Category: Statistics

J Math Biol. 2022 Jun 12;84(7):59. doi: 10.1007/s00285-022-01764-w.

ABSTRACT

The effective degree SIR model describes the dynamics of diseases with lifetime acquired immunity on a static random contact network. It is typically modeled as a system of ordinary differential equations describing the probability distribution of the infection status of neighbors of a susceptible node. Such a construct may not be used to study networks with an infinite degree distribution, such as an infinite scale-free network. We propose a new generating function approach to rewrite the effective degree SIR model as a nonlinear transport type partial differential equation. We show the existence and uniqueness of the solutions the are biologically relevant. In addition we show how this model may be reduced to the Volz model with the assumption that the infection statuses of the neighbors of an susceptible node are initially independent to each other. This paper paves the way to study the stability of the disease-free steady state and the disease threshold of the infinite dimensional effective degree SIR models.

PMID:35691964 | DOI:10.1007/s00285-022-01764-w

Prog Orthod. 2022 Jun 13;23(1):22. doi: 10.1186/s40510-022-00413-8.

ABSTRACT

BACKGROUND: Several semi-automatic software are available for the three-dimensional reconstruction of the airway from DICOM files. The aim of this study was to evaluate the accuracy of the segmentation of the upper airway testing four free source and one commercially available semi-automatic software. A total of 20 cone-beam computed tomography (CBCT) were selected to perform semi-automatic segmentation of the upper airway. The software tested were Invesalius, ITK-Snap, Dolphin 3D, 3D Slicer and Seg3D. The same upper airway models were manually segmented (Mimics software) and set as the gold standard (GS) reference of the investigation. A specific 3D imaging technology was used to perform the superimposition between the upper airway model obtained with semi-automatic software and the GS model, and to perform the surface-to-surface matching analysis. The accuracy of semi-automatic segmentation was evaluated calculating the volumetric mean differences (mean bias and limits of agreement) and the percentage of matching of the upper airway models compared to the manual segmentation (GS). Qualitative assessments were performed using color-coded maps. All data were statistically analyzed for software comparisons.

RESULTS: Statistically significant differences were found in the volumetric dimensions of the upper airway models and in the matching percentage among the tested software (p < 0.001). Invesalius was the most accurate software for 3D rendering of the upper airway (mean bias = 1.54 cm³; matching = 90.05%) followed by ITK-Snap (mean bias = – 2.52 cm³; matching = 84.44%), Seg 3D (mean bias = 3.21 cm³, matching = 87.36%), 3D Slicer (mean bias = – 4.77 cm³; matching = 82.08%) and Dolphin 3D (difference mean = – 6.06 cm³; matching = 78.26%). According to the color-coded map, the dis-matched area was mainly located at the most anterior nasal region of the airway. Volumetric data showed excellent inter-software reliability (GS vs semi-automatic software), with coefficient values ranging from 0.904 to 0.993, confirming proportional equivalence with manual segmentation.

CONCLUSION: Despite the excellent inter-software reliability, different semi-automatic segmentation algorithms could generate different patterns of inaccuracy error (underestimation/overestimation) of the upper airway models. Thus, is unreasonable to expect volumetric agreement among different software packages for the 3D rendering of the upper airway anatomy.

PMID:35691961 | DOI:10.1186/s40510-022-00413-8

Ann Surg Oncol. 2022 Jun 12. doi: 10.1245/s10434-022-11950-1. Online ahead of print.

ABSTRACT

BACKGROUND: Splenic artery (SpA) involvement heralds poor prognosis in pancreatic ductal adenocarcinoma (PDAC) of the body and tail but is not included in the resectability criteria. This study evaluated the prognostic impact of radiological SpA involvement in PDAC of the body and tail.

METHODS: Preoperative computed tomography images of patients who underwent distal pancreatectomy for resectable PDAC of the body and tail (n = 242) at our hospital between 2004 and 2018 were graded according to splenic vessel involvement status as clear, abutment, or encasement. Clinicopathological prognostic factors and overall survival (OS) and recurrence-free survival (RFS) rates were compared between the three groups. The prognostic value of radiological involvement status was assessed using Harrell’s concordance statistic (C-index) and time-dependent receiver-operating characteristic curve analysis and compared with pathological findings.

RESULTS: The diagnostic concordance rate was 0.87 (weighted κ statistic). Prognosis worsened with progression from clear, abutment, to encasement status. SpA encasement (hazard ratio [HR] 1.97, p = 0.04) predicted poor OS in multivariate Cox hazard regression analysis. SpA abutment (HR 1.77, p = 0.017) and encasement (HR 1.86, p = 0.034) independently predicted poor RFS. Splenic vein abutment and encasement were not significant predictors of poor OS or RFS. SpA encasement without adjuvant chemotherapy had the poorest prognosis because of early distant metastasis. The prognostic value was higher for radiological SpA involvement than for pathological SpA invasion.

CONCLUSIONS: Radiological SpA involvement status is a meaningful and reproducible prognostic indicator that can be used preoperatively for determining the treatment strategy in PDAC of the body and tail.

PMID:35691957 | DOI:10.1245/s10434-022-11950-1

Lifetime Data Anal. 2022 Jun 13. doi: 10.1007/s10985-022-09556-6. Online ahead of print.

ABSTRACT

The heterogeneous inverse Gaussian (IG) process is one of the most popular and most considered degradation models for highly reliable products. One difficulty with heterogeneous IG processes is the lack of analytic expressions for the Fisher information matrix (FIM). Thus, it is a challenge to find an optimum test plan using any information-based criteria with decision variables such as the termination time, the number of measurements and sample size. In this article, the FIM of an IG process with random slopes can be derived explicitly in an algebraic expression to reduce uncertainty caused by the numerical approximation. The D- and V-optimum test plans with/without a cost constraint can be obtained by using a profile optimum plan. Sensitivity analysis is studied to elucidate how optimum planning is influenced by the experimental costs and planning values of the model parameters. The theoretical results are illustrated by numerical simulation and case studies. Simulations, technical derivations and auxiliary formulae are available online as supplementary materials.

PMID:35691960 | DOI:10.1007/s10985-022-09556-6

Ann Surg Oncol. 2022 Jun 12. doi: 10.1245/s10434-022-11973-8. Online ahead of print.

ABSTRACT

BACKGROUND: Preoperative carcinoembryonic antigen (CEA) has been reported as a prognostic factor in patients with colorectal liver metastasis (CRLM) after hepatectomy. However, the impact of a preoperative “CEA uptrend” on prognosis after hepatectomy in these patients remains unknown. This study assessed the impact of CEA uptrend on prognosis in patients undergoing hepatectomy for CRLM.

METHODS: Consecutive patients with CRLM who underwent hepatectomy between 2009 and 2018 were retrospectively analyzed. Patients with CRLM for whom CEA was measured both around 1 month before (CEA-1m) and within 3 days (CEA-3d) before hepatectomy were enrolled. A CEA-3d higher than both the upper limit of normal (5 ng/ml) and CEA-1m was defined as a CEA uptrend.

RESULTS: Study participants comprised 212 patients with CRLM. Of these, 88 patients (41.5%) showed a CEA uptrend. CEA uptrend indicated better discriminatory ability (corrected Akaike information criteria, 733.72) and homogeneity (likelihood ratio chi-square value, 18.80) than CEA-3d or CEA-1m. Patients with CEA uptrend showed poorer overall survival than those without CEA uptrend (p < 0.001). After adjusting for known prognostic factors, the prognostic significance of CEA uptrend retained (hazard ratio 2.63, 95% confidence interval 1.63-4.26, p < 0.001). In subgroup analyses, the prognostic significance of CEA uptrend was retained irrespective of the status of RAS mutation or response to preoperative chemotherapy.

CONCLUSIONS: CEA uptrend offers better prediction of survival outcomes than conventional CEA measurements in patients undergoing hepatectomy for CRLM.

PMID:35691953 | DOI:10.1245/s10434-022-11973-8

ChemSusChem. 2022 Jun 12. doi: 10.1002/cssc.202201006. Online ahead of print.

ABSTRACT

The synthesis of acetic acid by formal isomerization of methyl formate (MF) was investigated using molecular catalysts. The base-catalyzed decarbonylation of MF, yielding CO and methanol in-situ , was integrated with their palladium-catalyzed recombination for the synthesis of acetic acid and methyl acetate in a one pot reaction . The complex [Pd(Cl) 2 (dppe)] (dppe = 1,2-bis(diphenylphosphino)-ethane) in combination with NaI as iodide source and NaOMe as base were identified as promising molecular components to enable the overall conversion. Sequential application of the statistical methods DoE (design of experiments) and simplex optimization was used in combination with thermodynamic analysis of the competing reaction pathways for experimental planning and data analysis. Starting from a proof-of-principle with a turnover number (TON) of 11, the catalytic system could thus be elaborated to allow quantitative conversion of MF with a TON of 43,000 whereby a yield of 83% of acetate groups and a yield of 74% for free acetic acid was obtained.

PMID:35691934 | DOI:10.1002/cssc.202201006

Neurologia (Engl Ed). 2022 Jun 9:S2173-5808(22)00067-0. doi: 10.1016/j.nrleng.2021.10.004. Online ahead of print.

ABSTRACT

BACKGROUND: Recent years have seen considerable changes in the prevention and treatment of acute ischaemic stroke in adult patients. However, the low incidence of paediatric stroke makes the development of specific guidelines more challenging. This study aims to clarify the situation of these children in our region in order to establish a regional protocol to improve the care provided to these patients.

METHODS: We performed a regional incidence study of pediatric stroke (≤ 15 years of age) in Aragon, Spain (1308728 population, 15% aged ≤ 15 years) between 2008 and 2019. Data were obtained from hospital discharge records, including deaths, from the regional health service of Aragón, according to ICD codes for cerebrovascular disease. We analysed demographic, clinical, diagnostic/therapeutic, and prognostic variables.

RESULTS: A total of 21 events were recorded: 8 ischaemic (38.1%) and 13 haemorrhagic strokes (61.9%). The mean age (SD) was 9.3 years (1.0). The sample included 12 boys and nine girls. No statistically significant differences were found between ischaemic and haemorrhagic strokes, except in the chief complaint (language and motor impairment in ischaemic stroke and headache in haemorrhagic stroke). None of the patients with ischaemic stroke received reperfusion therapies. Including the 3 patients who died during hospitalisation, eight patients (42.1%) had modified Rankin Scale scores > 2 at 12 months. Motor deficits were the most common sequela (n=9).

CONCLUSION: Though infrequent, paediatric stroke has an important functional impact. In Spain, Madrid was the first region to adapt the existing code stroke care networks for adult patients. In Aragon, this review has enabled us to work closely with the different stakeholders to offer a care plan for acute paediatric ischaemic stroke. Nevertheless, prospective national registries would be valuable to continue improving the care provided to these patients.

PMID:35691906 | DOI:10.1016/j.nrleng.2021.10.004

Acad Radiol. 2022 Jun 9:S1076-6332(22)00313-0. doi: 10.1016/j.acra.2022.05.011. Online ahead of print.

ABSTRACT

RATIONALE AND OBJECTIVES: To assess the effects of a change from free text reporting to structured reporting on resident reports, the proofreading workload and report turnaround times in the neuroradiology daily routine.

MATERIALS AND METHODS: Our neuroradiology section introduced structured reporting templates in July 2019. Reports dictated by residents during dayshifts from January 2019 to March 2020 were retrospectively assessed using quantitative parameters from report comparison. Through automatic analysis of text-string differences between report states (i.e. draft, preliminary and final report), Jaccard similarities and edit distances of reports following read-out sessions as well as after report sign-off were calculated. Furthermore, turnaround times until preliminary and final report availability to clinicians were investigated. Parameters were visualized as trending line graphs and statistically compared between reporting standards.

RESULTS: Three thousand five hundred thirty-eight reports were included into analysis. Mean Jaccard similarity of resident drafts and staff-reviewed final reports increased from 0.53 ± 0.37 to 0.79 ± 0.22 after the introduction of structured reporting (p < .001). Both mean overall edits on draft reports by residents following read-out sessions (0.30 ± 0.45 vs. 0.09 ± 0.29; p < .001) and by staff radiologists during report sign-off (0.17 ± 0.28 vs. 0.12 ± 0.23, p < .001) decreased. With structured reporting, mean turnaround time until preliminary report availability to clinicians decreased by 20.7 minutes (246.9 ± 207.0 vs. 226.2 ± 224.9; p < .001). Similarly, final reports were available 35.0 minutes faster on average (558.05 ± 15.1 vs. 523.0 ± 497.3; p = .002).

CONCLUSION: Structured reporting is beneficial in the neuroradiology daily routine, as resident drafts require fewer edits in the report review process. This reduction in proofreading workload is likely responsible for lower report turnaround times.

PMID:35691879 | DOI:10.1016/j.acra.2022.05.011

Vaccine. 2022 Jun 9:S0264-410X(22)00476-5. doi: 10.1016/j.vaccine.2022.04.048. Online ahead of print.

ABSTRACT

BACKGROUND: Influenza outbreaks in aged care facilities are a major public health concern. In response to the severe 2017 influenza season in Australia, enhanced influenza vaccines were introduced from 2018 onwards for those over 65 and more emphasis was placed on improving vaccination rates among aged care staff. During the COVID-19 pandemic, these efforts were then further escalated to reduce the additional burden that influenza could pose to facilities.

METHODS: An observational epidemiological study was conducted from 2018 to 2020 in nine Sydney (Australia) aged care facilities of the same provider. De-identified vaccination data and physical layout data were collected from participating facility managers from 2018 to 2020. Active surveillance of influenza-like illness was carried out from 2018 to 2020 influenza seasons. Correlation and Poisson regression analyses were carried out to explore the relationship between physical layout variables to occurrence of influenza cases.

RESULTS: Influenza cases were low in 2018 and 2019, and there were no confirmed influenza cases identified in 2020. Vaccination rates increased among staff by 50.5% and residents by 16.8% over the three-year period of surveillance from 2018 to 2020. For each unit increase in total number of beds, common areas, single rooms, all types of rooms (including double occupancy rooms), the influenza cases increased by 1.02 (95% confidence interval:1.018-1.025), 1.04 (95% confidence interval: 1.019-1.073), 1.03 (95% confidence interval: 1.016-1 0.038) and 1.02 (95% confidence interval:1.005-1.026) times which were found to be statistically significant. For each unit increase in the proportion of shared rooms, influenza cases increased by 1.004 (95% confidence interval:1.0001-1.207) which was found to be statistically significant.

CONCLUSIONS: There is a relationship between influenza case counts and aspects of the physical layout such as facility size, and this should be considered in assessing risk of outbreaks in aged care facilities. Increased vaccination rates in staff and COVID-19 prevention and control measures may have eliminated influenza in the studied facilities in 2020.

PMID:35691870 | DOI:10.1016/j.vaccine.2022.04.048

J Cardiothorac Vasc Anesth. 2022 May 13:S1053-0770(22)00337-8. doi: 10.1053/j.jvca.2022.05.012. Online ahead of print.

ABSTRACT

OBJECTIVE: To evaluate the effect of anticoagulation targets and intensity on bleeding events, thrombotic events, and transfusion requirements in patients with acute respiratory distress syndrome (ARDS) receiving venovenous extracorporeal membrane oxygenation (ECMO) and continuous-infusion heparin.

DESIGN: A retrospective cohort study.

SETTING: At a single-center, large academic medical center.

PARTICIPANTS: One hundred thirty-six critically ill patients.

INTERVENTIONS: The following three therapeutic targets were implemented over time and evaluated: (1) no protocol (September 2013-August 2016): no standardized anticoagulation protocol or transfusion thresholds; (2) <50 seconds (September 2016-January 2018): standardized activated partial thromboplastin time (aPTT) goal of <50 seconds, maximum heparin infusion rate of 1,200 units/h, transfusion threshold of hemoglobin (Hgb) <8 g/dL; and (3) 40-to-50 seconds (February 2018-December 2019): aPTT goal of 40-to-50 sec, no maximum heparin infusion rate, transfusion threshold of Hgb <7 g/dL.

MEASUREMENTS AND MAIN RESULTS: Continuous variables were compared using the Kruskal-Wallis test, and categorical variables were compared using Fisher exact tests. The primary endpoint, an incidence of at least 1 bleeding event, was highest in the no-protocol group though not statistically different among groups (39.3% v 26.7% v 34%, p = 0.5). Thrombotic complications were similar. The median units of packed red blood cells transfused were highest in the no-protocol group (3 v 2 v 0.5, p < 0.001).

CONCLUSION: Anticoagulation protocols standardizing aPTT goals to <50 or 40-to-50 seconds may be a reasonable strategy for patients receiving venovenous ECMO for ARDS. More restrictive hemoglobin transfusion thresholds, in combination with lower aPTT targets, may be associated with a reduction in transfusion requirements.

PMID:35691853 | DOI:10.1053/j.jvca.2022.05.012