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author:("Chen, longyan")
1.  A characterization of Chover-type law of iterated logarithm 
SpringerPlus  2014;3:386.
Let 0 < α ≤ 2 and − ∞ <β <∞. Let {Xn;n ≥ 1} be a sequence of independent copies of a real-valued random variable X and set Sn = X1+⋯+Xn, n ≥ 1. We say X satisfies the (α,β)-Chover-type law of the iterated logarithm (and write X∈CTLIL(α,β)) if almost surely. This paper is devoted to a characterization of X ∈CTLIL(α,β). We obtain sets of necessary and sufficient conditions for X∈CTLIL(α,β) for the five cases: α = 2 and 0 < β <∞, α = 2 and β = 0, 1<α<2 and −∞<β<∞, α = 1 and −∞ <β <∞, and 0 < α <1 and −∞ <β <∞. As for the case where α = 2 and −∞ <β <0, it is shown that X∉CTLIL(2,β) for any real-valued random variable X. As a special case of our results, a simple and precise characterization of the classical Chover law of the iterated logarithm (i.e., X∈CTLIL(α,1/α)) is given; that is, X∈CTLIL(α,1/α) if and only if where whenever 1< α ≤ 2.
Mathematics Subject Classification (2000)
Primary: 60F15; Secondary: 60G50
PMCID: PMC4132459  PMID: 25133089
(α,β)-Chover-type law of the iterated logarithm; Sums of i.i.d. random variables; Symmetric stable distribution with exponent α
2.  Impact of Etiology on the Outcomes in Heart Failure Patients Treated with Cardiac Resynchronization Therapy: A Meta-Analysis 
PLoS ONE  2014;9(4):e94614.
Cardiac resynchronization therapy (CRT) has been extensively demonstrated to benefit heart failure patients, but the role of underlying heart failure etiology in the outcomes was not consistently proven. This meta-analysis aimed to determine whether efficacy and effectiveness of CRT is affected by underlying heart failure etiology.
Methods and Results
Searches of MEDLINE, EMBASE and Cochrane databases were conducted to identify RCTs and observational studies that reported clinical and functional outcomes of CRT in ischemic cardiomyopathy (ICM) and non-ischemic cardiomyopathy (NICM) patients. Efficacy of CRT was assessed in 7 randomized controlled trials (RCTs) with 7072 patients and effectiveness of CRT was evaluated in 14 observational studies with 3463 patients In the pooled analysis of RCTs, we found that CRT decreased mortality or heart failure hospitalization by 29% in ICM patients (95% confidence interval [CI], 21% to 35%), and by 28% (95% CI, 18% to 37%) in NICM patients. No significant difference was observed between the 2 etiology groups (P = 0.55). In the pooled analysis of observational studies, however, we found that ICM patients had a 54% greater risk for mortality or HF hospitalization than NICM patients (relative risk: 1.54; 95% CI: 1.30–1.83; P<0.001). Both RCTs and observational studies demonstrated that NICM patients had greater echocardiographic improvements in the left ventricular ejection fraction and end-systolic volume, as compared with ICM patients (both P<0.001).
CRT might reduce mortality or heart failure hospitalization in both ICM and NICM patients similarly. The improvement of the left ventricular function and remodeling is greater in NICM patients.
PMCID: PMC3986107  PMID: 24732141
3.  HLA Polymorphism and Susceptibility to End-Stage Renal Disease in Cantonese Patients Awaiting Kidney Transplantation 
PLoS ONE  2014;9(3):e90869.
End-Stage Renal Disease (ESRD) is a worldwide public health problem. Currently, many genome-wide association studies have suggested a potential association between human leukocyte antigen (HLA) and ESRD by uncovering a causal relationship between HLA and glomerulonephritis. However, previous studies, which investigated the HLA polymorphism and its association with ESRD, were performed with the modest data sets and thus might be limited. On the other hand, few researches were conducted to tackle the Chinese population with ESRD. Therefore, this study aims to detect the susceptibilities of HLA polymorphism to ESRD within the Cantonese community, a representative southern population of China.
From the same region, 4541 ESRD patients who were waiting for kidney transplantation and 3744 healthy volunteer bone marrow donors (controls) were randomly chosen for this study. Polymerase chain reaction-sequence specific primer method was used to analyze the HLA polymorphisms (including HLA-A, HLA-B and HLA-DRB1 loci) in both ESRD patients and controls. The frequencies of alleles at these loci and haplotypes were compared between ESRD patients and controls.
A total of 88 distinct HLA alleles and 1361 HLA A-B-DRB1 haplotypes were detected. The frequencies of five alleles, HLA-A*24, HLA-B*55, HLA-B*54, HLA-B*40(60), HLA-DRB1*04, and one haplotype (HLA-A*11-B*27-DRB1*04) in ESRD patients are significantly higher than those in the controls, respectively.
Five HLA alleles and one haplotype at the HLA-A, HLA-B and HLA-DRB1 loci appear to be associated with ESRD within the Cantonese population.
PMCID: PMC3946267  PMID: 24603486
4.  A Comparison of Four Methods for the Analysis of N-of-1 Trials 
PLoS ONE  2014;9(2):e87752.
To provide a practical guidance for the analysis of N-of-1 trials by comparing four commonly used models.
The four models, paired t-test, mixed effects model of difference, mixed effects model and meta-analysis of summary data were compared using a simulation study. The assumed 3-cycles and 4-cycles N-of-1 trials were set with sample sizes of 1, 3, 5, 10, 20 and 30 respectively under normally distributed assumption. The data were generated based on variance-covariance matrix under the assumption of (i) compound symmetry structure or first-order autoregressive structure, and (ii) no carryover effect or 20% carryover effect. Type I error, power, bias (mean error), and mean square error (MSE) of effect differences between two groups were used to evaluate the performance of the four models.
The results from the 3-cycles and 4-cycles N-of-1 trials were comparable with respect to type I error, power, bias and MSE. Paired t-test yielded type I error near to the nominal level, higher power, comparable bias and small MSE, whether there was carryover effect or not. Compared with paired t-test, mixed effects model produced similar size of type I error, smaller bias, but lower power and bigger MSE. Mixed effects model of difference and meta-analysis of summary data yielded type I error far from the nominal level, low power, and large bias and MSE irrespective of the presence or absence of carryover effect.
We recommended paired t-test to be used for normally distributed data of N-of-1 trials because of its optimal statistical performance. In the presence of carryover effects, mixed effects model could be used as an alternative.
PMCID: PMC3913644  PMID: 24503561
5.  China collaborative study on dialysis: a multi-centers cohort study on cardiovascular diseases in patients on maintenance dialysis 
BMC Nephrology  2012;13:94.
Cardiovascular disease (CVD) is the main cause of death in patients on chronic dialysis. The question whether dialysis modality impacts cardiovascular risk remains to be addressed. China Collaborative Study on Dialysis, a multi-centers cohort study, was performed to evaluate cardiovascular morbidity during maintenance hemodialysis (HD) and peritoneal dialysis (PD).
The cohort consisted of chronic dialysis patients from the database of 9 of the largest dialysis facilities around China. The inclusion period was between January 1, 2005, and December 1, 2010. Cardiovascular morbidity was defined as the presence of clinically diagnosed ischemic heart disease, heart failure, peripheral vascular disease, and/or stroke. The patients who had cardiovascular morbidity before initiation of dialysis were excluded. Data collection was based on review of medical record.
A total of 2,388 adult patients (1,775 on HD and 613 on PD) were enrolled. Cardiovascular morbidity affected 57% patients and was comparable between HD and PD patients. However, clinically diagnosed ischemic heart disease and stroke was more prevalent in PD than HD patients. When the patients were stratified by age or dialysis vintage, the cardiovascular morbidity was significantly higher in PD than HD among those aged 50 years or older, or those receiving dialysis over 36 months. Multivariate analysis revealed that the risk factors for cardiovascular morbidity had different pattern in PD and HD patients. Hyperglycemia was the strongest risk factor for cardiovascular morbidity in PD, but not in HD patients. Hypertriglyceridemia and hypoalbuminemia were independently associated with CVD only in PD patients.
Cardiovascular morbidity during chronic dialysis was more prevalent in PD than HD patients among those with old age and long-term dialysis. Metabolic disturbance-related risk factors were independently associated with CVD only in PD patients. Better understanding the impact of dialysis modality on CVD would be an important step for prevention and treatment.
PMCID: PMC3502162  PMID: 22935444
Cardiovascular morbidity; Dialysis modality; Risk factor
6.  Acute and acute-on-chronic kidney injury of patients with decompensated heart failure: impact on outcomes 
BMC Nephrology  2012;13:51.
Acute worsening of renal function, an independent risk factor for adverse outcomes in acute decompensated heart failure (ADHF), occurs as a consequence of new onset kidney injury (AKI) or acute deterioration of pre-existed chronic kidney disease (CKD) (acute-on-chronic kidney injury, ACKI). However, the possible difference in prognostic implication between AKI and ACKI has not been well established.
We studied all consecutive patients hospitalized with ADHF from 2003 through 2010 in Nanfang Hospital. We classified patients as with or without pre-existed CKD based on the mean estimated glomerular filtration rate (eGFR) over a six-month period before hospitalization. AKI and ACKI were defined by RIFLE criteria according to the increase of the index serum creatinine.
A total of 1,005 patients were enrolled. The incidence of ACKI was higher than that of AKI. The proportion of patients with diuretic resistance was higher among patients with pre-existed CKD than among those without CKD (16.9% vs. 9.9%, P = 0.002). Compared with AKI, ACKI was associated with higher risk for in-hospital mortality, long hospital stay, and failure in renal function recovery. Pre-existed CKD and development of acute worsening of renal function during hospitalization were the independent risk factors for in-hospital death after adjustment by the other risk factors. The RIFLE classification predicted all-cause and cardiac mortality in both AKI and ACKI.
Patients with ACKI were at greatest risk of adverse short-term outcomes in ADHF. Monitoring eGFR and identifying CKD should not be ignored in patients with cardiovascular disease.
PMCID: PMC3411407  PMID: 22747708
Acute decompensated heart failure; Acute kidney injury; Acute-on-chronic kidney injury; Outcome

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