On bias in alcohol epidemiology and the search for the perfect study

The association between alcohol consumption and all-cause mortality: An umbrella review of systematic reviews using lifetime abstainers or low-volume drinkers as a reference group

BACKGROUND AND AIMS

Systematic reviews of the relationship between alcohol consumption and all-cause mortality have reported different relative risk (RR) curves, possibly due to the choice of reference group. Results have varied from 'J-shaped' curves, where low-volume consumption is associated with reduced risk, to monotonically increased risk with increasing consumption. We summarised the evidence on alcohol consumption and all-cause mortality exclusively from systematic reviews using lifetime abstainers or low-volume/occasional drinkers as the reference group.

METHODS

We conducted a systematic umbrella review of systematic reviews of the relationship between alcohol consumption and all-cause mortality in prospective cohort studies using a reference group of lifetime abstainers or low-volume/occasional drinkers. Several databases (PubMed/Medline/Embase/PsycINFO/Cochrane Library) were searched to March 2022. Reviews were assessed for risk of bias, and those with reference groups containing former drinkers were excluded.

RESULTS

From 2149 articles retrieved, 25 systematic reviews were identified, and five did not include former drinkers in the reference group. Four of the five included reviews had high risk of bias. Three reviews reported a J-shaped relationship between alcohol consumption and all-cause mortality with significant decreased risk for low-volume drinking (RR range 0.84 to 0.95), while two reviews did not. The one review at low risk of bias reported monotonically increased risk with greater consumption (RRs = 1.02, 1.13, 1.33 and 1.52 for low-, medium-, high- and higher-volume drinking, respectively, compared with occasional drinking). All five reviews reported significantly increased risk with higher levels of alcohol consumption (RR range 1.28 to 3.70). Sub-group analyses were reported by sex and age; however, there were evidence gaps for many important factors. Conversely, 17 of 20 excluded systematic reviews reported decreased mortality risk for low-volume drinking.

CONCLUSIONS

Over 70% of systematic reviews and meta-analyses published to March 2022 of all-cause mortality risk associated with alcohol consumption did not exclude former drinkers from the reference group and may therefore be biased by the 'sick-quitter effect'.

Alcohol consumption and associated risk factors in Burkina Faso: results of a population-based cross-sectional survey

OBJECTIVES

Lifestyle modifiable risk factors are a leading preventable cause of non-communicable diseases, with alcohol consumption among the most important. Studies characterising the prevalence of alcohol consumption in low-income countries are lacking. This study describes the prevalence of different levels of alcohol consumption in Burkina Faso and its associated factors.

DESIGN

Data from the 2013 Burkina Faso WHO STEPwise Approach to Surveillance survey were analysed. The prevalence of alcohol consumption over the last 30 days was recoded into categories according to WHO recommendations: low, mid or abusive alcohol consumption. Multinomial logistic regression analyses identified factors associated with the different levels of alcohol consumption.

SETTING

Population-based cross-sectional survey in Burkina Faso.

PARTICIPANTS

4692 participants of both sexes aged 25-64 years were included in the study.

RESULTS

In the whole sample, 3559 participants (75.8% (72.5%-78.7%)) were not consuming any alcohol, 614 (12.9% (10.9%-15.3%)) had low alcohol consumption, 399 (8.5% (7.1%-10.1%)) had mid alcohol consumption and 120 (2.7% (2.0%-3.7%)) had abusive consumption. Age was associated with alcohol intake with a gradient effect and older people having a higher level of consumption (adjusted OR (AOR): 2.36, 95% CI (1.59 to 3.51) for low consumption, 2.50 (1.54 to 4.07) for mid consumption and 2.37 (1.01 to 5.92) for abusive consumption in comparison with no consumption). Tobacco consumption was also significantly associated with alcohol intake with a gradient effect, those with higher tobacco consumption being at higher risk of abusive alcohol intake (AOR: 6.08 (2.75 to 13.4) for moderate consumption and 6.58 (1.96 to 22.11) for abusive consumption).

CONCLUSION

Our data showed an important burden of alcohol consumption in Burkina Faso, which varied with age and tobacco use. To effectively reduce alcohol consumption in Burkina Faso, comprehensive control and prevention campaigns should consider these associated factors.

Is Moderate Drinking Protective Against Heart Disease? The Science, Politics and History of a Public Health Conundrum

Policy Points For more than 40 years, most research by epidemiologists, social scientists, and alcohol policy experts found that moderate alcohol consumption was cardioprotective. In the early 2000s, that consensus was shaken by new critics who subjected the previous research to vigorous methodological and empirical analysis, precipitating a bitter controversy, seemingly unresolvable despite numerous observational epidemiological studies. The effort to finally put that debate to rest through a large, multiyear randomized controlled trial under the aegis of the National Institute on Alcohol Abuse and Alcoholism, generated external criticism and adverse newspaper coverage, particularly because the trial was largely funded by the alcohol industry, forcing National Institutes of Health leadership to abruptly terminate the study shortly after it started. In the absence of definitive evidence and given the contentious debate over the risks and benefits of moderate alcohol consumption, those who formulate health policy have a responsibility to clearly acknowledge to the public the existence of evidentiary uncertainty when making recommendations.

How should we set consumption thresholds for low risk drinking guidelines? Achieving objectivity and transparency using evidence, expert judgement and pragmatism

Most high-income nations issue guidelines on low-risk drinking to inform individuals' decisions about alcohol consumption. However, leading scientists have criticized the processes for setting the consumption thresholds within these guidelines for a lack of objectivity and transparency. This paper examines how guideline developers should respond to such criticisms and focuses particularly on the balance between epidemiological evidence, expert judgement and pragmatic considerations. Although concerned primarily with alcohol, our discussion is also relevant to those developing guidelines for other health-related behaviours. We make eight recommendations across three areas. First, recommendations on the use of epidemiological evidence: (1) guideline developers should assess whether the available epidemiological evidence is communicated most appropriately as population-level messages (e.g. suggesting reduced drinking benefits populations rather than individuals); (2) research funders should prioritize commissioning studies on the acceptability of different alcohol-related risks (e.g. mortality, morbidity, harms to others) to the public and other stakeholders; and (3) guideline developers should request and consider statistical analyses of epidemiological uncertainty. Secondly, recommendations to improve objectivity and transparency when translating epidemiological evidence into guidelines: (4) guideline developers should specify and publish their analytical framework to promote clear, consistent and coherent judgements; and (5) guideline developers' decision-making should be supported by numerical and visual techniques which also increase the transparency of judgements to stakeholders. Thirdly, recommendations relating to the diverse use of guidelines: (6) guideline developers and their commissioners should give meaningful attention to how guidelines are used in settings such as advocacy, health promotion, clinical practice and wider health debates, as well as in risk communication; (7) guideline developers should make evidence-based judgements that balance epidemiological and pragmatic concerns to maximize the communicability, credibility and general effectiveness of guidelines; and (8) as with scientific judgements, pragmatic judgements should be reported transparently.

Association of longitudinal alcohol consumption trajectories with coronary heart disease: a meta-analysis of six cohort studies using individual participant data

BACKGROUND

Studies have shown that alcohol intake trajectories differ in their associations with biomarkers of cardiovascular functioning, but it remains unclear if they also differ in their relationship to actual coronary heart disease (CHD) incidence. Using multiple longitudinal cohort studies, we evaluated the association between long-term alcohol consumption trajectories and CHD.

METHODS

Data were drawn from six cohorts (five British and one French). The combined analytic sample comprised 35,132 individuals (62.1% male; individual cohorts ranging from 869 to 14,247 participants) of whom 4.9% experienced an incident (fatal or non-fatal) CHD event. Alcohol intake across three assessment periods of each cohort was used to determine participants' intake trajectories over approximately 10 years. Time to onset for (i) incident CHD and (ii) fatal CHD was established using surveys and linked medical record data. A meta-analysis of individual participant data was employed to estimate the intake trajectories' association with CHD onset, adjusting for demographic and clinical characteristics.

RESULTS

Compared to consistently moderate drinkers (males: 1-168 g ethanol/week; females: 1-112 g ethanol/week), inconsistently moderate drinkers had a significantly greater risk of incident CHD [hazard ratio (HR) = 1.18, 95% confidence interval (CI) = 1.02-1.37]. An elevated risk of incident CHD was also found for former drinkers (HR = 1.31, 95% CI = 1.13-1.52) and consistent non-drinkers (HR = 1.47, 95% CI = 1.21-1.78), although, after sex stratification, the latter effect was only evident for females. When examining fatal CHD outcomes alone, only former drinkers had a significantly elevated risk, though hazard ratios for consistent non-drinkers were near identical. No evidence of elevated CHD risk was found for consistently heavy drinkers, and a weak association with fatal CHD for inconsistently heavy drinkers was attenuated following adjustment for confounding factors.

CONCLUSIONS

Using prospectively recorded alcohol data, this study has shown how instability in drinking behaviours over time is associated with risk of CHD. As well as individuals who abstain from drinking (long term or more recently), those who are inconsistently moderate in their alcohol intake have a higher risk of experiencing CHD. This finding suggests that policies and interventions specifically encouraging consistency in adherence to lower-risk drinking guidelines could have public health benefits in reducing the population burden of CHD. The absence of an effect amongst heavy drinkers should be interpreted with caution given the known wider health risks associated with such intake.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03133689 .