1,326 research outputs found
Finding the Right Distribution for Highly Skewed Zero-inflated Clinical Data
Discrete, highly skewed distributions with excess numbers of zeros often result in biased estimates and misleading inferences if the zeros are not properly addressed. A clinical example of children with electrophysiologic disorders in which many of the children are treated without surgery is provided. The purpose of the current study was to identify the optimal modeling strategy for highly skewed, zeroinflated data often observed in the clinical setting by: (a) simulating skewed, zero-inflated count data; (b) fitting simulated data with Poisson, Negative Binomial, Zero-Inflated Poisson (ZIP) and Zero-inflated Negative Binomial (ZINB) models; and, (c) applying the aforementioned models to actual, highlyskewed, clinical data of children with an EP disorder. The ZIP model was observed to be the optimal model based on traditional fit statistics as well as estimates of bias, mean-squared error, and coverage.  
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Public Health Approach to Improve Outcomes for Congenital Heart Disease Across the Life Span.
The impact of socio-economic status on health related quality of life for children and adolescents with heart disease
Background: Socioeconomic status (SES) is known to influence childrenâs health-related quality of life. Many SES indicators assess distinct dimensions of a familyâs position rather than measuring the same underlying construct. Many researchers, however, see SES indicators as interchangeable. The primary aim of this study was to determine which measure of SES had the strongest impact on health-related quality of life. Methods: This is a secondary analysis of the Pediatric Cardiac Quality of Life Inventory Validation Study. The SES variables were family income, Hollingshead Index (occupational prestige), and highest parent educational attainment level. Health-related quality of life was measured using the Pediatric Cardiac Quality of Life Inventory. Correlations tested the relationship among the three SES indicators. Regression-based modeling was used to calculate the strength of the association between SES measures and the Pediatric Cardiac Quality of Life Inventory. Results: The correlations among the SES measures were moderately high, with the correlation between the Hollingshead Index and parental education being r = 0.62 (95% CI = 0.56-0.65). There were equally high correlations between family income and the Hollingshead (r = 0.61, 95% CI = 0.57-0.65) and a slightly lower correlation between family income and parental education (r = 0.55, 95% CI = 0.52-0.59). Family income had the highest explanatory value compared to the Hollingshead Index or parental educational attainment, while controlling for sex, race, current cardiac status, and original diagnosis, accounting for 4-5% of the variation in patient and parent Pediatric Cardiac Quality of Life Inventory Total score, respectively, compared to the other SES measures. Conclusion: Family income as an SES measure demonstrated the greatest fidelity with respect to health-related quality of life as measured by the Pediatric Cardiac Quality of Life Inventory across respondent groups and explained more of the variation compared to the Hollingshead Index or highest parental educational attainment
A contemporary comparison of the effect of shunt type in hypoplastic left heart syndrome on the hemodynamics and outcome at stage 2 reconstruction
ObjectiveWe compare the hemodynamics and perioperative course of shunt type in hypoplastic left heart syndrome at the time of stage 2 reconstruction and longer-term survival.MethodsWe retrospectively reviewed the echocardiograms, catheterizations, and hospital records of all patients who had a stage 1 reconstruction between January 2002 and May 2005 and performed a cross-sectional analysis of hospital survivors.ResultsOne hundred seventy-six patients with hypoplastic left heart syndrome and variants underwent a stage 1 reconstruction with either a right ventricleâpulmonary artery conduit (n = 62) or a modified BlalockâTaussig shunt (n = 114). The median duration of follow-up is 29.1 months (range, 0-57 months). By means of KaplanâMeier analysis, there is no difference in survival at 3 years (right ventricleâpulmonary artery conduit: 73% [95% confidence limit, 59%â83%] vs modified BlalockâTaussig shunt: 69% [95% confidence limit, 59%â77%]; P = .6). One hundred twenty-four patients have undergone stage 2 reconstruction (78 modified BlalockâTaussig shunts and 46 right ventricleâpulmonary artery conduits). At the time of the stage 2 reconstruction, patients with right ventricleâpulmonary artery conduits were younger (153 days [range, 108â340 days]; modified BlalockâTaussig shunt, 176 days [range, 80â318 days]; P = .03), had lower systemic oxygen saturation (73% [range, 58%â85%] vs 77% [range, 57%â89%], P < .01), and had higher preoperative hemoglobin levels (15.8 g/dL [range, 13â21 g/dL] vs 14.8 g/dL [range, 12â19 g/dL], P < .01) compared with those of the modified BlalockâTaussig shunt group. By means of echocardiographic evaluation, there was a higher incidence of qualitative ventricular dysfunction in patients with right ventricleâpulmonary artery conduits (14/46 [31%] vs 9/73 [12%], P = .02). However, no difference was observed in common atrial pressure or the arteriovenous oxygen difference.ConclusionInterim analyses suggest no advantage of one shunt type over another. This report raises concern of late ventricular dysfunction and outcome in patients with a right ventricleâpulmonary artery conduit
Cosmetic outcomes and quality of life in children with cardiac implantable electronic devices
BackgroundAxillary implant location is an alternative implant location in patients for cardiac implantable electronic devices (CIEDs) for the purposes of improved cosmetic outcome. The impact from the patientâs perspective is unknown. The purpose of this study was to compare scar perception scores and quality of life (QOL) in pediatric patients with axillary CIED implant location versus the standard infraclavicular approach.MethodsThis is a multicenter prospective study conducted at eight pediatric centers and it includes patients aged from 8 to 18Â years with a CIED. Patients with prior sternotomy were excluded. Scar perception and QOL outcomes were compared between the infraclavicular and axillary implant locations.ResultsA total of 141 patients (83 implantable cardioverter defibrillator [ICD]/58 pacemakers) were included, 55 with an axillary device and 86 with an infraclavicular device. Patients with an ICD in the axillary position had better perception of scar appearance and consciousness. Patients in the axillary group reported, on average, a total Pediatric QOL Inventory score that was 6 (1, 11) units higher than the infraclavicular group, after adjusting for sex and race (PÂ =Â 0.02).ConclusionsQOL is significantly improved in axillary in comparison to the infraclavicular CIED position, regardless of device type. Scar perception is improved in patients with ICD in the axillary position.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147032/1/pace13522.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147032/2/pace13522_am.pd
Macroscopic Quantum Fluctuations in the Josephson Dynamics of Two Weakly Linked Bose-Einstein Condensates
We study the quantum corrections to the Gross-Pitaevskii equation for two
weakly linked Bose-Einstein condensates. The goals are: 1) to investigate
dynamical regimes at the borderline between the classical and quantum behaviour
of the bosonic field; 2) to search for new macroscopic quantum coherence
phenomena not observable with other superfluid/superconducting systems. Quantum
fluctuations renormalize the classical Josephson oscillation frequencies. Large
amplitude phase oscillations are modulated, exhibiting collapses and revivals.
We describe a new inter-well oscillation mode, with a vanishing (ensemble
averaged) mean value of the observables, but with oscillating mean square
fluctuations. Increasing the number of condensate atoms, we recover the
classical Gross-Pitaevskii (Josephson) dynamics, without invoking the
symmetry-breaking of the Gauge invariance.Comment: Submitte
Survival Data and Predictors of Functional Outcome an Average of 15âYears after the Fontan Procedure: The Pediatric Heart Network Fontan Cohort
ObjectiveMulticenter longitudinal outcome data for Fontan patients surviving into adulthood are lacking. The aim of this study was to better understand contemporary outcomes in Fontan survivors by collecting followâup data in a previously wellâcharacterized cohort.DesignBaseline data from the Fontan CrossâSectional Study (Fontan 1) were previously obtained in 546 Fontan survivors aged 11.9 ± 3.4âyears. We assessed current transplantâfree survival status in all subjects 6.8 ± 0.4âyears after the Fontan 1 study. Anatomic, clinical, and surgical data were collected along with socioeconomic status and access to health care.ResultsThirty subjects (5%) died or underwent transplantation since Fontan 1. Subjects with both an elevated (>21âpg/mL) brain natriuretic peptide and a low Child Health Questionnaire physical summary score (<44) measured at Fontan 1 were significantly more likely to die or undergo transplant than the remainder, with a hazard ratio of 6.2 (2.9â13.5). Among 516 Fontan survivors, 427 (83%) enrolled in this followâup study (Fontan 2) at 18.4 ± 3.4âyears of age. Although mean scores on functional health status questionnaires were lower than the general population, individual scores were within the normal range in 78% and 88% of subjects for the Child Health Questionnaire physical and psychosocial summary score, and 97% and 91% for the SFâ36 physical and mental aggregate score, respectively. Since Fontan surgery, 119 (28%) had additional cardiac surgery; 55% of these (n = 66) in the interim between Fontan 1 and Fontan 2. A catheter intervention occurred in 242 (57%); 32% of these (n = 78) after Fontan 1. Arrhythmia requiring treatment developed in 118 (28%) after Fontan surgery; 58% of these (n = 68) since Fontan 1.ConclusionsWe found 95% interim transplantâfree survival for Fontan survivors over an average of 7âyears of followâup. Continued longitudinal investigation into adulthood is necessary to better understand the determinants of longâterm outcomes and to improve functional health status.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110738/1/chd12193.pd
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Simulating the 128-ka Antarctic climate response to Northern Hemisphere ice sheet melting using the isotope-enabled HadCM3
Warmer than present Antarctic and Southern Ocean temperatures during the last interglacial, approximately 128,000 years ago, have been attributed to changes in northâsouth ocean heat transport, causing opposing hemispheric temperature anomalies. We investigate the magnitude of Antarctic warming and Antarctic ice core isotopic enrichment in response to Northern Hemisphere meltwater input during the early last interglacial. A 1,600âyear HadCM3 simulation driven by 0.25 Sv of meltwater input reproduces 50â60% of the peak Southern Ocean summer sea surface temperature anomaly, sea ice retreat, and ice core isotope enrichment. We also find a robust increase in the proportion of cold season precipitation during the last interglacial, leading to lower isotopic values at the Antarctic ice core sites. These results suggest that a HadCM3 simulation including 0.25 Sv for 3,000â4,000 years would reconcile the last interglacial observations, providing a potential solution for the last interglacial missing heat problem
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Impact of Surgical Complexity on HealthâRelated Quality of Life in Congenital Heart Disease Surgical Survivors
Background: Surgical complexity and related morbidities may affect longâterm patient quality of life (QOL). Aristotle Basic Complexity (ABC) score and Risk Adjustment in Congenital Heart Surgery (RACHSâ1) category stratify the complexity of pediatric cardiac operations. The purpose of this study was to examine the relationship between surgical complexity and QOL and to investigate other demographic and clinical variables that might explain variation in QOL in pediatric cardiac surgical survivors. Methods and Results: Pediatric Cardiac Quality of Life (PCQLI) study participants who had undergone cardiac surgery were included. The PCQLI database provided sample characteristics and QOL scores. Surgical complexity was defined by the highest ABC raw score or RACHSâ1 category. Relationships among surgical complexity and demographic, clinical, and QOL variables were assessed using ordinary least squares regression. A total of 1416 patientâparent pairs were included. Although higher ABC scores and RACHSâ1 categories were associated with lower QOL scores (P<0.005), correlation with QOL scores was poor to fair (r=â0.10 to â0.29) for all groups. Ordinary least squares regression showed weak association with R 2=0.06 to R 2=0.28. After accounting for singleâventricle anatomy, number of doctor visits, and time since last hospitalization, surgical complexity scores added no additional explanation to the variance in QOL scores. Conclusions: ABC scores and RACHSâ1 categories are useful tools for morbidity and mortality predictions prior to cardiac surgery and quality of care initiatives but are minimally helpful in predicting a child's or adolescent's longâterm QOL scores. Further studies are warranted to determine other predictors of QOL variation
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