Article
Medicine, General & Internal
Urszula Nowacka, Ioannis Papastefanou, Alexandra Bouariu, Argyro Syngelaki, Kypros H. Nicolaides
Summary: A new approach for predicting SGA, considering it a spectrum condition, has better predictive ability than traditional methods. However, the study found that second trimester levels of sFlt-1 and sFlt-1/PlGF are not useful in screening for SGA.
JOURNAL OF CLINICAL MEDICINE
(2021)
Article
Obstetrics & Gynecology
Kypros H. Nicolaides, Ioannis Papastefanou, Argyro Syngelaki, Ghalia Ashoor, Ranjit Akolekar
Summary: This study aimed to assess the predictive performance of a competing risks model for stillbirths related to placental dysfunction, based on a combination of maternal risk factors, estimated fetal weight, and uterine artery pulsatility index. The performance of this model was compared to a stillbirth-specific model and the Royal College of Obstetricians and Gynecologists (RCOG) guideline. The results showed that the competing risks model had similar predictive performance to the stillbirth-specific model and performed better than the RCOG guideline.
BJOG-AN INTERNATIONAL JOURNAL OF OBSTETRICS AND GYNAECOLOGY
(2022)
Article
Acoustics
I. Papastefanou, U. Nowacka, A. Syngelaki, V. Dragoi, G. Karamanis, D. Wright, K. H. Nicolaides
Summary: This study demonstrated that adding second-trimester estimated fetal weight (EFW) improves the prediction of small-for-gestational-age (SGA) neonates, particularly in cases of prematurity and severe smallness. Screening based on maternal characteristics and EFW can more accurately identify SGA neonates, enhancing the model's accuracy.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2021)
Article
Obstetrics & Gynecology
Ioannis Papastefanou, Urszula Nowacka, Argyro Syngelaki, Tanvi Mansukhani, George Karamanis, David Wright, Kypros H. Nicolaides
Summary: This study aimed to develop a new competing risks model for the prediction of small-for-gestational-age neonates based on a combination of maternal demographic characteristics and medical history with sonographic estimated fetal weight, uterine artery pulsatility index, and mean arterial pressure. The model showed superior performance in screening for small-for-gestational-age neonates compared to screening by maternal characteristics and medical history alone. The model demonstrated good calibration and detection rates in both the training and test data sets, confirming its internal validity.
AMERICAN JOURNAL OF OBSTETRICS AND GYNECOLOGY
(2021)
Article
Acoustics
I Papastefanou, D. Wright, A. Syngelaki, M. Lolos, K. Anampousi, K. H. Nicolaides
Summary: This study developed a new competing-risks model for predicting small-for-gestational-age (SGA) neonates, with PlGF showing better performance in predicting SGA compared to PAPP-A, especially in the presence of pre-eclampsia (PE). The model can be tailored to individual pregnancies and clinical requirements.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2021)
Article
Obstetrics & Gynecology
I Papastefanou, U. Nowacka, O. Buerger, R. Akolekar, D. Wright, K. H. Nicolaides
Summary: The detection rate for neonates that were SGA using the competing risk approach is almost double than that obtained with the RCOG guideline, indicating that the competing risks model performs better in predicting SGA infants compared to the existing RCOG guideline.
BJOG-AN INTERNATIONAL JOURNAL OF OBSTETRICS AND GYNAECOLOGY
(2021)
Article
Acoustics
I. Papastefanou, D. Wright, A. Syngelaki, K. Souretis, E. Chrysanthopoulou, K. H. Nicolaides
Summary: This study developed a new competing-risks model for predicting small-for-gestational-age (SGA) neonates based on maternal factors and biophysical and biochemical markers at 11-13 weeks' gestation. The model showed improved prediction for SGA cases with increasing prematurity, severity of smallness, coexistence of pre-eclampsia, and number of biomarkers. The new model was well-calibrated and could be used for personalized antenatal care plans.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2021)
Article
Acoustics
U. Nowacka, I Papastefanou, A. Bouariu, A. Syngelaki, R. Akolekar, K. H. Nicolaides
Summary: This study investigates the additional value of second-trimester placental growth factor (PlGF) in predicting small-for-gestational-age (SGA) neonates and examines second-trimester contingent screening strategies. The results show that the combination of maternal risk factors, estimated fetal weight (EFW), uterine artery pulsatility index (UtA-PI), and PlGF significantly improves the prediction of SGA compared to maternal risk factors alone. However, the incremental improvement decreases when PlGF is added to screening with a combination of maternal risk factors, EFW, and UtA-PI. By reserving measurements of UtA-PI and PlGF for a certain percentage of the population, similar detection rates and false-positive rates can be achieved. The study concludes that the combination of maternal risk factors, EFW, UtA-PI, and PlGF provides an effective prediction of SGA in the second trimester.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2022)
Article
Acoustics
G. Albaiges, I. Papastefanou, I. Rodriguez, P. Prats, M. Echevarria, M. A. Rodriguez, A. Rodriguez Melcon
Summary: This study examines the external validity of the new Fetal Medicine Foundation (FMF) competing-risks model for predicting small-for-gestational-age (SGA) neonates in midgestation. The study finds that the model performs well in a large independent Spanish population.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2023)
Article
Medicine, General & Internal
Olga Buerger, Tania Elger, Antonia Varthaliti, Argyro Syngelaki, Alan Wright, Kypros H. Nicolaides
Summary: In this study, we found that maternal characteristics and medical history can be used to predict the risk of Gestational Diabetes Mellitus (GDM), with a higher risk in twin pregnancies. Factors such as maternal age, weight, family history, racial background, and conception method all influence the risk of GDM.
JOURNAL OF CLINICAL MEDICINE
(2021)
Article
Mathematics, Applied
Subhankar Dutta, Hon Keung Tony Ng, Suchandan Kayal
Summary: In this paper, statistical inference methods are developed for a competing risks model with a hybrid censoring scheme and general family of inverted exponentiated distributions. Point and interval estimation methods are proposed based on maximum likelihood and Bayesian approaches, with both non-restricted and restricted parameter spaces considered. The paper proves the existence and uniqueness of maximum likelihood estimates and evaluates the performance of the proposed methods through Monte Carlo simulations and real data analysis. Concluding remarks and future research directions are also provided.
JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS
(2023)
Article
Statistics & Probability
Amulya Kumar Mahto, Chandrakant Lodhi, Yogesh Mani Tripathi, Liang Wang
Summary: This paper investigates inference for a competing risks model with latent failure times following Kumaraswamy distribution and partially observed causes of failure. The existence and uniqueness of maximum likelihood estimators of model parameters under generalized progressive hybrid censoring are established. Confidence intervals are obtained using asymptotic distribution theory, Bayes estimators and credible intervals are computed, and inference with order restricted shape parameters is discussed. The performance of all estimates is studied using Monte-Carlo simulations, and analysis of a real data set is presented for illustration purposes.
JOURNAL OF APPLIED STATISTICS
(2022)
Article
Mathematical & Computational Biology
Daniel Nevo, Malka Gorfine
Summary: This article investigates the causal effects of the Apolipoprotein E epsilon 4 allele (APOE) on late-onset Alzheimer's disease (AD) and death. A new estimation method is proposed for the scenario in which both AD and death are considered as outcomes, based on a stratification of the population and a novel assumption utilizing the time-to-event nature of the data. Nonparametric and semiparametric estimation methods are implemented to study the complex effect of APOE on AD and death.
Article
Engineering, Multidisciplinary
Prakash Chandra, Yogesh Mani Tripathi, Liang Wang, Chandrakant Lodhi
Summary: This paper discusses the estimation of a competing risks model with partially observed modes of failure. The authors explore the estimation of unknown parameters under non-order and order restrictions using classical and Bayesian approaches. They establish the uniqueness and existence of maximum likelihood estimators and derive interval estimators. Bayesian estimates and credible intervals are also developed for the model parameters. Additionally, the authors establish classical and Bayesian estimates when extra order information for the competing risks parameters is available. Extensive simulation studies and a numerical example are conducted to investigate the performance of different methods.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART O-JOURNAL OF RISK AND RELIABILITY
(2023)
Article
Mathematics
Abd El-Raheem M. Abd El-Raheem, Mona Hosny, Mahmoud H. Abu-Moussa
Summary: This article discusses the analysis of bi-causes of failure in competing risk models using exponential distribution, maximum likelihood estimates, and Bayesian estimates. Real data sets and a comprehensive simulation study are utilized to compare estimation methods and models.
Article
Acoustics
I. Papastefanou, U. Nowacka, A. Syngelaki, V. Dragoi, G. Karamanis, D. Wright, K. H. Nicolaides
Summary: This study demonstrated that adding second-trimester estimated fetal weight (EFW) improves the prediction of small-for-gestational-age (SGA) neonates, particularly in cases of prematurity and severe smallness. Screening based on maternal characteristics and EFW can more accurately identify SGA neonates, enhancing the model's accuracy.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2021)
Article
Obstetrics & Gynecology
Ioannis Papastefanou, Urszula Nowacka, Argyro Syngelaki, Tanvi Mansukhani, George Karamanis, David Wright, Kypros H. Nicolaides
Summary: This study aimed to develop a new competing risks model for the prediction of small-for-gestational-age neonates based on a combination of maternal demographic characteristics and medical history with sonographic estimated fetal weight, uterine artery pulsatility index, and mean arterial pressure. The model showed superior performance in screening for small-for-gestational-age neonates compared to screening by maternal characteristics and medical history alone. The model demonstrated good calibration and detection rates in both the training and test data sets, confirming its internal validity.
AMERICAN JOURNAL OF OBSTETRICS AND GYNECOLOGY
(2021)
Article
Genetics & Heredity
Yada Kunpalin, Jan Deprest, Ioannis Papastefanou, Emma Bredaki, Adalina Sacco, Francesca Russo, Jute Richter, Katrien Jansen, Sebastien Ourselin, Paolo De Coppi, Anna L. David, Fred Ushakov, Luc De Catte
Summary: In fetuses with isolated spina bifida aperta, nearly three-quarters had abnormal corpus callosum (CC), most commonly with partial agenesis in the splenium and rostrum. Larger lateral ventricle size was associated with partial agenesis of the CC.
PRENATAL DIAGNOSIS
(2021)
Article
Genetics & Heredity
Lennart van der Veeken, Annalisa Inversetti, Angela Galgano, Tom Bleeser, Ioannis Papastefanou, Johannes van de Merwe, Steffen Rex, Jan Deprest
Summary: The study conducted in a rabbit model suggests that fetal medications during fetal surgery do not have short-term neurocognitive effects.
PRENATAL DIAGNOSIS
(2021)
Article
Obstetrics & Gynecology
I Papastefanou, U. Nowacka, O. Buerger, R. Akolekar, D. Wright, K. H. Nicolaides
Summary: The detection rate for neonates that were SGA using the competing risk approach is almost double than that obtained with the RCOG guideline, indicating that the competing risks model performs better in predicting SGA infants compared to the existing RCOG guideline.
BJOG-AN INTERNATIONAL JOURNAL OF OBSTETRICS AND GYNAECOLOGY
(2021)
Article
Acoustics
U. Nowacka, I Papastefanou, A. Bouariu, A. Syngelaki, R. Akolekar, K. H. Nicolaides
Summary: This study investigates the additional value of second-trimester placental growth factor (PlGF) in predicting small-for-gestational-age (SGA) neonates and examines second-trimester contingent screening strategies. The results show that the combination of maternal risk factors, estimated fetal weight (EFW), uterine artery pulsatility index (UtA-PI), and PlGF significantly improves the prediction of SGA compared to maternal risk factors alone. However, the incremental improvement decreases when PlGF is added to screening with a combination of maternal risk factors, EFW, and UtA-PI. By reserving measurements of UtA-PI and PlGF for a certain percentage of the population, similar detection rates and false-positive rates can be achieved. The study concludes that the combination of maternal risk factors, EFW, UtA-PI, and PlGF provides an effective prediction of SGA in the second trimester.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2022)
Article
Obstetrics & Gynecology
Kypros H. Nicolaides, Ioannis Papastefanou, Argyro Syngelaki, Ghalia Ashoor, Ranjit Akolekar
Summary: This study aimed to assess the predictive performance of a competing risks model for stillbirths related to placental dysfunction, based on a combination of maternal risk factors, estimated fetal weight, and uterine artery pulsatility index. The performance of this model was compared to a stillbirth-specific model and the Royal College of Obstetricians and Gynecologists (RCOG) guideline. The results showed that the competing risks model had similar predictive performance to the stillbirth-specific model and performed better than the RCOG guideline.
BJOG-AN INTERNATIONAL JOURNAL OF OBSTETRICS AND GYNAECOLOGY
(2022)
Article
Acoustics
G. Ashoor, A. Syngelaki, I Papastefanou, K. H. Nicolaides, R. Akolekar
Summary: The study demonstrates that a model combining maternal risk factors, UtA-PI, and EFW at 19-24 weeks' gestation can effectively predict antepartum stillbirths due to impaired placentation, especially those occurring preterm.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2022)
Article
Genetics & Heredity
David Basurto, Francesca Maria Russo, Ioannis Papastefanou, Emma Bredaki, Karel Allegaert, Africa Pertierra, Anne Debeer, Luc De Catte, Liesbeth Lewi, Roland Devlieger, Paolo De Coppi, Eduard Gratacos, Olga Gomez, Jan Deprest
Summary: This study aimed to determine the prevalence of pulmonary hypertension (PAH) in left-sided congenital diaphragmatic hernia (CDH) and explore the predictors and contribution of PAH to mortality prediction. The results showed that PAH was associated with observed/expected-lung/head-ratio and fetoscopic endoluminal tracheal occlusion on postnatal day 1, and its occurrence further increased the risk of death. Antenatal prediction of PAH was limited, highlighting the need for more accurate predictors.
PRENATAL DIAGNOSIS
(2022)
Article
Acoustics
I Papastefanou, V Thanopoulou, S. Dimopoulou, A. Syngelaki, R. Akolekar, K. H. Nicolaides
Summary: This study developed a competing-risks model for predicting SGA neonates by incorporating sonographically estimated fetal weight (EFW) and biomarkers of impaired placentation at 36 weeks' gestation. The performance of the new model was compared with that of the traditional EFW < 10th percentile cut-off. The new model showed better predictive performance, especially when there was a longer time interval between assessment and delivery.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2022)
Editorial Material
Acoustics
I. Papastefanou, K. H. Nicolaides, L. J. Salomon
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2023)
Article
Acoustics
G. Albaiges, I. Papastefanou, I. Rodriguez, P. Prats, M. Echevarria, M. A. Rodriguez, A. Rodriguez Melcon
Summary: This study examines the external validity of the new Fetal Medicine Foundation (FMF) competing-risks model for predicting small-for-gestational-age (SGA) neonates in midgestation. The study finds that the model performs well in a large independent Spanish population.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2023)
Article
Acoustics
I. Papastefanou, E. Gyokova, B. Gungil, A. Syngelaki, K. H. Nicolaides
Summary: This study aims to investigate the association between birth weight and gestational age at delivery with adverse neonatal outcomes and describe the distribution of adverse neonatal outcomes within different risk strata derived from a population stratification scheme based on the midgestation risk assessment for small-for-gestational-age neonates. The results showed that birth weight has a continuous association with adverse neonatal outcomes, influenced by gestational age. Pregnancies at high risk of small-for-gestational-age, estimated at midgestation, are also at increased risk for adverse neonatal outcomes.
ULTRASOUND IN OBSTETRICS & GYNECOLOGY
(2023)
Article
Obstetrics & Gynecology
Ioannis Papastefanou, Ghalia Ashoor, Argyro Syngelaki, Ranjit Akolekar, Kypros H. Nicolaides
Summary: This study aimed to investigate the association between antepartum stillbirth and the distribution of neonatal/fetal weight for different gestational ages. The study found a continuous association between fetal weight and the weight of antepartum stillbirth, which was influenced by gestational age. The highest risk of stillbirth occurred in fetuses with weights below the 1st percentile between 24 and 28 weeks' gestation.
BJOG-AN INTERNATIONAL JOURNAL OF OBSTETRICS AND GYNAECOLOGY
(2023)