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1.
Epidemics ; 47: 100745, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38593727

RESUMEN

We analyse infectious disease case surveillance data to estimate COVID-19 spread and gain an understanding of the impact of introducing vaccines to counter the disease in Switzerland. The data used in this work is extensive and detailed and includes information on weekly number of cases and vaccination rates by age and region. Our approach takes into account waning immunity. The statistical analysis allows us to determine the effects of choosing alternative vaccination strategies. Our results indicate greater uptake of vaccine would have led to fewer cases with a particularly large effect on undervaccinated regions. An alternative distribution scheme not targeting specific age groups also leads to fewer cases overall but could lead to more cases among the elderly (a potentially vulnerable population) during the early stage of prophylaxis rollout.


Asunto(s)
Vacunas contra la COVID-19 , COVID-19 , SARS-CoV-2 , Humanos , COVID-19/prevención & control , COVID-19/epidemiología , COVID-19/inmunología , COVID-19/transmisión , Suiza/epidemiología , Vacunas contra la COVID-19/inmunología , Vacunas contra la COVID-19/administración & dosificación , SARS-CoV-2/inmunología , Anciano , Persona de Mediana Edad , Adulto , Programas de Inmunización , Adolescente , Niño , Adulto Joven , Vacunación/estadística & datos numéricos , Preescolar , Lactante
2.
R Soc Open Sci ; 10(7): 230448, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37476516

RESUMEN

Theoretical arguments and empirical investigations indicate that a high proportion of published findings do not replicate and are likely false. The current position paper provides a broad perspective on scientific error, which may lead to replication failures. This broad perspective focuses on reform history and on opportunities for future reform. We organize our perspective along four main themes: institutional reform, methodological reform, statistical reform and publishing reform. For each theme, we illustrate potential errors by narrating the story of a fictional researcher during the research cycle. We discuss future opportunities for reform. The resulting agenda provides a resource to usher in an era that is marked by a research culture that is less error-prone and a scientific publication landscape with fewer spurious findings.

4.
Hautarzt ; 70(3): 204-209, 2019 Mar.
Artículo en Alemán | MEDLINE | ID: mdl-30478600

RESUMEN

Digital papillary adenocarcinoma is a rare but well characterized carcinoma of the sweat glands, which apart from very few exceptions is localized in acral skin. This type of sweat gland carcinoma tends to recur locally and may cause delayed metastases in a few cases. We describe the clinical findings and the broad histopathologic spectrum of four cases of this rare adnexal carcinoma and give a short summary of the literature.


Asunto(s)
Adenocarcinoma Papilar/patología , Neoplasias de las Glándulas Sudoríparas/patología , Glándulas Sudoríparas/patología , Adenocarcinoma Papilar/cirugía , Adulto , Femenino , Dedos/patología , Humanos , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia , Neoplasias de las Glándulas Sudoríparas/cirugía , Resultado del Tratamiento
5.
Eur J Trauma Emerg Surg ; 45(1): 91-98, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-29238847

RESUMEN

PURPOSE: To find ways to reduce the rate of over-triage without drastically increasing the rate of under-triage, we applied a current guideline and identified relevant pre-hospital triage predictors that indicate the need for immediate evaluation and treatment of severely injured patients in the resuscitation area. METHODS: Data for adult trauma patients admitted to our level-1 trauma centre in a one year period were collected. Outpatients were excluded. Correct triage for trauma team activation was identified for patients with an ISS or NISS ≥ 16 or the need for ICU treatment due to trauma sequelae. In this retrospective analysis, patients were assigned to trauma team activation according to the S3 guideline of the German Trauma Society. This assignment was compared to the actual need for activation as defined above. 13 potential predictors were retained. The relevance of the predictors was assessed and 14 models of interest were considered. The performance of these potential triage models to predict the need for trauma team activation was evaluated with leave-one-out cross-validated Brier and logarithmic scores. RESULTS: A total of 1934 inpatients ≥ 16 years were admitted to our trauma department (mean age 48 ± 22 years, 38% female). Sixty-nine per cent (n = 1341) were allocated to the emergency department and 31% (n = 593) were treated in the resuscitation room. The median ISS was 4 (IQR 7) points and the median NISS 4 (IQR 6) points. The mortality rate was 3.5% (n = 67) corresponding to a standardized mortality ratio of 0.73. Under-triage occurred in 1.3% (26/1934) and over-triage in 18% (349/1934). A model with eight predictors was finally selected with under-triage rate of 3.3% (63/1934) and over-triage rate of 10.8% (204/1934). CONCLUSION: The trauma team activation criteria could be reduced to eight predictors without losing its predictive performance. Non-relevant parameters such as EMS provider judgement, endotracheal intubation, suspected paralysis, the presence of burned body surface of > 20% and suspected fractures of two proximal long bones could be excluded for full trauma team activation. The fact that the emergency physicians did a better job in reducing under-triage compared to our final triage model suggests that other variables not present in the S3 guideline may be relevant for prediction.


Asunto(s)
Servicios Médicos de Urgencia/normas , Servicio de Urgencia en Hospital/normas , Triaje/normas , Femenino , Alemania , Humanos , Unidades de Cuidados Intensivos/estadística & datos numéricos , Masculino , Persona de Mediana Edad , Guías de Práctica Clínica como Asunto , Resucitación , Estudios Retrospectivos , Centros Traumatológicos , Índices de Gravedad del Trauma
6.
Ann Oncol ; 29(6): 1423-1430, 2018 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-29648580

RESUMEN

Background: The addition of bevacizumab to temozolomide-based chemoradiotherapy (TMZ/RT â†’ TMZ) did not prolong overall survival (OS) in patients with newly diagnosed glioblastoma in phase III trials. Elderly and frail patients are underrepresented in clinical trials, but early reports suggested preferential benefit in this population. Patients and methods: ARTE was a 2 : 1 randomized, multi-center, open-label, non-comparative phase II trial of hypofractionated RT (40 Gy in 15 fractions) with bevacizumab (10 mg/kg×14 days) (arm A, N = 50) or without bevacizumab (arm B, N = 25) in patients with newly diagnosed glioblastoma aged ≥65 years. The primary objective was to obtain evidence for prolongation of median OS by the addition of bevacizumab to RT. Response was assessed by RANO criteria. Quality of life (QoL) was monitored by the EORTC QLQ-C30/BN20 modules. Exploratory studies included molecular subtyping by 450k whole methylome and gene expression analyses. Results: Median PFS was longer in arm A than in arm B (7.6 and 4.8 months, P = 0.003), but OS was similar (12.1 and 12.2 months, P = 0.77). Clinical deterioration was delayed and more patients came off steroids in arm A. Prolonged PFS in arm A was confined to tumors with the receptor tyrosine kinase (RTK) I methylation subtype (HR 0.25, P = 0.014) and proneural gene expression (HR 0.29, P = 0.025). In a Cox model of OS controlling for established prognostic factors, associations with more favorable outcome were identified for age <70 years (HR 0.52, P = 0.018) and Karnofsky performance score 90%-100% (HR 0.51, P = 0.026). Including molecular subtypes into that model identified an association of the RTK II gene methylation subtype with inferior OS (HR 1.73, P = 0.076). Conclusion: Efficacy outcomes and exploratory analyses of ARTE do not support the hypothesis that the addition of bevacizumab to RT generally prolongs survival in elderly glioblastoma patients. Molecular biomarkers may identify patients with preferential benefit from bevacizumab. Clinical trial registration number: NCT01443676.


Asunto(s)
Antineoplásicos Inmunológicos/uso terapéutico , Bevacizumab/uso terapéutico , Quimioradioterapia/mortalidad , Glioblastoma/tratamiento farmacológico , Glioblastoma/radioterapia , Calidad de Vida , Hipofraccionamiento de la Dosis de Radiación , Anciano , Anciano de 80 o más Años , Femenino , Estudios de Seguimiento , Glioblastoma/patología , Humanos , Masculino , Pronóstico , Tasa de Supervivencia
7.
Epidemiol Infect ; 143(16): 3423-33, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26018224

RESUMEN

Syndromic surveillance (SyS) systems currently exploit various sources of health-related data, most of which are collected for purposes other than surveillance (e.g. economic). Several European SyS systems use data collected during meat inspection for syndromic surveillance of animal health, as some diseases may be more easily detected post-mortem than at their point of origin or during the ante-mortem inspection upon arrival at the slaughterhouse. In this paper we use simulation to evaluate the performance of a quasi-Poisson regression (also known as an improved Farrington) algorithm for the detection of disease outbreaks during post-mortem inspection of slaughtered animals. When parameterizing the algorithm based on the retrospective analyses of 6 years of historic data, the probability of detection was satisfactory for large (range 83-445 cases) outbreaks but poor for small (range 20-177 cases) outbreaks. Varying the amount of historical data used to fit the algorithm can help increasing the probability of detection for small outbreaks. However, while the use of a 0·975 quantile generated a low false-positive rate, in most cases, more than 50% of outbreak cases had already occurred at the time of detection. High variance observed in the whole carcass condemnations time-series, and lack of flexibility in terms of the temporal distribution of simulated outbreaks resulting from low reporting frequency (monthly), constitute major challenges for early detection of outbreaks in the livestock population based on meat inspection data. Reporting frequency should be increased in the future to improve timeliness of the SyS system while increased sensitivity may be achieved by integrating meat inspection data into a multivariate system simultaneously evaluating multiple sources of data on livestock health.


Asunto(s)
Mataderos , Enfermedades Transmisibles/veterinaria , Monitoreo Epidemiológico , Animales , Enfermedades Transmisibles/epidemiología , Simulación por Computador , Estudios Prospectivos , Estudios Retrospectivos , Suiza/epidemiología , Factores de Tiempo
8.
Clin Microbiol Infect ; 21(7): 676.e1-4, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25882361

RESUMEN

Although some studies suggested specific foods/beverages as risk factors for travellers' diarrhoea (TD), details of transmission remain unclear. We assessed the influence of travel style (luxury/middle-class versus backpacking) on TD risk. TD attack rates were compared in a prospective study among travellers to India at the University of Zurich's Travel Clinic. Information on consumption of foods/beverages was collected. Seventy-one luxury/middle-class travellers and 21 backpackers completed the study; overall 37% suffered from TD (62% backpackers, 30% luxury/middle-class travellers, OR 4.43, p 0.022). Travel style rather than the consumption of specific foods/beverages appears to be a risk factor for TD development.


Asunto(s)
Diarrea/epidemiología , Viaje , Adolescente , Adulto , Anciano , Femenino , Humanos , India , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Factores de Riesgo , Adulto Joven
9.
Epidemiol Infect ; 143(9): 1982-9, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25400006

RESUMEN

Campylobacteriosis has been the most common food-associated notifiable infectious disease in Switzerland since 1995. Contact with and ingestion of raw or undercooked broilers are considered the dominant risk factors for infection. In this study, we investigated the temporal relationship between the disease incidence in humans and the prevalence of Campylobacter in broilers in Switzerland from 2008 to 2012. We use a time-series approach to describe the pattern of the disease by incorporating seasonal effects and autocorrelation. The analysis shows that prevalence of Campylobacter in broilers, with a 2-week lag, has a significant impact on disease incidence in humans. Therefore Campylobacter cases in humans can be partly explained by contagion through broiler meat. We also found a strong autoregressive effect in human illness, and a significant increase of illness during Christmas and New Year's holidays. In a final analysis, we corrected for the sampling error of prevalence in broilers and the results gave similar conclusions.


Asunto(s)
Infecciones por Campylobacter/epidemiología , Infecciones por Campylobacter/veterinaria , Campylobacter/aislamiento & purificación , Pollos , Enfermedades de las Aves de Corral/epidemiología , Animales , Infecciones por Campylobacter/microbiología , Humanos , Incidencia , Carne/microbiología , Enfermedades de las Aves de Corral/microbiología , Prevalencia , Estudios Retrospectivos , Estaciones del Año , Suiza/epidemiología
10.
Mol Psychiatry ; 20(1): 133-39, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24863145

RESUMEN

Although overweight and obesity are associated with poor health outcomes in the elderly, the biological bases of obesity-related behaviors during aging are poorly understood. Common variants in the FTO gene are associated with adiposity in children and younger adults as well as with adverse mental health in older individuals. However, it is unclear whether FTO influences longitudinal trajectories of adiposity and other intermediate phenotypes relevant to mental health during aging. We examined whether a commonly carried obesity-risk variant in the FTO gene (rs1421085 single-nucleotide polymorphism) influences adiposity and is associated with changes in brain function in participants within the Baltimore Longitudinal Study of Aging, one of the longest-running longitudinal aging studies in the United States. Our results show that obesity-related risk allele carriers of FTO gene show dose-dependent increments in body mass index during aging. Moreover, the obesity-related risk allele is associated with reduced medial prefrontal cortical function during aging. Consistent with reduced brain function in regions intrinsic to impulse control and taste responsiveness, risk allele carriers of FTO exhibit dose-dependent increments in both impulsivity and intake of fatty foods. We propose that a common neural mechanism may underlie obesity-associated impulsivity and increased consumption of high-calorie foods during aging.


Asunto(s)
Adiposidad/genética , Envejecimiento/genética , Conducta Alimentaria/fisiología , Conducta Impulsiva/fisiología , Polimorfismo de Nucleótido Simple/genética , Proteínas/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato , Índice de Masa Corporal , Encéfalo/diagnóstico por imagen , Dieta , Ingestión de Alimentos/genética , Femenino , Genotipo , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Obesidad/genética , Cintigrafía , Estados Unidos , Adulto Joven
11.
HIV Med ; 13(7): 387-97, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22257025

RESUMEN

OBJECTIVES: Smoking is the most prevalent modifiable risk factor for cardiovascular diseases among HIV-positive persons. We assessed the effect on smoking cessation of training HIV care physicians in counselling. METHODS: The Swiss HIV Cohort Study (SHCS) is a multicentre prospective observational database. Our single-centre intervention at the Zurich centre included a half day of standardized training for physicians in counselling and in the pharmacotherapy of smokers, and a physicians' checklist for semi-annual documentation of their counselling. Smoking status was then compared between participants at the Zurich centre and other institutions. We used marginal logistic regression models with exchangeable correlation structure and robust standard errors to estimate the odds of smoking cessation and relapse. RESULTS: Between April 2000 and December 2010, 11 056 SHCS participants had 121 238 semi-annual visits and 64 118 person-years of follow-up. The prevalence of smoking decreased from 60 to 43%. During the intervention at the Zurich centre from November 2007 to December 2009, 1689 participants in this centre had 6068 cohort visits. These participants were more likely to stop smoking [odds ratio (OR) 1.23; 95% confidence interval (CI) 1.07-1.42; P=0.004] and had fewer relapses (OR 0.75; 95% CI 0.61-0.92; P=0.007) than participants at other SHCS institutions. The effect of the intervention was stronger than the calendar time effect (OR 1.19 vs. 1.04 per year, respectively). Middle-aged participants, injecting drug users, and participants with psychiatric problems or with higher alcohol consumption were less likely to stop smoking, whereas persons with a prior cardiovascular event were more likely to stop smoking. CONCLUSIONS: An institution-wide training programme for HIV care physicians in smoking cessation counselling led to increased smoking cessation and fewer relapses.


Asunto(s)
Consejo Dirigido/métodos , Seropositividad para VIH/complicaciones , Capacitación en Servicio , Médicos/normas , Cese del Hábito de Fumar/métodos , Fumar/terapia , Adulto , Factores de Edad , Anciano , Estudios de Cohortes , Femenino , Humanos , Modelos Logísticos , Masculino , Trastornos Mentales/complicaciones , Persona de Mediana Edad , Motivación , Oportunidad Relativa , Relaciones Médico-Paciente , Médicos/tendencias , Estudios Prospectivos , Factores de Riesgo , Fumar/efectos adversos , Trastornos Relacionados con Sustancias/complicaciones , Suiza/epidemiología
12.
J Eur Acad Dermatol Venereol ; 26(1): 48-53, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-21414035

RESUMEN

BACKGROUND: Actinic keratoses (AK) are carcinomata in situ with the potential to develop into invasive carcinoma. Several studies have demonstrated that 3% diclofenac in 2.5% hyaluronic acid gel (HA) is effective and well tolerated in the treatment of AK. To date there are no large randomized multicentre trials with treatment durations longer than 90 days and histopathological control of treatment outcome. OBJECTIVE: The aim of this study was to investigate whether a prolonged treatment with diclofenac in HA of 6 vs. 3 months adds to the efficacy in treatment for AK and if this will influence tolerability and quality of life (QoL). METHODS: This was a multicentre, randomized open-label study in which 418 patients with mild to moderate AKs were randomized into two treatment groups. Group A received diclofenac in HA for 3 months and group B for 6 months. Treatment efficacy was assessed by size measurement and a final biopsy of a defined marker AK. Quality of life was measured using the Dermatology Life Quality Index questionnaire. RESULTS: Clinical complete clearance was observed in 40% in group A and in 45% in group B (P = 0.38). Histopathological clearance was confirmed in 30% in group A and in 40% in group B (P = 0.16). Treatment was well tolerated and QoL was significantly improved after treatment in both treatment groups. CONCLUSION: Treatment with diclofenac in HA is effective and well tolerated during a treatment period of 3 months as well as 6 months. Prolongation of the treatment duration did not significantly affect treatment outcome.


Asunto(s)
Antiinflamatorios no Esteroideos/uso terapéutico , Diclofenaco/uso terapéutico , Ácido Hialurónico/administración & dosificación , Queratosis Actínica/tratamiento farmacológico , Anciano , Anciano de 80 o más Años , Antiinflamatorios no Esteroideos/administración & dosificación , Diclofenaco/administración & dosificación , Diclofenaco/efectos adversos , Femenino , Alemania , Humanos , Ácido Hialurónico/efectos adversos , Masculino , Persona de Mediana Edad
13.
Stat Med ; 30(10): 1118-36, 2011 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-21484849

RESUMEN

Infectious disease counts from surveillance systems are typically observed in several administrative geographical areas. In this paper, a non-linear model for the analysis of such multiple time series of counts is discussed. To account for heterogeneous incidence levels or varying transmission of a pathogen across regions, region-specific and possibly spatially correlated random effects are introduced. Inference is based on penalized likelihood methodology for mixed models. Since the use of classical model choice criteria such as AIC or BIC can be problematic in the presence of random effects, models are compared by means of one-step-ahead predictions and proper scoring rules. In a case study, the model is applied to monthly counts of meningococcal disease cases in 94 departments of France (excluding Corsica) and weekly counts of influenza cases in 140 administrative districts of Southern Germany. The predictive performance improves if existing heterogeneity is accounted for by random effects.


Asunto(s)
Enfermedades Transmisibles/epidemiología , Brotes de Enfermedades , Dinámicas no Lineales , Vigilancia de la Población/métodos , Francia , Alemania , Humanos , Incidencia , Gripe Humana/epidemiología , Infecciones Meningocócicas/epidemiología , Análisis Numérico Asistido por Computador
14.
Curr Alzheimer Res ; 8(4): 361-5, 2011 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-21222595

RESUMEN

Changes in regional activity levels and network connectivity occur across the lifespan within the default mode network (DMN) of resting brain function. Changes with age are noted in most components of the DMN, especially in medial frontal/anterior cingulate and posterior cingulate/precuneus regions. Individuals with age-related disease such as mild cognitive impairment (MCI) and Alzheimer's disease (AD) demonstrate additional default-related changes particularly in posterior cingulate/precuneus and hippocampal regions. As these regions are areas of known pathologic change in both normal aging and age-related disease, examining DMN activity may allow future studies to more fully assess the relationship between pathology and function in these regions. The ability to form this structure-function link could allow us to determine critical factors involved in the decline or preservation of function in the presence of age-related neuropathology.


Asunto(s)
Mapeo Encefálico , Encéfalo/patología , Demencia/patología , Enfermedad de Alzheimer/complicaciones , Enfermedad de Alzheimer/patología , Trastornos del Conocimiento/etiología , Trastornos del Conocimiento/patología , Demencia/complicaciones , Humanos , Red Nerviosa/patología
15.
J Eur Acad Dermatol Venereol ; 25(4): 441-6, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20659308

RESUMEN

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading strains among multiresistant hospital microflora. In 2003, we noted an increase in the number of MRSA strain 35 among patients at the University of Zurich, Department of Dermatology. At the end of 2003, we implemented additional policies in hospital hygiene, which significantly decreased the number of MRSA infections. METHODS: This is a retrospective study on 65 consecutive patients at the Department of Dermatology, University Hospital of Zurich, in whom MRSA contamination was newly diagnosed during the period of 2003-2008. All isolated strains were genotyped. We implemented additional policies as strict hand hygiene and avoidance of sharing the same ointment pots or tubes amongst patients. As soon as the skin disease was healed, decolonization of MRSA was undertaken by a 5-day topical treatment. RESULTS: Of the 65 MRSA patients, 19 (29%) patients carried a genotypical strain (MRSA 35) that was identified to be specific for the Department of Dermatology. Three health care workers (HCWs) were tested positive. The outlined measures reduced the incidence of new transmissions of this specific strain MRSA 35 significantly (P=0.001) with a complete disappearance of new transmissions of MRSA 35 in the year 2008. Of the 65 patients, 15 (23%) patients became long-term carriers, among all (15/15; 100%) had persisting active skin lesions. CONCLUSIONS: Strict hand hygiene and avoidance of sharing ointments among patients were highly effective measures in controlling an outbreak of MRSA. Complete of near-to-complete remission of the underlying dermatoses, skin lesions or chronic wounds, is a prerequisite for complete decolonization of MRSA carriers.


Asunto(s)
Dermatología , Brotes de Enfermedades , Hospitales Universitarios/organización & administración , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Infecciones Estafilocócicas/prevención & control , Humanos , Incidencia , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiología , Suiza/epidemiología
16.
Epidemiol Infect ; 139(4): 505-15, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20619079

RESUMEN

The objective of this study was to characterize empirically the association between vaccination coverage and the size and occurrence of measles epidemics in Germany. In order to achieve this we analysed data routinely collected by the Robert Koch Institute, which comprise the weekly number of reported measles cases at all ages as well as estimates of vaccination coverage at the average age of entry into the school system. Coverage levels within each federal state of Germany are incorporated into a multivariate time-series model for infectious disease counts, which captures occasional outbreaks by means of an autoregressive component. The observed incidence pattern of measles for all ages is best described by using the log proportion of unvaccinated school starters in the autoregressive component of the model.


Asunto(s)
Brotes de Enfermedades , Vacuna contra el Sarampión-Parotiditis-Rubéola/administración & dosificación , Vacuna contra el Sarampión-Parotiditis-Rubéola/inmunología , Sarampión/epidemiología , Sarampión/prevención & control , Vacunación/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Alemania/epidemiología , Humanos , Incidencia , Lactante , Recién Nacido , Persona de Mediana Edad , Modelos Estadísticos , Adulto Joven
17.
Biometrics ; 66(4): 1295-305, 2010 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-20353460

RESUMEN

Calibration, the statistical consistency of forecast distributions and the observations, is a central requirement for probabilistic predictions. Calibration of continuous forecasts is typically assessed using the probability integral transform histogram. In this article, we propose significance tests based on scoring rules to assess calibration of continuous predictive distributions. For an ideal normal forecast we derive the first two moments of two commonly used scoring rules: the logarithmic and the continuous ranked probability score. This naturally leads to the construction of two unconditional tests for normal predictions. More generally, we propose a novel score regression approach, where the individual scores are regressed on suitable functions of the predictive variance. This conditional approach is applicable even for certain nonnormal predictions based on the Dawid-Sebastiani score. Two case studies illustrate that the score regression approach has typically more power in detecting miscalibrated forecasts than the other approaches considered, including a recently proposed technique based on conditional exceedance probability curves.


Asunto(s)
Biometría/métodos , Predicción , Modelos Estadísticos , Probabilidad , Calibración , Análisis de Regresión
18.
Digestion ; 81(4): 252-64, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20130407

RESUMEN

BACKGROUND: Environmental factors are thought to play an important role in the development of Crohn's disease (CD). Immune responses against auto-antigens or food antigens may be a reason for the perpetuation of inflammation. METHODS: In a pilot study, 79 CD patients and 20 healthy controls were examined for food immunoglobulin G (IgG). Thereafter, the clinical relevance of these food IgG antibodies was assessed in a double-blind cross-over study with 40 patients. Based on the IgG antibodies, a nutritional intervention was planned. The interferon (IFN)gamma secretion of T cells was measured. Eosinophil-derived neurotoxin was quantified in stool. RESULTS: The pilot study resulted in a significant difference of IgG antibodies in serum between CD patients and healthy controls. In 84 and 83% of the patients, respectively, IgG antibodies against processed cheese and yeast were detected. The daily stool frequency significantly decreased by 11% during a specific diet compared with a sham diet. Abdominal pain reduced and general well-being improved. IFNgamma secretion of T cells increased. No difference for eosinophil-derived neurotoxin in stool was detected. CONCLUSION: A nutritional intervention based on circulating IgG antibodies against food antigens showed effects with respect to stool frequency. The mechanisms by which IgG antibodies might contribute to disease activity remain to be elucidated.


Asunto(s)
Anticuerpos Antiidiotipos/inmunología , Enfermedad de Crohn/dietoterapia , Enfermedad de Crohn/inmunología , Hipersensibilidad a los Alimentos/inmunología , Inmunoglobulina G/inmunología , Dolor Abdominal/fisiopatología , Adolescente , Adulto , Análisis de Varianza , Enfermedad de Crohn/sangre , Estudios Cruzados , Defecación/fisiología , Progresión de la Enfermedad , Método Doble Ciego , Ensayo de Inmunoadsorción Enzimática , Neurotoxina Derivada del Eosinófilo/análisis , Neurotoxina Derivada del Eosinófilo/inmunología , Heces , Femenino , Alimentos , Estado de Salud , Humanos , Masculino , Persona de Mediana Edad , Proyectos Piloto , Probabilidad , Pronóstico , Recurrencia , Valores de Referencia , Medición de Riesgo , Resultado del Tratamiento , Adulto Joven
19.
Stat Med ; 29(12): 1325-39, 2010 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-20101670

RESUMEN

For bivariate meta-analysis of diagnostic studies, likelihood approaches are very popular. However, they often run into numerical problems with possible non-convergence. In addition, the construction of confidence intervals is controversial. Bayesian methods based on Markov chain Monte Carlo (MCMC) sampling could be used, but are often difficult to implement, and require long running times and diagnostic convergence checks. Recently, a new Bayesian deterministic inference approach for latent Gaussian models using integrated nested Laplace approximations (INLA) has been proposed. With this approach MCMC sampling becomes redundant as the posterior marginal distributions are directly and accurately approximated. By means of a real data set we investigate the influence of the prior information provided and compare the results obtained by INLA, MCMC, and the maximum likelihood procedure SAS PROC NLMIXED. Using a simulation study we further extend the comparison of INLA and SAS PROC NLMIXED by assessing their performance in terms of bias, mean-squared error, coverage probability, and convergence rate. The results indicate that INLA is more stable and gives generally better coverage probabilities for the pooled estimates and less biased estimates of variance parameters. The user-friendliness of INLA is demonstrated by documented R-code.


Asunto(s)
Teorema de Bayes , Pruebas Diagnósticas de Rutina/estadística & datos numéricos , Metaanálisis como Asunto , Modelos Estadísticos , Sesgo , Biomarcadores de Tumor/análisis , Bioestadística , Intervalos de Confianza , Humanos , Funciones de Verosimilitud , Modelos Lineales , Cadenas de Markov , Método de Montecarlo , Sensibilidad y Especificidad , Telomerasa/análisis , Neoplasias de la Vejiga Urinaria/diagnóstico , Neoplasias de la Vejiga Urinaria/enzimología
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