The analyses were carried out on 7319 participants who had complete data on mortality status, dietary assessment, and other covariates. Compared with these participants, who were included in the present analyses, those excluded were slightly older, more likely to be women, and of lower occupational grade.
Over the 18-y follow-up, 534 participants (7.3%) died. Analyses of cause of death (available for 7312 participants) showed that the majority of participants died of cancer (49.1%, n = 259) or CVD (26.8%, n = 141). Among the 141 CVD deaths, 52.5% were caused by CHD (n = 74) and 19.9% by stroke (n = 28). Of the 134 deaths that remained, 127 were classified as noncancer/non-CVD death (for 7 deaths, information on cause of death was missing). Comparison of characteristics of the participants by vital status is shown in .
Characteristics of participants according to survival status over 18 y of follow-up
The survival curves diverged as a function of the AHEI tertiles across the entire follow-up period, with the highest mortality seen among participants in the bottom tertile and the lowest mortality among those in the top tertile, as shown in . The age- and sex-adjusted hazard ratios (HR) for the top and the intermediate tertile of the AHEI compared with the lowest tertile were 0.65 (95% CI: 0.53, 0.80) and 0.74 (95% CI: 0.60, 0.90), respectively.
To identify potential confounders or mediators of these relationships, factors associated with AHEI tertiles were identified (). The multivariable-adjusted Cox proportional hazards models showed the association between AHEI tertiles and risk of all-cause mortality to be robust to adjustment for covariates. After sex, age, ethnic group, marital status, occupational grade, smoking habits, physical activity, and total energy intake were controlled for, to be in the higher tertiles of the AHEI was associated with a decreased risk of all-cause mortality (intermediate compared with bottom tertile HR: 0.79, 95% CI: 0.64, 0.97; top compared with bottom tertile HR: 0.73, 95% CI: 0.58, 0.91) and CVD mortality (intermediate compared with bottom tertile HR: 0.64, 95% CI: 0.42, 0.95; top compared with bottom tertile HR: 0.58, 95% CI: 0.37, 0.89) (results not shown). Further adjustment for BMI categories, inflammatory markers (C-reactive protein and interleukin-6), metabolic syndrome, prevalence of CVD, dyslipidemia, hypertension, and type 2 diabetes did not attenuate these results much (). Participants in the highest tertile of the AHEI score had ≈25% lower risk of all-cause mortality (HR: 0.76, 95% CI: 0.61, 0.95) and 40% lower risk of CVD mortality (HR: 0.58, 95% CI: 0.37, 0.91) compared with those in the lowest tertile. Adherence to the AHEI was not associated with cancer mortality (HR: 0.80, 95% CI: 0.58, 1.11) or noncancer/non-CVD deaths (HR: 0.89, 95% CI: 0.57, 1.41) ().
Cross-sectional associations between baseline characteristics and tertiles of Alternative Healthy Eating Index (AHEI) score
FIGURE 2. Associations between Alternative Healthy Eating Index (AHEI) tertiles (T) and all-cause and cause-specific mortality over 18 y of follow-up for the 7319 Whitehall II participants. Cox proportional hazards models were adjusted for sex, age, ethnic group, (more ...)
The associations between each AHEI component and mortality risk are shown in Table S4 under "Supplemental data" in the online issue. After adjustment for potential confounders, only 4 of the 9 components (nuts and soy, ratio of white to red meat, total fiber, and alcohol) were significantly associated with all-cause mortality risk. A decreased risk of CVD mortality was observed with consumption of nuts and soy and with moderate alcohol consumption.
To examine whether the effect of the total AHEI score on mortality is as strong as the sum of its separate component effects, we first compared a fully adjusted model (model 1), in which total AHEI score was included, with a second model (model 2), in which all of the 9 components of the AHEI score were included separately. Results of the likelihood ratio test indicated that the total AHEI score did not predict mortality risk as well as did the use of each component separately (P = 0.007), as shown in Table S5 under “Supplemental data” in the online issue. In other words, the coefficients for effects of the 9 components that comprised the total AHEI score were not all equal. Model 2 also showed that consumption of nuts and soy, total fiber, and moderate alcohol, and, to a lesser extent, the ratio of white to red meat, remained associated with a decreased risk of all-cause mortality, after adjustment for other AHEI components (Table S5 under “Supplemental data” in the online issue). No association was observed between other components of the AHEI and all-cause mortality risk.
Further analyses were performed to identify which of the AHEI components contributed most to the decreased mortality risk associated with adherence to the AHEI. Cox regression models were performed separately for each component and were adjusted for a modified total AHEI score that excluded the component considered in the analysis. Of the 9 components, consumption of nuts and soy and moderate alcohol intake were significantly associated with a decreased risk of all-cause mortality, independent of the modified AHEI score and after potential confounders were controlled for (). The observed attenuation of the association between the AHEI computed without the alcohol component and mortality risk suggested that this component makes a major contribution to the association between the AHEI and the risk of both all-cause mortality and CVD mortality. In addition, when the AHEI was computed without the nuts and soy component, a similar attenuation of the association between the modified AHEI and CVD mortality was observed, which highlights the importance of this component in the AHEI in the assessment of CVD mortality risk.
Association between Alternative Healthy Eating Index (AHEI) components and all-cause mortality risk and cardiovascular disease (CVD) mortality risk1