Biostatistics Commons^™

A Pairwise Likelihood Augmented Estimator For The Cox Model Under Left-Truncation, Fan Wu, Sehee Kim, Jing Qin, Rajiv Saran, Yi Li

The University of Michigan Department of Biostatistics Working Paper Series

Survival data collected from prevalent cohorts are subject to left-truncation and the analysis is challenging. Conditional approaches for left-truncated data under the Cox model are inefficient as they typically ignore the information in the marginal likelihood of the truncation times. Length-biased sampling methods can improve the estimation efficiency but only when the stationarity assumption of the disease incidence holds, i.e., the truncation distribution is uniform; otherwise they may generate biased estimates. In this paper, we propose a semi-parametric method for the Cox model under general left-truncation, where the truncation distribution is unspecified. Our approach is to make inference based on …

On Partial Identification Of The Pure Direct Effect, Caleb Miles, Phyllis Kanki, Seema Meloni, Eric Tchetgen Tchetgen

Harvard University Biostatistics Working Paper Series

No abstract provided.

Preparedness Of Hospitals In The Republic Of Ireland For An Influenza Pandemic, An Infection Control Perspective, Mary Reidy, Fiona Ryan, Dervla Hogan, Seán Lacey, Claire Buckley

Department of Mathematics Publications

When an influenza pandemic occurs most of the population is susceptible and attack rates can range as high as 40–50 %. The most important failure in pandemic planning is the lack of standards or guidelines regarding what it means to be ‘prepared’. The aim of this study was to assess the preparedness of acute hospitals in the Republic of Ireland for an influenza pandemic from an infection control perspective.

Novel Human Abcc9/Sur2 Brain-Expressed Transcripts And An Eqtl Relevant To Hippocampal Sclerosis Of Aging, Peter T. Nelson, Wang-Xia Wang, Bernard R. Wilfred, Angela Wei, James Dimayuga, Qingwei Huang, Eseosa T. Ighodaro, Sergey C. Artiushin, David W. Fardo

Sanders-Brown Center on Aging Faculty Publications

ABCC9 genetic polymorphisms are associated with increased risk for various human diseases including hippocampal sclerosis of aging. The main goals of this study were 1 > to detect the ABCC9 variants and define the specific 3′ untranslated region (3′UTR) for each variant in human brain, and 2 > to determine whether a polymorphism (rs704180) associated with risk for hippocampal sclerosis of aging pathology is also associated with variation in ABCC9 transcript expression and/or splicing. Rapid amplification of ABCC9 cDNA ends (3′RACE) provided evidence of novel 3′ UTR portions of ABCC9 in human brain. In silico and experimental studies were performed focusing on …

Sociodemographic Factors To Dengue Hemmorrhagic Fever Case In Indonesia, Desy Nuryunarsih

Kesmas

Demam berdarah dengue (DBD) adalah penyebab utama rawat inap dan kematian pada anak-anak. Indonesia adalah salah satu negara yang oleh WHO dikategorikan hyperendemicity dengan empat serotipe virus tersebar di daerah perkotaan. Faktor sosiodemografi dianggap sebagai faktor pendukung terjadinya DBD di Indonesia. Studi ini menggunakan data sekunder yang diunduh dari Basis Data Kesehatan Provinsi tahun 2010 Kementerian Kesehatan Republik Indonesia untuk menentukan korelasi antara ketiga faktor sosiodemografi dengan insiden DBD. Penelitian ini menggunakan metode kuantitatif deskripsi korelasi. Hasil penelitian menunjukkan bahwa dua faktor sosiodemografi terpilih memiliki korelasi linier dengan insiden DBD. Analisa regresi multivariat menunjukkan kecilnya korelasi antara insiden DBD dengan …

Penerapan Sistem Remunerasi Dan Kinerja Pelayanan, Tri Wisesa Soetisna, Dumilah Ayuningtyas, Misnaniarti Misnaniarti

Kesmas

Remuneration can influence worker`s motivation, and improve their performance. Likewise in hospital as capital-intensive, human resources-intensive as well as knowledge and technology-intensive health care institution. This study aimed to analyze employee’s perception of remuneration system implementation and adult cardiac surgery services unit’s performance at hospital. This study used a mixed method approach (quantitative and qualitative). Quantitative study design was cross-sectional using questionnaire for self-assesment. Meanwhile, qualitative study design was descriptive conducted through focus group discussion and document review on data in forms of schedule book, registration book, nursing notes and medical records. Data collection was conducted in 2013 at one …

Analisis Sif Kerja, Masa Kerja, Dan Budaya K3 Dengan Fungsi Paru Pekerja Tambang Batu Bara, Qomariyatus Sholihah, Aprizal Satria Hanafi, Wanti Wanti, Ahmad Alim Bachri, Sutarto Hadi

Kesmas

Penambangan batu bara merupakan salah satu sumber pencemaran udara berupa partikel debu batu bara yang dapat mengganggu kesehatan pernapasan bila terhirup manusia. Risiko kerja yang sering terjadi dapat berasal dari faktor pekerjaan atau perilaku pekerja sendiri, di antaranya sif kerja dan masa kerja. Tujuan penelitian adalah untuk mengetahui hubungan sif kerja, masa kerja, dan budaya keselamatan dan kesehatan kerja (K3) dengan fungsi paru pekerja tambang batu bara. Penelitian ini merupakan desain kasus kontrol dengan jumlah masing-masing sampel untuk kasus dan kontrol sebesar 178 responden. Penelitian dilakukan pada bulan Oktober November 2014 di PT. X Kalimantan Selatan. Hasil penelitian berdasarkan uji …

Tradisi Dan Lingkungan Sosial Memengaruhi Dukungan Menyusui Pada Bayi Berat Badan Lahir Rendah Di Kota Malang, Muladefi Choiriyah, Elsi Dwi Hapsari, Wiwin Lismidiati

Kesmas

Berat badan lahir rendah (BBLR) merupakan salah satu penyebab utama kematian bayi di dunia. World Health Organization tahun 2003 telah merekomendasikan menyusui sebagai salah satu penanganan BBLR. Namun, ibu yang memiliki bayi BBLR mengalami kesulitan di awal persalinan. Selain itu, menyusui di Indonesia juga dipengaruhi oleh sosial dan budaya yang dipercayai sehingga memengaruhi keputusan ibu untuk memilih tetap menyusui atau tidak sama sekali di periode awal postpartum. Tujuan penelitian ini untuk mengeksplorasi makna pengalaman ibu untuk tetap menyusui bayi dengan BBLR. Penelitian kualitatif ini dengan pendekatan fenomenologi. Tujuh orang partisipan adalah ibu yang pernah menyusui bayi BBLR. Pengumpulan data dilakukan …

Pendidikan Kesehatan Reproduksi Formal Dan Hubungan Seksual Pranikah Remaja Indonesia, Anggriyani Wahyu Pinandari, Siswanto Agus Wilopo, Djauhar Ismail

Kesmas

Transisi demografi kedua akan terjadi di Indonesia dan ditandai dengan revolusi seksual dan reproduksi. Masalah potensial di masa ini adalah peningkatan perilaku seksual pranikah, kehamilan yang tidak diinginkan, infeksi menular seksual dan penyalahgunaan obat. Penelitian ini bertujuan untuk menguji pengaruh pendidikan kesehatan reproduksi formal terhadap penundaan hubungan seksual pranikah pada remaja dan dewasa muda Indonesia. Penelitian potong lintang yang dianalisis sebagai kohort retrospektif menggunakan data Survei Kesehatan Reproduksi Remaja Indonesia tahun 2012 (10.980 laki-laki dan 8.902 perempuan). Efek pendidikan kesehatan reproduksi formal terhadap penundaan perilaku hubungan seksual dianalisis menggunakan kurva kaplan meier, uji log-rank, dan uji chi square, sedangkan analisis …

Assessment Of Nutrition Information System Using Health Metrics Network Framework, Mochamad Iqbal Nurmansyah, Catur Rosidati, Riastuti Kusuma Wardani, Badra Al-Aufa

Kesmas

Sistem informasi gizi (Sigizi) dikembangkan oleh Direktorat Bina Gizi Kementerian Kesehatan sejak 2011. Data Sigizi mencakup data penimbangan balita di posyandu, kasus gizi buruk, cakupan pemberian tablet Fe pada ibu hamil, konsumsi garam beryodium, pemberian vitamin A, dan ASI eksklusif. Penelitian ini bertujuan untuk mengukur kinerja pengelolaan Sigizi di Dinas Kesehatan Kota Tangerang Selatan menggunakan kerangka Health Metrics Network yang dikeluarkan oleh WHO tahun 2008. Sigizi merupakan sistem informasi yang diaplikasikan pada tingkat nasional dengan mekanisme pelaporan berjenjang, dari 508 kabupaten/kota menuju 34 provinsi dan bermuara di tingkat nasional. Di Provinsi Banten, terdapat delapan kabupaten/kota yang menjalankan Sigizi. Informan penelitian …

Sikap Remaja Terhadap Keperawanan Dan Perilaku Seksual Dalam Berpacaran, Desi Rusmiati, Sutanto Priyo Hastono

Kesmas

Laporan Survei Demografi dan Kesehatan Indonesia (SDKI) tahun 2007 dan 2012 menunjukkan terjadinya penurunan jumlah remaja yang memiliki sikap positif terhadap pentingnya mempertahankan keperawanan bagi seorang perempuan. Dari laporan yang sama juga diketahui adanya peningkatan perilaku seksual remaja dalam hal berpegangan tangan, berciuman bibir, petting, dan melakukan hubungan seksual. Penelitian ini bertujuan untuk membuktikan adanya hubungan antara sikap remaja terhadap keperawanan dengan perilaku seksual dalam berpacaran dengan melibatkan usia, jenis kelamin, pendidikan, tempat tinggal, usia pertama kali pacaran, pengetahuan, dan pengaruh teman sebaya sebagai variabel perancu. Penelitian ini merupakan penelitian kuantitatif dengan rancangan potong lintang menggunakan model faktor risiko dari …

Statistical Estimation Of T1 Relaxation Time Using Conventional Magnetic Resonance Imaging, Amanda Mejia, Elizabeth M. Sweeney, Blake Dewey, Govind Nair, Pascal Sati, Colin Shea, Daniel S. Reich, Russell T. Shinohara

UPenn Biostatistics Working Papers

Quantitative T₁ maps estimate T₁ relaxation times and can be used to assess diffuse tissue abnormalities within normal-appearing tissue. T₁ maps are popular for studying the progression and treatment of multiple sclerosis (MS). However, their inclusion in standard imaging protocols remains limited due to the additional scanning time and expert calibration required and susceptibility to bias and noise. Here, we propose a new method of estimating T₁ maps using four conventional MR images, which are intensity- normalized using cerebellar gray matter as a reference tissue and related to T₁ using a smooth regression model. Using …

Confident Difference Criterion: A New Bayesian Differentially Expressed Gene Selection Algorithm With Applications., Fang Yu, Ming-Hui Chen, Lynn Kuo, Heather Talbott, John S. Davis

Journal Articles: Biostatistics

BACKGROUND: Recently, the Bayesian method becomes more popular for analyzing high dimensional gene expression data as it allows us to borrow information across different genes and provides powerful estimators for evaluating gene expression levels. It is crucial to develop a simple but efficient gene selection algorithm for detecting differentially expressed (DE) genes based on the Bayesian estimators.

RESULTS: In this paper, by extending the two-criterion idea of Chen et al. (Chen M-H, Ibrahim JG, Chi Y-Y. A new class of mixture models for differential gene expression in DNA microarray data. J Stat Plan Inference. 2008;138:387-404), we propose two new gene …

C-Learning: A New Classification Framework To Estimate Optimal Dynamic Treatment Regimes, Baqun Zhang, Min Zhang

The University of Michigan Department of Biostatistics Working Paper Series

Personalizing treatment to accommodate patient heterogeneity and the evolving nature of a disease over time has received considerable attention lately. A dynamic treatment regime is a set of decision rules, each corresponding to a decision point, that determine that next treatment based on each individual’s own available characteristics and treatment history up to that point. We show that identifying the optimal dynamic treatment regime can be recast as a sequential classification problem and is equivalent to sequentially minimizing a weighted expected misclassification error. This general classification perspective targets the exact goal of optimally individualizing treatments and is new and fundamentally …

On Simple Relations Between Difference-In-Differences And Negative Outcome Control Of Unobserved Confounding, Tamar Sofer, David B. Richardson, Elena Colincino, Joel Schwartz, Eric J. Tchetgen Tchetgen

Harvard University Biostatistics Working Paper Series

No abstract provided.

Lepski's Method And Adaptive Estimation Of Nonlinear Integral Functionals Of Density, Rajarshi Mukherjee, Eric J. Tchetgen Tchetgen, James M. Robins

Harvard University Biostatistics Working Paper Series

No abstract provided.

Extended Followup Of A Cohort Of Chromium Production Workers, Herman Jones Gibb, Peter St. John Lees, Jing Wang, Keri O'Leary

Epidemiology Faculty Publications

Background

The current study evaluates the mortality of 2,354 workers first employed at a Baltimore chromate production plant between 1950 and 1974.

Methods

The National Death Index (NDI Plus) was used to determine vital status and cause of death. Cumulative chromium (VI) exposure and nasal and skin irritation were evaluated as risk factors for lung cancer mortality.

Results

There are 91,186 person-years of observation and 217 lung cancer deaths. Cumulative chromium (VI) exposure, nasal irritation, nasal perforation, nasal ulceration, and other forms of irritation (e.g., skin irritation) were associated with lung cancer mortality.

Conclusion

Cumulative chromium (VI) exposure was a …

Sexual Networks And Hiv Risk Among Black Men Who Have Sex With Men In 6 U.S. Cities, Hong-Van Tieu, Ting-Yuan Liu, Sophia Hussen, Matthew Connor, Lei Wang, Gregory Phillips Ii, + 11 More

Epidemiology Faculty Publications

Background

Sexual networks may place U.S. Black men who have sex with men (MSM) at increased HIV risk.

Methods

Self-reported egocentric sexual network data from the prior six months were collected from 1,349 community-recruited Black MSM in HPTN 061, a multi-component HIV prevention intervention feasibility study. Sexual network composition, size, and density (extent to which members are having sex with one another) were compared by self-reported HIV serostatus and age of the men. GEE models assessed network and other factors associated with having a Black sex partner, having a partner with at least two age category difference (age difference between …

Germline Mutation Detection In Next Generation Sequencing Data And Tp53 Mutation Carrier Probability Estimation For Li-Fraumeni Syndrome, Gang Peng

Dissertations and Theses (Open Access)

Next generation sequencing technology has been widely used in genomic analysis, but its application has been compromised by the missing true variants, especially when these variants are rare. We proposed a family-based variant calling method, FamSeq, integrating Mendelian transmission information with de novo mutation and sequencing data to improve the variant calling accuracy. We investigated the factors impacting the improvement of family-based variant calling in simulation data and validated it in real sequencing data. In both simulation and real data, FamSeq works better than the single individual based method.

In FamSeq, we implemented four different methods for the Mendelian genetic …

Computerizing Efficient Estimation Of A Pathwise Differentiable Target Parameter, Mark J. Van Der Laan, Marco Carone, Alexander R. Luedtke

U.C. Berkeley Division of Biostatistics Working Paper Series

Frangakis et al. (2015) proposed a numerical method for computing the efficient influence function of a parameter in a nonparametric model at a specified distribution and observation (provided such an influence function exists). Their approach is based on the assumption that the efficient influence function is given by the directional derivative of the target parameter mapping in the direction of a perturbation of the data distribution defined as the convex line from the data distribution to a pointmass at the observation. In our discussion paper Luedtke et al. (2015) we propose a regularization of this procedure and establish the validity …

Caffeine Consumption Contributes To Skin Intrinsic Fluorescence In Type 1 Diabetes., Karen M Eny, Trevor J Orchard, Rachel Grace Miller, John Maynard, Denis M Grant, Tina Costacou, Patricia A. Cleary, Barbara H Braffett, Andrew D Paterson, Dcct/Edic Research Group

GW Biostatistics Center

Background: A variant (rs1495741) in the gene for the N-acetyltransferase 2 (NAT2) protein is associated with skin intrinsic fluorescence (SIF), a noninvasive measure of advanced glycation end products and other fluorophores in the skin. Because NAT2 is involved in caffeine metabolism, we aimed to determine whether caffeine consumption is associated with SIF and whether rs1495741 is associated with SIF independently of caffeine.

Materials and Methods: SIF was measured in 1,181 participants with type 1 diabetes from the Epidemiology of Diabetes Interventions and Complications study. Two measures of SIF were used: SIF1, using a 375-nm excitation light-emitting diode (LED), and …

Drawing Valid Targeted Inference When Covariate-Adjusted Response-Adaptive Rct Meets Data-Adaptive Loss-Based Estimation, With An Application To The Lasso, Wenjing Zheng, Antoine Chambaz, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

Adaptive clinical trial design methods have garnered growing attention in the recent years, in large part due to their greater flexibility over their traditional counterparts. One such design is the so-called covariate-adjusted, response-adaptive (CARA) randomized controlled trial (RCT). In a CARA RCT, the treatment randomization schemes are allowed to depend on the patient’s pre-treatment covariates, and the investigators have the opportunity to adjust these schemes during the course of the trial based on accruing information (including previous responses), in order to meet a pre-specified optimality criterion, while preserving the validity of the trial in learning its primary study parameter.

In …

Negative Outcome Control For Unobserved Confounding Under A Cox Proportional Hazards Model, Eric J. Tchetgen Tchetgen, Tamar Sofer, David Richardson

Harvard University Biostatistics Working Paper Series

No abstract provided.

Survival Analysis With Functions Of Mis-Measured Covariate Histories: The Case Of Chronic Air Pollution Exposure In Relation To Mortality In The Nurses' Health Study, Xiaomei Liao, Molin Wang, Jaime E. Hart, Francine Laden, Donna Spiegelman

Harvard University Biostatistics Working Paper Series

Environmental epidemiologists are often interested in estimating the effect of functions of time-varying exposure histories, such as the 12-month moving average, in relation to chronic disease incidence or mortality. The individual exposure measurements that comprise such an exposure history are usually mis-measured, at least moderately, and, often, more substantially. To obtain unbiased estimates of Cox model hazard ratios for these complex mis-measured exposure functions, an extended risk set regression calibration (RRC) method for Cox models is developed and applied to a study of long-term exposure to the fine particulate matter ($PM_{2.5}$) component of air pollution in relation to all-cause mortality …

Nitrate And Nitrite Ingestion And Risk Of Ovarian Cancer Among Postmenopausal Women In Iowa, Maki Inoue-Choi, Rena R. Jones, Kristin E. Anderson, Kenneth P. Cantor, James R. Cerhan, Stuart Krasner, Kimberly Robien, Peter J. Weyer, Mary H. Ward

Epidemiology Faculty Publications

Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds (NOC), potential human carcinogens. We evaluated the association of nitrate and nitrite ingestion with postmenopausal ovarian cancer risk in the Iowa Women's Health Study. Among 28,555 postmenopausal women, we identified 315 incident epithelial ovarian cancers from 1986 to 2010. Dietary nitrate and nitrite intakes were assessed at baseline using food frequency questionnaire data. Drinking water source at home was obtained in a 1989 follow-up survey. Nitrate-nitrogen (NO₃-N) and total trihalomethane (TTHM) levels for Iowa public water utilities were linked to residences and average levels were …

Size And Power Of Tests Of Hypotheses On Survival Parameters From The Lindley Distribution With Covariates, Macaulay Okwuokenye, Karl E. Peace

Biostatistics: Faculty Publications

The Lindley model is considered as an alternative model facilitating analyses of time-to-event data with covariates. Covariate information is incorporated using the Cox’s proportional hazard model with the Lindley model at the timedependent component. Simulation studies are performed to assess the size and power of tests of hypotheses on parameters arising from maximum likelihood estimators of parameters in the Lindley model. Results are contrasted with that arising from Cox’s partial maximum likelihood estimator. The Linley model is used to analyze a publicly available data set and contrasted with other models.

Joint Modeling Of Treatment Effect On Time-To-Event Endpoint And Safety Covariates In Control Clinical Trial Data Analysis, Kao-Tai Tsai, Karl E. Peace

Biostatistics: Faculty Publications

It is a common practice to perform a separate analysis of efficacy and safety data from clinical trials to estimate the benefit and risk aspects of a particular treatment regimen. However, by doing so, one is likely to miss the complete picture of the treatment effect given that these data are generated from the same study subjects and therefore most likely will be correlated. Therefore, it is desirable to analyze these data jointly to obtain a more complete profile of the treatment regimen. A substantial number of statistical methodologies have been proposed in the last decade to model the time-to-event …

Fast, Accurate, And Reliable Molecular Docking With Quickvina 2, Amr Alhossary, Stephanus Daniel Handoko, Yuguang Mu, Chee-Keong Kwoh

Research Collection School Of Computing and Information Systems

Motivation: The need for efficient molecular docking tools for high-throughput screening is growing alongside the rapid growth of drug-fragment databases. AutoDock Vina ('Vina') is a widely used docking tool with parallelization for speed. QuickVina ('QVina 1') then further enhanced the speed via a heuristics, requiring high exhaustiveness. With low exhaustiveness, its accuracy was compromised. We present in this article the latest version of QuickVina ('QVina 2') that inherits both the speed of QVina 1 and the reliability of the original Vina.Results: We tested the efficacy of QVina 2 on the core set of PDBbind 2014. With the default exhaustiveness level …

Doubly Robust Estimation Of A Marginal Average Effect Of Treatment On The Treated With An Instrumental Variable, Lan Liu, Wang Miao, Baoluo Sun, James M. Robins, Eric J. Tchetgen Tchetgen

Harvard University Biostatistics Working Paper Series

No abstract provided.

One-Step Targeted Minimum Loss-Based Estimation Based On Universal Least Favorable One-Dimensional Submodels, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

Consider a study in which one observes n independent and identically distributed random variables whose probability distribution is known to be an element of a particular statistical model, and one is concerned with estimation of a particular real valued pathwise differentiable target parameter of this data probability distribution. The canonical gradient of the pathwise derivative of the target parameter, also called the efficient influence curve, defines an asymptotically efficient estimator as an estimator that is asymptotically linear with influence curve equal to the efficient influence curve.The targeted maximum likelihood estimator is a two stage estimator obtained by constructing a so …