Imperial College London


Faculty of MedicineSchool of Public Health

Clinical Trials Statistician



+44 (0)20 7594 1751nicholas.johnson




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Publication Type

11 results found

Glaysher M, Ward J, Aldhwayan M, Ruban A, Prechtl CG, Fisk HL, Chhina N, Al-Najim W, Smith C, Klimowska-Nassar N, Johnson N, Falaschetti E, Goldstone AP, Miras AD, Byrne JP, Calder PC, Teare Jet al., 2021, The effect of a duodenal-jejunal bypass liner on lipid profile and blood concentrations of long chain polyunsaturated fatty acids, Clinical Nutrition, Vol: 40, Pages: 2343-2354, ISSN: 0261-5614

Background & aimsDuodenal-jejunal bypass liners (DJBLs) prevent absorption in the proximal small intestine, the site of fatty acid absorption. We sought to investigate the effects of a DJBL on blood concentrations of essential fatty acids (EFAs) and bioactive polyunsaturated fatty acids (PUFAs).MethodsSub-study of a multicentre, randomised, controlled trial with two treatment groups. Patients aged 18–65 years with type-2 diabetes mellitus and body mass index 30–50 kg/m2 were randomised to receive a DJBL for 12 months or best medical therapy, diet and exercise. Whole plasma PUFA concentrations were determined at baseline, 10 days, 6 and 11.5 months; data were available for n = 70 patients per group.ResultsWeight loss was significantly greater in the DJBL group compared to controls after 11.5 months: total body weight loss 11.3 ± 5.3% versus 6.0 ± 5.7% (mean difference [95% CI] = 5.27% [3.75, 6.80], p < 0.001). Absolute concentrations of both EFAs, linoleic acid and α-linolenic acid, and their bioactive derivatives, arachidonic acid, eicosapentaenoic acid, docosapentaenoic acid and docosahexaenoic acid, were significantly lower in the DJBL group than in the control group at 6 and 11.5 months follow-up. Total serum cholesterol, LDL-cholesterol and HDL-cholesterol were also significantly lower in the DJBL group.ConclusionOne year of DJBL therapy is associated with superior weight loss and greater reductions in total serum cholesterol and LDL-cholesterol, but also depletion of EFAs and their longer chain derivatives. DJBL therapy may need to be offset by maintaining an adequate dietary intake of PUFAs or by supplementation.

Journal article

Ruban A, Glaysher MA, Miras AD, Goldstone AP, Prechtl CG, Johnson N, Li J, Aldhwayan M, Aldubaikhi G, Glover B, Lord J, Onyimadu O, Falaschetti E, Klimowska-Nassar N, Ashrafian H, Byrne J, Teare JPet al., 2020, A duodenal sleeve bypass device added to intensive medical therapy for obesity with type 2 diabetes: a RCT, Efficacy and Mechanism Evaluation, Vol: 7, Pages: 1-130, ISSN: 2050-4365

BackgroundThe EndoBarrier® (GI Dynamics Inc., Boston, MA, USA) is an endoluminal duodenal–jejunal bypass liner developed for the treatment of patients with obesity and type 2 diabetes mellitus. Meta-analyses of its effects on glycaemia and weight have called for larger randomised controlled trials with longer follow-up.ObjectivesThe primary objective was to compare intensive medical therapy with a duodenal–jejunal bypass liner with intensive medical therapy without a duodenal–jejunal bypass liner, comparing effectiveness on the metabolic state as defined by the International Diabetes Federation as a glycated haemoglobin level reduction of ≥ 20%. The secondary objectives were to compare intensive medical therapy with a duodenal–jejunal bypass liner with intensive medical therapy without a duodenal–jejunal bypass liner, comparing effectiveness on the metabolic state as defined by the International Diabetes Federation as a glycated haemoglobin level of < 42 mmol/mol, blood pressure of < 135/85 mmHg, and the effectiveness on total body weight loss. Additional secondary outcomes were to investigate the cost-effectiveness and mechanism of action of the effect of a duodenal–jejunal bypass liner on brain reward system responses, insulin sensitivity, eating behaviour and metabonomics.DesignA multicentre, open-label, randomised controlled trial.SettingImperial College Healthcare NHS Trust and University Hospital Southampton NHS Foundation Trust.ParticipantsPatients aged 18–65 years with a body mass index of 30–50 kg/m2 and with inadequately controlled type 2 diabetes mellitus who were on oral glucose-lowering medications.InterventionsParticipants were randomised equally to receive intensive medical therapy alongside a duodenal–jejunal bypass liner device (n = 85) or intensive medical therapy alone for 12 months (n = 85), and were followed up

Journal article

Lyon A, Babalis D, Morley-Smith AC, Hedger M, Suarez Barrientos A, Foldes G, Couch LS, Chowdhury RA, Tzortzis KN, Peters NS, Rog-Zielinska EA, Yang YH, Welch S, Bowles CT, Rahman Haley S, Bell AR, Rice A, Sasikaran T, Johnson NA, Falaschetti E, Parameshwar J, Lewis C, Tsui S, Simon A, Pepper J, Rudy JJ, Zsebo KM, MacLeod KT, Terracciano CM, Hajjar RJ, Banner N, Harding SEet al., 2020, Investigation of the safety and feasibility of AAV1/SERCA2a gene transfer in patients with chronic heart failure supported with a left ventricular assist device – the SERCA-LVAD TRIAL, Gene Therapy, Vol: 27, Pages: 579-590, ISSN: 0969-7128

The SERCA-LVAD trial was a phase 2a trial assessing the safety and feasibility of delivering an adeno-associated vector 1 carrying the cardiac isoform of the sarcoplasmic reticulum calcium ATPase (AAV1/SERCA2a) to adult chronic heart failure patients implanted with a left ventricular assist device. Enrolled subjects were randomised to receive a single intracoronary infusion of 1x1013 DNase-resistant AAV1/SERCA2a particles or a placebo solution in a double-blinded design, stratified by presence of neutralising antibodies to AAV. Elective endomyocardial biopsy was performed at 6 months unless the subject had undergone cardiac transplantation, with myocardial samples assessed for the presence of exogenous viral DNA from the treatment vector. Safety assessments including ELISPOT were serially performed. Although designed as a 24 subject trial, recruitment was stopped after five subjects had been randomised and received infusion due to the neutral result from the CUPID 2 trial. Here we describe the results from the 5 patients, which confirmed that viral DNA was delivered to the failing human heart in 2 patients receiving gene therapy with vector detectable at follow up endomyocardial biopsy or cardiac transplantation. Absolute levels of detectable transgene DNA were low, and no functional benefit was observed. There were no safety concerns in this small cohort. This trial identified some of the challenges of performing gene therapy trials in this LVAD patient cohort, which may help guide future trial design.

Journal article

Ruban A, Glaysher M, Miras A, Prechtl CG, Goldstone AP, Johnson NA, Aldhwayan M, Chhina N, Al-Najim W, Ashrafian H, Patel M, Byrne J, Teare JPet al., 2020, ONE YEAR OF DUODENAL-JEJUNAL BYPASS LINER THERAPY (ENDOBARRIER (R)) LEADS TO SIGNIFICANT CHANGES IN LIVER BIOCHEMISTRY ASSOCIATED WITH NON-ALCOHOLIC FATTY LIVER DISEASE, GI Fellows Sessions at Digestive Disease Week / 61st Annual Meeting of the Society-for-Surgery-of-the-Alimentary-Tract, Publisher: MOSBY-ELSEVIER, Pages: AB225-AB226, ISSN: 0016-5107

Conference paper

Cro S, Forbes G, Johnson NA, Kahan BCet al., 2020, Evidence of unexplained discrepancies between planned and conducted statistical analyses: a review of randomized trials, BMC Medicine, Vol: 18, ISSN: 1741-7015

Evidence of unexplained discrepancies between planned and conducted statistical analyses: a review of randomised trials

Journal article

Glaysher M, Ward J, Aldhwayan M, Ruban A, Prechtl C, Fisk H, Gelauf C, Chhina N, Al-Najim W, Smith C, Klimowska-Nassar N, Johnson N, Goldstone A, Miras A, Patel M, Byrne J, Calder P, Teare Jet al., 2020, The effect of a duodenal-jejunal bypass liner device (Endobarrier (R)) on lipid profile and blood concentrations of long chain polyunsaturated fatty acids, 11th Annual Scientific Meeting of the British-Obesity-and-Metabolic-Surgery-Society (BOMSS), Publisher: SPRINGER, Pages: S16-S17, ISSN: 0960-8923

Conference paper

Johnson NA, Sasikaran T, 2019, AVATAR-AF: Getting to the heart of data management for analysis (5 simple rules to follow to ensure data integrity), 5th International Clinical Trials Methodology Conference, Publisher: BMC

Conference paper

Mann I, Sasikaran T, Sandler B, Babalis D, Johnson N, Falaschetti E, Copley A, Tayebjee M, Todd D, Shepherd E, McCready J, Poulter N, Kanagaratnam Pet al., 2019, Ablation versus anti-arrhythmic therapy for reducing all hospital episodes from recurrent atrial fibrillation (AVATAR-AF): design and rationale, American Heart Journal, Vol: 214, Pages: 36-45, ISSN: 0002-8703

Atrial Fibrillation (AF) ablation using the cryoballoon is effective at reducing symptomatic AF episodes. The prevalence of AF is increasing with the aging population and access to such treatment would be enhanced by reducing the resource requirements. Relinquishing electrical mapping of the pulmonary veins (PV) removes the need for PV catheters, electrical recording equipment and staff trained in using this equipment. Moreover, the majority of complications are peri-procedural so overnight hospitalization maybe unnecessary. We tested this streamlined approach to AF ablation against medical therapy using the endpoint of time to all hospital episodes. METHODS: The AVATAR-AF study is a prospective, multicenter, randomized controlled trial testing the primary hypothesis that AF ablation done without PV mapping or overnight hospitalization is more effective than anti-arrhythmic drugs at reducing all hospital episodes related to recurrent atrial arrhythmias. We included a third arm to test a secondary hypothesis that confirming PV entrance block as per consensus guidelines can improve outcomes. Three hundred twenty-one patients with documented paroxysmal AF will be randomized in a 1:1:1 manner to one of three investigation arms: (1) AVATAR protocol cryoballoon ablation without assessment of acute PV isolation or overnight hospitalization; (2) medical therapy with anti-arrhythmic drugs; or (3) conventional cryoballoon ablation with assessment of acute PV isolation. The primary endpoint is defined as the time to all hospital episodes (including outpatient consultation) related to treatment for atrial arrhythmia. CONCLUSION: The AVATAR-AF study will determine whether the resource utilization for AF ablation can be reduced whilst maintaining superiority over medical therapy.

Journal article

Behary P, Tharakan G, Alexiadou K, Johnson N, Wewer Albrechtsen NJ, Kenkre J, Cuenco J, Hope D, Anyiam O, Choudhury S, Alessimii H, Poddar A, Minnion J, Doyle C, Frost G, Le Roux C, Purkayastha S, Moorthy K, Dhillo W, Holst JJ, Ahmed AR, Prevost AT, Bloom SR, Tan TMet al., 2019, Combined GLP-1, oxyntomodulin, and peptide YY improves body weight and glycemia in obesity and prediabetes/type 2 diabetes: a randomized single-blinded placebo controlled study, Diabetes Care, Vol: 42, Pages: 1446-1453, ISSN: 0149-5992

OBJECTIVE: Roux-en-Y gastric bypass (RYGB) augments postprandial secretion of glucagon-like peptide 1 (GLP-1), oxyntomodulin (OXM), and peptide YY (PYY). Subcutaneous infusion of these hormones ("GOP"), mimicking postprandial levels, reduces energy intake. Our objective was to study the effects of GOP on glycemia and body weight when given for 4 weeks to patients with diabetes and obesity. RESEARCH DESIGN AND METHODS: In this single-blinded mechanistic study, obese patients with prediabetes/diabetes were randomized to GOP (n = 15) or saline (n = 11) infusion for 4 weeks. We also studied 21 patients who had undergone RYGB and 22 patients who followed a very low-calorie diet (VLCD) as unblinded comparators. Outcomes measured were 1) body weight, 2) fructosamine levels, 3) glucose and insulin during a mixed meal test (MMT), 4) energy expenditure (EE), 5) energy intake (EI), and 6) mean glucose and measures of glucose variability during continuous glucose monitoring. RESULTS: GOP infusion was well tolerated over the 4-week period. There was a greater weight loss (P = 0.025) with GOP (mean change -4.4 [95% CI -5.3, -3.5] kg) versus saline (-2.5 [-4.1, -0.9] kg). GOP led to a greater improvement (P = 0.0026) in fructosamine (-44.1 [-62.7, -25.5] µmol/L) versus saline (-11.7 [-18.9, -4.5] µmol/L). Despite a smaller weight loss compared with RYGB and VLCD, GOP led to superior glucose tolerance after a mixed-meal stimulus and reduced glycemic variability compared with RYGB and VLCD. CONCLUSIONS: GOP infusion improves glycemia and reduces body weight. It achieves superior glucose tolerance and reduced glucose variability compared with RYGB and VLCD. GOP is a viable alternative for the treatment of diabetes with favorable effects on body weight.

Journal article

Behary P, Tharakan G, Alexiadou K, Johnson NA, Albrechtsen NJW, Cuenco J, Hope D, Dhillo W, Minnion JS, Frost G, Le Roux C, Purkayastha S, Moorthy K, Holst JJ, Ahmed A, Prevost T, Bloom S, Tan TMMet al., 2019, Combined GLP-1, Oxyntomodulin, and Peptide YY Improves Glycaemia and Body Weight in Obesity and Type 2 Diabetes: A Randomized, Single-Blinded Study, 79th Scientific Sessions of the American-Diabetes-Association (ADA), Publisher: AMER DIABETES ASSOC, ISSN: 0012-1797

Conference paper

Glaysher M, Mohanaruban A, Prechtl CG, Goldstone AP, Miras AD, Lord J, Chhina N, Falaschetti E, Johnson NA, Al-Najim W, smith C, Li JV, Patel M, Ahmed AR, Moore M, Poulter NR, Bloom S, Darzi A, Le Roux C, Byrne JP, teare Jet al., 2017, A randomised controlled trial of a duodenal-jejunal bypass sleeve device (EndoBarrier) compared with standard medical therapy for the management of obese subjects with type 2 diabetes mellitus, BMJ Open, Vol: 7, ISSN: 2044-6055

Introduction The prevalence of obesity and obesity-related diseases, including type 2 diabetes mellitus (T2DM), is increasing. Exclusion of the foregut, as occurs in Roux-en-Y gastric bypass, has a key role in the metabolic improvements that occur following bariatric surgery, which are independent of weight loss. Endoscopically placed duodenal-jejunal bypass sleeve devices, such as the EndoBarrier (GI Dynamics, Lexington, Massachusetts, USA), have been designed to create an impermeable barrier between chyme exiting the stomach and the mucosa of the duodenum and proximal jejunum. The non-surgical and reversible nature of these devices represents an attractive therapeutic option for patients with obesity and T2DM by potentially improving glycaemic control and reducing their weight.Methods and analysis In this multicentre, randomised, controlled, non-blinded trial, male and female patients aged 18–65 years with a body mass index 30–50 kg/m2 and inadequately controlled T2DM on oral antihyperglycaemic medications (glycosylated haemoglobin (HbA1c) 58–97 mmol/mol) will be randomised in a 1:1 ratio to receive either the EndoBarrier device (n=80) for 12 months or conventional medical therapy, diet and exercise (n=80). The primary outcome measure will be a reduction in HbA1c by 20% at 12 months. Secondary outcome measures will include percentage weight loss, change in cardiovascular risk factors and medications, quality of life, cost, quality-adjusted life years accrued and adverse events. Three additional subgroups will investigate the mechanisms behind the effect of the EndoBarrier device, looking at changes in gut hormones, metabolites, bile acids, microbiome, food hedonics and preferences, taste, brain reward system responses to food, eating and addictive behaviours, body fat content, insulin sensitivity, and intestinal tissue gene expression.

Journal article

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