Are there non-linear relationships between alcohol consumption and long-term health? Protocol for a systematic review of observational studies employing approaches to improve causal inference

Adverse childhood experience is associated with an increased risk of reporting chronic pain in adulthood: a stystematic review and meta-analysis

Background: Adverse childhood experiences (ACEs) have been shown to negatively affect health in adulthood. Estimates of associations between ACEs and chronic painful conditions are lacking.Objectives: This systematic review and meta-analysis aimed to evaluate associations between exposure to ACEs and chronic pain and pain-related disability in adults.Methods: We searched 10 electronic databases from inception to February 2023. We included observational studies assessing associations between direct ACEs (childhood sexual, physical, emotional abuse, or neglect) alone or in combination with indirect ACEs (witnessing domestic violence, household mental illness), and adult chronic pain (≥3 months duration) and pain-related disability (daily activities limited by chronic pain). Pairs of reviewers independently extracted data and assessed study risks of bias. Random-effect models were used to calculate pooled adjusted odds ratios [aOR]. Tau square [T2], 95% prediction intervals [95%PI] and I2 expressed the amount of heterogeneity, and meta-regressions and subgroup meta-analyses investigated sources of heterogeneity (PROSPERO: CRD42020150230).Results: We identified 85 studies including 826,452 adults of which 57 studies were included in meta-analyses. Study quality was generally good or fair (n = 70). The odds of reporting chronic pain in adulthood were significantly higher among individuals exposed to a direct ACE (aOR, 1.45, 95%CI, 1.38-1.53). Individuals reporting childhood physical abuse were significantly more likely to report both chronic pain (aOR, 1.50, 95CI, 1.39-1.64) and pain-related disability (1.46, 95CI, 1.03-2.08) during adulthood. Exposure to any ACEs alone or combined with indirect ACEs significantly increase the odds of adult chronic painful conditions (aOR, 1.53, 95%CI, 1.42-1.65) and pain-related disability (aOR, 1.29; 95%CI, 1.01-1.66). The risk of chronic pain in adulthood significantly increased from one ACE (aOR, 1.29, 95%CI, 1.22-1.37) to four or more ACEs (1.95, 95%CI, 1.73-2.19).Conclusions: Single and cumulative ACEs are significantly associated with reporting of chronic pain and pain-related disability as an adult.

Tools for assessing quality and risk of bias in Mendelian randomization studies: a systematic review

BACKGROUND

The use of Mendelian randomization (MR) in epidemiology has increased considerably in recent years, with a subsequent increase in systematic reviews of MR studies. We conducted a systematic review of tools designed for assessing risk of bias and/or quality of evidence in MR studies and a review of systematic reviews of MR studies.

METHODS

We systematically searched MEDLINE, Embase, the Web of Science, preprints servers and Google Scholar for articles containing tools for assessing, conducting and/or reporting MR studies. We also searched for systematic reviews and protocols of systematic reviews of MR studies. From eligible articles we collected data on tool characteristics and content, as well as details of narrative description of bias assessment.

RESULTS

Our searches retrieved 2464 records to screen, from which 14 tools, 35 systematic reviews and 38 protocols were included in our review. Seven tools were designed for assessing risk of bias/quality of evidence in MR studies and evaluation of their content revealed that all seven tools addressed the three core assumptions of instrumental variable analysis, violation of which can potentially introduce bias in MR analysis estimates.

CONCLUSION

We present an overview of tools and methods to assess risk of bias/quality of evidence in MR analysis. Issues commonly addressed relate to the three standard assumptions of instrumental variables analyses, the choice of genetic instrument(s) and features of the population(s) from which the data are collected (particularly in two-sample MR), in addition to more traditional non-MR-specific epidemiological biases. The identified tools should be tested and validated for general use before recommendations can be made on their widespread use. Our findings should raise awareness about the importance of bias related to MR analysis and provide information that is useful for assessment of MR studies in the context of systematic reviews.

Alcohol Use

Unhealthy alcohol use-the consumption of alcohol at a level that has caused or has the potential to cause adverse physical, psychological, or social consequences-is common, underrecognized, and undertreated. For example, data from the 2020 National Survey on Drug Use and Health indicate that 7.0% of adults reported heavy alcohol use in the previous month, and only 4.2% of adults with alcohol use disorder received treatment. Primary care is an important setting for optimizing screening and treatment of unhealthy alcohol use to promote individual and public health.

Microcephaly and Associated Risk Factors in Newborns: A Systematic Review and Meta-Analysis Study

Congenital microcephaly is caused by a multitude of drivers affecting maternal−fetal health during pregnancy. It is a rare outcome in high-income industrial countries where microcephaly rates are in the range of 0.3−0.9 per 1000 newborns. Prevalence of microcephaly varies considerably across developing countries and can go as high as 58 cases per 1000 live births in pregnancies exposed to infection by Zika virus (ZIKV). Not only ZIKV-infected pregnancies, but other drivers can modulate the occurrence and severity of this outcome. Here, we sought to test the ZIKV−microcephaly association vs. competing hypotheses using a meta-analysis with 8341 microcephaly cases pooled from 10,250,994 newborns in the Americas, Africa, and Asia. Analysis of risk ratios (RR) showed teratogens the most likely microcephaly-associated risk factor (RR = 3.43; 95%-CI 2.69−4.38; p-value < 0.0001), while the statistical significance of the ZIKV−microcephaly association was marginal (RR = 2.12; 95%-CI 1.01−4.48; p-value = 0.048). Other congenital infections showed strong but variable associations with microcephaly (RR = 15.24; 95%-CI 1.74−133.70; p-value = 0.014). Microcephaly cases were associated with impoverished socioeconomic settings, but this association was statistically non-significant (RR = 2.75; 95%-CI 0.55−13.78; p-value = 0.22). The marginal ZIKV−microcephaly association and statistical significance of the competing hypotheses suggest maternal ZIKV infection might not be a cause of microcephaly alone.

Is Alcohol Consumption Associated with a Lower Risk of Cardiovascular Events in Patients Treated with Statins? An Observational Real-World Experience

Alcohol consumption has long been associated with cardiovascular (CV) benefit, but it also has adverse potential. Statins are currently widely used for CV prevention. We evaluated whether alcohol use is associated with lower CV risk in patients on statins. We searched Intermountain Medical Center cardiac catheterization laboratory medical records for patients with a prescription history of statin use or non-use and a self-report of alcohol use or non-use. Alcohol and statin prescription data were available together with long-term (mean [SD], 4.4 [2.4] years) major adverse CV events (MACE, including death, myocardial infarction, stroke, and heart failure hospitalizations) in 1701 patients at primary and 3266 patients at secondary CV risk. MACE rates were lower for primary prevention alcohol users than non-users not on statins (adjusted hazard ratio [adj-HR] 0.50 (95% CI 0.33, 0.78, p = 0.002), but not for those on statins (adj-HR 0.84, CI 0.54, 1.32, p = 0.45). MACE rates for secondary prevention were not reduced by alcohol consumption either in statin non-users or users (adj HR 1.18, CI 0.85, 1.64, p = 0.33; adj HR 1.08, CI 0.87, 1.35, p = 0.45, respectively). These findings, together with other recent supportive studies, can help inform personal choices in alcohol consumption and professional society recommendations for CV prevention.

Association of Habitual Alcohol Intake With Risk of Cardiovascular Disease

IMPORTANCE

Observational studies have consistently proposed cardiovascular benefits associated with light alcohol consumption, while recent genetic analyses (ie, mendelian randomization studies) have suggested a possible causal link between alcohol intake and increased risk of cardiovascular disease. However, traditional approaches to genetic epidemiology assume a linear association and thus have not fully evaluated dose-response estimates of risk across different levels of alcohol intake.

OBJECTIVES

To assess the association of habitual alcohol intake with cardiovascular disease risk and to evaluate the direction and relative magnitude of cardiovascular risk associated with different amounts of alcohol consumption.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used the UK Biobank (2006-2010, follow-up until 2016) to examine confounding in epidemiologic associations between alcohol intake and cardiovascular diseases. Using both traditional (ie, linear) and nonlinear mendelian randomization, potential associations between alcohol consumption and cardiovascular diseases (eg, hypertension and coronary artery disease) as well as corresponding association shapes were assessed. Data analysis was conducted from July 2019 to January 2022.

EXPOSURES

Genetic predisposition to alcohol intake.

MAIN OUTCOMES AND MEASURES

The association between alcohol consumption and cardiovascular diseases, including hypertension, coronary artery disease, myocardial infarction, stroke, heart failure, and atrial fibrillation.

RESULTS

This study included 371 463 participants (mean [SD] age, 57.0 [7.9] years; 172 400 [46%] men), who consumed a mean (SD) 9.2 (10.6) standard drinks per week. Overall, 121 708 participants (33%) had hypertension. Light to moderate alcohol consumption was associated with healthier lifestyle factors, adjustment for which attenuated the cardioprotective epidemiologic associations with modest intake. In linear mendelian randomization analyses, a 1-SD increase in genetically predicted alcohol consumption was associated with 1.3-fold (95% CI, 1.2-1.4) higher risk of hypertension (P < .001) and 1.4-fold (95% CI, 1.1-1.8) higher risk of coronary artery disease (P = .006). Nonlinear mendelian randomization analyses suggested nonlinear associations between alcohol consumption and both hypertension and coronary artery disease: light alcohol intake was associated with minimal increases in cardiovascular risk, whereas heavier consumption was associated with exponential increases in risk of both clinical and subclinical cardiovascular disease.

CONCLUSIONS AND RELEVANCE

In this cohort study, coincident, favorable lifestyle factors attenuated the observational benefits of modest alcohol intake. Genetic epidemiology suggested that alcohol consumption of all amounts was associated with increased cardiovascular risk, but marked risk differences exist across levels of intake, including those accepted by current national guidelines.

Are there non-linear relationships between alcohol consumption and long-term health?: a systematic review of observational studies employing approaches to improve causal inference

Background

Research has long found ‘J-shaped’ relationships between alcohol consumption and certain health outcomes, indicating a protective effect of moderate consumption. However, methodological limitations in most studies hinder causal inference. This review aimed to identify all observational studies employing improved approaches to mitigate confounding in characterizing alcohol–long-term health relationships, and to qualitatively synthesize their findings.

Methods

Eligible studies met the above description, were longitudinal (with pre-defined exceptions), discretized alcohol consumption, and were conducted with human populations. MEDLINE, PsycINFO, Embase and SCOPUS were searched in May 2020, yielding 16 published manuscripts reporting on cancer, diabetes, dementia, mental health, cardiovascular health, mortality, HIV seroconversion, and musculoskeletal health. Risk of bias of cohort studies was evaluated using the Newcastle-Ottawa Scale, and a recently developed tool was used for Mendelian Randomization studies.

Results

A variety of functional forms were found, including reverse J/J-shaped relationships for prostate cancer and related mortality, dementia risk, mental health, and certain lipids. However, most outcomes were only evaluated by a single study, and few studies provided information on the role of alcohol consumption pattern.

Conclusions

More research employing enhanced causal inference methods is urgently required to accurately characterize alcohol–long-term health relationships. Those studies that have been conducted find a variety of linear and non-linear functional forms, with results tending to be discrepant even within specific health outcomes.

Trial registration

PROSPERO registration number CRD42020185861.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01486-5.