Longitudinal Phenotyping of Bariatric Surgery Patients
Conditions: Obesity, Diabetes Mellitus, Type 2
Sponsor: Imperial College London

 
1 
 
 
 
LPBSP Study Protocol 
 
 
 
 
Longitudinal Phenotyping of Bariatric Surgery Patients 
 
 
 
 
Version 1.5 (16/02/2019) 
 
 
 
 
MAIN SPONSOR: Imperial College London 
FUNDERS: Imperial College London 
STUDY COORDINATION CENTRE: St Mary’s Hospital 
NRES reference: 15/ES/0026 
Protocol number: 15SM2479 
IRAS project ID: 169767 
Tissue Bank registration: Gas-AD-15-020 
 
 
 
 
Protocol authorised by: 
 
Name & Role 
Date 
Signature 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
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Study Management Group 
 
Chief Investigator: Nicholas Penney  
 
Principal Investigator: Professor A Darzi 
 
Co-investigators: Mr S Purkayastha, Professor E Holmes 
 
Study Management: Nicholas Penney 
 
Study Coordination 
 
For general queries, supply of study documentation, and collection of data, please contact: 
 
Study Coordinator: Nicholas Penney 
 
Address: 10th Floor QEQM, St Mary’s Hospital, Imperial College Healthcare NHS Trust, 
London W2 1NY 
Tel: 07545461256 
E-mail: n.penney@imperial.ac.uk 
 
Clinical Queries 
 
Clinical queries should be directed to Mr S Purkayastha – Consultant Bariatric Surgeon, who 
will direct the query to the appropriate person. (purkayastha.purkayastha@nhs.net) 
 
Sponsor 
 
Imperial College London is the main research Sponsor for this study.  For further information 
regarding the sponsorship conditions, please contact the Head of Regulatory Compliance at: 
 
 
 
Joint Research Compliance Office 
Imperial College London & Imperial College Healthcare NHS Trust 
5th Floor, Lab Block 
Charing Cross Hospital 
Fulham Palace Road 
London 
W6 8RF 
Tel: 0203 311 0212 
Fax: 0203 311 0203 
 
 
Funder 
 
Imperial College London & the Diabetes Research and Wellness Foundation 
 
 
This protocol describes the ‘Phenotyping Bariatric Surgery Patients’ study and provides information 
about procedures for entering participants.  Every care was taken in its drafting, but corrections or 
amendments may be necessary. These will be circulated to investigators in the study.  Problems relating 
to this study should be referred, in the first instance, to the Chief Investigator.  
 

 
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This study will adhere to the principles outlined in the NHS Research Governance Framework for Health 
and Social Care (2nd edition). It will be conducted in compliance with the protocol, the Data Protection 
Act and other regulatory requirements as appropriate. 
 
Table of Contents 
 
1. 
INTRODUCTION 
6 
1.1 BACKGROUND 
6 
2.   
STUDY OBJECTIVES 
7 
3.   
STUDY DESIGN 
7 
3.1 STUDY OUTCOME MEASURES 
7 
4. 
PARTICIPANT ENTRY 
8 
4.1 PRE-REGISTRATION EVALUATIONS 
8 
4.2 INCLUSION CRITERIA 
8 
4.3 EXCLUSION CRITERIA 
8 
4.4 WITHDRAWAL CRITERIA 
8 
5. 
ADVERSE EVENTS 
8 
5.1 DEFINITIONS 
8 
5.3 REPORTING PROCEDURES 
8 
6. 
ASSESSMENT AND FOLLOW-UP 
9 
7. 
STATISTICS AND DATA ANALYSIS 
10 
8. 
REGULATORY ISSUES 
10 
8.1 ETHICS APPROVAL 
10 
8.2 CONSENT 
10 
8.3 CONFIDENTIALITY 
10 
8.4 INDEMNITY 
11 
8.5 SPONSOR 
11 
8.6 FUNDING 
11 
8.7 AUDITS AND INSPECTIONS 
11 
9. 
STUDY MANAGEMENT 
11 
11. 
PUBLICATION POLICY 
11 
12. 
REFERENCES 
11 
 
 
 
 
 
 

 
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GLOSSARY OF ABBREVIATIONS 
T2DM 
Type 2 Diabetes Mellitus 
LRYGB 
Laparoscopic Roux-en-Y Gastric Bypass 
LSG 
Laparoscopic Sleeve Gastrectomy 
mRYGB 
Mini Roux-en-Y Gastric Bypass 
LAGB 
Laparoscopic Adjustable Gastric Band 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
KEYWORDS 
Obesity, Bariatric surgery, Type 2 diabetes mellitus, Gut microbiome, Metabonome 
 
 
 
 

 
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STUDY SUMMARY 
 
TITLE Phenotyping of Bariatric Surgery Patients 
DESIGN Observational study of obese patients undergoing bariatric surgery 
AIMS To identify novel preoperative biomarkers of diabetes resolution 
following bariatric surgery 
OUTCOME 
MEASURES 
HbA1c, Weight / BMI 
POPULATION Obese (BMI>30kg/m2) patients undergoing bariatric surgery 
ELIGIBILITY See Inclusion / Exclusion criteria 
DURATION 18-month recruitment period. 2 year follow up 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
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1. 
INTRODUCTION  
 
1.1 
BACKGROUND 
Within the UK approximately 1 in 4 adults are now obese. This obesity epidemic is having a 
dramatic impact on the rise of associated chronic disease states such as type 2 diabetes 
mellitus (T2DM), cardiovascular disease and cancer, which in turn carry a significant global 
health and economic burden. The Department of Health estimates the financial cost to the 
NHS at £5 billion annually. Thus there is an urgent need for effective preventative and 
therapeutic strategies for the treatment of obesity. Disappointingly, the encouragement of 
lifestyle changes such as improved diet and increased exercise together with 
pharmacological therapies has proved largely ineffectual thus far. Hence surgical procedures 
have been developed to achieve more sustainable weight loss and are currently the gold 
standard treatment for morbid obesity. The procedures were originally designed to cause 
weight loss through gastric restriction and / or malabsorption. However, in addition to weight 
loss they have also been highly successful in the resolution of co-morbidities including 
diabetes, heart disease, sleep apnoea and in reducing cancer risk1. Due to these metabolic 
effects they are termed ‘metabolic’ procedures. The metabolic outcomes are achieved 
through both weight-dependent and interestingly, weight-independent mechanisms1, 2. 
Indeed, many of the metabolic effects are seen before weight loss has occurred. This is 
because bariatric surgery induces a complex systems wide metabolic effect including 
disruption of the gut microbiome-host metabolic axes. 
 
The gut microbiome has now been linked extensively with numerous disease states and it 
represents a novel therapeutic target in the treatment of obesity3. A low bacterial richness in 
the gut is associated with increased adiposity, insulin resistance and dyslipidaemia4. Indeed 
metagenome wide association studies have demonstrated the ability to identify T2DM 
patients based on their gut microbiome5. Convincingly, in an effort to establish causality, the 
colonisation of germ free mice with the faecal microbiota of twin pairs discordant for obesity 
results in significantly greater increases in body mass and adiposity in mice receiving the 
faecal microbiota from the obese twin6. However, the overwhelming disruption to the gut 
microbiome caused by bariatric surgery is only just being defined, as is its functional 
importance. This has been demonstrated in faecal transplant experiments using the gut 
microbiota from Roux-en-Y gastric bypass (RYGB) treated mice to transfect non-operated 
germ free mice, leading to significant weight loss and decreased fat mass compared to 
transfer of the gut microbiota from mice who had undergone sham surgery7. This is thought 
to be through mechanisms including: reduced energy harvest of non-digestible food types 
such complex carbohydrates and plant polysaccharides, increased gut permeability leading 
to increased systemic inflammation, altered bile acid metabolism and carbohydrate 
fermentation products such as short-chain fatty acids acting as signalling molecules to 
increase satiety8, 9. In particular BAs have emerged as key signalling molecules, acting 
through the Farnesoid X Factor nuclear receptor (FXR) and G protein-coupled bile acid 
receptor (TGR5) to induce a number of physiological changes including; increased incretin 
release, improved glucose homeostasis, improved satiety, altered gut microbiota – acting in 
a bi-directional way, and increased metabolic rate10, 11. In support of this, many of the 
beneficial effects seen after RYGB are reproduced in rats by simply diverting bile from the 
common bile duct to the mid to distal jejunum via a catheter10. Additionally, following Vertical 
Sleeve Gastrectomy (VSG) in mice, body fat is reduced and glucose tolerance improved 
compared to sham-operated controls. However, body fat and glucose tolerance do not 
significantly differ in FXR knockout mice after VSG. Furthermore, Bacteroides were reduced 
following VSG in the wild type mice but the gut microbiota was not altered in the FXR 
knockout mice suggesting that FXR signalling is important in mediating the beneficial effects 
of VSG, in part through its modulation of the gut microbiota11. 
 
 

 
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1.2 
RATIONALE FOR CURRENT STUDY 
From a clinical perspective, national and international guidelines for bariatric surgery have 
historically been based predominantly on weight. However, bariatric surgery is also highly 
successful in achieving remission of co-morbidities such as T2DM. The chance of remission 
does not appear to be weight dependent. In a recent meta-analysis T2DM remission was 
72% in patients with a BMI<35kg/m2 and 71% in patients with a BMI>35kg/m2 undergoing 
bariatric surgery12. Consequently, the latest guidelines by NICE in the UK have been 
updated to reflect the convincing body of evidence that surgery is also a highly successful 
and cost-effective treatment for T2DM patients who are less obese. As many as 2 million 
patients may be eligible for bariatric surgery under these new guidelines. However, 
unfortunately up to 30% of T2DM patients who undergo bariatric surgery do not achieve 
remission of their T2DM. There is currently no reliable method of identifying these patients 
preoperatively. T2DM remission does not appear to correlate with preoperative BMI or any 
other known clinical or biochemical marker reliably. Therefore novel preoperative biomarkers 
to help guide clinicians and policy makers select the ideal surgical candidates are urgently 
required to enable truly personalised healthcare. 
 
 
2.  STUDY OBJECTIVES 
We hypothesise that weight loss and the metabolic effects of bariatric surgery are achieved 
in part through a functional modification of the gut microbiome and altered microbiome – 
host metabonome interactions. We aim to elucidate these and other mechanisms of T2DM 
remission following bariatric surgery. We will explore both the weight dependent and weight 
independent mechanisms with the translational objectives of 1) identifying novel, surgical 
and non-surgical, therapeutic targets and 2) identifying novel biomarkers for preoperative 
prognostication of T2DM remission. 
 
 
3.  STUDY DESIGN 
 
Type of study: Longitudinal phenotyping of bariatric surgery patients with collection of tissue 
samples (blood, urine, faeces + resected stomach from VSG patients) and clinical data pre 
and postoperatively. 
 
Duration: Patients will be followed up 2 years postoperatively. Total study time including 
recruitment = 60 months. 
 
Patients: Obese patients undergoing bariatric surgery (RYGB / VSG / mRYGB / LAGB). 
 
3.1 
STUDY OUTCOME MEASURES 
The 10 clinical outcome measure will be diabetes remission defined as HbA1c <42mmol/mol. 
The 20 clinical outcomes will be partial diabetes remission (HbA1c <48mmol/mol), HbA1c 
reduction and % excess weight loss. 
 
These clinical outcomes will be mapped to metabonomic and metagenomic data to identify 
preoperative markers of diabetes remission and weight loss. 
 
 
 
 
 

 
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4. 
PARTICIPANT ENTRY  
 
4.1 
PRE-REGISTRATION EVALUATIONS  
Potential participants will have their notes screened by NHS team members to identify 
patients that meet the inclusion / exclusion criteria. They will then be asked if they are happy 
to talk to the research team to discuss the project and undergo informed consent to take 
part. 
 
4.2 
INCLUSION CRITERIA 
Referred to the Imperial Weight Centre (NHS) Tier 4 service team for consideration 
bariatric surgery (RYGB / VSG / mRYGB / LAGB), Obese (BMI>30kg/m2), Age ≥18, 
failure of efforts at lifestyle modification and dieting, fitness for anaesthesia and 
procedure, willingness to comply with the trial protocol. 
 
4.3 
EXCLUSION CRITERIA 
Previous bariatric surgery, previous major abdominal surgery*, pregnancy or intention to 
become pregnant during trial period, lack of capacity to consent. 
 
* = Small or large bowel resection, liver, pancreatic or splenic surgery, as these will influence 
the bacteria in the gut and / or the patient’s metabolic state, which we are studying. It will not 
include patients that have previously had an appendicectomy, cholecystectomy, hernia 
repairs or surgery on other organs not listed above. 
 
4.4 
WITHDRAWAL CRITERIA 
Grade IV or higher surgical complication (Modified Clavien classification). 
Patient choice for any reason. 
 
5. 
ADVERSE EVENTS 
As no added clinical interventions / procedures will occur in this study NO adverse events are 
expected as a result of participating. 
 
5.1 
DEFINITIONS   
Adverse Event (AE): any untoward medical occurrence in a patient or clinical study subject.   
 
Serious Adverse Event (SAE): any untoward and unexpected medical occurrence or effect 
that: 
• 
Results in death 
• 
Is life-threatening – refers to an event in which the subject was at risk of death 
at the time of the event; it does not refer to an event which hypothetically might 
have caused death if it were more severe 
 
• 
Requires 
hospitalisation, 
or 
prolongation 
of 
existing 
inpatients’ 
hospitalisation 
• 
Results in persistent or significant disability or incapacity 
• 
Is a congenital anomaly or birth defect 
 
Medical judgement should be exercised in deciding whether an AE is serious in other 
situations.  Important AEs that are not immediately life-threatening or do not result in death or 
hospitalisation but may jeopardise the subject or may require intervention to prevent one of 
the other outcomes listed in the definition above, should also be considered serious. 
 
5.3 
REPORTING PROCEDURES 
All adverse events should be reported.  Depending on the nature of the event the reporting 
procedures below should be followed.  Any questions concerning adverse event reporting 
should be directed to the Chief Investigator in the first instance.   

 
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5.3.1 Non serious AEs 
All such events, whether expected or not, should be recorded.   
 
5.3.2 Serious AEs 
An SAE form should be completed and faxed to the Chief Investigator within 24 hours.  
However, hospitalisations for elective treatment of a pre-existing condition do not need 
reporting as SAEs. 
 
All SAEs should be reported to the East of Scotland Research Ethics Service where in the 
opinion of the Chief Investigator, the event was: 
• 
‘related’, ie resulted from the administration of any of the research procedures; 
and 
• 
‘unexpected’, ie an event that is not listed in the protocol as an expected 
occurrence 
 
Reports of related and unexpected SAEs should be submitted within 15 days of the Chief 
Investigator becoming aware of the event, using the NRES SAE form for non-IMP studies.  
The Chief Investigator must also notify the Sponsor of all SAEs. 
 
Local investigators should report any SAEs as required by their Local Research Ethics 
Committee, Sponsor and/or Research & Development Office. 
 
Contact details for reporting SAEs 
Email: eosres.tayside@nhs.net 
Please send SAE forms to: TAyside medical Science Centre Residency Block Level 3, 
George Pirie Way, Ninewells Hospital and Medical School Dundee DD1 9SY 
Tel: 01382 383871 (Mon to Fri 09.00 – 17.00) 
 
6. 
ASSESSMENT AND FOLLOW-UP  
 
Patients will undergo follow up according to the usual bariatric surgery follow up protocol at 
the Imperial Weight Centre. 
• 
At patients usual preoperative, 3 month, 1 and 2 year postoperative outpatient 
appointments patients will provide additional samples of blood, urine and faeces for 
analysis. 
• 
Patients will be given brief online 24-hour diet recall questionnaires to complete while 
waiting for their usual outpatient appointments. They will then be asked to complete 
entries for two days following each hospital visit using a personal computer via a 
personal link to a secure website provided. 
• 
Patients will be sent home with 24-hour urine collection bottles. They will be asked to 
provide 24-hour collections for before surgery and the days before their 3-month and 1-
year outpatient visits. They will be able to return their samples when they attend these 
appointments. 
• 
At the time of surgery researchers will collect resected stomach tissue from LSG patients 
that would usually be disposed. 
• 
Clinical data will be retrieved from the medical notes preoperatively to 2 years 
postoperatively. 
 
Study End: 130 type 2 diabetic and 65 non-diabetic patients will be recruited and 
followed-up until 2 years postoperatively. 
 

 
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7. 
STATISTICS AND DATA ANALYSIS 
 
Multivariate statistical analysis will be performed on the generated metabonomic and 
metagenomic data sets. This will include unsupervised principal components analysis (PCA) 
and supervised partial least squares discriminant analysis with orthogonal signal correction 
(OPLS-DA) and O2-PLS between data sets. Mapping T2DM outcomes to metabonomic and 
metagenomic data will potentially identify novel preoperative biomarkers that are able to 
prognosticate T2DM resolution following bariatric surgery. 
 
Due to the complexity of metabonomic data sample size calculations are difficult and there is 
currently no standardised technique. We used peer-reviewed MetSizeR methodology to 
calculate appropriate sample sizes13. Using principal component analysis on an expected 
metabonomic data set of 300 metabolites of which 20% differentiate significantly and a 
targeted false discovery rate of 5%, over 15 samples are needed in each group. 
Approximately 30% of obese diabetic patients do not have resolution of disease following 
bariatric surgery12. To allow for an expected drop out rate of 20% at 1 year we will recruit 65 
patients undergoing RYGB and 65 patients undergoing VSG to achieve 15 patients with 
non-resolution of diabetes and 36 patients with resolution in each surgical group. We will 
also aim to recruit 65 non-diabetic patients undergoing surgery to act as a control group. 
This will enable comparison against diabetic patients that undergo remission after surgery. 
 
Four surgeons at the Imperial Weight Centre collectively perform approximately 220 RYGB 
and 180 VSG procedures a year. In previous years 25% of patients have had T2DM. 
However, we expect this percentage to rise since the introduction of new NICE guidelines 
encouraging bariatric surgery in diabetic patients in November 2014. We expect to recruit 1-
2 patients a week that meet the inclusion criteria and have completed recruitment after 18 
months. 
 
Data and all appropriate documentation will be stored for a minimum of 10 years after the 
completion of the study, including the follow-up period.   
 
 
8. 
REGULATORY ISSUES 
 
8.1 
ETHICS APPROVAL 
The Chief Investigator has obtained approval from the East of Scotland Research Ethics 
Committee.  The study will be submitted for a Site Specific Assessment (SSA) at each 
participating NHS Trust.  The Chief Investigator will require a copy of the Trust R&D approval 
letter before accepting participants into the study.  The study will be conducted in accordance 
with the recommendations for physicians involved in research on human subjects adopted by 
the 18th World Medical Assembly, Helsinki 1964 and later revisions. 
 
8.2 
CONSENT  
Consent to enter the study will be sought from each participant only after a full explanation 
has been given, an information leaflet offered and time allowed for consideration.  Signed 
participant consent will be obtained.  The right of the participant to refuse to participate without 
giving reasons will be respected. All participants are free to withdraw at any time from the 
protocol treatment without giving reasons and without prejudicing further treatment. 
 
8.3 
CONFIDENTIALITY 
The Chief Investigator will preserve the confidentiality of participants taking part in the study 
and is registered under the Data Protection Act. 
 

 
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8.4 
INDEMNITY 
Imperial College London holds negligent harm and non-negligent harm insurance policies 
which apply to this study. 
 
8.5 
SPONSOR 
Imperial College London will act as the main Sponsor for this study.  Delegated responsibilities 
will be assigned to the NHS trusts taking part in this study.   
 
8.6 
FUNDING 
The study is funded by the Diabetes Research and Wellness Foundation. 
 
8.7 
AUDITS  
The study may be subject to inspection and audit by Imperial College London under their remit 
as sponsor and other regulatory bodies to ensure adherence to GCP and the NHS Research 
Governance Framework for Health and Social Care (2nd edition).  
 
 
9. 
STUDY MANAGEMENT 
 
The day-to-day management of the study will be co-ordinated through Nicholas Penney.   
 
10. 
PUBLICATION POLICY 
 
The trial will be registered on ClinicalTrials.gov before the start of recruitment. 
The anonymous research data will be published in a scientific journal. This will be open-
access. 
Deidentified research data from this project will be deposited in public data repositories to 
ensure that the research community has long-term access to the data and that the research 
data is migrated to new formats, platforms, and storage media. 
 
 
10. 
REFERENCES 
 
1. 
Schauer PR, Bhatt DL, Kirwan JP, Wolski K, Brethauer SA, Navaneethan SD et al. 
Bariatric surgery versus intensive medical therapy for diabetes--3-year outcomes. N. 
Engl. J. Med. 2014; 370(21): 2002-13. 
 
2. 
Cummings BP, Bettaieb A, Graham JL, Stanhope KL, Kowala M, Haj FG et al. 
Vertical sleeve gastrectomy improves glucose and lipid metabolism and delays 
diabetes onset in UCD-T2DM rats. Endocrinology 2012; 153(8): 3620-32. 
 
3. 
Turnbaugh PJ, Ley RE, Mahowald MA, Magrini V, Mardis ER, Gordon JI. An obesity-
associated gut microbiome with increased capacity for energy harvest. Nature 2006; 
444(7122): 1027-31. 
 
4. 
Le Chatelier E, Nielsen T, Qin J, Prifti E, Hildebrand F, Falony G et al. Richness of 
human gut microbiome correlates with metabolic markers. Nature 2013; 500(7464): 
541-6. 
 
5. 
Qin J, Li Y, Cai Z, Li S, Zhu J, Zhang F et al. A metagenome-wide association study 
of gut microbiota in type 2 diabetes. Nature 2012; 490(7418): 55-60. 
 

 
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6. 
Ridaura VK, Faith JJ, Rey FE, Cheng J, Duncan AE, Kau AL et al. Gut microbiota 
from twins discordant for obesity modulate metabolism in mice. Science 2013; 
341(6150): 1241214. 
 
7. 
Liou AP, Paziuk M, Luevano JM, Jr., Machineni S, Turnbaugh PJ, Kaplan LM. 
Conserved shifts in the gut microbiota due to gastric bypass reduce host weight and 
adiposity. Sci. Transl. Med. 2013; 5(178): 178ra41. 
 
8. 
Tremaroli V, Backhed F. Functional interactions between the gut microbiota and host 
metabolism. Nature 2012; 489(7415): 242-9. 
 
9. 
Turnbaugh PJ, Hamady M, Yatsunenko T, Cantarel BL, Duncan A, Ley RE et al. A 
core gut microbiome in obese and lean twins. Nature 2009; 457(7228): 480-4. 
 
10. 
Kohli R, Setchell KD, Kirby M, Myronovych A, Ryan KK, Ibrahim SH et al. A surgical 
model in male obese rats uncovers protective effects of bile acids post-bariatric 
surgery. Endocrinology 2013; 154(7): 2341-51. 
 
11. 
Ryan KK, Tremaroli V, Clemmensen C, Kovatcheva-Datchary P, Myronovych A, 
Karns R et al. FXR is a molecular target for the effects of vertical sleeve gastrectomy. 
Nature 2014; 509(7499): 183-8. 
 
12. 
Panunzi S, De Gaetano A, Carnicelli A, Mingrone G. Predictors of Remission of 
Diabetes Mellitus in Severely Obese Individuals Undergoing Bariatric Surgery: Do 
BMI or Procedure Choice Matter? A Meta-Analysis. Ann. Surg. 2014. 
 
13. 
Nyamundanda G, Gormley IC, Fan Y, Gallagher WM, Brennan L. MetSizeR: 
selecting the optimal sample size for metabolomic studies using an analysis based 
approach. BMC Bioinformatics 2013; 14: 338.