Study Design and Subjects
This cohort study included patients undergoing antiplatelet therapy with coronary artery disease (CAD) who were hospitalized at the First Affiliated Hospital of Xinjiang Medical University from January 2016 to December 2020, with detailed data collection on genetic profiles and clinical characteristics. The study protocol was approved by the institutional ethical review board (Approval No. K202106-24).
Inclusion and Exclusion Criteria
Inclusion criteria were patients aged 18 and above receiving clopidogrel therapy, including conformed to the diagnostic criteria for coronary artery disease (1); underwent genetic testing for CYP2C19, ABCB1, and PON1; were scheduled to receive antiplatelet therapy with clopidogrel or ticagrelor in combination with aspirin. Exclusion criteria included patients with incomplete genetic data or those on alternative antiplatelet regimens: those lacking basic information, genetic testing, or other relevant test data; those with a history of severe liver or kidney dysfunction or malignant tumours; those also using other anticoagulant medications such as warfarin or rivaroxaban; those whose antiplatelet therapy lasted less than six months. 5) Those unable to complete follow-up.
Data Collection
Data from the participating patients were collected through the medical record management system, including but not limited to gender, age, body mass index (BMI), hypertension, diabetes, smoking history, disease classification, surgical history, and diagnosis and treatment information. In addition, related biochemical indicators were collected, such as routine blood tests, liver and kidney function, lipid levels, and imaging data, such as left ventricular ejection fraction. Genomic DNA was extracted from blood samples, including the *2, *3, *17 alleles of CYP2C19, ABCB1 C3435T, and PON1 Q192R. In this study, due to the complexity of real-world data and the lack of standardization, we first cleansed the dataset to ensure the accuracy and validity of the analysis.
Outcome Measures and Follow-Up
The primary outcome measure of this study was the incidence rate of major cardiovascular adverse events (MACE) and bleeding events following treatment. Information on the patients' detailed use of antiplatelet drugs and any occurrences and timing of adverse cardiovascular events was collected through rehospitalization records and telephone follow-ups. In this study, MACE include cardiac death, non-fatal myocardial infarction, heart failure, revascularization, ischemic stroke, and cardiac rehospitalization, among others. Bleeding events are presented in Table 1 (21).
Table 1
Definition of bleeding classification
Definition | Manifestation (Meets one of the following) | Haemoglobin drop Value | Transfusion of whole blood or packed red cells |
Life-Threatening Bleeding | Fatal bleeding, intracranial haemorrhage, or cardiac tamponade due to haemorrhage, bleeding leading to shock or hypotension requiring vasopressor therapy or surgery | > 50 g/L | ≥ 4 U |
Other Serious Bleeding | Disabling (e.g., permanent loss of vision) | 30–50 g/L | 2–3 U |
Moderate Bleeding | Requires medical intervention for haemostasis (e.g., epistaxis requiring a device for haemostasis) | | |
Minor Bleeding | Other (gum bleeding, bruising, bleeding at the injection site) not requiring medical intervention | | |
Table 1 < Here>
Group strategy
Genotyping of the CYP2C19 gene includes wild type *1/*1, heterozygous mutants *1/*2, *1/*3, *1/*17, *2/*17, *3/*17, and homozygous mutants *2/*2, *3/*3, *2/*3, *17/*17; ABCB1 C3435T genotypes are categorized as wild type (CC), heterozygous (CT), and homozygous mutant (TT). PON1 Q192R genotypes are classified as wild type (GG), heterozygous (GA), and homozygous mutant (AA). Based on the rate of drug metabolism, CYP2C19 genotypes are classified into four metabolizer phenotypes: ultra-rapid metabolizer (UM) *17/*17, *1/*17; extensive metabolizer (EM) *1/*1; intermediate metabolizer (IM) *1/*2, *1/*3, *2/*17, *3/*17; and poor metabolizer (PM) *2/*2, *2/*3, *3/*3 (9). The combined effects of CYP2C19*2, *3, *17, ABCB1 C3435T, and PON1 Q192R genes were categorized as 6 levels in this study: Level − 1 (bleeding risk), Level 0 (normal), Level 1 (low risk of clopidogrel resistance), Level 2 (moderate risk of clopidogrel resistance), Level 3 (high risk of clopidogrel resistance), and Level 4 (very high risk of clopidogrel resistance), as detailed in Table 2.
Table 2
The risk level of the gene combination
Level | CYP2C19 | PON1 Q192R | ABCB1 C3435T |
Level − 1 (bleeding risk) | UM (*1/*17 or *17/*17) | GG | CC/CT/TT |
Level 0 (normal) | EM (*1/*1) | GG | CC/CT |
UM (*1/*17 or *17/*17) | GA/AA | CC/CT/TT |
Level 1 (low risk of clopidogrel resistance) | EM (*1/*1) | GG | TT |
EM (*1/*1) | GA | CC/CT |
IM (*1/*2 or *1/*3 or *2/*17 or *3/*17) | GG | CC/CT/TT |
Level 2 (moderate risk of clopidogrel resistance) | EM (*1/*1) | GA | TT |
IM (*1/*2 or *1/*3 or *2/*17 or *3/*17) | GA | CC/CT/TT |
Level 3 (high risk of clopidogrel resistance) | EM (*1/*1) | AA | CC/CT/TT |
IM (*1/*2 or *1/*3 or *2/*17 or *3/*17) | AA | CC/CT/TT |
PM (*2/*3) | GG/GA | CC/CT/TT |
PM(*3/*3) | GG/GA/AA | CC/CT/TT |
Level 4 (very high risk of clopidogrel resistance) | PM(*2/*3 or *2/*2) | AA | CC/CT/TT |
Note: Ultra-rapid metabolizer (UM) *17/*17, *1/*17; Extensive metabolizer (EM) *1/*1; Intermediate metabolizer (IM) *1/*2, *1/*3, *2/*17, *3/*17; and Poor metabolizer (PM) |
Table 2 < Here>
According to the guidelines for coronary heart disease and the latest expert consensus on dual antiplatelet therapy (1, 22), referring to the clinical guidelines published by PharmGKB and CPIC (9), and taking into account the actual conditions of our institution, has developed the following antiplatelet therapy plans. For patients at Level − 1, a combined treatment plan of clopidogrel (75 mg/day) and aspirin (100 mg/day) is recommended. If the patient experiences bleeding events or is at risk of bleeding, it is advised to reduce the clopidogrel dose to 50 mg/day. At Level 0 and Level 1, patients maintain a combination of clopidogrel (75 mg/day) with aspirin (100 mg/day). For patients at Level 2, ticagrelor (90 mg, twice a day) is recommended, or increasing the clopidogrel dose to 150 mg/day, combined with aspirin (100 mg/day). For patients at Level 3 and Level 4, it is suggested to use ticagrelor (90 mg, twice a day) in place of clopidogrel, in combination with aspirin (100 mg/day).
Based on whether the patient's antiplatelet treatment plan is consistent with the recommendations of the genetic testing results, the patients are divided into two groups: Group A: Treatment plan consistent with genetic testing recommendations; Group B: Treatment plan not consistent with genetic testing recommendations. This study aims to compare the incidence of major adverse cardiovascular events (MACE) in patients with coronary heart disease between the two treatment plans and to assess the clinical value of antiplatelet therapy guided by the results of multigene testing.
Statistical Methods
Descriptive statistics will be reported for baseline data. For continuous data, normality tests will be performed first; if each group satisfies normality and the variances between groups are equal, the t-test will be used for intergroup comparison; otherwise, the non-parametric Wilcoxon rank-sum test will be considered. The chi-square test was used for unordered outcomes for categorical data, and the non-parametric Wilcoxon rank-sum test was used for ordered data.
Multifactorial Cox regression models were utilized to assess the impact of genetic and clinical factors on MACE and haemorrhage outcomes, both before and after IPTW adjustment. Confounding factors were controlled to ensure robust analysis. This study used the propensity score to estimate the inverse probability of treatment weight (IPTW), achieved through the following steps: Selecting covariates based on multivariate Cox regression and clinical expert opinion to select related confounding factors. Based on past literature studies and expert opinions, 15 variables are included as confounding factors: gender, age, ethnicity, BMI, smoking status, whether diabetes was diagnosed and disease type, whether surgical procedure was given, monocyte percentage, platelet count, mean platelet volume, uric acid, low-density lipoprotein, left ventricular ejection fraction, and bleeding risk. The standard mead difference of each selected covariate was reported. All statistical analyses will be performed using R software.