Evangelos Kalampokis

Dr. Evangelos Kalampokis

University of Macedonia

Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2011 in International Journal of Web Engineering and Technology
Verified
Journal Article
Closed access
EKEvangelos Kalampokis
Evangelos Kalampokis
ETEfthimios Tambouris
Efthimios Tambouris
Konstantinos A. TarabanisKonstantinos A. Tarabanis
Konstantinos A. Tarabanis
Open government data (OGD) refers to making public sector information freely available in open formats and ways that enable public access and facilitate exploitation. Lately, a large number of OGD initiatives launched worldwide aiming to implement one-stop portals acting as single points of access to governmental data. At the same time, the so-called linked data technologies emerged aiming at publishing structured data on the web in such a way that enables semantically enriching data, uniform access to data, and linking of data. In this paper, we first propose a classification scheme for OGD initiatives based on the relevant literature. We thereafter, review and analyse OGD initiatives based on the proposed scheme. We finally present an architecture and prototype implementation for the most advanced OGD class in our scheme, which enables linking decentralised data.

14 October 2013 in Internet Research
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Journal Article
Closed access
EKEvangelos Kalampokis
Evangelos Kalampokis
ETEfthimios Tambouris
Efthimios Tambouris
KTKonstantinos Tarabanis
Konstantinos Tarabanis

1 January 2011
Verified
Book Chapter
Open access
PDF file
EKEvangelos Kalampokis
Evangelos Kalampokis
ETEfthimios Tambouris
Efthimios Tambouris
Konstantinos A. TarabanisKonstantinos A. Tarabanis
Konstantinos A. Tarabanis
Public sector information constitutes a valuable primary material for added-value services and products, which however remains unexploited. Recently, Open Government Data (OGD) initiatives emerged worldwide aiming to make public data freely available to everyone, without limiting restrictions. Despite its potential however there is currently a lack of roadmaps, guidelines and benchmarking frameworks to drive and measure OGD progress. This is particularly true as proposed stage models for measuring eGovernment progress focus on services and do not sufficiently consider data. In this paper, we capitalize on literature on eGovernment stage models and OGD initiatives to propose a stage model for OGD. The proposed model has two main dimensions, namely organizational & technological complexity and added value for data consumers. We anticipate the proposed model will open up a scientific discussion on OGD stage models and will be used by practitioners for constructing roadmaps and for benchmarking just like the European Union stage model is currently used for measuring public service online sophistication.

16 June 2023 in Cardiovascular Digital Health Journal
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Journal Article
Open access
CTConstantine Tarabanis
Constantine Tarabanis
EKEvangelos Kalampokis
Evangelos Kalampokis
MKMahmoud Khalil
Mahmoud Khalil
CACarlos L. Alviar
Carlos L. Alviar
LCLarry A. Chinitz
Larry A. Chinitz
LJLior Jankelson
Lior Jankelson
A lack of explainability in published machine learning (ML) models limits clinicians' understanding of how predictions are made, in turn undermining uptake of the models into clinical practice. The purpose of this study was to develop explainable ML models to predict in-hospital mortality in patients hospitalized for myocardial infarction (MI). Adult patients hospitalized for an MI were identified in the National Inpatient Sample between January 1, 2012, and September 30, 2015. The resulting cohort comprised 457,096 patients described by 64 predictor variables relating to demographic/comorbidity characteristics and in-hospital complications. The gradient boosting algorithm eXtreme Gradient Boosting (XGBoost) was used to develop explainable models for in-hospital mortality prediction in the overall cohort and patient subgroups based on MI type and/or sex. The resulting models exhibited an area under the receiver operating characteristic curve (AUC) ranging from 0.876 to 0.942, specificity 82% to 87%, and sensitivity 75% to 87%. All models exhibited high negative predictive value ≥0.974. The SHapley Additive exPlanation (SHAP) framework was applied to explain the models. The top predictor variables of increasing and decreasing mortality were age and undergoing percutaneous coronary intervention, respectively. Other notable findings included a decreased mortality risk associated with certain patient subpopulations with hyperlipidemia and a comparatively greater risk of death among women below age 55 years. The literature lacks explainable ML models predicting in-hospital mortality after an MI. In a national registry, explainable ML models performed best in ruling out in-hospital death post-MI, and their explanation illustrated their potential for guiding hypothesis generation and future study design.

Verified
Journal Article
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PDF file
Alexandros LaiosAlexandros Laios
Alexandros Laios
EKEvangelos Kalampokis
Evangelos Kalampokis
RJRACHEAL LOUISE JOHNSON
RACHEAL LOUISE JOHNSON
ATAmudha Thangavelu
Amudha Thangavelu
CTConstantine Tarabanis
Constantine Tarabanis
DJDiederick de Jong
Diederick de Jong
Complete surgical cytoreduction (R0 resection) is the single most important prognosticator in epithelial ovarian cancer (EOC). Explainable Artificial Intelligence (XAI) could clarify the influence of static and real-time features in the R0 resection prediction. We aimed to develop an AI-based predictive model for the R0 resection outcome, apply a methodology to explain the prediction, and evaluate the interpretability by analysing feature interactions. The retrospective cohort finally assessed 571 consecutive advanced-stage EOC patients who underwent cytoreductive surgery. An eXtreme Gradient Boosting (XGBoost) algorithm was employed to develop the predictive model including mostly patient- and surgery-specific variables. The Shapley Additive explanations (SHAP) framework was used to provide global and local explainability for the predictive model. The XGBoost accurately predicted R0 resection (area under curve [AUC] = 0.866; 95% confidence interval [CI] = 0.8–0.93). We identified “turning points” that increased the probability of complete cytoreduction including Intraoperative Mapping of Ovarian Cancer Score and Peritoneal Carcinomatosis Index < 4 and 4, patient’s age < 60 years, and largest tumour bulk < 5 cm in a surgical environment of optimized infrastructural support. We demonstrated high model accuracy for the R0 resection prediction in EOC patients and provided novel global and local feature explainability that can be used for quality control and internal audit.

15 July 2022 in Cancers
Verified
Journal Article
Open access
PDF file
Alexandros LaiosAlexandros Laios
Alexandros Laios
EKEvangelos Kalampokis
Evangelos Kalampokis
RJRACHEAL LOUISE JOHNSON
RACHEAL LOUISE JOHNSON
SMSarika Munot
Sarika Munot
ATAmudha Thangavelu
Amudha Thangavelu
DJDiederick de Jong
Diederick de Jong
(1) Background: Surgical cytoreduction for epithelial ovarian cancer (EOC) is a complex procedure. Encompassed within the performance skills to achieve surgical precision, intra-operative surgical decision-making remains a core feature. The use of eXplainable Artificial Intelligence (XAI) could potentially interpret the influence of human factors on the surgical effort for the cytoreductive outcome in question; (2) Methods: The retrospective cohort study evaluated 560 consecutive EOC patients who underwent cytoreductive surgery between January 2014 and December 2019 in a single public institution. The eXtreme Gradient Boosting (XGBoost) and Deep Neural Network (DNN) algorithms were employed to develop the predictive model, including patient- and operation-specific features, and novel features reflecting human factors in surgical heuristics. The precision, recall, F1 score, and area under curve (AUC) were compared between both training algorithms. The SHapley Additive exPlanations (SHAP) framework was used to provide global and local explainability for the predictive model; (3) Results: A surgical complexity score (SCS) cut-off value of five was calculated using a Receiver Operator Characteristic (ROC) curve, above which the probability of incomplete cytoreduction was more likely (area under the curve [AUC] = 0.644; 95% confidence interval [CI] = 0.598–0.69; sensitivity and specificity 34.1%, 86.5%, respectively; p = 0.000). The XGBoost outperformed the DNN assessment for the prediction of the above threshold surgical effort outcome (AUC = 0.77; 95% [CI] 0.69–0.85; p < 0.05 vs. AUC 0.739; 95% [CI] 0.655–0.823; p < 0.95). We identified “turning points” that demonstrated a clear preference towards above the given cut-off level of surgical effort; in consultant surgeons with <12 years of experience, age 4, and a Peritoneal Carcinomatosis Index >7, in a surgical environment with the optimization of infrastructural support. (4) Conclusions: Using XAI, we explain how intra-operative decisions may consider human factors during EOC cytoreduction alongside factual knowledge, to maximize the magnitude of the selected trade-off in effort. XAI techniques are critical for a better understanding of Artificial Intelligence frameworks, and to enhance their incorporation in medical applications.