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We define measures of effect used in public health evaluations, which include the risk difference and the risk ratio, the population-attributable risk, years of life lost or gained, disability-adjusted life years, quality-adjusted life years, and the incremental costeffectiveness ratio. Except for the risk ratio, all of these are absolute effect measures. For constructing externally generalizable absolute measures of effect when there is superior fit of the multiplicative model, we suggest using the multiplicative model to estimate relative risks, which will often be obtained in simple linear formwith no interactions, and then converting these to the desired absolute measure. The externally generalizable absolute measure of effect can be obtained by suitably standardizing to the risk factor distribution of the population to which the results are to be generalized. External generalizability will often be compromised when absolutemeasures are computed from study populations with risk factor distributions different from those of the population to whom the results are to be generalized, even when these risk factors are not confounders of the intervention effect. [ABSTRACT FROM AUTHOR]

Counterfactual frameworks and statistical methods for supporting causal inference are powerful tools to clarify scientific questions and guide analyses in public health research. Counterfactual accounts of causation contrast what would happen to a population’s health under alternative exposure scenarios. A long-standing debate in counterfactual theory relates to whether sex, race, and biological characteristics, including obesity, should be evaluated as causes, given that these variables do not directly correspond to clearly defined interventions. We argue that sex, race, and biological characteristics are important health determinants. Quantifying the overall health effects of these variables is often a natural starting point for disparities research. Subsequent assessments of biological or social pathways mediating those effects can facilitate the development of interventions designed to reduce disparities. [ABSTRACT FROM AUTHOR]

The article discusses the 40th anniversary of the Nurses' Health Study (NHS) as of 2016 in relation to the author's views about public health interventions and methods for eliminating bias that is attributable to measurement error and misclassification. Controversies involving longitudinal cohort studies that use food frequency questionnaires to assess dietary intake over time are examined, along with various American epidemiological research methodologies.

Objectives. To review the contribution of the Nurses' Health Studies (NHSs) to diet assessment methods and evidence-based nutritional policies and guidelines. Methods. We performed a narrative review of the publications of the NHS and NHS II between 1976 and 2016. Results. Through periodic assessment of diet by validated dietary questionnaires over 40 years, the NHSs have identified dietary determinants of diseases such as breast and other cancers; obesity; type 2 diabetes; cardiovascular, respiratory, and eye diseases; and neurodegenerative and mental health disorders. Nutritional biomarkers were assessed using blood, urine, and toenail samples. Robust findings, from the NHSs, together with evidence from other large cohorts and randomized dietary intervention trials, have contributed to the evidence base for developing dietary guidelines and nutritional policies to reduce intakes of trans fat, saturated fat, sugar-sweetened beverages, red and processed meats, and refined carbohydrates while promoting higher intake of healthy fats and carbohydrates and overall healthful dietary patterns. Conclusions. The long-term, periodically collected dietary data in the NHSs, with documented reliability and validity, have contributed extensively to our understanding of the dietary determinants of various diseases, informing dietary guidelines and shaping nutritional policy. [ABSTRACT FROM AUTHOR]

Objectives. To compare changes in self-reported sexual orientation of women living in states with any recognition of same-sex relationships (e.g., hospital visitation, domestic partnerships) with those of women living in states without such recognition. Methods. We calculated the likelihood of women in the Nurses' Health Study II (n = 69 790) changing their reported sexual orientation between 1995 and 2009. Results. We used data from the Nurses' Health Study II and found that living in a state with same-sex relationship recognition was associated with changing one's reported sexual orientation, particularly from heterosexual to sexual minority. Individuals who reported being heterosexual in 1995 were 30% more likely to report a minority orientation (i.e., bisexual or lesbian) in 2009 (risk ratio = 1.30; 95% confidence interval = 1.05, 1.61) if they lived in a state with any recognition of same-sex relationships compared with those who lived in a state without such recognition. Conclusions. Policies recognizing same-sex relationships may encourage women to report a sexual minority orientation. Future research is needed to clarify how other social and legal policies may affect sexual orientation self-reports. [ABSTRACT FROM AUTHOR]

Objectives. We investigated associations of smoking and coronary heart disease (CHD) by age. Methods. Data came from the Pooling Project on Diet and Coronary Heart Disease (8 prospective studies, 1974-1996; n = 192 067 women and 74 720 men, aged 40-89 years). Results. During follow-up, 4326 cases of CHD were reported. Relative to never smokers, CHD risk among current smokers was highest in the youngest and lowest in the oldest participants. For example, among women aged 40 to 49 years the hazard ratio was 8.5 (95% confidence interval [CI] = 5.0, 14) and 3.1 (95% CI = 2.0, 4.9) among those aged 70 years or older. The largest absolute risk differences between current smokers and never smokers were observed among the oldest participants. Finally, the majority of CHD cases among smokers were attributable to smoking. For example, attributable proportions of CHD by age group were 88% (40-49 years), 81% (50-59 years), 71% for (60-69 years), and 68% (‡ 70 years) among women who smoked. Conclusions. Among smokers, the majority of CHD cases are attributable to smoking in all age groups. Smoking prevention is important, irrespective of age. [ABSTRACT FROM AUTHOR]