Critique 201: The marked effect of lifestyle on mortality — 26 June 2017
Larsson SC, Kaluza J, Wolk A. Combined impact of healthy lifestyle factors on lifespan: two prospective cohorts. J Int Med 2017. Pre-publication. Doi: 10.1111.joim.12637.
Background: The impact of multiple healthy lifestyle factors on survival time is unclear.
Objective: The aim of this study was to examine differences in survival time associated with a healthy lifestyle vs a less healthy lifestyle.
Methods: This study consisted of 33 454 men (Cohort of Swedish Men) and 30 639 women (Swedish Mammography Cohort) aged 45 to 83 years and free of cancer and cardiovascular disease at baseline. The healthy lifestyle factors included: (1) nonsmoking; (2) physical activity at least 150 min/week; (3) alcohol consumption of 0–14 drinks/week; (4) and healthy diet defined as a modified Dietary Approaches to Stop Hypertension Diet score above the median. Cox proportional hazards regression models and Laplace regression were used to estimate respectively hazard ratios of all-cause mortality and differences in survival time.
Results: During follow-up from 1998 through 2014, 8630 deaths among men and 6730 deaths among women were ascertained through linkage to the Swedish Cause of Death Register. Each of the four healthy lifestyle factors was inversely associated with all-cause mortality and increased survival time. Compared with individuals with no or one healthy lifestyle factor, the multivariable hazard ratios of all-cause mortality for individuals with all four health behaviors were 0.47 (95% 95% confidence interval [CI] 0.44-0.51) in men and 0.39 (95% CI 0.35-0.44) in women. This corresponded to a difference in survival time of 4.1 (95% CI 3.6-4.6) years in men and 4.9 (95% CI 4.3-5.6) years in women.
Conclusion: Adopting healthy lifestyle behaviors may markedly increase lifespan.
Previous similar studies have shown a large benefit on the risk of mortality related to adhering to varying numbers of “healthy lifestyle” behaviors; in this study, they were non-smoking, being physically active, not being a heavy drinker, and having a higher dietary score (the DASH-diet in this case). The study shows markedly beneficial effects of such lifestyle factors in terms of mortality risk and duration of life.
The authors summarize their findings as following: “The main finding of this study of middle-aged and older men and women is that adherence to four healthy lifestyle factors is significantly inversely associated with all-cause mortality and increased survival time. Adherence to all four desirable lifestyle behaviors, compared with none or one, was associated with more than a halving of all-cause mortality and a difference in survival time of 4.1 years in men and 4.9 years in women.”
Specific comments by Forum members: A number of strengths of this study were noted by reviewer Ellison: “This study was based on large samples of representative populations of men and women in Sweden; by recruiting older subjects, aged 45-83 at baseline, they were assured of an adequate number of deaths to judge effects on mortality during approximately 15 ½ years of follow up. The authors appropriately waited until 20% of their cohort had died (more than 15,000 deaths) before calculating survival, using Laplace regression. In their analyses, they adjusted for education, family history of MI before age 60 or cancer, use of aspirin, and sedentary leisure activities; in supplementary analyses, they also adjusted for diabetes, hypertension, dyslipidemia, and body mass index.”
Ellison added: “At the same time, there were some notable weaknesses: all current smokers were evaluated as a single group, so the level of smoking and previous smoking could not be evaluated. Further, the authors included both never drinkers and consumers of up to 14 drinks/week in one group, versus consumers of >14 drinks/week, so potential differences between non-drinking versus light/moderate consumption cannot be determined. Also, there was incomplete data on the pattern of drinking, and no data on the type of beverage consumed.”
Forum member Finkel stated: “My chief reservation about this study is that it adds nothing new, for these types of results have been published before. It is always good to have confirmatory data from other hands, and, as said, the numbers are impressive. I would hope for studies that further extended our understanding of some of the intricacies of drinking’s effects that still confound us.”
Reviewer Goldfinger noted: “There is an important message in that adopting healthy life habits can help one reach their greatest potential for a longer life, even if the individual may be challenged by genetic or socioeconomic predisposition to earlier demise. Unfortunately, with respect to alcohol in this paper, one can only conclude that not being a heavy drinker leads to a longer life. If, however, the number of non-drinkers was not substantial in the population, one could extrapolate that mild to moderate drinking improved longevity.” He added: “I have to say that I am impressed that the authors included alcohol consumption as a lifestyle factor to look at, considering the continued bias against studies that define a benefit from any alcohol consumption.”
Forum member Skovenborg contributed additional data on these cohorts that were not included in the present paper: “Concerning the question about the drinking habits of the two cohorts, an answer may be found in a recent paper by Larsson et al (2017) based on studies of the same cohorts: ‘Alcohol consumption was inversely associated with MI in both men and women (P trend <0.001); compared with light drinkers, the multivariable HRs were 0.70 (95% CI, 0.56–0.87) in men who consumed > 28 drinks/week and 0.32 (95% CI, 0.15–0.67) in women who consumed 15–21 drinks/week. Alcohol consumption was not inversely associated with HF risk. Of the Cohort of Swedish men (n=40.590), 1844 were never drinkers, 2357 were former drinkers, 29.996 were current drinkers (< 1 – 14 drinks/week), and 6.393 were current heavy drinkers (15 – >28 drinks/week). Of the Swedish Mammography Cohort (n=34.022), 4126 were never drinkers, 908 were former drinkers, 28.089 were current drinkers (<1 – 14 drinks/week), and 902 were current heavy drinkers (15 – >28 drinks/week). Accordingly 73.9% of the Swedish men and 82.5% of the Swedish women were moderate drinkers.’”
Some previous studies relating lifestyle factors to mortality: Forum member Stockley summarized some other studies on this topic. “This paper builds very nicely on others undertaken over the past decade providing similar results. For example, a study of 16,958 US individuals followed for 18 years by the US Centers for Disease Control and Prevention (CDC) examined the relationship between four low-risk behaviours and mortality (Ford et al). These authors reported that ‘Moderate consumption of alcohol’ was considered as one of ‘four healthy lifestyle behaviours that exert a powerful and beneficial effect on mortality.’ Moderate or low-risk alcohol consumption was defined as less than or equal to 2 drinks/day but more than 0 for men and less than or equal to 1 drink/day but more than 0 for women. The other low-risk behaviours were non-smoking, eating a healthy diet, and physical activity.
“The authors of this CDC study stated that: ‘The number of low-risk behaviours was inversely related to the risk for mortality. Compared with participants who had no low-risk behaviours, which included abstinence from alcohol as well as excessive alcohol consumption, those who had all four experienced significantly reduced all-cause mortality, mortality from malignant neoplasms [cancers], major cardiovascular disease, and other causes.’ In other words, the men and women were 63% less likely to die, 66% less likely to die from a malignant neoplasms, 65% less likely to die from major cardiovascular disease and 57% less likely to die from other causes. Considering the potential dangers of excessive drinking, these CDC study authors also conducted sensitivity analyses omitting moderate alcohol use; the mortality risk for those who also consumed alcohol was significantly lower than for those having only the three other behaviours.
“In another study, Chiuve et al also included light-to-moderate alcohol consumption (5 to 30 g/day) as one of five low-risk behaviours associated with a reduced risk of coronary heart disease irrespective of concurrent medication for hypertension or hypercholesterolemia. These behaviours were based on the Healthy Eating Index (HEI), created by the US Department of Agriculture to assess how well the US population met dietary recommendations based on the Food Guide Pyramid and the Dietary Guidelines for Americans. The HEI defined moderate alcohol consumption of 1.5 to 2.5 drinks/day as ideal servings for men and 0.5 to 1.5 drinks/day as ideal for women on the basis of the lower risk of cardiovascular disease associated with moderate alcohol consumption (McCullough et al).
“A similar, little publicised Australian study of 7989 individuals aged 65-83 years followed for five years showed consistent results (Spencer et al). The eight selected low-risk behaviours included having no more than two alcoholic (total 20 g alcohol) drinks/day. Individuals with five or more of the selected low-risk behaviours had a lower risk of death from any cause within five years compared with those having less than five. More importantly the study showed that while most individuals already have some healthy habits, almost all could make changes to their diet and lifestyle to improve their health. The study did not suggest abstinence from alcohol, and avoidance of heavier alcohol consumption is also inferred.
“In addition, Lee et al showed that although light-to-moderate drinkers may have better risk factor profiles than non-drinkers, including higher socioeconomic status and fewer functional limitations (such as activities of daily living, instrumental activities of daily living and mobility), which explain some of the survival advantage associated with alcohol consumption, light-to-moderate drinkers still maintain their survival advantage even after adjustment for these factors. Further, Sun et al recently showed that in addition to lower mortality, women who were moderate alcohol consumers and who had survived to age 70 years and older generally had less disability and disease, and more signs of ‘successful ageing.’ For ‘regular’ light-to-moderate alcohol consumers (consuming some alcohol on 5-7 days/week), there was an approximately 50% greater chance of such successful ageing compared with non-drinkers.”
Overall, Forum members considered that the present study strongly supports the cumulative scientific data on the importance of following a healthy lifestyle. While not smoking is certainly a major factor, having a healthy diet, exercising, and consuming light to moderate amounts of alcohol all make additional contributions. Such data emphasize that regardless of whether people may have an unfavorable genetic profile or are socially disadvantaged, if they follow a healthy lifestyle their mortality risk will be markedly reduced and they are likely to have a significantly longer lifespan.
References from Forum critique
Chiuve SE, McCullough ML, Sacks FM, Rimm EB. Healthy lifestyle factors in the primary prevention of coronary heart disease among men: benefits among users and nonusers of lipid-lowering and antihypertensive medications. Circulation 2006;114:160-167.
Ford ES, Zhao G, Tsai K, Li C. Low-risk lifestyle behaviors and all-cause mortality: findings from the National Health and Nutrition Examination Survey III Mortality Study. Am J Pub Health 2011;101:1922-1929.
Larsson SC, Wallin A, Wolk A. Contrasting association between alcohol consumption and risk of myocardial infarction and heart failure: Two prospective cohorts. Inter J Cardiol 2017;231:207–210.
Lee SJ, Sudore RL, Williams BA, Lindquist K, Chen HL, Covinsky KE. Functional limitations, socioeconomic status, and all-cause mortality in moderate alcohol drinkers. J Am Geriatr Soc 2009;57:955–962.
McCullough ML, Feskanich D, Stampfer MJ, Giovannucci EL, Rimm EB, Hu FB, Spiegelman D, Hunter DJ, Colditz GA, Willett WC. Diet quality and major chronic disease risk in men and women: moving toward improved dietary guidance. Am J Clin Nutr 2002;76:1261-1271.
Spencer CA, Jamrozik K, Norman PE, Lawrence-Brown M. A simple lifestyle score predicts survival in healthy elderly men. PrevMed 2005;40:712-717.
Sun Q, Townsend MK, Okereke OI, Rimm EB, Hu FB, Stampfer MJ, et al. Alcohol consumption at midlife and successful ageing in women: a prospective cohort analysis in the Nurses’ Health Study. PLoSMed 2011;8:e1001090.
The aim of the present study was to examine differences in the risk of mortality and in survival associated with a healthy lifestyle versus a less healthy lifestyle. The analyses were based on a total of more than 60,000 Swedish men and women who were followed in one of two studies; at baseline, the subjects were aged 45 to 83 years and were free of cancer and cardiovascular disease. The goal was to evaluate the effects of four “healthy” lifestyle factors: (1) nonsmoking; (2) physical activity at least 150 min/week; (3) alcohol consumption of 0–14 drinks/week; and (4) a healthy diet, with the latter defined as a modified Dietary Approaches to Stop Hypertension (DASH) Diet score above the median. Cox proportional hazards regression models and Laplace regression were used to estimate respectively hazard ratios of all-cause mortality and differences in survival time.
The authors report: “Compared with individuals with no or one healthy lifestyle factor, the multivariable hazard ratios of all-cause mortality for individuals with all four health behaviors were 0.47 (95% confidence interval [CI] 0.44-0.51) in men and 0.39 (95% CI 0.35-0.44) in women. This corresponded to a difference in survival time of 4.1 (95% CI 3.6-4.6) years in men and 4.9 (95% CI 4.3-5.6) years in women.”
Forum members considered this to be a well-done study on a large cohort with complete follow-up data on mortality. Notable weaknesses included the fact that never drinkers and consumers of 0 to 14 drinks/week were considered in one group (thus, including lifetime abstainers, ex-drinkers, and current moderate drinkers); these subjects were compared with consumers of >14 drinks/week. Thus potential differences between abstinence versus light/moderate consumption could not be determined. Further, there were incomplete data on the pattern of drinking, and no data on the type of beverage consumed were reported. Nevertheless, the reduction in mortality for subjects following a healthy lifestyle was impressive: a reduction by half, or more, in the risk of mortality and a 4- to 5-year longer lifespan.
Based on a number of previous studies that evaluated similar lifestyle factors and mortality, the results of this study were not unexpected. Still, they strongly support the remarkable effects on mortality and survival of these lifestyle factors. While not smoking was clearly the factor with the strongest effect on reducing mortality, having a healthy diet, exercising, and consuming light to moderate amounts of alcohol all make additional contributions. This is an important message in that even individuals who may be challenged by genetic or socioeconomic predispositions to earlier demise, adopting certain lifestyle habits can help them reach their greatest potential for a longer and healthier lifespan.
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Contributions to this critique by the International Scientific Forum on Alcohol Research were provided by the following members:
R. Curtis Ellison, MD, Professor of Medicine & Public Health, Boston University School of Medicine, Boston, MA, USA
Harvey Finkel, MD, Hematology/Oncology, Boston University Medical Center, Boston, MA, USA
Tedd Goldfinger, DO, FACC, Desert Cardiology of Tucson Heart Center, University of Arizona School of Medicine, Tucson, AZ, USA
Erik Skovenborg, MD, specialized in family medicine, member of the Scandinavian Medical Alcohol Board, Aarhus, Denmark
Creina Stockley, PhD, MSc Clinical Pharmacology, MBA; Health and Regulatory Information Manager, Australian Wine Research Institute, Glen Osmond, South Australia, Australia