Summary
The limitations of the well‐known LASSO regression as a variable selector are tested when there exists dependence structures among covariates. We analyse both the classic situation with n ≥ p ...and the high dimensional framework with p > n. Known restrictive properties of this methodology to guarantee optimality, as well as inconveniences in practice, are analysed and tested by means of an extensive simulation study. Examples of these drawbacks are showed making use of different dependence scenarios. In order to search for improvements, a broad comparison with LASSO derivatives and alternatives is carried out. Eventually, we give some guidance about what procedures work best in terms of the considered data nature.
Functional data analysis is a field of growing importance in Statistics. In particular, the functional linear model with scalar response is surely the model that has attracted more attention in both ...theoretical and applied research. Two of the most important methodologies used to estimate the parameters of the functional linear model with scalar response are functional principal component regression and functional partial least-squares regression. We provide an overview of estimation methods based on these methodologies and discuss their advantages and disadvantages. We emphasise that the role played by the functional principal components and by the functional partial least-squares components that are used in estimation appears to be very important to estimate the functional slope of the model. A functional version of the best subset selection strategy usual in multiple linear regression is also analysed. Finally, we present an extensive comparative simulation study to compare the performance of all the considered methodologies that may help practitioners in the use of the functional linear model with scalar response.
Epiretinal membrane (ERM) formation is a known postoperative complication following retinal detachment (RD) repair surgery. Prophylactic peeling of the internal limiting membrane (ILM) during surgery ...has been shown to reduce the risk of developing postoperative ERM formation. Some baseline characteristics and degrees of surgical complexity may act as risk factors for ERM development. In this review we aimed to investigate the benefit of ILM peeling in patients without significant proliferative vitreoretinopathy (PVR) who underwent pars plana vitrectomy for RD repair. A literature search using PubMed and various keywords retrieved relevant papers from which data were extracted and analyzed. Finally, the results of 12 observational studies (3420 eyes) were summarized. ILM peeling significantly reduced the risk of postoperative ERM formation (RR = 0.12, 95% CI 0.05-0.28). The groups did not differ in final visual acuity (SMD 0.14 logMAR (95% CI - 0.03-0.31)). The risk of RD recurrence (RR = 0.51, 95% CI 0.28-0.94) and the need for secondary ERM surgery (RR = 0.05, 95% CI 0.02-0.17) were also higher in the non-ILM peeling groups. In summary, although prophylactic ILM peeling appears to reduce the rate of postoperative ERM, this benefit does not translate into consistent visual recovery across studies and potential complications must be considered.
Two independent random elements taking values in a separable Hilbert space are considered. The aim is to develop a test with bootstrap calibration to check whether they have the same distribution or ...not. A transformation of both random elements into a new separable Hilbert space is considered so that the equality of expectations of the transformed random elements is equivalent to the equality of distributions. Thus, a bootstrap test procedure to check the equality of means can be used in order to solve the original problem. It will be shown that both the asymptotic and bootstrap approaches proposed are asymptotically correct and consistent. The results can be applied, for example, in functional data analysis. In practice, the test can be solved with simple operations in the original space without applying the mentioned transformation, which is used only to guarantee the theoretical results. Empirical results and comparisons with related methods support and complement the theory.
Introduction
Graves' disease is an autoimmune disorder. Goiter and Graves' orbitopathy are frequently seen clinically. It would be helpful for the diagnosis, grading, prognosis, and treatment of this ...condition if it was possible to find serum biomarkers to establish a connection between the plasma levels of these compounds and orbital changes.
Methods
A retrospective study was performed by revising the medical records of 44 patients with Graves' orbitopathy and 15 controls. The Osirix software (Pixmeo, Geneva, Switzerland) was used for manual orbital measurements. Plasma levels of Graves' orbitopathy substances were obtained in the analytical review of the patients.
Results
A greater muscle volume was observed in patients with Graves' orbitopathy in relation to the control group (
p
< 0.001). The clinical activity score (CAS) was associated to total muscle mass (
p
= 0.013) and retrorbital fat (
p
= 0.048). Our results indicated a direct relationship between serum concentrations of anti-thyroid peroxidase antibodies and inferior rectus thickening (
p
= 0.036); however, we did not observe a positive correlation between other muscle volumes and serum concentrations of various thyroid-related substances.
Conclusions
This study is the first that uses Osirix measurement software to manually assess orbital features in patients with Graves' orbitopathy. These measurements were compared to the outcomes of tests performed in a laboratory. Among several serum biomarkers, anti-thyroid peroxidase appears to be a reliable biomarker that correlates positively with inferior rectus muscle thickness in patients with thyroid eye disease. This may help to improve the management of this disease.
The prognosis of uveal melanoma is significantly influenced by the risk of metastasis, which varies according to clinical and genetic features. Driver mutations can predict the likelihood of disease ...progression and survival, although the data in the literature are inconsistent. This meta-analysis aimed to evaluate the prognostic significance of driver mutations, including GNAQ, GNA11, BAP1, and SF3B1, in the advancement of uveal melanoma. A comprehensive search of databases yielded relevant studies, and data from 13 studies (848 eyes) were synthesized to assess the impact of these mutations on metastasis-free survival. The BAP1 mutation and negative immunohistochemistry were associated with a higher risk of metastasis (logHR = 1.44, 95% CI 1.05–1.83). GNAQ, GNA11, and SF3B1 mutations did not show a significant increase in risk. In summary, BAP1 has proven to reliably predict the likelihood of disease progression in uveal melanoma, while further studies are needed to establish the significance of other driver mutations.
More than 50% of patients with uveal melanoma end up developing metastases. Currently, there is no standard first-line treatment that facilitates proper management of the metastatic disease.
A ...systematic review of the last 40 years in PubMed with an exhaustive and strict selection of studies was conducted, in which the unit of measurement was overall survival (OS) expressed in Kaplan-Meier curves or numerically.
After the selection process, 110 articles were included. Regional therapies, such as intra-arterial liver chemotherapy (OS: 2, 9-22 months), isolated liver perfusion (OS: 9, 6-27, 4 months), or selective internal radiation therapy (OS: 18 months in monotherapy and 26 months in combination with other therapies) showed some superiority when compared to systemic therapies, such as chemotherapy (OS: 4, 6-17 months), immunotherapy (OS: 5-19, 1 month), immunosuppression (OS: 11 months), or targeted therapy (OS: 6-12 months), without being significant.
The results of this review suggest that there are no important differences in OS when comparing the different current treatment modalities. Most of the differences found seem to be explained by the heterogenicity of the different studies and the presence of biases in their design, rather than actual extensions of patient survival.
The GNAQ and GNA11 genes are mutated in almost 80–90% of uveal melanomas in a mutually exclusive pattern. These genes encode the alpha subunits of the heterotrimeric G proteins, Gq and G11; thus, ...mutations of these genes result in the activation of several important signaling pathways, including phospholipase C, and activation of the transcription factor YAP. It is well known that both of them act as driver genes in the oncogenic process and it has been assumed that they do not play a role in the prognosis of these tumours. However, it has been hypothesised that mutations in these genes could give rise to molecularly and clinically distinct types of uveal melanomas. It has also been questioned whether the type and location of mutation in the GNAQ and GNA11 genes may affect the progression of these tumours. All of these questions, except for their implications in carcinogenesis, remain controversial. Uveal melanoma has a distinctive genetic profile, and specific recurrent mutations, which make it a potential candidate for treatment with targeted therapy. Given that the most frequent mutations are those observed in the GNAQ and GNA11 genes, and that both genes are involved in oncogenesis, these molecules, as well as the downstream signalling pathways in which they are involved, have been proposed as promising potential therapeutic targets. Therefore, in this review, special attention is paid to the current data related to the possible prognostic implications of both genes from different perspectives, as well as the therapeutic options targeting them.
This paper presents new specification tests for a general synchronous additive concurrent model formulation. As a novelty, our proposal does not require a preliminary model or error structure ...estimation. No tuning parameters are involved either. We develop a suitable test statistic using the martingale difference divergence coefficient. As a result, this statistic measures the departure from the conditional mean independence in the concurrent model framework, considering the information of all observed time instants. In particular, global as well as partial dependence tests are introduced. Then, we allow one to quantify the effect of a group of covariates or to apply covariates selection one by one. We obtain its asymptotic distribution under the null and propose a bootstrap algorithm to compute the
p
-values in practice. Through simulations, we illustrate our method, and its performance is compared to existing competitors. In addition, we use this in the analysis of three real datasets related to gait data, flu activity, and casual bike rentals.
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