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Featured researches published by Onur Keskin.


Journal of Hepatology | 2015

Incidence and predictors of hepatocellular carcinoma in Caucasian chronic hepatitis B patients receiving entecavir or tenofovir

George V. Papatheodoridis; George N. Dalekos; Cihan Yurdaydin; Maria Buti; John Goulis; Pauline Arends; Vana Sypsa; Spilios Manolakopoulos; G. Mangia; Nikolaos K. Gatselis; Onur Keskin; Savvoula Savvidou; Bettina E. Hansen; Christos Papaioannou; Kostantinos Galanis; Ramazan Idilman; Massimo Colombo; Rafael Esteban; Harry L.A. Janssen; P. Lampertico

BACKGROUND & AIMS The risk of hepatocellular carcinoma (HCC) in Caucasian patients with chronic hepatitis B (CHB), treated with entecavir (ETV) or tenofovir (TDF), is unclear. We evaluated the incidence and predictors of HCC and the accuracy of existing HCC risk scores in Caucasian CHB patients receiving ETV/TDF. METHODS This large, multicentre, retrospective cohort study included 1666 adult Caucasian CHB patients under ETV/TDF for 39 months. CHB without cirrhosis, compensated and decompensated cirrhosis were present in 67%, 39%, and 3% of patients, respectively. The predictability of baseline parameters and three risk scores (GAG-HCC, CU-HCC, and REACH-B), developed in Asian patients, was assessed. RESULTS The cumulative probability of HCC was 1.3%, 3.4%, and 8.7% at year-1, year-3, and year-5 after ETV/TDF onset. Older age and lower platelets were strong independent HCC predictors in the total population and in the subgroups of cirrhotic and non-cirrhotic patients, while liver disease severity was an independent HCC predictor in the total population and in the cirrhotics. GAG-HCC, CU-HCC, and REACH-B risk scores were associated with HCC development only in the univariable but not in the multivariable analyses and offered poor to modest predictability. CONCLUSIONS HCC can still develop in Caucasian CHB patients treated with ETV/TDF. Besides the well-known predictors of HCC, such as older age, male gender and more advanced liver disease, lower platelets represent an independent factor of higher HCC risk. The applicability and predictability of HCC risk scores developed in Asian patients are poor or modest in Caucasian CHB patients, for whom different risk scores are required.


Hepatology | 2017

The risk of hepatocellular carcinoma decreases after the first 5 years of entecavir or tenofovir in Caucasians with chronic hepatitis B

George V. Papatheodoridis; Ramazan Idilman; George N. Dalekos; Maria Buti; Heng Chi; Florian van Boemmel; Jose Luis Calleja; Vana Sypsa; John Goulis; Spilios Manolakopoulos; A. Loglio; Spyros I. Siakavellas; Onur Keskin; Nikolaos K. Gatselis; Bettina E. Hansen; Maria Lehretz; Juan de la Revilla; Savvoula Savvidou; Anastasia Kourikou; Ioannis Vlachogiannakos; Kostantinos Galanis; Cihan Yurdaydin; T. Berg; Massimo Colombo; Rafael Esteban; Harry L.A. Janssen; P. Lampertico

Whether there is a change of hepatocellular carcinoma (HCC) incidence in chronic hepatitis B patients under long‐term therapy with potent nucleos(t)ide analogues is currently unclear. We therefore assessed the HCC incidence beyond year 5 of entecavir/tenofovir (ETV/TDF) therapy and tried to determine possible factors associated with late HCC occurrence. This European, 10‐center, cohort study included 1,951 adult Caucasian chronic hepatitis B patients without HCC at baseline who received ETV/TDF for ≥1 year. Of them, 1,205 (62%) patients without HCC within the first 5 years of therapy have been followed for 5‐10 (median, 6.8) years. HCCs have been diagnosed in 101/1,951 (5.2%) patients within the first 5 years and 17/1,205 (1.4%) patients within 5‐10 years. The yearly HCC incidence rate was 1.22% within and 0.73% after the first 5 years (P = 0.050). The yearly HCC incidence rate did not differ within and after the first 5 years in patients without cirrhosis (0.49% versus 0.47%, P = 0.931), but it significantly declined in patients with cirrhosis (3.22% versus 1.57%, P = 0.039). All HCCs beyond year 5 developed in patients older than 50 years at ETV/TDF onset. Older age, lower platelets at baseline and year 5, and liver stiffness ≥12 kPa at year 5 were independently associated with more frequent HCC development beyond year 5 in multivariable analysis. No patient with low Platelets, Age, Gender‐Hepatitis B score at baseline or year 5 developed HCC. Conclusion: The HCC risk decreases beyond year 5 of ETV/TDF therapy in Caucasian chronic hepatitis B patients, particularly in those with compensated cirrhosis; older age (especially ≥50 years), lower platelets, and liver stiffness ≥12 kPa at year 5 represent the main risk factors for late HCC development. (Hepatology 2017;66:1444–1453).


Acta Radiologica | 2016

A comparison of liver fat content as determined by magnetic resonance imaging-proton density fat fraction and MRS versus liver histology in non-alcoholic fatty liver disease:

Ilkay S. Idilman; Onur Keskin; Azim Celik; Berna Savas; Atilla Halil Elhan; Ramazan Idilman; Musturay Karcaaltincaba

Background Many imaging methods have been defined for quantification of hepatic steatosis in non-alcoholic fatty liver disease (NAFLD). However, studies comparing the efficiency of magnetic resonance imaging-proton density fat fraction (MRI-PDFF), magnetic resonance spectroscopy (MRS), and liver histology for quantification of liver fat content are limited. Purpose To compare the efficiency of MRI-PDFF and MRS in the quantification of liver fat content in individuals with NAFLD. Material and Methods A total of 19 NAFLD patients underwent MRI-PDFF, MRS, and liver biopsy for quantification of liver fat content. The MR examinations were performed on a 1.5 HDx MRI system. The MRI protocol included T1-independent volumetric multi-echo gradient-echo imaging with T2* correction and spectral fat modeling and MRS with STEAM technique. Results A close correlation was observed between liver MRI-PDFF- and histology- determined steatosis (r = 0.743, P < 0.001) and between liver MRS- and histology-determined steatosis (r = 0.712, P < 0.001), with no superiority between them (ƶ = 0.19, P = 0.849). For quantification of hepatic steatosis, a high correlation was observed between the two MRI methods (r = 0.986, P < 0.001). MRI-PDFF and MRS accurately differentiated moderate/severe steatosis from mild/no hepatic steatosis (P = 0.007 and 0.013, respectively), with no superiority between them (AUCMRI-PDFF = 0.881 ± 0.0856 versus AUCMRS = 0.857 ± 0.0924, P = 0.461). Conclusion Both MRI-PDFF and MRS can be used for accurate quantification of hepatic steatosis.


Journal of Viral Hepatitis | 2015

Long-term entecavir or tenofovir disoproxil fumarate therapy in treatment-naïve chronic hepatitis B patients in the real-world setting

Ramazan Idilman; F. Gunsar; M. Koruk; Onur Keskin; C. E. Meral; M. Gulsen; Atilla Halil Elhan; U.S. Akarca; Cihan Yurdaydin

The aim of this study was to determine the long‐term efficacy of entecavir (ETV) and tenofovir disoproxil fumarate (TDF) on the natural course of disease in chronic hepatitis B patients (CHB) with/without cirrhosis in clinical practice. A total of 355 treatment‐naïve CHB patients were enrolled into the study. The primary outcome measure was viral suppression as defined by serum HBV DNA level <20 IU/mL. A secondary outcome measure was to determine the development of Hepatocellular carcinoma (HCC). Virological and biochemical responses were similar between the two treatment groups over time. The presence of cirrhosis and hepatitis B e antigen (HBeAg) positivity did not appear to impact viral suppression. The cumulative probability of HBeAg loss was 41% at 4 years of therapy. Hepatitis B surface antigen (HBsAg) loss occurred in four patients. Model for End‐Stage Liver Disease score was significantly improved from baseline to week 48 and 96 under antiviral therapy (P = 0.013, P = 0.01). HCC was diagnosed in 17 patients (4.8%). The cumulative probability of the development of HCC was 3.3% at 1 year and 7.3% at 4 years of therapy. The development of HCC was independently associated with older age (P = 0.031) and the presence of cirrhosis (P = 0.004). Serum creatinine levels and creatinine clearance remained stable over time. ETV and TDF effectively maintained virological and biochemical responses in long‐term follow‐up of CHB patients with/without cirrhosis. HCC may still develop, although at a lower rate, and is more likely to develop in patients with cirrhosis, especially in older patients.


Clinical Gastroenterology and Hepatology | 2015

Association Between Level of Hepatitis D Virus RNA at Week 24 of Pegylated Interferon Therapy and Outcome

Onur Keskin; Heiner Wedemeyer; Ali Tüzün; Kalliopi Zachou; Xheni Deda; George N. Dalekos; B. Heidrich; Selcen Pehlivan; Stefan Zeuzem; Kendal Yalçin; Selim Gurel; Fehmi Tabak; Ramazan Idilman; Hakan Bozkaya; Michael P. Manns; Cihan Yurdaydin

BACKGROUND & AIMS Interferon is the only effective treatment for chronic hepatitis D virus (HDV) infection. No rules have been set for stopping treatment based on viral kinetics. We analyzed data from an international study of hepatitis D treatment to identify factors associated with outcomes of pegylated interferon treatment, with and without adefovir. METHODS We analyzed data from the Hep-Net-International Delta Hepatitis Intervention Trial on 50 patients with compensated liver disease who tested positive for anti-HDV and HDV RNA. Subjects received pegylated interferon α 2a, with adefovir or placebo, or only adefovir, for 48 weeks. Twenty-four weeks after treatment ended, 41 patients were evaluated for levels of HDV RNA and DNA, liver enzymes, and hepatitis B surface antigen (HBsAg); liver biopsy specimens were analyzed for fibrosis. Response to therapy was defined as end-of-treatment response or post-treatment week 24 virologic response. In both cases virologic response was associated with undetectable HDV RNA levels. Patients with less than a 1 log decrease in HDV RNA at the end of treatment were considered null responders. RESULTS Based on univariate and multivariate analysis, the level of HDV RNA at week 24 of treatment was associated more strongly with response to therapy than other factors analyzed. The level of HBsAg at week 24 of treatment was associated with a response to therapy only in univariate analysis. Lack of HDV RNA at week 24 of treatment, or end of treatment, identified responders with positive predicted values of 71% and 100%, respectively. At 24 weeks after treatment, a decrease in HDV RNA level of less than 1 log, combined with no decrease in HBsAg level, identified null responders with a positive predictive value of 83%. A decrease in HDV RNA level of more than 2 log at week 24 of treatment identified null responders with a negative predictive value of 95%. CONCLUSIONS Based on an analysis of data from a large clinical trial, the level of HDV RNA at week 24 of treatment with pegylated interferon, with or without adefovir for 48 weeks, can identify patients who will test negative for HDV RNA 24 weeks after the end of treatment. This information can be used to help physicians manage patients receiving therapy for chronic hepatitis D.


Digestion | 2012

Clinical Profiles, Endoscopic and Laboratory Features and Associated Factors in Patients with Autoimmune Gastritis

Irfan Soykan; Mustafa Yakut; Onur Keskin; Mehmet Bektas

Background/Aims: Autoimmune gastritis (AIG) may predispose to gastric carcinoid tumors or adenocarcinomas and may also cause unexplained iron and/or vitamin B12 deficiency. The aims of this study were to explore clinical manifestations, endoscopic findings and laboratory features of patients with AIG. Methods: 109 patients with AIG were enrolled into the study. In addition to demographic and clinical data, gastric lesions, serum gastrin, vitamin B12, antiparietal cell antibody (APA), current Helicobacter pylori status, and anti-H. pylori IgG were also investigated. Results: The mean age of the patients was 53.06 ± 12.7 years (range 24–81; 72 (66.1%) women). The most common main presenting symptom was abdominal symptoms in 51 patients, consultation for iron and/or vitamin B12 deficiency in 36, and non-specific symptoms including intermittent diarrhea in 15 patients. Endoscopic lesions were detected in 17 patients, hyperplastic polyps in 8, gastric carcinoid tumor in 4, fundic gland polyps in 3, and adenomatous polyps in 2 patients. H. pylori was negative in all patients in biopsy specimens; however, anti-H. pylori IgG was positive in 30 (27.5%) patients. 91 patients (83.4%) were positive for APA. Conclusion: In patients with AIG, the main symptoms prompted for clinical investigation were: abdominal symptoms, iron/B12 deficiency and non-specific symptoms. 20% of patients with AIG had various gastric lesions including type I gastric carcinoids. None of the patients were positive for H. pylori by means of invasive tests; however, anti-H. pylori IgG was found in 27.5% of patients. Patients referring with non-specific abdominal symptoms such as bloating, diarrhea and iron/B12 deficiency should be investigated for the presence of AIG.


Scandinavian Journal of Gastroenterology | 2014

Impact of sequential proton density fat fraction for quantification of hepatic steatosis in nonalcoholic fatty liver disease

Ilkay S. Idilman; Onur Keskin; Atilla Halil Elhan; Ramazan Idilman; Musturay Karcaaltincaba

Abstract Objective. To determine the utility of sequential MRI-estimated proton density fat fraction (MRI-PDFF) for quantification of the longitudinal changes in liver fat content in individuals with nonalcoholic fatty liver disease (NAFLD). Methods. A total of 18 consecutive individuals (M/F: 10/8, mean age: 47.7 ± 9.8 years) diagnosed with NAFLD, who underwent sequential PDFF calculations for the quantification of hepatic steatosis at two different time points, were included in the study. All patients underwent T1-independent volumetric multi-echo gradient-echo imaging with T2* correction and spectral fat modeling. Results. A close correlation for quantification of hepatic steatosis between the initial MRI-PDFF and liver biopsy was observed (rs = 0.758, p < 0.001). The median interval between two sequential MRI-PDFF measurements was 184 days. From baseline to the end of the follow-up period, serum GGT level and homeostasis model assessment score were significantly improved (p = 0.015, p = 0.006, respectively), whereas BMI, serum AST, and ALT levels were slightly decreased. MRI-PDFFs were significantly improved (p = 0.004). A good correlation between two sequential MRI-PDFF calculations was observed (rs = 0.714, p = 0.001). With linear regression analyses, only delta serum ALT levels had a significant effect on delta MRI-PDFF calculations (r2 = 38.6%, p = 0.006). At least 5.9% improvement in MRI-PDFF is needed to achieve a normalized abnormal ALT level. The improvement of MRI-PDFF score was associated with the improvement of biochemical parameters in patients who had improvement in delta MRI-PDFF (p < 0.05). Conclusions. MRI-PDFF can be used for the quantification of the longitudinal changes of hepatic steatosis. The changes in serum ALT levels significantly reflected changes in MRI-PDFF in patients with NAFLD.


Clinics and Research in Hepatology and Gastroenterology | 2013

The association between precancerous gastric lesions and serum pepsinogens, serum gastrin, vascular endothelial growth factor, serum interleukin-1 Beta, serum toll-like receptor-4 levels and Helicobacter pylori Cag A status

Mustafa Yakut; Necati Örmeci; Harun Erdal; Onur Keskin; Zihni Karayel; Hüseyin Tutkak; Irfan Soykan

BACKGROUND AND OBJECTIVE The aim of this study was to investigate the association between serum pepsinogens, serum gastrin, serum vascular endothelial growth factor, serum interleukin-1 Beta, serum toll-like receptor-4 levels and Helicobacter pylori Cag A status in patients with various gastric precancerous lesions. METHODS One hundred and sixty two consecutive patients with various gastric lesions [38 (23.5%) H. pylori positive chronic non-atrophic gastritis, 45 (27.8%) autoimmune gastritis, 42 intestinal metaplasia and 37 dysplasia] were enrolled into the study. Serum pepsinogen I and II, gastrin 17, vascular endothelial growth factor, interleukin-1 Beta, toll-like receptor-4 levels, H. pylori Cag A status were evaluated. RESULTS H. pylori was positive in 98 (60.5%) patients and 38 of these patients were Cag A positive. Serum pepsinogen level was significantly lower in patients with autoimmune atrophic gastritis compared to the patients with non-atrophic chronic gastritis (p<0.001), intestinal metaplasia (P<0.001) and dysplasia (P=0.002). Mean serum gastrin was 1209.6±268.48 pg/mL in patients with autoimmune atrophic gastritis and 234.95±184.018 pg/mL in patients with chronic non-atrophic gastritis. Mean toll-like receptor-4 level was 0.56±0.098 ng/mL in patient with dysplasia, and this value was higher compared to patients with chronic non-atrophic gastritis (P=0.007), autoimmune atrophic gastritis (P=0.003) and intestinal metaplasia (P=0.006). Interleukin-1 Beta level was significantly lower in patients with dysplasia compared to patients with chronic non-atrophic gastritis (P=0.034). CONCLUSIONS Serum pepsinogens, serum gastrin and H. pylori Cag A status are important tests in detecting gastric precancerous lesions. However, toll-like receptor-4 may be a sensitive test to differentiate the patients with dysplasia from the other precancerous gastric lesions. Non-invasive tests are sensitive in the diagnosis of gastric precancerous lesions.


Antiviral Therapy | 2014

Efficacy of tenofovir in adefovir-experienced patients compared with treatment-naive patients with chronic hepatitis B.

Onur Keskin; Ormeci Ac; Baran B; Gökhan Kabaçam; Tüzün A; Ersin Karatayli; Filiz Akyuz; Senem Karatayli; A.M. Bozdayi; Onel D; Badur S; Ramazan Idilman; Sabahattin Kaymakoglu; Cihan Yurdaydin

BACKGROUND Tenofovir (TDF) has similar antiviral efficacy in both treatment-naive and lamivudine-resistant chronic hepatitis B (CHB) patients. Data on TDF use in patients with adefovir (ADV) resistance is inconsistent. The aim of our study was to assess antiviral efficacy of TDF against nucleoside analogue-naive (NN) and ADV-resistant (ADV-R) CHB and suboptimal responders to ADV (ADV-S). METHODS A database of 135 CHB patients treated with TDF was analysed. A total of 37 patients with incomplete data were excluded and analysis was performed in 98 (44 NN, 30 ADV-R and 24 ADV-S). Patients with primary ADV-R mutations had either A181T/V or N236T mutations or both. HBV DNA was measured at 3-month intervals until month 24. Primary outcome measures were comparison of the decline of HBV DNA between the three treatment groups. RESULTS NN patients had higher baseline HBV DNA compared with ADV-R and ADV-S patients (6.08 log10 IU/ml versus 5.53 and 4.88, respectively; P=0.002). By exponential regression analysis, HBV DNA decline kinetics differed between the three groups. HBV DNA decline was faster in NN patients compared to ADV-R and ADV-S CHB patients (P=0.002 and P=0.004, respectively). Undetectable HBV DNA was achieved in 77.2%, 60% and 75% of NN, ADV-R and ADV-S CHB patients, respectively, at month 12 (P= not significant). CONCLUSIONS HBV DNA decline is slower in ADV-experienced patients compared with treatment-naive patients. The clinical significance of this slow response may be important in patients with critical liver reserve and high viral load. Optimal combination treatment (TDF+ entecavir) could be considered in these patients.


Liver International | 2017

Non-invasive fibrosis score for hepatitis delta.

Gunnar Lewon Lutterkort; A. Wranke; Cihan Yurdaydin; Eva Budde; Max Westphal; Ralf Lichtinghagen; Judith Stift; B. Bremer; Svenja Hardtke; Onur Keskin; Ramazan Idilman; Armin Koch; M.P. Manns; Hans Peter Dienes; H. Wedemeyer; Benjamin Heidrich

Identifying advanced fibrosis in chronic hepatitis delta patients and thus in need of urgent treatment is crucial. To avoid liver biopsy, non‐invasive fibrosis scores may be helpful but have not been evaluated for chronic hepatitis delta yet.

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