During my specialist medical training in gastroenterology I was awarded a Wellcome Trust doctoral Clinical Training Fellowship in 1999 to examine the mucosal immune response to the gut infection . I was awarded The Digestive Disease Foundation (CORE) National Research Prize for this work.Since my appointment at St George’s in 2002 I have expanded my portfolio of research interests and the award of Comprehensive Research Network (CRN) funded research programmed activities in 2009 has allowed me to increase my research activity substantially.

My research interests are primarily focused on IBD and GI infection with over 100 peer reviewed publications, many appear in high impact international journals such as the Lancet, Nature Genetics and Gastroenterology ,and substantial income from grants and trials.  I have been Principal Investigator  for more than 20 clinical studies both  NIHR funded and commercial Clinical Research Network  adopted observational and therapeutic clinical studies.

I have led several successful local and national collaborations with NHS and academic partners including Imperial College London, Leeds University and have international links with Christian Medical College, Velore, India. The impact of my work is growing as evidenced by nearly 1500 citations of my work in the literature and its translation into clinical guidelines.

Alongside my research activity, I am a full time NHS clinician, with activities including out-patient and in-patient consultation, endoscopy, service development and education. I was Clinical Director of Specialist Medicine at  St George’s University Hospitals NHS Foundation Trust between 2008 and 2011 including a portfolio for education and research.

I have been South London Gastroenterology Clinical Research Network Lead and a national Gastroenterology CRN committee member since 2011 and oversee a portfolio of commercial and NIHR funded clinical trials. In this role I have driven recruitment to clinical studies in Gastroenterology, which has more than doubled, both regionally and at St George’s.

I am co-investigator on a large NIHR project grant studying ways in which to improve IBD patients’ chronic symptoms.


The three major themes to my research portfolio are:

(1) The study of health related outcomes in IBD and GI infection. This includes national studies evaluating the health burden of Clostridium difficile infection in IBD. I am currently leading collaboration with researchers at Imperial College London examining long-term surgical outcomes and prescribing patterns in IBD patients studying an IBD population cohort over 20 years using a UK national dataset. Since 2008 our group has published many original articles in this field.

(2) Non-invasive techniques in the diagnosis and assessment of IBD and GI infection. Successful projects include an evaluation of the role of proteomics technology in the diagnosis of Tuberculosis and IBD, in collaboration with Professor Krishna at SGUL, we published our findings in the Lancet. We have also evaluated novel ultrasound techniques, in collaboration with the Radiology team at St George’s University Hospitals NHS Foundation Trust , for in the diagnosis and assessment of IBD.

(3) Clinical observational and therapeutic studies . We have recruited more than 400 patients to a range of studies outlined below. Examples include recruitment of more than 200 patients to the international IBD genetics consortium contributing to a recent paper published in Nature Genetics on rare genetic determinants of IBD. HALT-IT is a large international NIHR funded trial of a treatment for GI bleeds-I am local PI and we have enrolled more than 50 patients, one of the largest recruiters in the UK. I have been instrumental in enterprise development and was awarded 2 NHS innovation awards for development of proteomic–based diagnostic methods and a novel endoscopic device.

I enjoy a wide range of teaching and educational activities at St George’s including Final year medical examiniation and interviewing prospective medical students. As Director for the Early Years clinical Experience (EYCE) Undergraduate Medicine course since early 2014 I have led the development and inception of this course for 1st and 2nd years devised to provide an experience of the clinical milieu in the early years of medical training. I  supervise and mentor several MD/PhD  clinical research fellows.

selected publications

Alexakis C, Saxena S, Chhaya V, Cecil E, Curcin V, Pollok R. Do Thiopurines Reduce the Risk of Surgery in Elderly Onset Inflammatory Bowel Disease? A 20-Year National Population-Based Cohort Study. Inflamm Bowel Dis. 2017 Apr;23(4):672-680.

Alexakis C, Gordon K, Mellor R, Chong H, Mortimer P, Pollok R. Ano-genital granulomatosis and Crohn’s disease: a case series of males presenting with genital lymphoedema. J Crohns Colitis. 2016 Sep 28. pii: jjw173.

Kumar S, Pollok R, Muscat I, Planche T. Diagnosis and outcome of Clostridium difficile infection by toxin enzyme immunoassay and PCR in an island population. J Gastroenterol Hepatol. 2016 Aug 9. doi: 10.1111/jgh.13504.

Subramanian V, Chatu S, Echterdiek F, Banerjee A, Finlayson C, Pollok RC. Patients with Endoscopically Visible Polypoid Adenomatous Lesions Within the Extent of Ulcerative Colitis Have an Increased Risk of Colorectal Cancer Despite Endoscopic Resection. Dig Dis Sci. 2016 Oct;61(10):3031-6. doi: 10.1007/s10620-016-4246-7. Epub 2016 Jul 12.

Aliment Pharmacol Ther. 2016 Sep;44(5):482-94. doi: 10.1111/apt.13700. Epub 2016 Jul 4.

Chhaya V, Saxena S, Cecil E, Subramanian V, Curcin V, Majeed A, Pollok RC.

World J Gastroenterol. 2016 Feb 21;22(7):2165-78. doi: 10.3748/wjg.v22.i7.2165.

World J Gastrointest Surg. 2015 Dec 27;7(12):360-9. doi: 10.4240/wjgs.v7.i12.360.

Chhaya V, Pollok RC, Cecil E, Subramanian V, Curcin V, Majeed A, Saxena S. Impact of early thiopurines on surgery in 2770 children and young people diagnosed with inflammatory bowel disease: a national population-based study. Aliment Pharmacol Ther. 2015 Oct;42(8):990-9. doi: 10.1111/apt.13361. Epub 2015 Aug 13.

Chhaya V, Saxena S, Cecil E, Chatu S, Subramanian V, Curcin V, Majeed A, Pollok RC. The impact of timing and duration of thiopurine treatment on colectomy in ulcerative colitis: a national population-based study of incident cases between 1989-2009. Aliment Pharmacol Ther. 2015 Jan;41(1):87-98.

Chhaya V, Saxena S, Cecil E, Subramanian V, Curcin V, Majeed A, Pollok RC. Impact of Timing and duration of thiopurine treatment on first Perianalsurgery in Crohn’s Disease:UK population-based Study. Inflamm Bowel Dis. 2015 Jan 7

Prescott NJ,..UK IBD Genetics Consortium,..Pollok R  et al.  Pooled sequencing of 531 genes in inflammatory bowel disease identifies an associated rare variant in BTNL2 and implicates other immune related genes. Nature Genetics  2015

Chatu S, Subramanian V, Saxena S, Pollok RC. The role of thiopurines in reducing the need for surgical resection in Crohn’s disease: a systematic review and meta-analysis. Am J Gastroenterol. 2014 Jan;109(1):23-34

Chatu S, Saxena S, Subramanian V, Curcin V, Yadegarfar G, Gunn L, Majeed A, Pollok RC. The Impact of Timing and Duration of Thiopurine Treatment on First Intestinal Resection in Crohn’s Disease: National UK Population-Based Study 1989-2010. Am J Gastroenterol. 2014 Jan 28

Kumar S, Hakim AF, Alexakis CF, Chhaya VF, Tzias DF, Pilcher JF, Pollok RC. Small intestinal contrast ultrasonography for the detection of small bowel complications in Crohn’s disease: correlation with intra-operative findings and MR enterography. Gastroenterology and Hepatology.  2014; 1440-1746

S Chatu, V Chhaya, R Holmes, P Neild, JY Kang, RC Pollok, A Poullis. Factors associated with vitamin D deficiency in a multicultural inflammatory bowel disease cohort. Frontline Gastroenterology  4 (1), 51-56, 2013 4 2013

Chatu S, Pilcher J, Saxena SK, Fry DH, Pollok RC. Diagnostic accuracy of small intestine ultrasonography using an oral contrast agent in Crohn’s disease: Comparative study from the UK.Clin Radiol. 2012 Jun;67(6):553-9.

Assessment of administrative data for evaluating the shifting acquisition of Clostridium difficile infection in England. Jen MH, Saxena S, Bottle A, Pollok R, Holmes A, Aylin P. J Hosp Infect. 2012 Mar; 80(3):229-37. Epub 2012 Feb 4

Meta-analysis: diagnostic medical radiation exposure in inflammatory bowel disease. Chatu S, Subramanian V, Pollok RC. Aliment Pharmacol Ther. 2012 Mar;35(5):529-39. Epub 2012 Jan 13

Diagnostic accuracy of small intestine ultrasonography using an oral contrast agent in Crohn’s disease: Comparative study from the UK. Chatu S, Pilcher J, Saxena SK, Fry DH, Pollok RC. Clin Radiol. 2011 Dec 31.

Acute upper gastrointestinal bleeding: identifying low risk patients. Chakrabarty G, Groves C, Pollok R. Gut. 2011

Increased health burden associated with Clostridium difficile diarrhoea in patients with inflammatory bowel disease. Jen MH, Saxena S, Bottle A, Aylin P, Pollok RC. Aliment Pharmacol Ther. 2011 Jun;33(12):1322-31

Unusual causes of diarrhoea and peripheral oedema. Gayatri Chakrabarty, RCG Pollok, P Mortimer. Gastroenterology Today  2011; 21(1): 18-19

Primary cytomegalovirus infectious colitis complicating Crohn’s disease successfully treated with oral valganciclovir. Subramanian V, Finlayson C, Harrison T, Rice P, Pollok R. J Crohn’s Colitis. 2010; 4:199-202

JF Rahier..Pollok R.. et al. European evidence-based Consensus guidelines on the management of opportunistic infections in inflammatory bowel disease. J Crohn’s and Colitis 2010 Jun;4(2):199-202

Pollok RCG. Treatment of Clostridium difficile. N Engl J Med. 2009 Feb 5;360(6):636

Subramanian V,  Saxena S, Kang JY, and Pollok R. Pre-operative steroid use in patients with Inflammatory Bowel Disease and post-operative complications: meta-analysis. Am J Gatroenterol. . 2008; 103:2373-81.

Subramanian V, Beharry N, Pollok RC. Determining the proximal extent of ulcerative colitis: white cell scan correlates well with histological assessment.  Aliment Pharmacol Ther. 2007 Feb 15;25(4):441-6.

Agranoff D, Fernandez-Reyes D, Papadopoulos M, Rojas S, Herbster M, Loosemore A, Tarelli T, Sheldon J, Schwenk A, Pollok RCG, Rayner C, Krishna S. Identification of diagnostic markers for tuberculosis by serum proteomic fingerprinting. Lancet 2006 Sep 16;368(9540):1012-21.

Subramanian V, Pollok RC, Kang JY, Kumar D. Systematic review of postoperative complications in patients with inflammatory bowel disease treated with immunomodulators.Br J Surg 2006 Jul; 93(7):793-9

Zulu I, Kelly P, Sianongo S, Kaonga K, McDonald V, Farthing M, Pollok RC. Nitazoxanide for persistent diarrhoea in Zambian AIDS patients: a randomised controlled trial. Aliment Pharmacol Ther 2005; 21: 757-763

Irving PM, Alstead EM, Greaves RR, Feakins RM, Pollok RC, Rampton DS. Acute mesenteric infarction: an important cause of abdominal pain in ulcerative colitis. Eur J Gastro Hepatol. 2005 ; 17(12): 1429-1432

RCG Pollok.Investigation of chronic diarrhoea. Gut. 2004 May;53(5):770

JY Kang, A Dhar, R Pollok et al. Diverticular disease of the colon: ethnic differences in frequency. Aliment Pharmacol Ther 2004; 19:765-69

IS Lean, Ac Stuart, M Bajaj-Elliott, RCG Pollok, MJG Farthing, V McDonald. IL-4 and TGF-beta have opposing regulatory effect on interferon–gamma mediated inhibition of Cryptosporidium parvum. Infec  Immun 2003; 71(8): 4580-85

RCG Pollok et al. Interferon-gamma induces enterocyte resistance to infection against the intracellular pathogen Cryptosporidium parvum. Gastroenterology 2001; 120: 99-107

T Blanchard, L Milne, RCG Pollok. Lancet 1994; 343: 922. Clostridium difficile diarrhoea and rifabutin. Early chemotherapy of neuro-schistosomiasis. Lancet  1993; 341: 959. RCG Pollok, R Bendall, A Moody, PL Chiodini, DR Churchill. Traveller’s diarrhoea associated with “Cyanobacterium-like-bodies”.Lancet 1992; 340: 556-557