publications

2026

1. PDS

   Safety and Effectiveness of Apixaban Versus Rivaroxaban in Atrial Fibrillation Patients in Singapore: An Active-Comparator, New-User Cohort Study

   Aaron Jun Yi Yap, Hui Xing Tan, Anna Schultze, and 5 more authors

   Pharmacoepidemiology and Drug Safety, Apr 2026

   Abs DOI

   Purpose: There are few comparative studies for Apixaban and Rivaroxaban in Asian Atrial Fibrillation (AF) patients. Our primary objectives were to investigate the relative safety and effectiveness of Apixaban versus Rivaroxaban for (1) all bleeding (major and clinically relevant non-major bleeding), and (2) a composite of ischemic strokes or all-cause mortality outcomes. In modified intention-to-treat analyses adjusted on confounders identified in directed acyclic graphs, initiating Rivaroxaban at the point of index AF was associated with a small increased risk of all bleeding as compared to Apixaban over 2 years (HR = 1.26, 95% CI: 1.04-1.53).

2. BMC

   Management of older adults consulting in GP surgery practices with back pain in UK Clinical Practice Research Datalink Aurum: population based study

   Aaron Jun Yi Yap, Jessica Harris, and Emma M. Clark

   BMC Musculoskeletal Disorders, Mar 2026

   Abs DOI

   The management of older adults with back pain in GP surgery practices is currently not well understood. We aimed to describe this and investigate if there are factors associated with variability in treatment.

3. medRxiv

   Adjusting for medication use in GWAS and its impact on Mendelian randomization analyses: an example of systolic blood pressure in UK Biobank

   Aaron Jun Yi Yap, Aimee L. Hanson, Gareth J. Griffith, and 1 more author

   Jan 2026

   Preprint

   Abs DOI

   Medication use is common in large-scale population cohorts, and can modify phenotypic traits of interest. This can potentially bias effect estimates in genome-wide association studies (GWAS) and impact downstream analyses such as Mendelian randomization (MR). We compared seven different methods of adjusting for antihypertensive use in a systolic blood pressure (SBP) GWAS of 407,960 White British individuals in the UK Biobank.

2025

1. DrugSaf

   Effectiveness of Transformer-Based Large Language Models in Identifying Adverse Drug Reaction Relations from Unstructured Discharge Summaries in Singapore

   Yen Ling Koon, Yan Tung Lam, Hui Xing Tan, and 12 more authors

   Drug Safety, Jun 2025

   Abs DOI

   Transformer-based large language models (LLMs) have transformed the field of natural language processing and led to significant advancements in various text processing tasks. However, the applicability of these LLMs in identifying related drug-adverse event (AE) pairs within clinical context may be limited by the prevalent use of non-standard sentence structures and grammar.

2024

1. PDS

   Validation of a Major and Clinically Relevant Nonmajor Bleeding Phenotyping Algorithm on Electronic Health Records

   Aaron Jun Yi Yap, Desmond Chun Hwee Teo, Pei San Ang, and 4 more authors

   Pharmacoepidemiology and Drug Safety, Aug 2024

   Abs DOI

   Purpose: Bleeding is an important health outcome of interest in epidemiological studies. We aimed to develop and validate rule-based algorithms to identify (1) major bleeding and (2) all clinically relevant bleeding (CRB) within real-world electronic healthcare data. During validation, diagnosis codes alone yielded low sensitivities for major bleeding (0.16) and CRB (0.24), although specificities and PPV were high (>0.97).

2. Vaccine

   Acute autoimmune hepatitis following COVID-19 mRNA vaccination: A population-based study using electronic health records in Singapore

   Amelia Jing Jing Ng, Desmond Chun Hwee Teo, Sreemanee Raaj Dorajoo, and 4 more authors

   Vaccine, Dec 2024

   Abs DOI

   Reports of COVID-19 vaccine-induced autoimmune hepatitis (AIH) have been largely limited to case reports and case series. We conducted a nationwide study using observed-over-expected and Self-Controlled Case Series analyses for acute presentations of AIH warranting admission. Our findings suggest that COVID-19 mRNA vaccination does not appear to be associated with increased risk of acute AIH requiring admissions in the population.