Category: Statistics

Neurosurg Focus. 2023 Jan;54(1):E9. doi: 10.3171/2022.10.FOCUS22608.

ABSTRACT

OBJECTIVE: Sacroiliac joint (SIJ) fusion utilizing intraoperative navigation requires a standard reference frame, which is often placed using a percutaneous pin. Proper placement ensures the correct positioning of SIJ fusion implants. There is currently no grading scheme for evaluation of pin placement into the pelvis. The purpose of this study was to evaluate the occurrence of ideal percutaneous pin placement into the posterior ilium during navigated SIJ fusion.

METHODS: After IRB approval was obtained, electronic medical records and intraoperative computed tomography images of patients who underwent navigated SIJ fusion by the senior author between October 2013 and January 2020 were reviewed. A pin placement grading scheme and the definition of “ideal” placement were developed by the authors and deemed acceptable by fellow attending surgeons. Six attending surgeons completed two rounds of pin placement grading, and statistical analysis was conducted.

RESULTS: Of 90 eligible patients, 73.3% had ideal pin placement, 17.8% medial/lateral breach, and 8.9% complete miss. Male patients were 3.7 times more likely to have ideal placement than females (p < 0.05). There was no relationship between BMI, SIJ fusion laterality, or pin placement laterality and ideal placement. Interobserver reliability was 0.72 and 0.70 in the first and second rounds, respectively, and defined as “substantial agreement.” Intraobserver reliability ranged from 0.74 (substantial agreement) to 0.92 (almost perfect agreement).

CONCLUSIONS: Nonideal pin placement occurred in 26.7% of cases, but a true “miss” into the sacrum was rare. Ideal pin placement was more likely in males and was not associated with BMI, SIJ fusion laterality, or pin placement laterality. The grading scheme developed has high intraobserver and interobserver reliability, indicating that it is reproducible and can be used for future studies. When placing percutaneous pins, surgeons must be aware of factors that can decrease placement accuracy, regardless of location.

PMID:36587403 | DOI:10.3171/2022.10.FOCUS22608

Neurosurg Focus. 2023 Jan;54(1):E8. doi: 10.3171/2022.10.FOCUS22601.

ABSTRACT

OBJECTIVE: A CSF leak is a potential complication in a lumbar laminectomy. An analysis of the author’s surgical experience identified inadvertent durotomies that occurred when resecting the ligamentum flavum at its insertion into the superior aspect of the caudal lamina. Anatomical analyses of the lumbar canal diameter demonstrate that the insertion point of the caudal ligamentum flavum is the most constrained area of the canal. The surgical technique was modified to eliminate the need for direct action in that anatomical region after the author compared the efficacy of piecemeal resection of the ligamentum flavum with en bloc resection with a laminotomy of the caudal lamina beyond the insertion point of the ligamentum flavum in the lumbar laminectomy.

METHODS: An analysis of a single surgeon’s experience managing 147 consecutive patients with lumbar stenosis who underwent single-level lumbar hemilaminectomies over a 4-year period was performed. Patients were managed with either piecemeal resection (cohort 1) or en bloc resection with a laminotomy beyond the caudal insertion (cohort 2) of the ligamentum flavum.

RESULTS: Seventy-seven patients underwent piecemeal resection (cohort 1), and 70 underwent en bloc resection (cohort 2). There were 5 CSF leaks (6.4%) in cohort 1. There were no CSF leaks in cohort 2. There was a statistically significant difference in operative times between the two groups (p = 0.04), but there was no statistically significant difference in patient-reported outcomes at 6 months between the groups.

CONCLUSIONS: En bloc resection of the ligamentum flavum with a laminotomy below the caudal insertion point appears to decrease the risk of a CSF leak by working beyond the most constrained diameter of the lumbar canal to release the caudal insertion of the ligamentum flavum.

PMID:36587402 | DOI:10.3171/2022.10.FOCUS22601

Mol Oncol. 2023 Jan 1. doi: 10.1002/1878-0261.13371. Online ahead of print.

ABSTRACT

The identification of the high-efficiency and non-invasive biomarkers for hepatocellular carcinoma (HCC) detection is urgently needed. This study aims to screen out potential autoantibodies to tumor-associated antigens (TAAbs) and to assess their diagnostic value for HCC. Fifteen potential TAAbs were screened out from the Human Proteome Microarray by 30 HCC sera and 22 normal control sera, of which 8 passed multiple-stage validations by ELISA with a total of 1,625 human serum samples from normal controls (NCs) and patients with HCC, liver cirrhosis, chronic hepatitis B, gastric cancer, esophageal cancer and colorectal cancer. Finally, an immunodiagnostic model including 6 TAAbs (RAD23A, CAST, RUNX1T1, PAIP1, SARS, PRKCZ) was constructed by logistic regression, and yielded the area under curve (AUC) of 0.835 and 0.788 in training and validation sets, respectively. The serial serum samples from HCC model mice were tested to explore the change in TAAbs during HCC formation, and an increasing level of autoantibodies was observed. In conclusion, the panel of 6 TAAbs can provide potential value for HCC detection, and the strategy to identify novel serological biomarkers can also provide new clues in understanding immunodiagnostic biomarkers.

PMID:36587394 | DOI:10.1002/1878-0261.13371

Int Ophthalmol. 2023 Jan 1. doi: 10.1007/s10792-022-02625-7. Online ahead of print.

ABSTRACT

PURPOSE: To evaluate the effectiveness of incobotulinumtoxinA (Xeomin^®) in treating upper eyelid retraction in patients with Graves orbitopathy (GO) initially scheduled for surgery via two different application sites.

METHODS: This is a comparative, prospective study, conducted at the Department of Ophthalmology, Medical School, University Hospital Centre Zagreb, EUGOGO site (EUropean Group On Graves’ Orbitopathy) in Croatia from January 2020 till January of 2021 in accordance with national health headquarter recommendations. All patients were classified as inactive with marked eyelid retraction and randomly divided into groups according to application sites. Group A underwent transconjunctival application (18 eyes) and group B transcutaneous application (20 eyes) of incobotulinumtoxinA. The primary end point of this study was lowering the eyelid, to alleviate anterior eye segment symptoms and achieve acceptable aesthetic appearance until surgery becomes available.

RESULTS: There were no nonresponders and we found no statistically significant difference in the degree of lowering the eyelid between the two application sites. Following rules for avoiding spread of SARS-CoV-19, none of the patients included in this study were infected. Moreover, participants reported diminishing of anterior eye segment irritation and improved aesthetics.

CONCLUSION: Treatment of inactive GO patients with incobotulinumtoxinA for upper eyelid retraction is efficient and safe and can be used as an adjuvant treatment while patients wait for surgery, by alleviating symptoms and improving the level of aesthetic satisfaction without causing a threat to anterior eye segment and visual function. The study showed that effect of treatment was the same, whether we applied the toxin transconjunctivaly or transcutaneously.

PMID:36587368 | DOI:10.1007/s10792-022-02625-7

Chaos. 2022 Dec;32(12):123103. doi: 10.1063/5.0106922.

ABSTRACT

Quantitatively assessing the level of confidence on a test score can be a challenging problem, especially when the available information is based on multiple criteria. A concrete example beyond the usual grading of tests occurs with recommendation letters, where a recommender assigns a score to a candidate, but the reliability of the recommender must be assessed as well. Here, we present a statistical procedure, based on Bayesian inference and Jaynes’ maximum entropy principle, that can be used to estimate the most probable and expected score given the available information in the form of a credible interval. Our results may provide insights on how to properly state and analyze problems related to the uncertain evaluation of performance in learning applied to several contexts, beyond the case study of the recommendation letters presented here.

PMID:36587360 | DOI:10.1063/5.0106922

Chaos. 2022 Dec;32(12):123118. doi: 10.1063/5.0118717.

ABSTRACT

The aim of this study is to formulate a new methodology based upon informational tools to detect patients with cardiac arrhythmias. As it is known, sudden death is the consequence of a final arrhythmia, and here lies the relevance of the efforts aimed at the early detection of arrhythmias. The information content in the time series from an electrocardiogram (ECG) signal is conveyed in the form of a probability distribution function, to compute the permutation entropy proposed by Bandt and Pompe. This selection was made seeking its remarkable conceptual simplicity, computational speed, and robustness to noise. In this work, two well-known databases were used, one containing normal sinus rhythms and another one containing arrhythmias, both from the MIT medical databank. For different values of embedding time delay τ, normalized permutation entropy and statistical complexity measure are computed to finally represent them on the horizontal and vertical axes, respectively, which define the causal plane H×C. To improve the results obtained in previous works, a feature set composed by these two magnitudes is built to train the following supervised machine learning algorithms: random forest (RF), support vector machine (SVM), and k nearest neighbors (kNN). To evaluate the performance of each classification technique, a 10-fold cross-validation scheme repeated 10 times was implemented. Finally, to select the best model, three quality parameters were computed, namely, accuracy, the area under the receiver operative characteristic (ROC) curve (AUC), and the F1-score. The results obtained show that the best classification model to detect the ECG coming from arrhythmic patients is RF. The values of the quality parameters were at the same levels reported in the available literature using a larger data set, thus supporting this proposal that uses a very small-sized feature space to train the model later used to classify. Summarizing, the attained results show the possibility to discriminate both groups of patients, with normal sinus rhythm or arrhythmic ECG, showing a promising efficiency in the definition of new markers for the detection of cardiovascular pathologies.

PMID:36587353 | DOI:10.1063/5.0118717

Chaos. 2022 Dec;32(12):121103. doi: 10.1063/5.0128743.

ABSTRACT

The role of topological heterogeneity in the origin of extreme events in a network is investigated here. The dynamics of the oscillators associated with the nodes are assumed to be identical and influenced by mean-field repulsive interactions. An interplay of topological heterogeneity and the repulsive interaction between the dynamical units of the network triggers extreme events in the nodes when each node succumbs to such events for discretely different ranges of repulsive coupling. A high degree node is vulnerable to weaker repulsive interactions, while a low degree node is susceptible to stronger interactions. As a result, the formation of extreme events changes position with increasing strength of repulsive interaction from high to low degree nodes. Extreme events at any node are identified with the appearance of occasional large-amplitude events (amplitude of the temporal dynamics) that are larger than a threshold height and rare in occurrence, which we confirm by estimating the probability distribution of all events. Extreme events appear at any oscillator near the boundary of transition from rotation to libration at a critical value of the repulsive coupling strength. To explore the phenomenon, a paradigmatic second-order phase model is used to represent the dynamics of the oscillator associated with each node. We make an annealed network approximation to reduce our original model and, thereby, confirm the dual role of the repulsive interaction and the degree of a node in the origin of extreme events in any oscillator associated with a node.

PMID:36587354 | DOI:10.1063/5.0128743

Chaos. 2022 Dec;32(12):122101. doi: 10.1063/5.0124274.

ABSTRACT

Sharp changes in state, such as transitions from survival to extinction, are hallmarks of evolutionary dynamics in biological systems. These transitions can be explored using the techniques of statistical physics and the physics of nonlinear and complex systems. For example, a survival-to-extinction transition can be characterized as a non-equilibrium phase transition to an absorbing state. Here, we review the literature on phase transitions in evolutionary dynamics. We discuss directed percolation transitions in cellular automata and evolutionary models, and models that diverge from the directed percolation universality class. We explore in detail an example of an absorbing phase transition in an agent-based model of evolutionary dynamics, including previously unpublished data demonstrating similarity to, but also divergence from, directed percolation, as well as evidence for phase transition behavior at multiple levels of the model system’s evolutionary structure. We discuss phase transition models of the error catastrophe in RNA virus dynamics and phase transition models for transition from chemistry to biochemistry, i.e., the origin of life. We conclude with a review of phase transition dynamics in models of natural selection, discuss the possible role of phase transitions in unraveling fundamental unresolved questions regarding multilevel selection and the major evolutionary transitions, and assess the future outlook for phase transitions in the investigation of evolutionary dynamics.

PMID:36587338 | DOI:10.1063/5.0124274

Chaos. 2022 Dec;32(12):123131. doi: 10.1063/5.0129066.

ABSTRACT

Noakes and Stoyanov [Mathematics 9, 2434 (2021)] introduced a method of recovering strictly convex planar obstacles from their set of traveling times. We provide an extension of this construction for obstacles on Riemannian surfaces under some general curvature conditions. It is required that no smooth geodesic intersects more than two obstacles.

PMID:36587331 | DOI:10.1063/5.0129066

Chaos. 2022 Dec;32(12):123136. doi: 10.1063/5.0097187.

ABSTRACT

White noise is a fundamental and fairly well understood stochastic process that conforms to the conceptual basis for many other processes, as well as for the modeling of time series. Here, we push a fresh perspective toward white noise that, grounded on combinatorial considerations, contributes to giving new interesting insights both for modeling and theoretical purposes. To this aim, we incorporate the ordinal pattern analysis approach, which allows us to abstract a time series as a sequence of patterns and their associated permutations, and introduce a simple functional over permutations that partitions them into classes encoding their level of asymmetry. We compute the exact probability mass function (p.m.f.) of this functional over the symmetric group of degree n, thus providing the description for the case of an infinite white noise realization. This p.m.f. can be conveniently approximated by a continuous probability density from an exponential family, the Gaussian, hence providing natural sufficient statistics that render a convenient and simple statistical analysis through ordinal patterns. Such analysis is exemplified on experimental data for the spatial increments from tracks of gold nanoparticles in 3D diffusion.

PMID:36587330 | DOI:10.1063/5.0097187