Impact of the aldehyde dehydrogenase 2 (ALDH2) gene testing on alcohol drinking behaviors among the Chinese Han population: study protocol of a single-center, open-label, randomized, controlled clinical trial

Abstract

Background

Alcohol consumption may induce multiple disorders, and decreased alcohol consumption has been proved to be effective to reduce the incidence of alcohol-associated diseases and mortality. Pharmacotherapy is the most common option for the management of alcohol problems; however, it suffers from multiple problems. Non-pharmaceutical interventions are therefore of urgent need to change alcohol intake among alcohol users. Aldehyde dehydrogenase 2 (ALDH2), which encodes the ALDH2 gene, is an important enzyme in ethanol metabolism. Previous studies have demonstrated that individuals harboring ALDH2 gene mutations are more likely to present discomfort symptoms and are more susceptible to multiple cancers. It is hypothesized that ALDH2 gene testing may reduce alcohol consumption and the incidence of alcohol-associated disorders among unhealthy alcohol users.

Methods

A single-center, open-label, randomized, controlled clinical trial was designed, aiming to recruit 940 unhealthy alcohol users at ages of 18 to 60 years. All participants are randomized into the interventional and control groups, and both groups are given alcohol consumption health education. In addition, blood samples are collected from participants in the interventional group for ALDH2 gene testing, with testing reports issued, while ALDH2 gene testing is not performed in the control group. Changes in alcohol intake, hazardous drinking days, and alcohol-associated adverse events are recorded prior to and post-interventions. The primary outcome is alcohol intake, and the secondary outcomes are hazardous drinking days and alcohol-associated adverse events.

Discussion

This trial will provide strong evidence regarding the impact of ALDH2 gene testing on alcohol use behaviors.

Trial registration

The study has been registered in the Chinese Clinical Trial Registry (registration no. ChiCTR2400087726) on 2 August 2024.

Administrative information

Note: the numbers in curly brackets in this protocol refer to SPIRIT checklist item numbers. The order of the items has been modified to group similar items (see http://www.equator-network.org/reporting-guidelines/spirit-2013-statement-defining-standard-protocol-items-for-clinical-trials/).

Title {1}	Impact of the aldehyde dehydrogenase 2 (ALDH2) gene testing on alcohol drinking behaviors among the Chinese Han population: Study protocol of a single-center, open-label, randomized, controlled clinical trial
Trial registration {2a and 2b}.	The study has been registered in the Chinese Clinical Trial Registry (registration no. ChiCTR2400087726) on 2 August 2024, at https://www.chictr.org.cn/showproj.html?proj=230720.
Protocol version {3}	2023-09-27,V1.0
Funding {4}	This study was supported by the grants from the Startup Fund for scientific research, Fujian Medical University (Grant no. 2022QH1245). The funder had no role in the design, data collection and analysis, decision to publish, or preparation of the manuscript.
Author details {5a}	DLL Department of Clinical Pharmacy, Nanping First Hospital Affiliated to Fujian Medical University, Nanping 353000, Fujian Province, China YNW Department of Health Examinations, Nanping First Hospital Affiliated to Fujian Medical University, Nanping 353000, Fujian Province, China KJL Department of Clinical Pharmacy, Nanping First Hospital Affiliated to Fujian Medical University, Nanping 353000, Fujian Province, China QLL Department of Health Examinations, Nanping First Hospital Affiliated to Fujian Medical University, Nanping 353000, Fujian Province, China ZHJ Department of Clinical Pharmacy, Nanping First Hospital Affiliated to Fujian Medical University, Nanping 353000, Fujian Province, China ZCW Department of Clinical Pharmacy, Nanping First Hospital Affiliated to Fujian Medical University, Nanping 353000, Fujian Province, China
Name and contact information for the trial sponsor {5b}	trial sponsor : Zhaochun Wu，53018640@qq.com
Role of sponsor {5c}	The sponsor designed and conceived the trial. The funder had no role in the design, data collection and analysis, decision to publish, or preparation of the manuscript.

Introduction

Background and rationale {6a}

Alcohol, with ethanol as its main component, has been widely used in humans since the beginning of human history, and Chinese alcohol drinking culture has a long history [1]. With the development of the alcohol industry and trade globalization, alcoholic beverages are easily available anywhere and anytime. It is well known that alcohol consumption is closely associated with an increasingly growing disease incidence and mortality [2]. Alcohol has been proven to induce more than 60 types of disorders, including liver cancer, epilepsy, stroke, hepatic cirrhosis, alcohol dependence, unconscious injury, and intentional injury. It is estimated that 4% of global disease burdens are attributable to alcohol, which is comparable to the disability and mortality due to tobacco and hypertension [3]. It has been demonstrated that daily consumption of 30 to 60 g alcohol is reported to result in a 41% increase in the risk of diseases [4]. Reduction in alcohol intake among alcohol consumers is therefore paid much attention to across the world.

Pharmacotherapy is one of the most common options for the management of alcohol problems. Three chemicals have been approved for the treatment of alcohol use disorders by the United States Food and Drug Administration (FDA) until now, including disulfiram, acamprosate, and naltrexone, and aldehyde dehydrogenase (ALDH) inhibitor disulfiram is the first agent approved by the FDA for pharmacotherapy of alcohol use disorders. The main procedure of alcohol metabolism is ethanol metabolism into acetaldehyde via ethanol dehydrogenase, followed by acetaldehyde metabolism into acetic acid via ALDH. Disulfiram may irreversibly inhibit ALDH, resulting in aldehyde accumulation. Therefore, simultaneous administration of alcohol and disulfiram may cause aldehyde accumulation, thus resulting in multiple discomfort symptoms, including tachycardia, headache, nausea, and vomiting. Since disulfiram may cause alcohol-aversive responses if mixed with alcohol [5], the therapeutic efficacy of this agent is heavily determined by patients’ incentives for administration [6]. Acamprosate may act on the glutamate system through mediating the activated glutamatergic state and may serve as an N-methyl-D-aspartate receptor agonist [7]. It has been demonstrated that acamprosate is effective in promoting abstinence and preventing the recurrence of abstinence among patients with alcohol abstinence, and it is therefore recommended as an important agent for auxiliary treatment among patients with alcohol abstinence. The most common treatment-related adverse events of acamprosate include diarrhea, nausea, vomiting, stomachache, headache, and dizziness [8]. Naltrexone, an opioid receptor antagonist, has been found to be effective in reducing alcohol cravings and alcoholism recurrence [9], with nausea, headache, dizziness, and sleep disorders as common treatment-induced adverse events [10]. Nevertheless, pharmacotherapy suffers from problems of low compliance and high incidence of adverse events for the management of alcohol problems. Non-pharmaceutical interventions are therefore of an urgent need as alternatives to pharmacotherapy for effective management of alcohol drinking behaviors.

Genetic diagnosis aims to decipher the pathogenesis of a disease at a gene level. Disease is an abnormal physiological and biochemical process caused by human, genetic, or environmental factors, or jointly caused by genetic and environmental factors. Mild disorder may manifest as a transient pathophysiological process, while severe forms may progress into irreversible pathological alterations, even mortality [11]. ALDH2, also known as alcohol dehydrogenase, is an important enzyme in ethanol metabolism, which encodes the ALDH2 gene [12]. The prevalence of the ALDH2 gene mutation is estimated to be 50% among the Chinese Han population. A significantly lower ALDH activity and higher incidence of cancers are detected among individuals harboring ALDH2 gene mutations than those without ALDH2 gene mutations [13], and facial blushing, palpitation, and nausea are observed among individuals harboring ALDH2 gene mutations following alcohol consumption [14]. Genetic diagnosis of alcohol metabolizing enzymes offers more individualized and objective data than conventional healthcare data, which may provide valuable insights into the management of harmful drinking behaviors.

Given higher and higher needs for health[15], this trial aims to examine the effect of ALDH2 gene testing on alcohol drinking behaviors and alcohol intake reductions among unhealthy alcohol users, so as to reduce the incidence of alcohol-associated disorders and mortality and alleviate medical burdens.

Objectives {7}

This trial aims to examine the impact of ALDH2 gene testing on alcohol drinking behaviors among unhealthy alcohol users.

Trial design {8}

This single-center, open-label, randomized, controlled clinical trial has been approved by the Medical Ethics Review Committee of Nanping First Hospital Affiliated to Fujian Medical University (approval no. NPSY202309019) and registered in the Chinese Clinical Trial Registry (registration no. ChiCTR2400087726). Figure 1 displays the flowchart of the study.

Fig. 1

Flowchart of the trial

Methods: participants, interventions, and outcomes

Study setting {9}

This single-center clinical trial will be conducted in the Department of Health Examinations, Nanping First Hospital Affiliated to Fujian Medical University.

Eligibility criteria {10}

Inclusion criteria

(1) Age of 18 to 60 years; (2) Male or female; (3) Positive for unhealthy alcohol consumption screening: Alcohol Use Disorders Identification Test (AUDIT) score of 4 and higher among men and 3 and higher among women.

Exclusion criteria

(1) Unwilling to sign the informed consent; (2) Development of liver diseases, such as viral hepatitis, hepatic cirrhosis, or liver cancer; (3) Development of gastrointestinal disorders, such as gastric ulcer, gastritis, or cholecystitis; (4) Development of cardio-cerebrovascular diseases, such as myocardial infarction, coronary atherosclerosis, or arrhythmia; or (5) Presence of severe mental disorders.

Who will take informed consent? {26a}

The investigators will inform participants of the purpose of and potential benefits from this trial, and signed informed consent will be obtained from all participants.

Additional consent provisions for collection and use of participant data and biological specimens {26b}

There is no plan for additional consent provisions for the collection and use of participant data and biological specimens. All biological blood specimens collected in this study are only available for this trial and will be ruined following testing.

Interventions

Explanation for the choice of comparators {6b}

Blood samples are not collected for ALDH2 gene testing in the control group, and all subjects will be only given alcohol consumption health education.

Intervention description {11a}

Blood samples are collected from participants in the interventional group for ALDH2 gene testing, with gene testing reports issued, and the gene testing reports will be delivered to participants using the China Post Express Mail Service. The investigators will explain the reports to participants by telephone, and all participants will be given health education on alcohol consumption. In addition, investigators will offer a detailed explanation of the testing results and provide genetic counseling, in order to avoid participants’ misunderstanding of gene testing results.

Criteria for discontinuing or modifying allocated interventions {11b}

Participants will be followed up 12 months post-interventions, and interventions will continue unless the following conditions occur.

• a) Participants fail to receive follow-up on time and have a low compliance to follow-up.

• b) Participants withdraw actively from the trial. Participants have the right to withdraw from the trial at any time, for any reason, including randomization into the interventional group and unwillingness to receive gene testing results. (Investigators will strive to identify and record the reasons of withdrawal.)

Strategies to improve adherence to interventions {11c}

Participants will be informed of details of the trial at recruitment, and the importance of completing the follow-up will be highlighted. In addition, senior doctors in the department of health examinations will provide consultations on health to participants. Before participants agree to receive gene tests, investigators will invite doctors from department of health examinations to provide pre-test genetic counseling, and complicated genetic problems will ask for help from professional doctors from department of medical genetics. After gene testing results are released, post-test genetic counseling will be provided to all participants. In addition, investigators pay close attention to participants’ psychological changes, and doctors will offer appropriate interventions for psychological counseling upon identification of negative emotion.

Relevant concomitant care permitted or prohibited during the trial {11d}

Not applicable, since no concomitant nursing is required during the study period.

Provisions for post-trial care {30}

Not applicable, since no concomitant nursing is required during the study period.

Outcomes {12}

Primary outcome

The primary outcome is alcohol intake, which is defined as the mean volume of alcoholic beverages at standard drinks per week during the past 30 days, with the volume of pure alcohol defined as a multiplication of the volume of alcoholic beverages consumed and the alcohol content of alcoholic beverages. A standard drink equals to 10 g of pure alcohol. Changes in alcohol intake will be compared prior to interventions and 1 month post-interventions.

Secondary outcomes

Hazardous drinking days (defined as ≥ 61 g pure alcohol per day for men and ≥ 41 g pure alcohol per day for women) and alcohol-associated adverse events (including alcohol-associated diseases, traffic accidents, accidental injury and death). Changes in hazardous drinking days will be compared prior to interventions and 1 month post-interventions, and the presence of alcohol-associated adverse events will be investigated within 1 year post-interventions.

Participant timeline {13}

Figure 2 outlines the schedule of enrollment, interventions, and assessments. −t₁, time before allocation, including eligibility screening and obtaining informed consent; t0, collection of based data and randomization into interventional and control groups, followed by implementation of interventions; 1 st month, 1 month post-intervention, collection of participants’ alcohol intake, hazardous drinking days, and presence of alcohol-associated adverse events 1 month post-intervention; 12-month, 1 year post-intervention, collection of participants’ presence of alcohol-associated adverse events.

Fig. 2

Schedule of enrollment, interventions, and assessments

Sample size {14}

The sample size is predominantly estimated based on the primary outcome. In this study, the primary outcome is the difference in the mean weekly numbers of alcoholic beverages at standard drinks per week between interventional and control groups. Like the brief alcohol interventional study [16], the weekly alcohol intake reduced by 1.5 standard drinks. The less alcohol consumed, the better. A reduction in weekly alcohol intake by one drink may reduce the health risk. Therefore, the superiority margin is assigned as 1 in this trial. All participants are randomized to the interventional and control groups at a ratio of 1:1. Based on literature review [17], the difference between the two groups is 16.9, σ1 = 105.43, σ2 = 51.17, two-sided α = 0.05, β = 0.20, superiority margin = 1, and at least 427 subjects are required in each group, as revealed by Student’s t test. Considering a 10% loss to follow-up and refusal to visit, at least 470 subjects are required in each group. Therefore, a total of 940 subjects will be recruited.

Recruitment {15}

This single-center clinical trial will be conducted in the Department of Health Examinations, Nanping First Hospital Affiliated to Fujian Medical University. Individuals with periodical health examinations pay more attention to health than others.

Assignment of interventions: allocation

Sequence generation {16a}

Block randomization is employed with a block size of 6, and participants in each block were randomly assigned to interventional or control groups at a ratio of 1:1. Random number sequence is generated using the SAS software by an independent statistician.

Concealment mechanism {16b}

The generated random number sequence is transferred to sequentially coded, sealed, opaque envelopes. After participants meeting the inclusion and exclusion criteria sign the informed consent, envelopes are given according to the codes and unsealed under witnesses’ supervision. The date of unsealing, codes of envelopes, and allocation results are recorded. Following allocation, both participants and investigators are open to grouping.

Implementation {16c}

Independent statisticians generate random allocation sequences using a computerized random number generator, and investigators open the envelope and allocate participants into groups.

Assignment of interventions: blinding

Who will be blinded {17a}

This is an open-label clinical trial, and grouping is not blind to participants or investigators.

Procedure for unblinding if needed {17b}

This is an open-label clinical trial, and investigators will explain ALDH2 gene testing to participants.

Data collection and management

Plans for assessment and collection of outcomes {18a}

Participants’ demographics and follow-up data are collected by well-trained nurses in the Department of Health Examinations by means of timeline follow back (TLFB) combined with the Alcohol Use Disorders Identification Test (AUDIT) and structured interviews, including alcohol intake, days of hazardous alcohol use, and alcohol-associated adverse events. Electronic case report forms (ECRFs) are the main sources of files and will be completed on time by investigators. AUDIT will be used for screening of hazardous and harmful alcohol consumers.

Plans to promote participant retention and complete follow-up {18b}

During the recruitment period, participants will be informed of the complete trial data and the importance of completing follow-up. Following interventions, a 1-year follow-up will be conducted among participants. Investigators will conduct a telephone follow-up with participants at a scheduled follow-up time, and inform participants of active reports of alcohol-associated adverse events to investigators. Loss to follow-up is evaluated once every half a year to timely identify potential factors leading to loss to follow-up, and corresponding interventions will be implemented to solve these problems.

Data management {19}

All participants’ data will be stored at a highly safe database to assure the security, and all data will be subjected to periodical back-up. Signed paper forms will be stored in locked rooms. All participants’ personal identity data (such as names, contact information) will be separated from the study data and will be linked with the study data via unique object identifiers. Access to data is restricted to authorized investigators, and all data transmission and storage are processed with data encryption techniques. Storage of genetic data should meet Chinese national criterion Information security technology—Security requirements of genetic recognition data (GB/T 41806-2022), and data encryption is employed to assure data confidentiality, integrity, and availability. Data storage instruments are reviewed by the institutional ethical review committee and evaluated for safety. In addition, genetic recognition data should be subjected to de-identification processing during the storage, and genetic recognition data and related information are stored separately and assigned different access permissions. The duration of data storage is 10 years following the end of the trial, and all data are destroyed safely according to the requirements of the institutional ethical review committee. All original data and all procedures in analyses will be recorded in ECRFs and the SPSS software to allow understanding and repeated use of these data in the future.

Confidentiality {27}

All participants’ data will be protected, and each participant’s trial data will be labeled with codes. Identifiable participants’ data and codes will be stored in a safe database, and separated from the trial data.

Plans for collection, laboratory evaluation, and storage of biological specimens for genetic or molecular analysis in this trial/future use {33}

Blood samples are collected from all participants in the interventional group, and sent to the laboratory for gene testing. All biological blood samples collected in this trial are only available for this trial, and will be destructed following testing.

Statistical methods

Statistical methods for primary and secondary outcomes {20a}

As for the primary outcome alcohol intake, we first test the normality of data distribution. If the data do not follow normal distribution, Mann-Whitney U test will be employed to compare means between interventional and control groups. If the data follow approximate normal distribution, or the data follow normal distribution after transformations, independent-sample t test will be employed to compare means between groups. In addition, linear regression analysis is performed for adjustment for potential confounding factors, including gender, educational level, and initial alcohol consumption.

The secondary outcome hazardous drinking days usually does not follow normal distribution, and the Mann-Whitney U test will be employed to compare means between the interventional and control groups. Poisson regression analysis is performed for adjustment for potential confounding factors, and negative binomial regression analysis will be employed if there is data overdispersion.

In addition, the incidence of the secondary outcome alcohol-associated adverse events is compared using a chi-square test between interventional and control groups, and a logistic regression model will be employed to estimate the likelihood of alcohol-associated adverse events for adjustment of confounding factors.

Interim analyses {21b}

The steering committee of this clinical trial will supervise the procedure of the study and analyze data once every half a year, and there is no plan for a mid-term analysis.

Methods for additional analyses (e.g., subgroup analyses) {20b}

Exploratory subgroup analyses will be performed to investigate the variations in interventional effects specified by gender, educational level, baseline drinking behaviors, and other demographic variables. These analyses will be performed by incorporating interaction terms in regression models to assess potential differential intervention effects across subgroups.

Methods in analysis to handle protocol non-adherence and any statistical methods to handle missing data {20c}

Data management is conducted by a specific investigator to assure the data integrity. Inevitable data missing will be processed under missing at random (MAR) and missing not at random (MNAR) hypotheses, followed by sensitivity analysis.

Plans to give access to the full protocol, participant level data, and statistical code {31c}

The full protocol, participant level data, and statistical code will be available upon request by contact with the corresponding author.

Oversight and monitoring

Composition of the coordinating centre and trial steering committee {5 d}

The steering committee of this clinical trial is consisted of Drs. Zhenghua Jiang and Yingneng Wen, who are responsible for study design, supervision of study procedures and implementation, and provision of feedback and advice to the daily working group of the clinical trial. The daily working group of the clinical trial is consisted of the principal investigator, assistant investigator, data management staff, and statisticians, and this group holds a meeting every month to discuss the implementation and quality improvements of interventions.

Composition of the data monitoring committee, its role and reporting structure {21a}

There is no independent data supervisory committee in this clinical trial, and the steering committee will supervise the trial, which is responsible for supervising the progress of the trial, monitoring the data security of the trial, and solving any problems during the trial. The steering committee will hold a meeting once every half a year to review the trial implementation and data quality.

Adverse event reporting and harms {22}

All registered participants will acquire principal investigator’s contact from the copy of the informed consent. All adverse events reported by participants or observed by investigators will be recorded in case report forms, and all alcohol toxicity, treatment discontinuation or termination, and study protocol deviation will be recorded.

Frequency and plans for auditing trial conduct {23}

This study will be supervised by the Clinical Research Administration of Nanping First Hospital Affiliated to Fujian Medical University, which is responsible for project approval review, process management, quality management, and file management and coordination of ethics review.

Plans for communicating important protocol amendments to relevant parties (e.g. trial participants, ethical committees) {25}

If there is a need for revision of the study protocol, the principal investigator will be firstly informed, and the principal investigator will acquire the revised protocol version. Any behaviors against the agreement will be recorded in the report form.

Dissemination plans {31a}

The results of this single-center, open-label, randomized, controlled clinical trial will be published in peer-reviewed journals, and released in academic meetings, without restrictions of publication.

Discussion

ALDH2 is one of the important enzymes in alcohol metabolism in humans, and it is an important rate-limiting enzyme in acetaldehyde metabolism. Acetaldehyde has cytotoxic and carcinogenic roles, and ALDH2 activity affects acetaldehyde levels. Low alcohol metabolism and possible acetaldehyde accumulation are observed among individuals harboring ALDH2 gene mutations, resulting in discomfort following alcohol consumption. This randomized clinical trial aims to examine the impact of ALDH2 gene testing on alcohol use behaviors among unhealthy alcohol drinkers. To the best of our knowledge, this is the first clinical trial to evaluate the effect of ALDH2 gene testing on alcohol use behaviors among the Chinese Han population.

Whether individuals without ALDH2 gene mutations think that they have a strong alcohol metabolic ability following gene testing and therefore increase alcohol intake is a concern. Investigators will inform participants of gene testing results and harmfulness of alcohol use by telephone. Gene tests are not available in the control group, which may be regarded as “no additional benefits,” resulting in preference for the interventional group during recruitment. This problem remains to be solved. Investigators offer other benefits to subjects in the control group, such as free health counseling and small gift compensation to allow equal benefits between interventional and control groups. Alcohol consumption usually rises during holidays, notably the Spring Festival holiday, which may affect the follow-up results. Whether to avoid the Spring Festival holiday to perform this trial is also an issue that deserves consideration.

This trial has the following limitations. First, this trial enrolls unhealthy alcohol users from a single center, and the impact of ALDH2 gene testing on alcohol consumption behaviors remains unclear in other regions, among other ethnic populations, and other alcohol consumers. Second, all data are captured from participants’ follow-up, and there may be a deviation. Third, this is an open-label study, and participants’ grouping may affect the changes of alcohol consumption. Fourth, the primary outcome is 1-month alcohol consumption, with a short follow-up period. The long-term changes of participants’ alcohol consumption behaviors may require a longer follow-up period. Therefore, further studies with the addition of biomarkers as outcome measures, increased sample size, and extension of study period are warranted.

Trial status

The current protocol is version 1.0, dated 27 September 2023. This 28-month study will initiate in September 2024, and the final participant will be included in December 2025.