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  1. Article ; Online: Estimation of hurst exponent for sequential monitoring of clinical trials with covariate adaptive randomization.

    Yang, Yiping / Zhu, Hongjian / Lai, Dejian

    Contemporary clinical trials

    2022  Volume 120, Page(s) 106887

    Abstract: Background: Classical Brownian motion (BM) has been commonly used in monitoring clinical trials including those with covariate adaptive randomization (CAR). Independent increment property is commonly assumed in the sequential monitoring process of the ... ...

    Abstract Background: Classical Brownian motion (BM) has been commonly used in monitoring clinical trials including those with covariate adaptive randomization (CAR). Independent increment property is commonly assumed in the sequential monitoring process of the clinical trials with CAR designs. However, in reality, correlation may exist in the error terms of the underlying model, resulting in dependent increment in the sequential monitoring process.
    Methods: We conducted simulations for estimating the Hurst exponent to evaluate the stochastic property in the covariate adaptive randomized clinical trials under two scenarios: 1. CAR designs with independent and identically distributed error terms. 2. CAR designs with correlated error terms. The theoretical properties of covariate adaptive randomized clinical trials with correlated error structure were investigated. A test statistic including the covariance pattern of the error terms was proposed.
    Conclusion: In our study, the sequential test statistics under CAR procedure is shown to be asymptotically Brownian motion when the error structure is correctly specified. Further, Brownian motion is a special case of fractional Brownian motion when Hurst exponent equals to 0.5. Our simulations are consistent with the theoretical asymptotic results.
    MeSH term(s) Causality ; Humans ; Models, Statistical ; Random Allocation ; Randomized Controlled Trials as Topic/methods ; Research Design
    Language English
    Publishing date 2022-08-18
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 2182176-8
    ISSN 1559-2030 ; 1551-7144
    ISSN (online) 1559-2030
    ISSN 1551-7144
    DOI 10.1016/j.cct.2022.106887
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    In stock of ZB MED Cologne/Königswinter

    Zs.A 1581: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
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  2. Article: Variability analysis of epileptic EEG using the maximal overlap discrete wavelet transform.

    Follis, Jack L / Lai, Dejian

    Health information science and systems

    2020  Volume 8, Issue 1, Page(s) 26

    Abstract: Purpose: To determine if there is a difference in the wavelet variances of seizure and non-seizure channels in the EEG of an epileptic subject.: Methods: A six-level decomposition was applied using the Maximal Overlap Discrete Wavelet Transform ( ... ...

    Abstract Purpose: To determine if there is a difference in the wavelet variances of seizure and non-seizure channels in the EEG of an epileptic subject.
    Methods: A six-level decomposition was applied using the Maximal Overlap Discrete Wavelet Transform (MODWT). The wavelet variance and 95% CIs were calculated for each level of the decomposition. The number of changes in variance for each level were found using a change-point detection method of Whitcher. The Kruskal-Wallis test was used to determine if there were differences in the median number of change points within channels and across frequency bands (levels).
    Results: No distinctive pattern was found for the wavelet variances to differentiate the seizure and non-seizure channels. The seizure channels tended to have lower variances for each level and overall, but this pattern only held for one of the three seizure channels (RAST4). The median number of change points did not differ between the seizure and non-seizure channels either within each channel or across the frequency bands.
    Conclusion: The use of the MODWT in examining the variances and changes in variance did not show specific patterns which differentiate between seizure and non-seizure channels.
    Language English
    Publishing date 2020-09-15
    Publishing country England
    Document type Journal Article
    ZDB-ID 2697647-X
    ISSN 2047-2501
    ISSN 2047-2501
    DOI 10.1007/s13755-020-00118-4
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  3. Article: Applications of Covariate Adjusted Nonparametric Methods to CCTRN Clinical Trials.

    Ye, Jiabu / Lai, Dejian / Moye, Lemuel A / Davis, Barry R

    Communications in statistics. Case studies, data analysis and applications

    2022  Volume 8, Issue 4, Page(s) 728–737

    Abstract: CCTRN is a Cardiovascular Cell Therapy Research Network. There were three randomized double blinded controlled stem cell clinical trials conducted in its first phase. The main results of these three clinical trials were published with conventional ... ...

    Abstract CCTRN is a Cardiovascular Cell Therapy Research Network. There were three randomized double blinded controlled stem cell clinical trials conducted in its first phase. The main results of these three clinical trials were published with conventional parametric models such as T test and nonparametric test such as Wilcoxon rank sum test without adjusting covariates. In this article, we conducted further analysis of the primary outcomes of these studies using a class of covariate adjusted nonparametric methods.
    Language English
    Publishing date 2022-09-22
    Publishing country United States
    Document type Journal Article
    ISSN 2373-7484
    ISSN 2373-7484
    DOI 10.1080/23737484.2022.2126414
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  4. Article ; Online: Sequential monitoring of covariate adaptive randomized clinical trials with sample size re-estimation.

    Yu, Jun / Lai, Dejian

    Contemporary clinical trials

    2019  Volume 87, Page(s) 105874

    Abstract: Once scientific questions are determined, other design features of clinical trials including increasing the power while controlling the type I error rate, planning interim analysis, and achieving treatment balance among subgroups will be either required ... ...

    Abstract Once scientific questions are determined, other design features of clinical trials including increasing the power while controlling the type I error rate, planning interim analysis, and achieving treatment balance among subgroups will be either required or preferred. We propose to sequentially monitor the covariate adaptive randomization (CAR) procedures with sample size re-estimation (SSR) to satisfy a variety of design objectives of clinical trials. However, each of the three adaptive designs (sequential monitoring, CAR, and SSR) poses a challenge to the control of the type I error rate. In this paper, we investigated how to utilize the advantages of the three adaptive methods and control the type I error rate. We proved that the asymptotic joint distribution of the sequential statistics follows the asymptotic canonical joint distribution defined in Jennison and Turnbull [14]. Besides, numerical studies demonstrated that our methods could control the type I error rate, increase the power, and lead to much-improved treatment balance across subgroups.
    MeSH term(s) Bias ; Data Interpretation, Statistical ; Humans ; Models, Statistical ; Random Allocation ; Randomized Controlled Trials as Topic/methods ; Research Design ; Sample Size
    Language English
    Publishing date 2019-10-31
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2182176-8
    ISSN 1559-2030 ; 1551-7144
    ISSN (online) 1559-2030
    ISSN 1551-7144
    DOI 10.1016/j.cct.2019.105874
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 1581: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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  5. Article ; Online: Spatial Analysis of Industrial Benzene Emissions and Cancer Incidence Rates in Texas.

    Mungi, Chinmay / Lai, Dejian / Du, Xianglin L

    International journal of environmental research and public health

    2019  Volume 16, Issue 15

    Abstract: This paper presents a spatial analysis of the association between industrial benzene emissions and the 10-year incidence rates of cancers likely to be associated with benzene exposure (Lymphohematopoietic, lung and lip cancers) at the county level in ... ...

    Abstract This paper presents a spatial analysis of the association between industrial benzene emissions and the 10-year incidence rates of cancers likely to be associated with benzene exposure (Lymphohematopoietic, lung and lip cancers) at the county level in Texas. The spatial distribution of incident cases of the above cancers between 2004 and 2013 was assessed at the county level and found to have positive spatial auto-correlation. Subsequently, point pattern analysis was performed on industrial emissions of benzene reported to the Toxic Release Inventory (TRI), revealing a non-random spatial pattern. Universal kriging was performed using the industrial emissions data to derive estimates of ambient benzene levels at the county level. An ordinary linear regression model was fitted using the incidence rates as the outcome and the estimated benzene level along with chosen covariates and the residuals were assessed for lingering spatial auto-correlation. As the residuals showed that spatial auto-correlation persists, a spatial conditional auto-regression (CAR) model was fitted instead. In the spatial CAR linear regression model, estimated levels of ambient benzene were not found to be significantly associated with the 10-year incidence rates of lymphohematopoietic, lung and lip cancers at the county level.
    MeSH term(s) Air Pollutants/analysis ; Benzene/analysis ; Humans ; Incidence ; Industry ; Linear Models ; Neoplasms/epidemiology ; Spatial Analysis ; Texas/epidemiology
    Chemical Substances Air Pollutants ; Benzene (J64922108F)
    Language English
    Publishing date 2019-07-24
    Publishing country Switzerland
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1660-4601
    ISSN (online) 1660-4601
    DOI 10.3390/ijerph16152627
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  6. Article: Fractional Brownian motion and long term clinical trial recruitment.

    Zhang, Qiang / Lai, Dejian

    Journal of statistical planning and inference

    2015  Volume 141, Issue 5, Page(s) 1783–1788

    Abstract: Prediction of recruitment in clinical trials has been a challenging task. Many methods have been studied, including models based on Poisson process and its large sample approximation by Brownian motion (BM), however, when the independent incremental ... ...

    Abstract Prediction of recruitment in clinical trials has been a challenging task. Many methods have been studied, including models based on Poisson process and its large sample approximation by Brownian motion (BM), however, when the independent incremental structure is violated for BM model, we could use fractional Brownian motion to model and approximate the underlying Poisson processes with random rates. In this paper, fractional Brownian motion (FBM) is considered for such conditions and compared to BM model with illustrated examples from different trials and simulations.
    Language English
    Publishing date 2015-09-01
    Publishing country Netherlands
    Document type Journal Article
    ISSN 0378-3758
    ISSN 0378-3758
    DOI 10.1016/j.jspi.2010.11.028
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  7. Article ; Online: Analysis of Annual Costs of Mobile Clinics in the Southern United States.

    Attipoe-Dorcoo, Sharon / Delgado, Rigoberto / Lai, Dejian / Gupta, Aditi / Linder, Stephen

    Journal of primary care & community health

    2020  Volume 11, Page(s) 2150132720980623

    Abstract: Introduction: Mobile clinics provide an efficient manner for delivering healthcare services to at-risk populations, and there is a need to understand their economics. This study analyzes the costs of operating selected mobile clinic programs ... ...

    Abstract Introduction: Mobile clinics provide an efficient manner for delivering healthcare services to at-risk populations, and there is a need to understand their economics. This study analyzes the costs of operating selected mobile clinic programs representing service categories in dental, dental/preventive, preventive care, primary care/preventive, and mammography/primary care/preventive.
    Methods: The methodology included a self-reported survey of 96 mobile clinic programs operating in Texas, North Carolina, Georgia, and Florida; these states did not expand Medicaid and have a large proportion of uninsured individuals. Data were collected over an 8-month period from November 2016 to July 2017. The cost analyses were conducted in 2018, and were analyzed from the provider perspective. The average annual estimated costs; as well the costs per patient in each mobile clinic program within different service delivery types were assessed. Costs reported in the study survey were classified into recurrent direct costs and capital costs.
    Results: Results indicate that mean operating costs range from about $300 000 to $2.5 million with costs increasing from mammography/primary care/preventive delivery to dental/preventive. The majority of mobile clinics provided dental care followed by dental/preventive. The cost per patient visit for all mobile clinic service types ranged from $65 to $529, and appears to be considerably less than those reported in the literature for fixed clinic services.
    Conclusion: The overall costs of all delivery types in mobile clinics were lower than the costs of providing care to Medicare beneficiaries in federally funded health centers, making mobile clinics a sound economic complement to stationary healthcare facilities.
    MeSH term(s) Aged ; Florida ; Georgia ; Health Care Costs ; Humans ; Medicare ; Mobile Health Units ; North Carolina ; Texas ; United States
    Language English
    Publishing date 2020-12-21
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2550221-9
    ISSN 2150-1327 ; 2150-1319
    ISSN (online) 2150-1327
    ISSN 2150-1319
    DOI 10.1177/2150132720980623
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  8. Article ; Online: Statistical modeling of extracellular vesicle cargo to predict clinical trial outcomes for hypoplastic left heart syndrome.

    Hoffman, Jessica R / Park, Hyun-Ji / Bheri, Sruti / Platt, Manu O / Hare, Joshua M / Kaushal, Sunjay / Bettencourt, Judith L / Lai, Dejian / Slesnick, Timothy C / Mahle, William T / Davis, Michael E

    iScience

    2023  Volume 26, Issue 10, Page(s) 107980

    Abstract: Cardiac-derived c-kit+ progenitor cells (CPCs) are under investigation in the CHILD phase I clinical trial (NCT03406884) for the treatment of hypoplastic left heart syndrome (HLHS). The therapeutic efficacy of CPCs can be attributed to the release of ... ...

    Abstract Cardiac-derived c-kit+ progenitor cells (CPCs) are under investigation in the CHILD phase I clinical trial (NCT03406884) for the treatment of hypoplastic left heart syndrome (HLHS). The therapeutic efficacy of CPCs can be attributed to the release of extracellular vesicles (EVs). To understand sources of cell therapy variability we took a machine learning approach: combining bulk CPC-derived EV (CPC-EV) RNA sequencing and cardiac-relevant
    Language English
    Publishing date 2023-09-21
    Publishing country United States
    Document type Journal Article
    ISSN 2589-0042
    ISSN (online) 2589-0042
    DOI 10.1016/j.isci.2023.107980
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  9. Article: Group sequential test under fractional Brownian motion in monitoring clinical trials

    Lai, Dejian

    Statistical methods & applications : journal of the Italian Statistical Society Vol. 19, No. 2 , p. 277-286

    2010  Volume 19, Issue 2, Page(s) 277–286

    Author's details Dejian Lai
    Language English
    Publisher Springer
    Publishing place Berlin ; Heidelberg
    Document type Article
    ZDB-ID 2082218-2 ; 2098826-6
    ISSN 1613-981X ; 1618-2510
    ISSN (online) 1613-981X
    ISSN 1618-2510
    Database ECONomics Information System

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  10. Article: A Comparative Study of Handicap-free Life Expectancy of China in 1987 and 2006

    Lai, Dejian

    Social indicators research. 2009 Jan., v. 90, no. 2

    2009  

    Abstract: After the first large scale national sampling survey on handicapped persons in 1987, China conducted its second national sampling survey in 2006. Using the data from these two surveys and the national life tables, we computed and compared the expected ... ...

    Abstract After the first large scale national sampling survey on handicapped persons in 1987, China conducted its second national sampling survey in 2006. Using the data from these two surveys and the national life tables, we computed and compared the expected years of life free of handicapped condition by the Sullivan method. The expected years of life lived with handicap for the Chinese population increased from 4.87 years for males and 5.81 years for females in 1987 to 5.55 years and 6.32 years in 2006, respectively. The same trend was observed for people in working ages (15-64) and old ages (65+). However, the expected years of life lived with handicap decreased for children (0-14). Our results also showed that the effect of skeletal handicap increased notably for both sexes. Healthy life expectancy is an important indicator in measuring quality of life of a population. Our study utilized this measurement to quantify one aspect of quality of life of the Chinese population.
    Language English
    Dates of publication 2009-01
    Size p. 257-265.
    Publisher Springer Netherlands
    Publishing place Dordrecht
    Document type Article
    ZDB-ID 2018687-3
    ISSN 1573-0921 ; 0303-8300
    ISSN (online) 1573-0921
    ISSN 0303-8300
    DOI 10.1007/s11205-008-9256-1
    Database NAL-Catalogue (AGRICOLA)

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