Comparison of child adiposity indices in prediction of hypertension in early adulthood

We aimed to compare child body mass index (BMI) in prediction of hypertension in early adulthood with 4 other adiposity indices (waist circumference [WC], waist circumferenceâ toâ height ratio [WHtR], waistâ toâ hip ratio [WHR], and triceps skinfold [TSF]). The cohort from the China Health and Nutrition Survey 1993â 2011 consisted of 1444 adults aged 18â 36 years who were examined in childhood and early adulthood. Child adiposity indices and adult blood pressure (BP) were transformed into ageâ , sexâ , and survey yearâ specific Zâ scores. Adult hypertension was defined as BP â ¥130/80 mm Hg as per the 2017 American College of Cardiology/American Heart Association guidelines. Adult hypertension prevalence was 32.9% during a mean followâ up of 10.1 years. Childhood BMI showed stronger correlation with adult BP than WHR and TSF (PS for difference <.05). Child BMI showed the better prediction of adult hypertension compared with WHtR, WHR, and TSF using area under the receiver operating characteristic curves (PS for difference <.05). Per SD change in the predictor, child BMI (relative risk [95% confidence interval], 1.11 [1.04â 1.18]) and WC (1.12 [1.05â 1.20]) were significantly associated with adult hypertension using covariateâ adjusted Poisson models with robust standard errors. Child BMI performed equally or better compared with 4 other adiposity indices in predicting adult hypertension.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152666/1/jch13734.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152666/2/jch13734_am.pd

Anonymizing data via polynomial regression

The amount of confidential information accessible through the Internet is growing continuously. In this scenario, the improvement of anonymizing methods becomes crucial to avoid revealing sensible information of individuals. Among several protection methods proposed, those based on the use of linear regressions are widely utilized. However, there is not a reason to assume that linear regression is better than using more complex polynomial regressions. In this paper, we present PoROP-k, a family of anonymizing methods able to protect a data set using polynomial regressions. We show that PoROP-k not only reduces the loss of information, but it also obtains a better level of protection compared to previous proposals based on linear regressions.Postprint (author’s final draft

Increasing polynomial regression complexity for data anonymization

Pervasive computing and the increasing networking needs usually demand from publishing data without revealing sensible information. Among several data protection methods proposed in the literature, those based on linear regression are widely used for numerical data. However, no attempts have been made to study the effect of using more complex polynomial regression methods. In this paper, we present PoROP-k, a family of anonymizing methods able to protect a data set using polynomial regressions. We show that PoROP-k not only reduces the loss of information, but it also obtains a better level of protection compared to previous proposals based on linear regressions.Peer ReviewedPostprint (published version

Parameter determination of ONN (Ordered Neural Networks)

The need for data privacy motivates the development of new methods that allow to protect data minimizing the disclosure risk without losing information. In this paper, we propose a new protection method for numerical data called Ordered Neural Networks (ONN) method. ONN presents a new way to protect data based on the use of Artificial Neural Networks (ANN). ONN combines the use of ANN with a new strategy for preprocessing data consisting in the vectorization, sorting and partitioning of all the values in the attributes to be protected in the data set. We also present an statistical analysis that allows to understand the most important parameters affecting the quality of our method, and we show that it is possible to find a good configuration for these parameters. Finally, we compare our method to the best methods presented in the literature, using data provided by the US Census Bureau. Our experiments show that ONN outperforms the previous methods proposed in the literature, proving that the use of ANNs in these situations is convenient to protect the data efficiently without losing the statistical properties of the set.Postprint (author’s final draft

Orthogonal Decomposition of Left Ventricular Remodeling in Myocardial Infarction

BACKGROUND: Left ventricular size and shape are important for quantifying cardiac remodeling in response to cardiovascular disease. Geometric remodeling indices have been shown to have prognostic value in predicting adverse events in the clinical literature, but these often describe interrelated shape changes. We developed a novel method for deriving orthogonal remodeling components directly from any (moderately independent) set of clinical remodeling indices. RESULTS: Six clinical remodeling indices (end-diastolic volume index, sphericity, relative wall thickness, ejection fraction, apical conicity, and longitudinal shortening) were evaluated using cardiac magnetic resonance images of 300 patients with myocardial infarction, and 1991 asymptomatic subjects, obtained from the Cardiac Atlas Project. Partial least squares (PLS) regression of left ventricular shape models resulted in remodeling components that were optimally associated with each remodeling index. A Gram-Schmidt orthogonalization process, by which remodeling components were successively removed from the shape space in the order of shape variance explained, resulted in a set of orthonormal remodeling components. Remodeling scores could then be calculated that quantify the amount of each remodeling component present in each case. A one-factor PLS regression led to more decoupling between scores from the different remodeling components across the entire cohort, and zero correlation between clinical indices and subsequent scores. CONCLUSIONS: The PLS orthogonal remodeling components had similar power to describe differences between myocardial infarction patients and asymptomatic subjects as principal component analysis, but were better associated with well-understood clinical indices of cardiac remodeling. The data and analyses are available from www.cardiacatlas.org

Information Maximizing Component Analysis of Left Ventricular Remodeling Due to Myocardial Infarction

Background: Although adverse left ventricular shape changes (remodeling) after myocardial infarction (MI) are predictive of morbidity and mortality, current clinical assessment is limited to simple mass and volume measures, or dimension ratios such as length to width ratio. We hypothesized that information maximizing component analysis (IMCA), a supervised feature extraction method, can provide more efficient and sensitive indices of overall remodeling. Methods: IMCA was compared to linear discriminant analysis (LDA), both supervised methods, to extract the most discriminatory global shape changes associated with remodeling after MI. Finite element shape models from 300 patients with myocardial infarction from the DETERMINE study (age 31–86, mean age 63, 20 % women) were compared with 1991 asymptomatic cases from the MESA study (age 44–84, mean age 62, 52 % women) available from the Cardiac Atlas Project. IMCA and LDA were each used to identify a single mode of global remodeling best discriminating the two groups. Logistic regression was employed to determine the association between the remodeling index and MI. Goodness-of-fit results were compared against a baseline logistic model comprising standard clinical indices. Results: A single IMCA mode simultaneously describing end-diastolic and end-systolic shapes achieved best results (lowest Deviance, Akaike information criterion and Bayesian information criterion, and the largest area under the receiver-operating-characteristic curve). This mode provided a continuous scale where remodeling can be quantified and visualized, showing that MI patients tend to present larger size and more spherical shape, more bulging of the apex, and thinner wall thickness. Conclusions: IMCA enables better characterization of global remodeling than LDA, and can be used to quantify progression of disease and the effect of treatment. These data and results are available from the Cardiac Atlas Project (http://www.cardiacatlas.org)

Atlas-Based Quantification of Cardiac Remodeling Due to Myocardial Infarction

Myocardial infarction leads to changes in the geometry (remodeling) of the left ventricle (LV) of the heart. The degree and type of remodeling provides important diagnostic information for the therapeutic management of ischemic heart disease. In this paper, we present a novel analysis framework for characterizing remodeling after myocardial infarction, using LV shape descriptors derived from atlas-based shape models. Cardiac magnetic resonance images from 300 patients with myocardial infarction and 1991 asymptomatic volunteers were obtained from the Cardiac Atlas Project. Finite element models were customized to the spatio-temporal shape and function of each case using guide-point modeling. Principal component analysis was applied to the shape models to derive modes of shape variation across all cases. A logistic regression analysis was performed to determine the modes of shape variation most associated with myocardial infarction. Goodness of fit results obtained from end-diastolic and end-systolic shapes were compared against the traditional clinical indices of remodeling: end-diastolic volume, end-systolic volume and LV mass. The combination of end-diastolic and endsystolic shape parameter analysis achieved the lowest deviance, Akaike information criterion and Bayesian information criterion, and the highest area under the receiver operating characteristic curve. Therefore, our framework quantitatively characterized remodeling features associated with myocardial infarction, better than current measures. These features enable quantification of the amount of remodeling, the progression of disease over time, and the effect of treatments designed to reverse remodeling effects

Atlas-Based Analysis of Cardiac Shape and Function: Correction of Regional Shape Bias Due to Imaging Protocol for Population Studies

Background: Cardiovascular imaging studies generate a wealth of data which is typically used only for individual study endpoints. By pooling data from multiple sources, quantitative comparisons can be made of regional wall motion abnormalities between different cohorts, enabling reuse of valuable data. Atlas-based analysis provides precise quantification of shape and motion differences between disease groups and normal subjects. However, subtle shape differences may arise due to differences in imaging protocol between studies. Methods: A mathematical model describing regional wall motion and shape was used to establish a coordinate system registered to the cardiac anatomy. The atlas was applied to data contributed to the Cardiac Atlas Project from two independent studies which used different imaging protocols: steady state free precession (SSFP) and gradient recalled echo (GRE) cardiovascular magnetic resonance (CMR). Shape bias due to imaging protocol was corrected using an atlas-based transformation which was generated from a set of 46 volunteers who were imaged with both protocols. Results: Shape bias between GRE and SSFP was regionally variable, and was effectively removed using the atlas-based transformation. Global mass and volume bias was also corrected by this method. Regional shape differences between cohorts were more statistically significant after removing regional artifacts due to imaging protocol bias. Conclusions: Bias arising from imaging protocol can be both global and regional in nature, and is effectively corrected using an atlas-based transformation, enabling direct comparison of regional wall motion abnormalities between cohorts acquired in separate studies