Evaluación de la significación estadística y cálculo del intervalo de confianza de la razón de mortalidad estandarizada

ResumenLa razón de mortalidad estandarizada (RME) es la razón entre el número de muertes observadas (D) y el número de muertes esperadas (E), tomando como base las tasas de mortalidad de una población de referencia. En el análisis de la RME han sido propuestos varios tests para la evaluación de su significación estadística y para el cálculo de sus intervalos de confianza.En el presente estudio, donde se han calculado las RME de dos causas de muerte en 27 distritos sanitarios de Castilla-La Mancha, la significación estadística de las diferentes RME se ha valorado mediante un test que utiliza la probabilidad exacta de Poisson y mediante cuatro tests que usan aproximaciones normales a Poisson: 1) cálculo de un estadístico Z basado en la asunción de que una variable de Poisson con media E tiene un error estándar √E; 2) estadístico Z con corrección de continuidad; 3) estadístico Z basado en la transformación de la variable en su raíz cuadrada; y 4) estadístico Z creado por Byar como aproximación al test exacto. Se han obtenido, igualmente, los intervalos de confianza mediante el método exacto y mediante tres métodos aproximados; 1) el de Byar; 2) el basado en el estadístico Z no corregido; y 3) el que se basa en la raíz cuadrada de una variable de Poisson.Los resultados obtenidos con los métodos exactos y con el método Byar son muy similares, por lo que se recomienda la utilización de este último como práctica rutinaria, tanto para la evaluación estadística de una RME, como para el cálculo de sus intervalos de confianzaSummaryThe standardized mortality ratio (SMR) is the ratio of the number of deaths observed (D) to the number expected (E), on the basis of the mortality rates of some reference population. Several procedures have been proposed inorder to test its significance and to estimate its confidence intervals.In this study, the SMR of two causes of death in 27 healths areas of Castilla-La Mancha have been calculated. The significance has been evaluated by exact Poisson test and by four methods approximating the Poisson distribution by the normal: 1) a Z statistic based on the assumption that a Poisson variate with expectation E has a standard deviation equal to √E; 2) the Z statistic with a continuity correction; 3) a Z statistic based on the square root transformation of a Poisson variable and 4) an approximation of the exact test by Byar. Also, theconfidence intervals have been estimated by exact method and by three approximate procedures: 1) by Byar; 2) by Z statistic uncorrected and 3) by the square root transformation of the Poisson distribution.With the exact methods and Byar procedure the results were very similar; therefore, using the last to testing significance and estimate the confidence intervals of SMR, is suggested

Efficient methodologies for system matrix modelling in iterative image reconstruction for rotating high-resolution PET

A fully 3D iterative image reconstruction algorithm has been developed for high-resolution PET cameras composed of pixelated scintillator crystal arrays and rotating planar detectors, based on the ordered subsets approach. The associated system matrix is precalculated with Monte Carlo methods that incorporate physical effects not included in analytical models, such as positron range effects and interaction of the incident gammas with the scintillator material. Custom Monte Carlo methodologies have been developed and optimized for modelling of system matrices for fast iterative image reconstruction adapted to specific scanner geometries, without redundant calculations. According to the methodology proposed here, only one-eighth of the voxels within two central transaxial slices need to be modelled in detail. The rest of the system matrix elements can be obtained with the aid of axial symmetries and redundancies, as well as in-plane symmetries within transaxial slices. Sparse matrix techniques for the non-zero system matrix elements are employed, allowing for fast execution of the image reconstruction process. This 3D image reconstruction scheme has been compared in terms of image quality to a 2D fast implementation of the OSEM algorithm combined with Fourier rebinning approaches. This work confirms the superiority of fully 3D OSEM in terms of spatial resolution, contrast recovery and noise reduction as compared to conventional 2D approaches based on rebinning schemes. At the same time it demonstrates that fully 3D methodologies can be efficiently applied to the image reconstruction problem for high-resolution rotational PET cameras by applying accurate pre-calculated system models and taking advantage of the system's symmetries

Socioeconomic determinants of sarcopenic obesity and frail obesity in community-dwelling older adults: The Seniors-ENRICA Study

Information on the association between socioeconomic status (SES) throughout life and sarcopenic obesity is scarce, whereas no study has been focused on the association between SES and frail obesity. This analysis estimated the prevalence of sarcopenic obesity and frail obesity, and their associations with SES in older adults. Data were collected in 2012 from 1,765 non-institutionalized individuals aged ≥65 participating in the Seniors-ENRICA study in Spain, by using standardized techniques and equipment. SES throughout life was evaluated with the father's occupation, participant's educational level, former own occupation, and current poor housing condition. Overall, 17.2% of participants had sarcopenic obesity, and 4.0% frail obesity. No association was found between SES and sarcopenic obesity. In contrast, the prevalence of frail obesity was higher in those with lower education, having worked in manual job, and currently having poor housing condition. Having ≥1 social disadvantages throughout life was associated with higher prevalence of frail obesity. The prevalence of this disorder increased by 1.49 (95% CI: 1.21-1.85) times for each social disadvantage added. The OR (95% CI) of frail obesity was 3.13 (1.71-5.7) for those having 3 or 4 vs. 0 or 1 social disadvantages, implying a more complex process beginning early in life.Data collection was funded by the following grants: PI13/0288; PI14/0009; PI16/01460; PI16/01512; and PI16/00609 (State Secretary of R+D and FEDER/FSE). BM-F was supported by a CIBERCV contract, RFP-T was supported by the National Government of Ecuador through the National Institution of Higher Education, Science, Technology and Innovation-SENESCYT, and ML research activity is funded by Agencia Aragonesa para la Investigación y el Desarrollo (ARAID

Projector Model for Efficient List-Mode Reconstruction in PET Scanners with Parallel Planar Detectors

We have developed a new projector model specifically tailored for fast list-mode tomographic reconstructions in Positron emission tomography (PET) scanners with parallel planar detectors. The model provides an accurate estimation of the probability distribution of coincidence events defined by pairs of scintillating crystals. This distribution is parameterized with 2D elliptical Gaussian functions defined in planes perpendicular to the main axis of the tube of response (TOR). The parameters of these Gaussian functions have been obtained by fitting Monte Carlo simulations that include positron range, acolinearity of gamma rays, as well as detector attenuation and scatter effects. The proposed model has been applied efficiently to list-mode reconstruction algorithms. Evaluation with Monte Carlo simulations over a rotating high resolution PET scanner indicates that this model allows to obtain better recovery to noise ratio in OSEM (ordered-subsets, expectation-maximization) reconstruction, if compared to list-mode reconstruction with symmetric circular Gaussian TOR model, and histogram-based OSEM with precalculated system matrix using Monte Carlo simulated models and symmetries

MicroRNA-223 is a novel negative regulator of HSP90B1 in CLL

Background MicroRNAs are known to inhibit gene expression by binding to the 3′UTR of the target transcript. Downregulation of miR-223 has been recently reported to have prognostic significance in CLL. However, there is no evidence of the pathogenetic mechanism of this miRNA in CLL patients. Methods By applying next-generation sequencing techniques we have detected a common polymorphism (rs2307842), in 24% of CLL patients, which disrupts the binding site for miR-223 in HSP90B1 3′UTR. We investigated whether miR-223 directly targets HSP90B1 through luciferase assays and ectopic expression of miR-223. Quantitative real-time polymerase chain reaction and western blot were used to determine HSP90B1 expression in CLL patients. The relationship between rs2307842 status,HSP90B1 expression and clinico-biological data were assessed. Results HSP90B1 is a direct target for miR-223 by interaction with the putative miR-223 binding site. The analysis in paired samples (CD19+ fraction cell and non-CD19+ fraction cell) showed that the presence of rs2307842 and IGHV unmutated genes determined HSP90B1 overexpression in B lymphocytes from CLL patients. These results were confirmed at the protein level by western blot. Of note, HSP90B1 overexpression was independently predictive of shorter time to the first therapy in CLL patients. By contrast, the presence of rs2307842 was not related to the outcome. Conclusions HSP90B1 is a direct target gene of miR-223. Our results provide a plausible explanation of why CLL patients harboring miR-223 downregulation are associated with a poor outcome, pointing out HSP90B1 as a new pathogenic mechanism in CLL and a promising therapeutic target. Keywords Chronic lymphocytic leukemia MicroRNAs Next-generation sequencingEuropean Commision (EC). Funding FP7/SP1/HEALTH. Project Code: 30624

Regional variations in and correlates of disability-free life expectancy among older adults in China

<p>Abstract</p> <p>Background</p> <p>Considerable socioeconomic and health inequalities have been reported in China. However, because of a lack of appropriate data, limited research has been conducted on variations in disability-free life expectancy (DFLE) among older adults. This study aimed to use the most up-to-date disability survey data to explore geographical variations in DFLE at age 60 in China and to identify the socioeconomic and health care factors that partially account for these variations.</p> <p>Methods</p> <p>This study used 2006 mortality data extrapolated from the 1990 and 2000 Census and disability data from a national disability survey conducted in 2006. Disability was performance based and was diagnosed by trained physicians. DFLE was calculated by region using the Sullivan method. Multiple linear regression models by gender were conducted to explore correlates of DFLE.</p> <p>Results</p> <p>DFLE at age 60 varied widely by region, from 11.2 to 20.8 years in 2006. Per capita gross domestic product, proportion of urban residents, and access to health care were the primary factors associated with geographical variations in DFLE.</p> <p>Conclusion</p> <p>The pattern of differences in DFLE by region mirrors the pattern of regional economic development in China. Countermeasures to decrease regional differences in DFLE include accelerating regional economic development and improving health care distribution.</p

Diseño de la asignatura de Bioquímica del Grado de Fisioterapia: elaboración de materiales para el aprendizaje a través de la clase invertida

Sección Deptal. de Bioquímica y Biología Molecular (Medicina)Fac. de MedicinaFALSEsubmitte