Research Areas:

• Cystic fibrosis (CF)
  
  • Gastroenterology: I established and lead Australia's first CF Gastroenterology research program across the lifespan (from infants to adults), including gut microbiome and inflammation and diet/nutritional issues.
  • Exocrine and endocrine pancreas including CF-related diabetes
  • Diagnostic issues 
• Gut microbiome, gut inflammation and dietary intakes in chronic childhood diseases
  
  • Chronic diseases with gastrointestinal issues and/or underlying gastrointestinal pathogenesis
  • Evaluation of taxonomic and functional alterations of the gut microbiome to identify pathogenic mechanisms, correlations with clinical phenotype, and uncover novel therapeutic interventions.
  • Role of diet - "Let your food be your medicine and your medicine be your food." (Hippocrates)
  • Impact of gut on distant organs e.g. "gut-brain" axis (on mental health and quality of life), "gut-lung" axis, "gut-skin" axis 
• Pancreatic diseases and pancreatitis
  
  • Across the lifespan (children and adults)

Examples of Research Achievements:

CF gastroenterology

• Dr Ooi has clinical-research expertise and interests in gastrointestinal issues in CF including gut inflammation, changes in the gut microbiome, pancreatitis, pancreatic insufficiency and the emerging issue of increased risk of gastrointestinal cancers.
• OOI et al. Gastroenterology 2011;140(1):153–161 (https://www.ncbi.nlm.nih.gov/pubmed/20923678). This is the first study to unravel the complex relationship between severity of cystic fibrosis transmembrane conductance regulator (CFTR) mutations and risk of pancreatitis. Developed & validated a novel surrogate measure of CF mutation and genotype severity, known as the “Pancreatic Insufficiency Prevalence (PIP)” score, with wide clinical & research application.  This score has been used clinically to predict pancreatitis risk and for patient education. This score has been used in research to classify cystic fibrosis (CF) patients by CFTR genotype. Methodology to derive score also directly adapted to study other CF phenotypes. 
• His recent works has extended into understanding the disease processes affecting the gastrointestinal tract in CF, using faecal biomarkers (Pang et al. J Gastroenterol Hepatol 2015, Dhaliwal et al. J Pediatr Gastroenterol Nutr 2015, Ooi et al. Dig Dis Sci 2015, Garg et al. J Cyst Fibros 2017, Garg et al. J Cyst Fibros 2018). 
• Nielsen,…OOI (SENIOR AUTHOR). Sci Rep 2016;6:24857 (https://www.ncbi.nlm.nih.gov/pubmed/27143104). Identified potential window of therapeutic opportunity in early childhood for CF gut dysbiosis, and provided justification for a probiotic trial in very young children with CF (AUD1.3M by the CF Foundation, USA) & industry engagement (national & international) for probiotic research. 
• OOI CY, et al (FIRST AUTHOR). Impact of CFTR modulation with Ivacaftor on Gut Microbiota and Intestinal Inflammation. Sci Rep. 2018;8(1):17834. This is the first study demonstrating CFTR modulators reduced gut inflammation and dysbiosis.
• McKay I,…. OOI CY (SENIOR AUTHOR). Diet and the gut-lung axis in cystic fibrosis - direct & indirect links. Gut Microbes. 2023;15(1):2156254. This pivotal study was the first to demonstrate a diet-gut-lung axis in CF. Highlighting the translational potential of dietary interventions to improve both gut & lung health, this study has pioneered a new field of diet-based interventional research.
• Kumar, OOI et al (CO-FIRST AUTHORS). JAMA Pediatr 2016;170(6):562-9 (https://www.ncbi.nlm.nih.gov/pubmed/27064572). NIH funded. Showed childhood recurrent/chronic pancreatitis has different causative factors compared to adults, with genetic causes most frequent. The most frequent mutation identified were CFTR mutations. Findings incorporated/cited by 3 international guidelines. Genetic tests now recommended as part of routine workup for children with recurrent/chronic pancreatitis. 

CF diagnostic issues and non-classic manifestations

• Dr Ooi is passionate about diagnostic issues related to children and adults with single-organ manifestations of CF (Ooi et al. Thorax 2012, Ooi et al. Thorax 2014) and newborn screen positive infants with an indeterminate diagnosis of CF (Ooi et al. Pediatrics 2015). He has experience in electrophysiological diagnostic tests, including the nasal potential difference test and intestinal ion channel measurement. He developed a novel diagnostic test for CF known as the “combined ion channel measurement” (Ooi et al. Ann Am Thorac Soc 2014).
• OOI et al. Thorax 2012;67(7):618-24 (https://www.ncbi.nlm.nih.gov/pubmed/22504961). Found the same CF patients who undergo same diagnostic tests can have different diagnostic outcomes geographically due to different guidelines. Led experts to revise into a single, global CF diagnostic guideline. Received an editorial & voted one of best 2012 articles by Thorax editor.
• OOI et al. Pediatrics 2015;135(6):e1377-85 (https://www.ncbi.nlm.nih.gov/pubmed/25963003). Findings showed decades-old clinical practice of discharging infants with inconclusive CF diagnosis to be inappropriate. 10% of these infants developed CF and risked missing out early therapies. Informed new international management guidelines.
• Barben J, et al. Updated guidance on the management of children with cystic fibrosis transmembrane conductance regulator-related metabolic syndrome/cystic fibrosis screen positive, inconclusive diagnosis (CRMS/CFSPID). J Cyst Fibros. 2021 Sep;20(5):810-819. 

Standards of care

• Simmonds NJ, et al. ECFS standards of care on CFTR-related disorders: Identification and care of the disorders. J Cyst Fibros. 2024;23(4):590-602.
• Burgel PR, et al. Standards for the care of people with cystic fibrosis (CF); recognising and addressing CF health issues. J Cyst Fibros. 2024;23(2):187-202.

Pancreatitis and pancreatic diseases 

• Dr Ooi is an international expert in childhood pancreatitis. He has developed clinical tools for predicting severe (https://www.ncbi.nlm.nih.gov/pubmed/23403441) and biliary causes (https://www.ncbi.nlm.nih.gov/pubmed/24013807) of acute pancreatitis in children.
• He is Chief Investigator of an international randomised controlled trial in paediatric acute pancreatitis, the first in the field. This showed early feeding is safe and the trial’s early feeding protocol has become adopted internationally as standard clinical care and referenced in guidelines (doi.org/10.1136/flgastro-2024-102788; PMID:37336694).
• He is the sole Australian Chief Investigator of INSPPIRE consortium (International Study Group of Pediatric Pancreatitis) for recurrent/chronic pancreatitis, enabling global-scale registry and biobank research.
• Dr Ooi is a founding member and paediatric representative of Australia New Zealand Alliance for Pancreatic Research (led by Prof Minoti Apte), bridging his pancreatitis research into adulthood.