Epidemiology & Biostatistics Research Works

Permanent URI for this collectionhttp://hdl.handle.net/1903/7128

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Start date: 2000End date: 2009

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    A method for analyzing censored survival phenotype with gene expression data
    (Springer Nature, 2008-10-06) Wu, Tongtong; Sun, Wei; Yuan, Shinsheng; Chen, Chun-Houh; Li, Ker-Chau
    Survival time is an important clinical trait for many disease studies. Previous works have shown certain relationship between patients' gene expression profiles and survival time. However, due to the censoring effects of survival time and the high dimensionality of gene expression data, effective and unbiased selection of a gene expression signature to predict survival probabilities requires further study. We propose a method for an integrated study of survival time and gene expression. This method can be summarized as a two-step procedure: in the first step, a moderate number of genes are pre-selected using correlation or liquid association (LA). Imputation and transformation methods are employed for the correlation/LA calculation. In the second step, the dimension of the predictors is further reduced using the modified sliced inverse regression for censored data (censorSIR). The new method is tested via both simulated and real data. For the real data application, we employed a set of 295 breast cancer patients and found a linear combination of 22 gene expression profiles that are significantly correlated with patients' survival rate. By an appropriate combination of feature selection and dimension reduction, we find a method of identifying gene expression signatures which is effective for survival prediction.
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    Hepatitis B vaccinations among Koreans: Results from 2005 Korea National Cancer Screening Survey
    (Springer Nature, 2009-11-25) Juon, Hee-Soon; Choi, Kui Son; Park, Eun-Cheol; Kwak, Min-Son; Lee, Sunmin
    Liver cancer is one of most commonly diagnosed cancers among Koreans. Chronic hepatitis B virus (HBV) infection is a major risk factor for liver cancer. HBV infection can be prevented by effective screening and vaccination programs. The purpose of this study is to examine the status of HBV infection and the predictors associated with HBV vaccination. The study population was derived from the 2005 Korea National Cancer Screening Survey (KNCSS). The KNCSS is an annual cross-sectional survey that uses a nationally-representative random sampling to investigate cancer screening rates. A total of 1,786 Koreans over 40 years of age participated in this study. Of all the participants, 5.9% reported HBV positive (HBsAg+, HBsAb-), 41.8% were HBV negative but protected (HBsAg-, HBsAb+), and 52.3% were unprotected (HBsAg-, HBsAb-). Among unprotected individuals (n = 934), 23.1% reported to have received the vaccination. About half of those who had vaccinations completed the 3-shot vaccine series. In multiple analyses, education, having private cancer insurance, alcohol use, having regular check-up, and doing regular exercise were associated with completed HBV vaccination. This study result suggests that we need a liver cancer education program to increase HBV awareness and to increase the liver cancer prevention message among low educated populations.
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    Assessing Health Concerns and Barriers in a Heterogeneous Latino Community
    (The Johns Hopkins University Press, 2006) Martinez, Iveris L.; Carter-Pokras, Olivia
    Introduction. Major health issues and barriers to health services for Latino immigrants were identified through community-based participatory research in Baltimore city. Methods. In collaboration with community partners, five focus groups were conducted among Latino adults from 10 countries and health service providers. Findings. Priorities across groups included chronic diseases, HIV/AIDS and STDs, mental health, and the need for ancillary services. Community members and providers did not always agree on what health matters were of primary concern. Participants expected to receive health information at the point of service. Barriers to receiving health services and information span linguistic, financial, logistical, legal, and cultural matters. Conclusions. This formative research illustrates the complexity and interrelatedness of health priorities and barriers created by social issues such as employment, legal status, and related stressors.