Modelling asset correlations: A nonparametric approach

This article proposes a time-varying nonparametric estimator and a time-varying semiparametric estimator of the correlation matrix. We discuss representation, estimation based on kernel smoothing and inference. An extensive Monte Carlo simulation study is performed to compare the semiparametric and nonparametric models with the DCC speci fication. Our bivariate simulation results show that the semiparametric and nonparametric models are best in DGPs with gradual changes or structural breaks in correlations. However, in DGPs with rapid changes or constancy in correlations the DCC delivers the best outcome. Moreover, in multivariate simulations the semiparametric and nonparametric models fare the best in DGPs with substantial time-variability in correlations, while when allowing for little variability in the correlations the DCC is the dominant speci fication. The methodologies are illustrated by estimating the correlations for two interesting portfolios. The rst portfolio consists of the equity sectors SPDRs and the S&P 500 composite, while the second one contains major currencies that are actively traded in the foreign exchange market. Portfolio evaluation results show that the nonparametric estimator generally dominates its competitors, with a statistically significant lower portfolio variance

Abuse in the caregiving relationship between older people with memory disorders and family caregivers: A systematic review

Aim To synthesize what is known about elder abuse and relationship factors associated with abuse between caregivers and older people with memory disorders at home. Background Concerns about abuse in the caring relationship between older people with memory disorders and family caregivers have increased. Abuse is associated with negative outcomes on older people's health, quality of life, and zest for life. Abuse in the caring relationship manifests in financial exploitation, neglect, mistreatment, and physical issues. Design Systematic review. Data Sources Databases including Scopus, PubMed/Medline, SveMed+, Cinalh, SonINDEX, and ProQuest were searched using keywords about abuse in the caring relationship between older people with memory disorders and family caregivers at home. Articles published between 2005–2019 were retrieved and underwent data analysis and knowledge synthesis. Review Methods The review was presented under the categories of the dyadic approach of elder abuse in connection with the role of caregiver (risk) and care recipient (vulnerability) by Fulmer et al. (2005). Results The search process led to 12 quantitative studies, including an intervention, a prospective, nine surveys, and a cross‐sectional structural interview. Findings were synthesized and presented under ‘personal’, ‘physical and psychological’, and ‘social’ domains indicating the bilateral roles of caregiver and care recipient leading to abuse. Conclusion This review depicted factors influencing abuse in the caring relationship between older people with memory disorders and their family caregivers at home. They included family caregivers’ psychological issues, knowledge of memory disorders and modifications, previous caring relationship, social support, number of care recipients, and care recipients’ functional level. Impact This review identifies what influences elder abuse by family caregivers using the dyadic approach and explains how abuse can be prevented through suggested strategies. The review findings are relevant to multidisciplinary healthcare providers and can guide the provision of support, screening and assessment, educational programs, and legislative initiatives

Episodic abdominal pain characteristics are not associated with clinically relevant improvement of health status after cholecystectomy

BACKGROUND: Cholecystectomy is the therapy of first choice in patients with uncomplicated symptomatic cholecystolithiasis, but it remains unclear which patients truly benefit in terms of health status improvement. Patients generally present with episodic abdominal pain of varying frequency, duration, and intensity. We assessed whether characteristics of abdominal pain episodes are determinants of clinically relevant improvement of health status after cholecystectomy. METHODS: In a post hoc analysis of a prospective multicenter cohort study, patients of ≥18 years of age with uncomplicated symptomatic cholecystolithiasis subjected to cholecystectomy were included. Preoperatively, patients received a structured interview and a questionnaire consisting of the visual analogue scale (VAS; range 0–100) and gastrointestinal quality of life index (GIQLI). At 12 weeks after cholecystectomy, the GIQLI was again administered. Logistic regression analyses were performed to determine significant associations. RESULTS: Questionnaires were sent to 261 and returned by 166 (63.6 %) patients (128 females, mean age at surgery 49.5 ± 13.8). A total of 131 (78.9 %) patients reported a clinically relevant improvement of health status. The median (interquartile range) frequency, duration, and intensity of abdominal pain episodes were 0.38 (0.18–0.75) a week, 4.00 (2.00–8.00) hours, and 92 (77–99), respectively. None of the characteristics was associated with a clinically relevant improvement of health status at 12 weeks after cholecystectomy. CONCLUSIONS: Characteristics of abdominal pain episodes cannot be used to inform patients with symptomatic cholecystolithiasis who are skeptic about the timing of cholecystectomy for optimal benefit. Timing of cholecystectomy should therefore be based on other characteristics and preferences

Postgraduate Research Studies handbook

2001 handbook for Postgraduate Research Studie

Familial Mediterranean Fever and Hyperimmunoglobulinemia D syndrome: two diseases with distinct clinical, serologic, and genetic features

Item does not contain fulltex

Incident Gallstones During Somatostatin Analog Treatment are Associated with Acute Biliary Complications Especially After Discontinuation

INTRODUCTION: Gallstones are a known adverse effect of somatostatin analogs, but the exact incidence and clinical implications are unknown. OBJECTIVES: The aim of this study was to investigate the incidence of gallstones on imaging and related complications in unbiased trial data. METHODS: Data from the DIPAK 1 trial, in which 305 polycystic kidney disease patients were randomized to standard of care (SoC) or lanreotide for 120 weeks, were used. Magnetic resonance imaging (MRI) was performed at baseline and end of treatment and was assessed for the presence, number, and size of gallstones. For all patients who had gallstones at the end of the trial, we obtained follow-up after the trial. RESULTS: Of 249 patients with data available, 11 patients randomized to lanreotide and four randomized to SoC had gallstones at baseline. During the study, new gallstones were formed in 19/124 patients using lanreotide (15%) and 1/125 patients receiving SoC (1%). The odds ratio for gallstone formation with lanreotide use was 25.9 (95% confidence interval 3.37–198.8; p  20 stones in 69% of patients) and small (≤ 3 mm in 63% of patients). Of the 19 patients with incident gallstones during lanreotide treatment, 9 experienced gallstone-associated complications, 8 of whom experienced gallstone-associated complications after discontinuation of treatment (median time after discontinuation 2.5 years). In patients with gallstones at baseline and in patients receiving SoC, no complications occurred. CONCLUSIONS: Treatment with a somatostatin analog leads to the formation of multiple, small gallstones that are associated with severe complications, especially after discontinuation of therapy. CLINICAL TRIAL REGISTRY WEBSITE AND TRIAL NUMBER: ClinicalTrials.gov (https://clinicaltrials.gov); NCT01616927. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40268-021-00342-7

A randomized controlled trial to compare a restrictive strategy to usual care for the effectiveness of cholecystectomy in patients with symptomatic gallstones (SECURE trial protocol)

BACKGROUND: Five to 22 % of the adult Western population has gallstones. Among them, 13 to 22 % become symptomatic during their lifetime. Cholecystectomy is the preferred treatment for symptomatic cholecystolithiasis. Remarkably, cholecystectomy provides symptom relief in only 60-70 % of patients. The objective of this trial is to compare the effectiveness of usual (operative) care with a restrictive strategy using a standardized work-up with stepwise selection for cholecystectomy in patients with gallstones and abdominal complaints. DESIGN AND METHODS: The SECURE-trial is designed as a multicenter, randomized, parallel-arm, non-inferiority trial in patients with abdominal symptoms and ultrasound proven gallstones or sludge. If patients meet the inclusion criteria they will be randomized to either usual care or the restrictive strategy. Patients in the usual care group will be treated according to the physician's knowledge and preference. Patients in the restrictive care group will be treated with interval evaluation and stepwise selection for laparoscopic cholecystectomy. In this stepwise selection, patients strictly meeting the preselected criteria for symptomatic cholecystolithiasis will be offered a cholecystectomy. Patients not meeting these criteria will be assessed for other diagnoses and re-evaluated at 3-monthly intervals. Follow-up consists of web-based questionnaires at 3, 6, 9 and 12 months. The main end point of this trial is defined as the proportion of patients being pain-free at 12 months follow-up. Pain will be assessed with the Izbicki Pain Score and Gallstone Symptom Score. Secondary endpoints will be the proportion of patients with complications due to gallstones or cholecystectomy, the association between the patients' symptoms and treatment and work performance, and ultimately, cost-effectiveness. DISCUSSION: The SECURE trial is the first randomized controlled trial examining the effectiveness of usual care versus restrictive care in patients with symptomatic gallstones. The outcome of this trial will inform clinicians whether a more restrictive strategy can minimize persistent pain in post-operative patients at least as good as usual care does, but at a lower cholecystectomy rate. (The Netherlands National Trial Register NTR4022, 17th December 2012) TRIAL REGISTRATION: The Netherlands National Trial Register NTR4022 http://www.zonmw.nl/nl/projecten/project-detail/scrutinizing-inefficient-use-of-c holecystectomy-a-randomized-trial-concerning-variation-in-practi/samenvatting/