Pre-Engraftment Syndrome after Unrelated Cord Blood Transplantation: A Predictor of Engraftment and Acute Graft-versus-Host Disease

AbstractPre-engraftment syndrome (PES) is poorly characterized, and its clinical significance and the prognostic impact after unrelated cord blood transplantation (CBT) are unclear. To address these issues, we retrospectively analyzed the incidence, risk factors, and clinical outcomes of PES in unrelated CBT recipients. Data of 381 patients who received unrelated CBT from 18 medical centers in Korea were reviewed. PES was defined as unexplained fever >38.3°C not associated with infection, and/or unexplained skin rash with or without evidence of fluid retention before neutrophil recovery. PES developed in 102 patients (26.8%) at a median of 7 days after CBT. Of these patients, 74 patients (72.5%) received intravenous corticosteroid at a median dose of 1 mg/kg/day, and of these, 95% showed clinical improvement. Risk factors for developing PES included low risk disease, myeloablative conditioning, graft-versus-host disease (GVHD) prophylaxis without methotrexate or corticosteroid, and >5.43 x 107/kg infused nucleated cells. Absence of PES was one of the risk factors for graft failure in multivariate analysis. The cumulative incidence of grade II to grade IV acute GVHD by 100 days after CBT was higher in patients with PES than in those without PES (56.0% versus 34.4%, P < .01). PES was not associated with chronic GVHD, treatment-related mortality, relapse, or overall survival. PES seems to be common after CBT and may be associated with enhanced engraftment without significant morbidity

A simultaneous test of unit root and level change

Testing the existence of unit root and|or level change is necessary in order to understand the underlying processes of time series. In many studies carried out so far, the focus was only on a single aspect of unit root and level change, therefore limiting a full assessment of the given problems. Our study aims to find a solution to the given problems by testing the two hypotheses simultaneously. We derive the likelihood ratio test statistic based on the state space model, and their distributions are created by the simulation method. The performance of the proposed method is validated by simulated time series and also applied to two Korean macroeconomic time series to confirm its practical application. This analysis can provide a solution to determine the underlying structure of arguable time series. Copyright © 2009 John Wiley & Sons, Ltd.

Effect of general health checks on the treatment of chronic diseases: accounting for self-selection in the retrospective cohort study using Korea National Health Insurance data

Objective This study examines the effect of general health checks on the detection and treatment of diabetes and hypertension with controlling for the self-selection problem of undergoing general health checks.Design Retrospective observational cohort study.Setting Sample Research Database offered by Korean National Health Insurance Service, between 2002 and 2013.Participants Two datasets, focusing on diabetes and hypertensions one by one, are constructed. The number of participants for the datasets is 133 329 (diabetes) and 101 738 (hypertension), respectively.Methods A bivariate probit model with selection was adopted to investigate the impact of general health checks on the diagnosis of critical chronic diseases. The dependent variable was an indicator variable denoting whether a participant has been treated for diabetes (or hypertension) or not for the first time during the sample period. An indicator variable that indicates whether that participant is eligible for free general health checks or not in the focal year (year of the first treatment or last year in the sample) was used as instrument variables to control for the self-selection problem of undergoing general health checks.Results We found that there exists substantial self-selection between undergoing general health checks and diagnosis for chronic diseases. The correlations between the unobserved factors influencing the decisions to obtain general health checks and those determining the detection of chronic diseases are highly significant and positive (ie, 0.188 (p&lt;0.001) in diabetes and 0.220 (p&lt;0.001) in hypertension). We confirmed that these positive, significant correlations generate upward bias in the estimated effect of general health checks on the detection and treatment of diabetes (0.312 (p&lt;0.001) when self-selection ignored but 0.099 (p&lt;0.001) when self-selection considered) and hypertension (0.293 (p&lt;0.001) when self-selection ignored but insignificant when self-selection considered). The effect of general health checks and people’s self-selection behaviour may differ by socio-economic characteristics of individuals. The general health check is effective in detecting chronic diseases among low-income individuals rather than high-income individuals, implying that general health checks are contributing to helping medically underprivileged low-income people detect and treat their chronic diseases. High-income individuals showed stronger self-selection behaviour than low-income individuals and this may overstate the effect of general health checks if the self-selection is overlooked, particularly among high-income individuals.Conclusion Self-selection due to unobserved factors between undergoing general health checks and diagnosis of chronic diseases are substantial. After accounting for this, the effect of general health checks on the detection and treatment of diabetes and hypertension is insignificant or marginal. The increases in the treatments of the two diseases following general health checks are 1% and insignificant in diabetes and hypertension, respectively

Bridging telecommunications service: its concept and related management strategy

This paper defines a new concept "bridging telecommunications service" (BTS) in the telecommunication service market. It is a service concept related to the substitution of consecutive generations of telecommunications services. The roles and characteristics of BTS are identified and related management strategies are developed against the background of the typical life cycle of telecommunications service: new service development, marketing, and service termination strategies. Management strategies developed in this paper are examined and their implications drawn out in two representative cases: CT-2 service in Korea and PHS service in Japan.Bridging telecommunications service Major telecommunications service Management strategy CT-2 service PHS service

Managing and modeling the price reduction effect in mobile telecommunications traffic

As needs for telecommunications services diversify, an increasingly wide range of services is becoming available in the market. Service price reduction is one strategy used by service providers to retain existing subscribers. A price reduction for one service, however, can affect the individual-level usage for other services. Price reductions can also be imposed on a service provider by regulation. For these reasons, understanding how price reductions affect service usage is of growing importance to the telecommunications industry for purposes of pricing and tariff development. In this paper, an individual-level usage model for telecommunications services is developed and the effects on usage of a price reduction are analyzed. The model is applied to age-stratified aggregate traffic data for a Korean mobile telecommunication service provider. Finally, a 0-1 integer programming model is proposed for choosing which market segment should be targeted with a price reduction to minimize revenue loss. These models can be applied to market segmentation and price reduction strategy.Individual telecommunications traffic Error correction behavior Market segmentation Price reduction