Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Mark Levstik is active.

Publication


Featured researches published by Mark Levstik.


Hepatology | 2012

Feasibility and diagnostic performance of the FibroScan XL probe for liver stiffness measurement in overweight and obese patients

Robert P. Myers; Gilles Pomier-Layrargues; Richard Kirsch; Aaron Pollett; Andres Duarte-Rojo; David Wong; Melanie Beaton; Mark Levstik; Pam Crotty; Magdy Elkashab

Failure of liver stiffness measurement (LSM) by transient elastography (TE, FibroScan) and unreliable results occur in ≈5% and 15% of patients, respectively, mainly due to obesity. In this multicenter study, we evaluated the feasibility and performance of the novel FibroScan XL probe in 276 patients with chronic liver disease (42% viral hepatitis, 46% nonalcoholic fatty liver disease [NAFLD]) and a body mass index (BMI) ≥28 kg/m2. Patients underwent liver biopsy and TE with the standard M and XL probes. TE failure was defined as no valid LSMs and unreliable examinations as <10 valid LSMs or an interquartile range (IQR)/LSM >30% or success rate <60%. Probe performance for diagnosing ≥F2 fibrosis and cirrhosis (F4) versus biopsy were examined using areas under receiver operating characteristic curves (AUROC). FibroScan failure was less frequent with the XL probe than the M probe (1.1% versus 16%) and the XL probe was more often reliable (73% versus 50%; both P < 0.00005). Reliable results with the XL probe were obtained in 61% of patients in whom the M probe was unreliable. Among 178 patients with ≥10 valid LSMs using both probes, liver stiffness was highly correlated between probes (ρ = 0.86; P < 0.0005); however, median liver stiffness was lower using the XL probe (6.8 versus 7.8 kPa; P < 0.00005). The AUROC of the XL and M probes were similar for ≥F2 fibrosis (0.83 versus 0.86; P = 0.19) and cirrhosis (0.94 versus 0.91; P = 0.28). Conclusion: Compared with the M probe, the FibroScan XL probe reduces TE failure and facilitates reliable LSM in obese patients. Although the probes have comparable accuracy, lower liver stiffness cutoffs will be necessary when the XL probe is used to noninvasively assess liver fibrosis. (HEPATOLOGY 2012)


Liver International | 2012

Controlled Attenuation Parameter (CAP): a noninvasive method for the detection of hepatic steatosis based on transient elastography.

Robert P. Myers; Aaron Pollett; Richard Kirsch; Gilles Pomier-Layrargues; Melanie Beaton; Mark Levstik; Andres Duarte-Rojo; David Wong; Pam Crotty; Magdy Elkashab

Accurate tools for the noninvasive detection of hepatic steatosis are needed. The Controlled Attenuation Parameter (CAP) specifically targets liver steatosis using a process based on transient elastography.


Journal of Hepatology | 2012

Discordance in fibrosis staging between liver biopsy and transient elastography using the FibroScan XL probe

Robert P. Myers; Gilles Pomier-Layrargues; Richard Kirsch; Aaron Pollett; Melanie Beaton; Mark Levstik; Andres Duarte-Rojo; David Wong; Pam Crotty; Magdy Elkashab

BACKGROUND & AIMS The FibroScan XL probe facilitates liver stiffness measurement (LSM) by transient elastography (TE) in obese patients, yet factors affecting its accuracy have not been described. Our objectives were to examine the prevalence, risk factors, and causes of discordance between fibrosis estimated by the FibroScan XL probe and biopsy. METHODS Two hundred and ten patients with chronic liver disease (45% viral hepatitis, 55% nonalcoholic fatty liver disease (NAFLD) and a body mass index (BMI) ≥ 28 kg/m(2)) underwent liver biopsy and TE with the FibroScan XL probe. Predictors of discordance ≥ 2 fibrosis stages between measures, which occurred in 11% of patients (n=24), were identified by comparing patient, TE, and biopsy characteristics of discordant and non-discordant cases. RESULTS Fibrosis estimated by the FibroScan XL probe was greater than biopsy in 75% (18/24) of discordant cases. Although biopsy quality was not associated with discordance, discordant cases were less likely to have ≥ 10 valid shots (75% vs. 97%; p=0.001), a success rate ≥ 60% (67% vs. 95%; p <0.0005), and an interquartile range over median liver stiffness (IQR/M) <21% (37% vs. 57%; p=0.07) than non-discordant cases. However, only increased BMI (odds ratio [OR] 1.09 per kg/m(2); 95% confidence interval [CI] 1.01-1.18; p=0.04) was independently associated with discordance; liver stiffness was of borderline significance (OR 1.73 per log(10)-transformed value; 95% CI 0.95-3.18; p=0.08). Discordance was 4- to 5-fold more frequent among patients with severe obesity (BMI ≥ 40 kg/m(2): 32% vs. 8%) and liver stiffness above the median of 7.0 kPa (20% vs. 4%; both p <0.0005). CONCLUSIONS Discordance between liver fibrosis estimated by biopsy and TE using the FibroScan XL probe was infrequent in this obese population. Patients with severe obesity and elevated liver stiffness have the greatest risk of discordance.


Alimentary Pharmacology & Therapeutics | 2012

Meta‐analysis: vasoactive medications for the management of acute variceal bleeds

Malcolm Wells; Nilesh Chande; Paul C. Adams; Melanie Beaton; Mark Levstik; E. Boyce; Marko Mrkobrada

Vasoactive medications such as vasopressin, somatostatin and their analogues (terlipressin, vapreotide and octreotide) are commonly used for the treatment of acute variceal bleeding. However, the risks and benefits of these interventions are not well understood.


Medical Education | 2012

Representing complexity well: a story about teamwork, with implications for how we teach collaboration

Lorelei Lingard; Allan McDougall; Mark Levstik; Natasha Chandok; Marlee M. Spafford; Catherine F. Schryer

Medical Education 2012: 46: 869–877


Alimentary Pharmacology & Therapeutics | 2013

Phase II clinical trial of phlebotomy for non-alcoholic fatty liver disease

Melanie Beaton; Subrata Chakrabarti; Mark Levstik; Mark Speechley; Paul Marotta; Paul C. Adams

Elevated iron indices are described in non‐alcoholic fatty liver disease and iron reduction has been suggested as a potential therapy.


Alimentary Pharmacology & Therapeutics | 2012

The safety and efficacy of antitumour necrosis factor-alpha therapy for inflammatory bowel disease in patients post liver transplantation: a case series

Amindeep Sandhu; T. Alameel; Cheryl Dale; Mark Levstik; Nilesh Chande

The role of antitumour necrosis factor‐alpha (anti‐TNF) therapy for inflammatory bowel disease (IBD) among liver transplant recipients is largely unknown given the rarity of this population and the paucity of literature on the subject.


Transplantation | 2011

Increased risk of severe recurrence of hepatitis C virus in liver transplant recipients of donation after cardiac death allografts.

Roberto Hernandez-Alejandro; Kris Croome; Douglas Quan; Mohamed Mawardi; Natasha Chandok; Cheryl Dale; Vivian C. McAlister; Mark Levstik; William Wall; Paul Marotta

Background. In hepatitis C virus (HCV) recipients of donation after cardiac death (DCD) grafts, there is suggestion of lower rates of graft survival, indicating that DCD grafts themselves may represent a significant risk factor for severe recurrence of HCV. Methods. We evaluated all DCD liver transplant recipients from August 2006 to February 2011 at our center. Recipients with HCV who received a DCD graft (group 1, HCV+ DCD, n=17) were compared with non-HCV recipients transplanted with a DCD graft (group 2, HCV− DCD, n=15), and with a matched group of HCV recipients transplanted with a donation after brain death (DBD) graft (group 3, HCV+ DBD, n=42). Results. A trend of poorer graft survival was seen in HCV+ patients who underwent a DCD transplant (group 1) compared with HCV− patients who underwent a DCD transplant (group 2) (P=0.14). Importantly, a statistically significant difference in graft survival was seen in HCV+ patients undergoing DCD transplant (group 1) (73%) as compared with DBD transplant (group 3) (93%)(P=0.01). There was a statistically significant increase in HCV recurrence at 3 months (76% vs. 16%) (P=0.005) and severe HCV recurrence within the first year (47% vs. 10%) in the DCD group (P=0.004). Conclusions. HCV recurrence is more severe and progresses more rapidly in HCV+ recipients who receive grafts from DCD compared with those who receive grafts from DBD. DCD liver transplantation in HCV+ recipients is associated with a higher rate of graft failure compared with those who receive grafts from DBD. Caution must be taken when using DCD grafts in HCV+ recipients.


Canadian Journal of Gastroenterology & Hepatology | 2006

Clinical Recommendations for the Use of Recombinant Human Erythropoietin in Patients with Hepatitis C Virus Being Treated with Ribavirin

Morris Sherman; Lawrence Cohen; Mary Anne Cooper; Magdy Elkashab; Victor Feinman; David Fletcher; Nigel Girgrah; Jenny Heathcote; Mark Levstik; William B McNaull; David Wong; Florence Wong; Colina Yim

Today, combination antiviral therapy with pegylated interferon-alpha and ribavirin (RBV) allows many patients infected with hepatitis C virus (HCV) to achieve a sustained virological response, which is equivalent to cure. Data also support the clinical benefit of combination antiviral therapy in patients coinfected with HCV and HIV, and in patients who have received a liver transplant. Antiviral therapy with pegylated interferon-alpha and RBV is, however, associated with a high incidence and significant magnitude of anemia. This anemia may have several mechanisms, including bone marrow suppression and hemolysis. In addition, patients coinfected with HIV may have both pre-existing and RBV-associated anemia. Management of anemia in patients with HCV through RBV dose reduction or treatment discontinuation may compromise the effectiveness of treatment, because studies have demonstrated that treatment adherence or maintenance of antiviral therapy dose is an important predictor of sustained virological response. Anemia associated with combination antiviral therapy in patients with HCV is frequently associated with an inadequate or blunted endogenous erythropoietin response. Accumulating evidence now supports the use of recombinant human erythropoietin (rHuEpo) to manage anemia in these patients, with the objective of maintaining the RBV dose, but clinical standards are lacking. The present article reviews the data relevant to the use of rHuEpo in this patient population and proposes a set of clinical practice standards to assist clinicians in selecting patients for rHuEpo and in implementing rHuEpo therapy effectively.


Transplantation Proceedings | 2012

Should a Lower Quality Organ Go to the Least Sick Patient? Model for End-Stage Liver Disease Score and Donor Risk Index as Predictors of Early Allograft Dysfunction

Kristopher P. Croome; Paul Marotta; William Wall; Cheryl Dale; Mark Levstik; Natasha Chandok; Roberto Hernandez-Alejandro

BACKGROUND There is a global tendency to justify transplanting extended criteria organs (ECD; Donor Risk Index [DRI] ≥ 1.7) into recipients with a lower Model for End-Stage Liver Disease (MELD) score and to transplant standard criteria organs (DRI < 1.7) into recipients with a higher MELD scores. There is a lack of evidence in the current literature to justify this assumption. METHODS A review of our prospectively entered database for donation after brain death (DBD) liver transplantation (n = 310) between January 1, 2006, and September 30, 2010, was performed. DRI was dichotomized as <1.7 and ≥ 1.7. Recipients were divided into 3 strata, those with high (≥ 27), moderate (15-26), and low MELD (<15) scores. The recently validated definition of early allograft dysfunction (EAD) was used. We analyzed EAD and its relation with donor DRI and recipient MELD scores. RESULTS The overall incidence of EAD was 24.5%. Mortality in the first 6 months in recipients with EAD was 20% compared with 3.4% for those without EAD (relative risk [RR], 5.56, 95% confidence interval [CI], 1.96-15.73; P < .001). Graft failure rate in the first 6 months in those with EAD was 27% compared with 5.8% for those without EAD (RR, 4.63; 95% CI, 2.02-10.6; P < .001). In patients with low MELD scores, a significantly increased rate of EAD (25%) was seen in patients transplanted with a high DRI liver compared with those transplanted with a low DRI liver (6.25%; P = .012). In moderate and high MELD recipients, there was no significant difference in the rate of EAD in patients transplanted with a high DRI liver (62%) compared with those transplanted with a low DRI liver (59%). CONCLUSION These results suggest that contrary to common belief it is not justified to preferentially allocate organs with higher DRI to recipients with lower MELD scores.

Collaboration


Dive into the Mark Levstik's collaboration.

Top Co-Authors

Avatar

Melanie Beaton

University of Western Ontario

View shared research outputs
Top Co-Authors

Avatar

Paul Marotta

University of Western Ontario

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Natasha Chandok

University of Western Ontario

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Cheryl Dale

University of Western Ontario

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Paul C. Adams

University of Western Ontario

View shared research outputs
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge