Computation of Lyapunov functions for systems with multiple attractors

We present a novel method to compute Lyapunov functions for continuous-time systems with multiple local attractors. In the proposed method one first computes an outer approximation of the local attractors using a graphtheoretic approach. Then a candidate Lyapunov function is computed using a Massera-like construction adapted to multiple local attractors. In the final step this candidate Lyapunov function is interpolated over the simplices of a simplicial complex and, by checking certain inequalities at the vertices of the complex, we can identify the region in which the Lyapunov function is decreasing along system trajectories. The resulting Lyapunov function gives information on the qualitative behavior of the dynamics, including lower bounds on the basins of attraction of the individual local attractors. We develop the theory in detail and present numerical examples demonstrating the applicability of our method

Gastrointestinal bleeding in Iceland and in broader terms – a review

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadBráð blæðing frá meltingarvegi er algeng ástæða komu á bráðamóttöku og innlagnar á spítala. Þessum blæðingum er vanalega skipt í efri og neðri meltingarvegarblæðingar. Í þessari yfirlitsgrein verður farið yfir nýgengi þessara blæðinga, áhættuþætti, orsakir, þátt blóðþynningarlyfja, mat á alvarleika blæðinga, meðferðarúrræði og horfur. Reynt verður að varpa ljósi á þetta viðfangsefni í íslensku heilbrigðiskerfi en einnig í víðara samhengi

Gastrointestinal bleeding in Iceland and in broader terms – a review

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadBráð blæðing frá meltingarvegi er algeng ástæða komu á bráðamóttöku og innlagnar á spítala. Þessum blæðingum er vanalega skipt í efri og neðri meltingarvegarblæðingar. Í þessari yfirlitsgrein verður farið yfir nýgengi þessara blæðinga, áhættuþætti, orsakir, þátt blóðþynningarlyfja, mat á alvarleika blæðinga, meðferðarúrræði og horfur. Reynt verður að varpa ljósi á þetta viðfangsefni í íslensku heilbrigðiskerfi en einnig í víðara samhengi

Increased incidence of autoimmune hepatitis is associated with wider use of biological drugs.

To access publisher's full text version of this article click on the hyperlink belowBACKGROUND & AIMS: Population-based studies on the epidemiology of autoimmune hepatitis (AIH) are scarce. Drug-induced AIH (DIAIH) is increasingly recognized in association with immunomodulatory therapy. We aimed to determine the incidence, prevalence and natural history of AIH in a population-based setting. METHODS: We collected data of new diagnosis of AIH in Iceland from 2006 to 2015. Cases were identified through search of diagnostic codes and text search for AIH within electronical medical records of all hospitals in Iceland and through records of smooth muscle antibodies (SMA) test results by the only laboratory in the country analyzing SMA. Patients were included in the final analysis if they received the clinical diagnosis of AIH or were started on immunosuppressive therapy. RESULTS: The mean annual incidence of AIH in Iceland was 2.2 cases per 100 000 inhabitants. Point prevalence on 31 December 2015 was 27/100 000. The median age at diagnosis was 56 years and 86% of patients were of female gender. DIAIH was suspected in 13 of 71 patients (18%) of which eight cases were related to infliximab. Immunosuppressive treatment was started in all but two patients. At the end of follow-up (median 4.8 years) 66 of 71 (93%) patients were alive. CONCLUSION: The incidence and prevalence rates of AIH in Iceland are the highest reported so far in a population-based setting. Higher incidence can partly be explained by the increasing use of biological drugs. Immunosuppressive therapy was very effective in achieving remission and prognosis was favorable

Hepatitis due to Epstein-Barr virus and cytomegalovirus: clinical features and outcomes.

To access publisher's full text version of this article click on the hyperlink belowTo determine the frequency of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) hepatitis among those with acute CMV and EBV infection in a population based setting and to compare these two types of hepatitis and analyze the outcomes.A retrospective search was undertaken on all patients with IgM antibodies to CMV and EBV during the period of 2006-2015 in the virological database of the University Hospital of Iceland covering the metropolitan area of Reykjavík (population 202,255). Patients with available liver tests at the University Hospital and/or admitted to this institution were included and relevant clinical data obtained from medical records.Overall, 190 patients had acute EBV infection during the study period and 118 patients were diagnosed with acute CMV. Overall, 82% of patients with acute EBV infection had hepatitis, males 43%, median age 17 years, 15% had jaundice and 26% hospitalized. Among those with acute CMV infection, 69% had elevated liver tests, 63% males, median age 33 years, 9% had jaundice and also 26% hospitalized. Overall, 17% of those with CMV hepatitis were immunosuppressed, 6% were pregnant and 4% developed Guillain-Barré syndrome following the infection.A high proportion of patients with acute CMV and EBV developed hepatitis and jaundice, most of those patients have good prognosis. Patients with CMV hepatitis were more often immunosuppressed, required hospitalization or were pregnant in comparison with patients with EBV hepatitis

Lower gastrointestinal bleeding: incidence, etiology, and outcomes in a population-based setting.

To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.To investigate the incidence and outcomes of acute lower gastrointestinal bleeding (ALGIB) in a population-based setting and examine the role of drugs potentially associated with GIB.National University Hospital of Icelan

Causes of gastrointestinal bleeding in oral anticoagulant users compared to non-users in a population-based study.

To access publisher's full text version of this article click on the hyperlink belowBackground/aims: Causes of gastrointestinal bleeding (GIB) in patients on oral anticoagulants (OACs) are not well established. The aims of the study were to compare the causes of GIB in patients on OACs and those not on OAC therapy. Methods: A nationwide study of all GIB events in patients on OACs in Iceland from 2014-2019 was conducted. Bleeding events were obtained through ICD-10 codes and review of endoscopy databases, confirmed by review of medical records. For comparison, patients not on OACs from previous Icelandic population-based studies were used. Results: Among 752 GIB events in 12,005 patients on OACs, 273 (1.9%) had verified upper and 391 (2.7%) had verified lower GIB. For lower GIB, multivariate analysis showed that OAC users were more likely to have colonic polyps (OR 6.6, 95% CI: 2.4 - 17.8, p < .001) or colorectal cancer (OR 3.7, 95% CI: 2.0 - 7.0, p < .001) but less likely to have ischemic colitis (OR 0.11, 95% CI: 0.04 - 0.26, p < .001). For upper GIB, bleeding from mucosal erosions (OR 4.0 95% CI: 2.5 - 7.9, p < .001) and angiodysplasia (OR 3.6, 95%CI: 1.5 - 8.6, p = .003) were more common in OAC users. Conclusions: A high proportion of GIB caused by colonic polyps and colorectal cancer among OAC patients indicates that OACs treatment may facilitate cancer diagnosis. The low proportion of ischemic colitis among those on OACs suggests that OACs provide a protective effect against ischemic colitis. OACs seem to increase the bleeding from angiodysplasia and mucosal erosive disease. Keywords: Gastrointestinal bleeding; anticoagulation; colon cancer; ischemic colitis.Eimskipasjodur University of Iceland Scientific grant of Landspital

Rivaroxaban Is Associated With Higher Rates of Gastrointestinal Bleeding Than Other Direct Oral Anticoagulants : A Nationwide Propensity Score-Weighted Study.

To access publisher's full text version of this article click on the hyperlink belowBackground: Gastrointestinal bleeding (GIB) rates for direct oral anticoagulants (DOACs) and warfarin have been extensively compared. However, population-based studies comparing GIB rates among different DOACs are limited. Objective: To compare rates of GIB among apixaban, dabigatran, and rivaroxaban. Design: Nationwide population-based cohort study. Setting: Landspítali-The National University Hospital of Iceland and the 4 regional hospitals in Iceland. Patients: New users of apixaban, dabigatran, and rivaroxaban from 2014 to 2019. Measurements: Rates of GIB were compared using inverse probability weighting, Kaplan-Meier survival estimates, and Cox regression. Results: In total, 2157 patients receiving apixaban, 494 patients receiving dabigatran, and 3217 patients receiving rivaroxaban were compared. For all patients, rivaroxaban had higher overall rates of GIB (3.2 vs. 2.5 events per 100 person-years; hazard ratio [HR], 1.42 [95% CI, 1.04 to 1.93]) and major GIB (1.9 vs. 1.4 events per 100 person-years; HR, 1.50 [CI, 1.00 to 2.24]) compared with apixaban. Rivaroxaban also had higher GIB rates than dabigatran, with similar point estimates, although the CIs were wider and included the possibility of a null effect. When only patients with atrial fibrillation were included, rivaroxaban was associated with higher rates of overall GIB than apixaban (HR, 1.40 [CI, 1.01 to 1.94]) or dabigatran (HR, 2.04 [CI, 1.17 to 3.55]). Dabigatran was associated with lower rates of upper GIB than rivaroxaban in both analyses. Limitations: Unmeasured confounding and small subgroup analyses. Conclusion: Rivaroxaban was associated with higher GIB rates than apixaban and dabigatran regardless of treatment indication.Icelandic Centre for Research Landspitali University Hospital Research Fun