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Dive into the research topics where Alex J. Walker is active.

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Featured researches published by Alex J. Walker.


Journal of Hepatology | 2016

Impact of direct acting antiviral therapy in patients with chronic hepatitis C and decompensated cirrhosis

Graham R. Foster; William L. Irving; Michelle C.M. Cheung; Alex J. Walker; Benjamin Hudson; Suman Verma; John McLauchlan; David Mutimer; Ashley Brown; W. Gelson; Douglas C. MacDonald; Kosh Agarwal

BACKGROUND & AIMS All oral direct acting antivirals (DAAs) effectively treat chronic hepatitis C virus (HCV) infection, but the benefits in advanced liver disease are unclear. We compared outcomes in treated and untreated patients with decompensated cirrhosis. METHODS Patients with HCV and decompensated cirrhosis or at risk of irreversible disease were treated in an expanded access programme (EAP) in 2014. Treatment, by clinician choice, was with sofosbuvir, ledipasvir or daclatasvir, with or without ribavirin. For functional outcome comparison, untreated patients with HCV and decompensated cirrhosis who were registered on a database 6months before treatment was available were retrospectively studied. Primary endpoint was sustained virological response 12weeks post antiviral treatment (treated cohort) and the secondary endpoint (both cohorts) was adverse outcomes (worsening in MELD score or serious adverse event) within 6months. RESULTS 467 patients received treatment (409 decompensated cirrhosis). Viral clearance was achieved in 381 patients (81.6%) - 209 from 231 (90.5%) with genotype 1 and 132 from 192 (68.8%) with genotype 3. MELD scores improved in treated patients (mean change -0.85) but worsened in untreated patients (mean+0.75) (p<0.0001). Patients with initial serum albumin <35g/L, aged >65 or with low (<135mmol/L) baseline serum sodium concentrations were least likely to benefit from therapy. CONCLUSIONS All oral DAAs effectively cured HCV in patients with advanced liver disease. Viral clearance was associated with improvement in liver function within 6months compared to untreated patients. The longer term impact of HCV treatment in patients with decompensated cirrhosis remains to be determined.


Journal of Hepatology | 2016

Outcomes after successful direct acting antiviral therapy for patients with chronic hepatitis C and decompensated cirrhosis

Michelle C.M. Cheung; Alex J. Walker; Benjamin Hudson; Suman Verma; John McLauchlan; David Mutimer; Ashley Brown; W. Gelson; Douglas C. MacDonald; Kosh Agarwal; Graham R. Foster; William L. Irving

BACKGROUND & AIMS Direct-acting antivirals have become widely used for patients with chronic hepatitis C virus infection with decompensated cirrhosis. Virological responses are excellent and early improvements in liver function, at least in a proportion of patients, have been observed but the longer term impact of viral clearance on end-stage liver disease complications is unclear. METHODS Prospective study of patients with decompensated cirrhosis who received 12weeks of all-oral direct-acting antivirals through the English Expanded Access Programme. Endpoints were deaths, liver transplantation, hepatocellular carcinoma, serious decompensation events, sepsis or hospitalisations, and MELD scores between start of therapy to 15months post-treatment start. An untreated cohort of patients was retrospectively studied over 6months for comparison. RESULTS Amongst 317/406 patients who achieved sustained virological response at 24weeks post-treatment, there were 9 deaths (3%), 17 new liver cancers (5%), 39 transplantations (12%) and 52 with serious decompensations (16%), over 15months. When compared to the first six months from treatment start and to untreated patients, there was a reduction in incidence of decompensations [30/406 (7%) in months 6-15 and 72/406 (18%) in months 0-6 for treated patients vs. 73/261 (28%) in untreated patients]. There was no significant difference in liver cancer incidence (10/406 (2.5%) in months 6-15 and 17/406 (4%) in months 0-6 for treated patients vs. 11/261 (4%) in untreated patients). CONCLUSIONS This study suggests that antiviral therapy in patients with decompensated cirrhosis led to prolonged improvement in liver function, with no evidence of paradoxical adverse impact nor increase in liver malignancy. LAY SUMMARY This is a report of a large group of patients in England who have hepatitis C virus (HCV) infection with advanced liver disease. They have been treated with new anti-HCV drugs, which cured the infection in the majority. This study looks at their outcomes a year following treatment, in terms of deaths, cancers and other complications of advanced liver disease. We conclude that in most patients anti-HCV treatment is beneficial even in advanced liver disease.


European Journal of Cancer | 2013

Incidence of venous thromboembolism in patients with cancer – A cohort study using linked United Kingdom databases

Alex J. Walker; Timothy R. Card; Joe West; Colin J Crooks; Matthew J. Grainge

BACKGROUND Accurate population-based data are needed on the incidence of venous thromboembolism (VTE) in patients with different cancers in order to inform guidelines on which hospitalised and ambulatory cancer patients should receive VTE prophylaxis. METHODS We conducted a cohort study using data from the Clinical Practice Research Datalink, linked to Hospital Episode Statistics, Cancer Registry data and Office for National Statistics cause of death data. We determined the incidence rates (cases per 1000 person-years) of VTE separately for 24 cancer sites. To determine relative risk, incidence rates were compared to frequency-matched controls (by age) with no record of cancer. FINDINGS We identified 83,203 cancer patients and 577,207 controls. New cases of VTE were diagnosed in 3352 cancer patients, and 6353 controls. The absolute rate of VTE in all cancers was 13.9 per 1000 person-years (95% confidence interval [CI] 13.4-14.4), corresponding to an age, sex and calendar year adjusted hazard-ratio of 4.7 (CI 4.5-4.9) between cancer patients and the general population. Rates varied greatly by cancer site (range; 98 (CI 80-119) in pancreatic cancer to 3.1 (CI 1.5-6.5) in thyroid cancer), age (range; 16.9 for patients over 80 years to 4.9 for those under 30 years) and time from diagnosis (range; 75 in the first three months to 8.4, >1 year after diagnosis). INTERPRETATION VTE is strongly linked to cancer, but the annual rate varies greatly by cancer site, proximity to diagnosis and age. Prophylaxis guidelines should take account of cancer site and such intervention should also be targeted towards the three months following diagnosis.


European Journal of Neuroscience | 2008

5‐Fluorouracil chemotherapy affects spatial working memory and newborn neurons in the adult rat hippocampus

Sarah Mustafa; Alex J. Walker; G.W. Bennett; Peter Wigmore

Chemotherapy‐associated memory deficits in adults are prevalent with systemic treatment utilizing 5‐fluorouracil (5‐Fu). 5‐Fu disrupts cell proliferation and readily crosses the blood–brain barrier. Proliferating cells within the adult dentate gyrus of the hippocampus give rise to new neurons involved in memory and learning and require neurotrophic factors such as brain‐derived neurotrophic factor (BDNF) to nurture this process of adult neurogenesis. Some of these proliferating cells are anatomically and functionally supported by vascular endothelial cells. We propose that systemically administered 5‐Fu chemotherapy will cause deficits in hippocampal memory that are associated with altered BDNF levels and proliferating cells (particularly vascular‐associated cells) in the dentate gyrus. This was tested by determining the effect of 5‐Fu on spatial working memory as modelled by the object location recognition test. Numbers of vascular‐associated (VA) and non‐vascular‐associated (NVA) proliferating cells in the dentate gyrus were measured using double‐labelling immunohistochemistry with markers of proliferation (Ki67) and endothelial cells (RECA‐1). 5‐Fu‐induced changes in hippocampal BDNF and doublecortin (DCX) protein levels were quantified using Western immunoblotting. 5‐Fu chemotherapy caused a marginal disruption in spatial working memory and did not alter the total proliferating cell counts or the percentage of VA and NVA proliferating cells in the dentate gyrus. In contrast, 5‐Fu significantly reduced BDNF and DCX levels in the hippocampus, indicating alterations in neurotrophin levels and neurogenesis. These findings highlight the usefulness of animal models of ‘chemobrain’ for understanding the mechanisms that underlie chemotherapy‐associated declines in cognitive performance and memory.


British Journal of Cancer | 2011

Tricyclic antidepressants and the incidence of certain cancers : a study using the GPRD

Alex J. Walker; Timothy R. Card; Timothy E. Bates; Kenneth Muir

Background:Several studies suggest links between cancer and tricyclic antidepressant use.Methods:A case–control study using the General Practice Research Database examined whether previous tricyclic usage was associated with reduced incidence of brain (with glioma as a sub-category), breast, colorectal, lung and prostate cancers. Conditional logistic regression adjusted for age, gender, general practice, depression, smoking, body mass index, alcohol use and non-steroidal anti-inflammatory drug use.Results:A total of 31 953 cancers were identified, each matched with up to two controls. We found a statistically significant reduction in tricyclic prescriptions compared with controls in glioma (odds ratio (OR) =0.59, 95% confidence interval (CI)=0.42–0.81) and colorectal cancer patients (OR=0.84, CI=0.75–0.94). These effects were dose-dependent (P-values for trend, glioma=0.0005, colorectal=0.001) and time-dependant (P-values for trend glioma=0.0005, colorectal=0.0086). The effects were cancer-type specific, with lung, breast and prostate cancers largely unaffected by antidepressant use.Conclusion:The biologically plausible, specific and dose- and time-dependant inverse association that we have found suggests that tricyclics may have potential for prevention of both colorectal cancer and glioma.


British Journal of Cancer | 2012

Aspirin and other non-steroidal anti-inflammatory drug use and colorectal cancer survival: a cohort study

Alex J. Walker; Matthew J. Grainge; Timothy R. Card

Background:Aspirin has been widely reported to reduce the incidence of colorectal cancer. Recently, a survival benefit after diagnosis has also been suggested. Data regarding such a benefit are to date contradictory. This study examines the effect of non-steroidal anti-inflammatory drug (NSAID) use on mortality in colorectal cancer in a larger patient cohort than previously to further clarify this effect, especially in terms of exposure timing and dosing.Methods:A study using the General Practice Research Database assessed whether aspirin or NSAID exposure in the year immediately following diagnosis affected all-cause mortality in a cohort of 13 994 colorectal cancer patients. Cox proportional hazards modelling adjusted for age, gender, smoking, body mass index and comorbidity.Results:Overall mortality was slightly lower in patients treated with aspirin, (hazard ratio (HR)=0.91; 95% confidence interval (CI)=0.82–1.00). This effect was observed only in patients treated with prophylaxis-dose aspirin (HR=0.89, CI=0.80–0.98) and only in patients taking aspirin before diagnosis (HR=0.86, CI=0.76–0.98). Differential effects were observed depending on the time after diagnosis. Up to 5 years, a reduction in mortality was observed for aspirin users (HR=0.83, CI=0.75–0.92), whereas after 10 years there was an increase in mortality (HR=1.94, CI=1.26–2.99). For NSAID use, no significant effect was observed on overall mortality (HR=1.07, CI=0.98–1.15). High-dose NSAID use was associated with a slight increase in mortality (HR=1.41, CI=1.26–1.56).Interpretation:These findings provide further indication that aspirin may be beneficial in reducing mortality in colorectal cancer during the first 5 years. The same cannot be said for other NSAIDs, where a small increase in mortality was observed.


The American Journal of Gastroenterology | 2015

Causes of Death in People with Liver Cirrhosis in England Compared with the General Population: A Population-Based Cohort Study

Sonia Ratib; Kate M. Fleming; Colin J Crooks; Alex J. Walker; Joe West

OBJECTIVES:There is a need for unbiased estimates of cause-specific mortality by etiology in patients with liver cirrhosis. The aim of this study is to use nationwide linked electronic routine healthcare data from primary and secondary care alongside the national death registry data to report such estimates.METHODS:We identified from the linked Clinical Practice Research Datalink (CPRD) and English Hospital Episode Statistics adults with an incident diagnosis of liver cirrhosis linked to the Office for National Statistics between 1998 and 2009. Age-matched controls from the CPRD general population were selected. We calculated the cumulative incidence (adjusting for competing risks) and excess risk of death by 5 years from diagnosis for different causes of death, stratified by etiology and stage of disease.RESULTS:Five thousand one hundred and eighteen patients with cirrhosis were matched to 152,903 controls. Among compensated patients, the 5-year excess risk of liver-related death was higher than that of any other cause of death for all patients, except those of unspecified etiology. For example, those of alcohol etiology had 30.8% excess risk of liver-related death (95% confidence interval (CI): 27.9%, 33.1%) compared with 9.9% excess risk of non-liver-related death. However, patients of unspecified etiology had a higher excess risk of non-liver-related compared with liver-related death (10.7% vs. 6.7%). This was due to a high excess risk of non-liver neoplasm death (7.7%, 95% CI: 5.9%, 9.5%). All decompensated patients had a higher excess of liver-related mortality than any other cause.CONCLUSIONS:In order to reduce associated mortality among people with liver cirrhosis, patients’ care pathways need to be tailored depending on the etiology and stage of the disease.


Blood | 2016

When are breast cancer patients at highest risk of venous thromboembolism? A cohort study using English health care data

Alex J. Walker; Joe West; Timothy R. Card; Colin J Crooks; Cliona C. Kirwan; Matthew J. Grainge

Patients with breast cancer are at increased risk of venous thromboembolism (VTE), particularly in the peridiagnosis period. However, no previous epidemiologic studies have investigated the relative impact of breast cancer treatments in a time-dependent manner. We aimed to determine the impact of breast cancer stage, biology, and treatment on the absolute and relative risks of VTE by using several recently linked data sources from England. Our cohort comprised 13,202 patients with breast cancer from the Clinical Practice Research Datalink (linked to Hospital Episode Statistics and Cancer Registry data) diagnosed between 1997 and 2006 with follow-up continuing to the end of 2010. Cox regression analysis was performed to determine which demographic, treatment-related, and biological factors independently affected VTE risk. Women had an annual VTE incidence of 6% while receiving chemotherapy which was 10.8-fold higher (95% confidence interval [CI], 8.2-14.4; absolute rate [AR], 59.6 per 1000 person-years) than that in women who did not receive chemotherapy. After surgery, the risk was significantly increased in the first month (hazard ratio [HR], 2.2; 95% CI, 1.4-3.4; AR, 23.5; reference group, no surgery), but the risk was not increased after the first month. Risk of VTE was noticeably higher in the 3 months after initiation of tamoxifen compared with the risk before therapy (HR, 5.5; 95% CI, 2.3-12.7; AR, 24.1); however, initiating therapy with aromatase inhibitors was not associated with VTE (HR, 0.8; 95% CI, 0.5-1.4; AR, 28.3). In conclusion, women receiving chemotherapy for breast cancer have a clinically important risk of VTE, whereas an increased risk of VTE immediately after endocrine therapy is restricted to tamoxifen.


Journal of Thrombosis and Haemostasis | 2014

Variation in the risk of venous thromboembolism in people with colorectal cancer: a population‐based cohort study from England

Alex J. Walker; Joe West; Timothy R. Card; David J. Humes; Matthew J. Grainge

Patients with colorectal cancer are at high risk of developing venous thromboembolism (VTE), and recent international guidelines have advised extended prophylaxis for some of these patients following surgery or during chemotherapy. However, our understanding of which patients are at increased risk, and to what extent, is limited.


Thrombosis Research | 2014

Venous thromboembolism in children with cancer – A population-based cohort study

Alex J. Walker; Matthew J. Grainge; Timothy R. Card; Joe West; Susanna Ranta; Jonas F. Ludvigsson

Introduction Cancer is a known risk factor for venous thromboembolism (VTE) in adults, but population-based data in children are scarce. Materials and methods We conducted a cohort study utilising linkage of the Clinical Practice Research Database (primary care), Hospital Episodes Statistics (secondary care), UK Cancer Registry data and Office for National Statistics cause of death data. From these databases, we selected 498 children with cancer diagnosed between 1997 and 2006 and 20,810 controls without cancer. We calculated VTE incidence rates in children with cancer vs. controls, and hazard ratios (HRs) using Cox regression. Results We identified four VTE events in children with cancer compared with four events in the larger control population corresponding to absolute risks of 1.52 and 0.06 per 1000 person-years respectively. The four children with VTE and cancer were diagnosed with hematological, bone or non-specified cancer. Childhood cancer was hence associated with a highly increased risk of VTE (HR adjusted for age and sex: 28.3; 95%CI = 7.0-114.5). Conclusions Children with cancer are at increased relative risk of VTE compared to those without cancer. Physicians could consider thromboprophylaxis in children with cancer to reduce their excess risk of VTE however the absolute risk is extremely small and the benefit gained therefore would need to be balanced against the risk invoked of implementing such a strategy. Novelty & Impact Statements While there is a reasonable level of knowledge about the risk of VTE in adult populations, it is not well known whether this risk is reflected in paediatric patients. We found a substantial increase in risk of VTE in children with cancer compared to a child population without cancer. While this finding is important, the absolute risk of VTE is still low and must be balanced with the risks of anticoagulation.

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Joe West

University of Nottingham

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William L. Irving

Nottingham University Hospitals NHS Trust

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Benjamin Hudson

University Hospitals Bristol NHS Foundation Trust

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Colin J Crooks

University of Nottingham

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