-risk factors as compared to those with zero low-risk factors; for males, the difference was 12.2 (95% CI: 10.1–14.2) years.
- During a median of 33.9 years follow-up of females and 27.2 years follow-up of males, 42,167 deaths were recorded (13,953 deaths from cancer and 10,689 deaths from CVD).
- A combination of five low-risk lifestyle factors was associated with a HR (95% CI) of 0.26 (0.22-0.31) for all-cause mortality, 0.35 (0.27–0.465) for cancer mortality and 0.18 (0.12–0.26) for CVD mortality as compared with participants with zero low-risk factors.
- In a sensitivity analysis using a low-risk score without moderate alcohol intake, the projected life expectancy at age 50 was on average 11.4 (95% CI: 9.5–13.3) years longer among female Americans with four low-risk factors as compared to those with zero low-risk factors; for males, the difference was 10.0 (95% CI: 9.2–10.9) years.
- The study indicates a maximum of 20.5 years difference in life expectancy at age 50 in females (19.6 years among males) who adhered to the highest expanded lifestyle score compared to the lowest expanded score.
Other Important Findings
- Each individual component of a healthy lifestyle showed a significant association with risk of total mortality, cancer mortality and CVD mortality.
- The low-risk lifestyle factors were associated with lower risk of cause-specific mortality in females and males similarly.
- The study found that low-income residents in relatively wealthy areas, such as New York and San Francisco, had significantly longer life expectancies than those in poorer regions, such as Gary, Indiana, and Detroit, Michigan.
Limitations Noted in the Document
- Diet and lifestyle factors were self-reported, leading to potential measurement errors, although repeated measures were used to mitigate this.
- Lifestyle factors were analyzed using dichotomized values, potentially overlooking the gradient in mortality risk.
- Baseline comorbid conditions and medical therapies were not fully considered.
- The study cohorts were primarily composed of Caucasian health professionals, limiting the generalizability to other ethnic and racial groups.
Conclusion
The findings of this study underscore the substantial impact of healthy lifestyle choices on life expectancy in the US population. The research suggests that adopting a healthy lifestyle, characterized by factors such as never smoking, maintaining a healthy weight, engaging in regular physical activity, consuming a healthy diet, and moderate alcohol consumption, can significantly extend lifespan. The study’s estimates indicate that the life expectancy gap between the US and other industrialized nations could be narrowed by improving lifestyle factors. The consistent association between healthy lifestyle factors and reduced mortality risks emphasizes the potential for prevention strategies. The study’s insights are critical for informing health policies and promoting public health initiatives. The research supports the idea that promoting healthy lifestyles is a crucial step toward improving the overall health and longevity of the US population. “Our findings suggest that the gap in life expectancy between the US and other developed countries could be narrowed by improving lifestyle factors.” The study also stresses the importance of addressing the social determinants of health to create environments that support healthy choices. The research promotes the idea that healthy lifestyle intervention should be a top priority for national health policy and preventive care should be an indispensable part of the health care system.