All cause mortality and the case for age specific alcohol consumption guidelines: pooled analyses of up to 10 population based cohorts
What is already known on this topic
Alcohol intake is increasing among people aged ≥65 years and, in conjunction with greater morbidity and prescription drug use, this age group is at risk of alcohol related problems because of impaired metabolism of alcohol with age. Meta-analyses of observational data repeatedly indicate that, compared with non-drinkers, moderate consumption may be protective against cardiovascular diseases and all cause mortality. It is unclear from existing evidence whether the protective effect of moderate alcohol consumption is both real and applicable to older populations.
What this study adds
Data from up to 10 cohorts representative of the English population, suggest that previous associations indicating a protective effect between alcohol intake and all cause mortality may have been partly attributable to inappropriate selection of the referent group and weak adjustment for confounders. When compared with self reported never drinkers, protective associations were largely limited to women drinkers aged 65 years or more. Little to no protection was present in other age-sex groups.
Objectives To examine the suitability of age specific limits for alcohol consumption and to explore the association between alcohol consumption and mortality in different age groups.
Design Population based data from Health Survey for England 1998-2008, linked to national mortality registration data and pooled for analysis using proportional hazards regression. Analyses were stratified by sex and age group (50-64 and ≥65 years).
Setting Up to 10 waves of the Health Survey for England, which samples the non-institutionalised general population resident in England.
Participants The derivation of two analytical samples was based on the availability of comparable alcohol consumption data, covariate data, and linked mortality data among adults aged 50 years or more. Two samples were used, each utilising a different variable for alcohol usage: self reported average weekly consumption over the past year and self reported consumption on the heaviest day in the past week. In fully adjusted analyses, the former sample comprised Health Survey for England years 1998-2002, 18 368 participants, and 4102 deaths over a median follow-up of 9.7 years, whereas the latter comprised Health Survey for England years 1999-2008, 34 523 participants, and 4220 deaths over a median follow-up of 6.5 years.
Main outcome measure All cause mortality, defined as any death recorded between the date of interview and the end of data linkage on 31 March 2011.
Results In unadjusted models, protective effects were identified across a broad range of alcohol usage in all age-sex groups. These effects were attenuated across most use categories on adjustment for a range of personal, socioeconomic, and lifestyle factors. After the exclusion of former drinkers, these effects were further attenuated. Compared with self reported never drinkers, significant protective associations were limited to younger men (50-64 years) and older women (≥65 years). Among younger men, the range of protective effects was minimal, with a significant reduction in hazards present only among those who reported consuming 15.1-20.0 units/average week (hazard ratio 0.49, 95% confidence interval 0.26 to 0.91) or 0.1-1.5 units on the heaviest day (0.43, 0.21 to 0.87). The range of protective effects was broader but lower among older women, with significant reductions in hazards present ≤10.0 units/average week and across all levels of heaviest day use. Supplementary analyses found that most protective effects disappeared where calculated in comparison with various definitions of occasional drinkers.
Conclusions Beneficial associations between low intensity alcohol consumption and all cause mortality may in part be attributable to inappropriate selection of a referent group and weak adjustment for confounders. Compared with never drinkers, age stratified analyses suggest that beneficial dose-response relations between alcohol consumption and all cause mortality may be largely specific to women drinkers aged 65 years or more, with little to no protection present in other age-sex groups. These protective associations may, however, be explained by the effect of selection biases across age-sex strata.
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