Biostatistics Commons^™

Analysis Of Covariance (Ancova) In Randomized Trials: More Precision, Less Conditional Bias, And Valid Confidence Intervals, Without Model Assumptions, Bingkai Wang, Elizabeth Ogburn, Michael Rosenblum

Johns Hopkins University, Dept. of Biostatistics Working Papers

Covariate adjustment" in the randomized trial context refers to an estimator of the average treatment effect that adjusts for chance imbalances between study arms in baseline variables (called “covariates"). The baseline variables could include, e.g., age, sex, disease severity, and biomarkers. According to two surveys of clinical trial reports, there is confusion about the statistical properties of covariate adjustment. We focus on the ANCOVA estimator, which involves fitting a linear model for the outcome given the treatment arm and baseline variables, and trials with equal probability of assignment to treatment and control. We prove the following new (to the best …

Substance Use Patterns Among Women Living With Hiv Compared With The General Female Population Of Canada, Mostafa Shokoohi, Greta R Bauer, Angela Kaida, Ashley Lacombe-Duncan, Mina Kazemi, Brenda Gagnier, Alexandra De Pokomandy, Mona Loutfy

Epidemiology and Biostatistics Publications

BACKGROUND: HIV infection and substance use synergistically impact health outcomes of people with HIV. In this study, we assessed the prevalence of substance use among women living with HIV (WLWH) and compared them with expected values from general data.

METHODS: Cigarette smoking, frequency of alcohol consumption, last-month non-prescribed cannabis use (vs. last-year use), and last 3 months regular (≥once/week) and occasional (

RESULTS: Compared to expected estimates from general population women, a higher proportion of WLWH reported daily cigarette smoking (SPD: 26.8% [95% CI: 23.9, 29.7]), smoking ≥20 cigarettes/day (SPD: 11.6% [9.8, 13.6]), regular non-prescribed cannabis use (SPD: 8.0% [4.1, …

Family Physician Remuneration Schemes And Specialist Referrals: Quasi-Experimental Evidence From Ontario, Canada., Sisira Sarma, Nirav Mehta, Rose Anne Devlin, Koffi Ahoto Kpelitse, Lihua Li

Epidemiology and Biostatistics Publications

Understanding how family physicians respond to incentives from remuneration schemes is a central theme in the literature. One understudied aspect is referrals to specialists. Although the theoretical literature has suggested that capitation increases referrals to specialists, the empirical evidence is mixed. We push forward the empirical research on this question by studying family physicians who switched from blended fee-for-service to blended capitation in Ontario, Canada. Using several health administrative databases from 2005 to 2013, we rely on inverse probability weighting with fixed-effects regression models to account for observed and unobserved differences between the switchers and nonswitchers. Switching from blended fee-for-service …

Interrupted Time Series Design To Evaluate The Effect Of The Icd-9-Cm To Icd-10-Cm Coding Transition On Injury Hospitalization Trends, Svetla Slavova, Julia F. Costich, Huong Luu, Judith Fields, Barbara A. Gabella, Sergey Tarima, Terry L. Bunn

Biostatistics Faculty Publications

Background: Implementation of the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) in the U.S. on October 1, 2015 was a significant policy change with the potential to affect established injury morbidity trends. This study used data from a single state to demonstrate 1) the use of a statistical method to estimate the effect of this coding transition on injury hospitalization trends, and 2) interpretation of significant changes in injury trends in the context of the structural and conceptual differences between ICD-9-CM and ICD-10-CM, the new ICD-10-CM-specific coding guidelines, and proposed ICD-10-CM-based framework for reporting of injuries by intent …

An Interval-Censored Proportional Hazards Model, John M. Williamson, Hung-Mo Lin, Hae-Young Kim

NYMC Faculty Publications

We fit a Cox proportional hazards (PH) model to interval-censored survival data by first subdividing each individual's failure interval into non-overlapping sub-intervals. Using the set of all interval endpoints in the data set, those that fall into the individual's interval are then used as the cut points for the sub-intervals. Each sub-interval has an accompanying weight calculated from a parametric Weibull model based on the current parameter estimates. A weighted PH model is then fit with multiple lines of observations corresponding to the sub-intervals for each individual, where the lower end of each sub-interval is used as the observed failure …

In Memoriam: Irina V. Tarasevich, Marina Eremeeva

Biostatistics, Epidemiology & Environmental Health Sciences: Faculty Publications

Article published in New Microbes and New Infections.

Gaw20: Methods And Strategies For The New Frontiers Of Epigenetics And Pharmacogenomics, Nathan L. Tintle, David W. Fardo, Marzia De Andrade, Stella Aslibekyan, Julia N. Bailey, Justo Lorenzo Bermejo, Rita M. Cantor, Saurabh Ghosh, Philip Melton, Xuexua Wang, Jean W. Maccluer, Laura Almasy

Biostatistics Faculty Publications

GAW20 provided a platform for developing and evaluating statistical methods to analyze human lipid-related phenotypes, DNA methylation, and single-nucleotide markers in a study involving a pharmaceutical intervention. In this article, we present an overview of the data sets and the contributions analyzing these data. The data, donated by the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) investigators, included data from 188 families (N = 1105) which included genome-wide DNA methylation data before and after a 3-week treatment with fenofibrate, single-nucleotide polymorphisms, metabolic syndrome components before and after treatment, and a variety of covariates. The contributions from individual …

Association Analyses Of Repeated Measures On Triglyceride And High-Density Lipoprotein Levels: Insights From Gaw20, Saurabh Ghosh, David W. Fardo

Biostatistics Faculty Publications

Background: The GAW20 group formed on the theme of methods for association analyses of repeated measures comprised 4sets of investigators. The provided “real” data set included genotypes obtained from a human whole-genome association study based on longitudinal measurements of triglycerides (TGs) and high-density lipoprotein in addition to methylation levels before and after administration of fenofibrate. The simulated data set contained 200 replications of methylation levels and posttreatment TGs, mimicking the real data set.

Results: The different investigators in the group focused on the statistical challenges unique to family-based association analyses of phenotypes measured longitudinally and applied a wide spectrum of …

Latent Tuberculosis Infection Is Associated With Increased Unstimulated Levels Of Interferon-Gamma In Lima, Peru, Moises A. Huaman, David Henson, Paola L. Rondan, Eduardo Ticona, Gustavo Miranda, Richard J. Kryscio, Raquel Mugruza, Ernesto Aranda, Cesar Ticona, Susan Abarca, Paula Heredia, Andres Aguirre, Timothy R. Sterling, Beth A. Garvy, Carl J. Fichtenbaum

Internal Medicine Faculty Publications

Background

We previously reported increased unstimulated blood levels of interferon-gamma in persons with latent tuberculosis infection (LTBI) in the United States, suggesting enhanced immune activation in LTBI. To investigate this further in a TB-endemic setting, we assessed interferon-gamma levels in persons with and without LTBI in Peru.

Methods

We analyzed data from patients with and without a recent type 1 (spontaneous) acute myocardial infarction (AMI) who were enrolled from two public hospital networks in Lima, Peru, and underwent LTBI testing using the QuantiFERON® TB Gold In-tube (QFT) assay. Participants with a positive QFT test were defined as having LTBI, whereas …

The Impact Of Peer Support On The Risk Of Future Hospital Readmissions Among Older Adults With A Medical Illness And Co-Occurring Depression, Kyaien O. Conner, Tamara Cadet, Monique J. Brown, Joshua T. Barnett

Faculty Publications

Older adults account for 60% of all preventable hospital readmissions. Although not all readmissions are preventable, evidence indicates that up to 75% of hospital readmissions can be prevented with enhanced patient education, pre-discharge assessment, and effective care upon discharge. Social support, specifically peer support, after discharge from hospital may be a crucial factor in minimizing the risk of preventable hospital readmission. The pilot study reported here evaluated the relationship between peer support and hospital readmissions in a sample of depressed older adults (N = 41) who were recently discharged from hospital due to a medical condition and who simultaneously had …

Cross-Sectional Hiv Incidence Estimation Accounting For Heterogeneity Across Communities, Yuejia Xu, Oliver B. Laeyendecker, Rui Wang

Harvard University Biostatistics Working Paper Series

No abstract provided.

Effectiveness Of 4-Aminopyridine For The Management Of Spasticity In Spinal Cord Injury: A Systematic Review, Joshua Weiner, Jane Hsieh, Amanda Mcintyre, Robert Teasell

Epidemiology and Biostatistics Publications

Background: Spasticity is a common secondary complication of spinal cord injury (SCI), which can severely impact functional independence and quality of life. 4-Aminopyridine (4-AP) is a potassium channel blocker that has been studied as an intervention for spasticity in individuals with SCI. Objective: To conduct a systematic review of the available evidence regarding the effectiveness of 4-AP for the management of spasticity in individuals with SCI. Methods: A comprehensive literature search was conducted on five electronic databases for articles published in English up to January 2017. Studies were included if (1) the sample size was three or more subjects, (2) …

Factors Influencing Immunisation Schedule Adherence And Completion At The Regional Level In The Philippines, Paolo Miguel Manalang Vicerra

Kesmas

Penyebab utama kematian bayi sebagian besar dapat dicegah dan terdapat alasan baik dari sisi suplai maupun permintaan layanan kesehatan hal itu dapat terus berlangsung. Penelitian ini bertujuan memastikan faktor-faktor yang memengaruhi perilaku layanan kesehatan preventif imunisasi bayi di Filipina yang tepat waktu karena tingkat kelengkapan, atau kepatuhan, telah stabil dalam beberapa dekade terakhir. Metode yang digunakan adalah pembuatan model statistik di tingkat subnasional. Sampel berisi bayi yang lahir sebelum Survei Demografi dan Kesehatan Nasional Filipina tahun 2013 untuk menentukan kepatuhan yang tepat terhadap jadwal imunisasi yang dimandatkan oleh pemerintah. Hal ini melibatkan penggabungan 17 wilayah administratif negara ke tiga wilayah …

Husband’S Support For Their Wives In Antenatal Care Visit, Awalia Hanifah, Hadi Pratomo, Giang Hoang

Kesmas

Di wilayah Puskesmas Cimanggis, Kota Depok, cakupan kunjungan antenatal pertama (K1) dan kunjungan ke-4 (K4) sebesar 99,4% (2013) dan 91% (2014). Dukungan suami ibu hamil merupakan salah satu faktor yang berperan penting dalam kunjungan antenatal pada ibu hamil. Penelitian ini bertujuan menilai faktor predisposisi, pemungkin dan penguat dari dukungan suami terhadap ANC istrinya dengan menggunakan pendekatan kualitatif dengan desain Rapid Assessment Procedure. Lima suami dan istrinya yang sedang hamil dipilih sebagai informan serta dua bidan puskesmas sebagai informan kunci. Analisis data menggunakan matriks data kualitatif dan teknik analisis tematik. Hasil penelitian menunjukkan bahwa faktor predisposisi, pemungkin dan penguat dari suami …

Influential Host Factors To The Incidence Of Hiv/Aids In Key Populations In Pati District, Dwi Murtono, Puguh Riyanto, Zahroh Shaluhiyah

Kesmas

Human Immunodeficiency Virus (HIV) dan Acquired Immune Deficiency Syndrome (AIDS) merupakan penyakit berbahaya di dunia yang salah satu metode penularannya adalah melalui hubungan seksual. Penelitian ini bertujuan menjelaskan faktor-faktor yang berpengaruh terhadap kejadian HIV/AIDS pada populasi kunci. Penelitian dilakukan dari bulan Maret sampai September 2016. Penelitian analitik observasional dengan rancangan kasus kontrol pada populasi kunci di Kabupaten Pati. Kasus sebanyak 53 pasien positif HIV/AIDS, sedangkan kontrol sebanyak 53 pasien negative HIV/AIDS.Pengambilan sampel menggunakan teknik consecutive sampling. Data diperoleh dari riwayat medis dan wawancara kuesioner. Penelitian ini menggunakan uji kai kuadrat pada analisis bivariat dan regresi logistik ganda pada analisis multivariat. …

Unsafe Behavior Of Workers In Rotary Lathe Section In One Of The Plywood Industries In East Kalimantan, Iwan Muhamad Ramdan, Dyyka Indah Wijayanti

Kesmas

Kecelakaan kerja dan penyakit akibat kerja masih menjadi masalah kesehatan dunia, dua faktor utama penyebabnya adalah perilaku dan kondisi lingkungan kerja yang tidak aman. Penelitian sebelumnya membuktikan penyebab utamanya adalah faktor perilaku yang tidak aman. Penelitian ini bertujuan menganalisis faktor-faktor yang berhubungan dengan perilaku tidak aman dalam bekerja pada tenaga kerja di PT IAW dan menganalisis faktor yang paling berpengaruh. Penelitian potong lintang dilakukan pada bulan Juli sampai Agustus 2016 terhadap 104 sampel penelitian. Variabel bebas terdiri dari persepsi, komunikasi, pengawasan, ketersediaan alat pelindung diri (APD), pelatihan dan suhu lingkungan kerja. Variabel terikat adalah perilaku tidak aman. Analisis data menggunakan …

Direct Experience With Cervical Cancer Patient, Husband Support, And Self-Perception As Determinant Factors Of Women’S Desire To Take Via Screening Test, Nur Anisah Rahmawati, Linda Dewanti

Kesmas

Kanker serviks menyebabkan 10.3% kematian pada perempuan di Indonesia. Inspeksi visual asam asetat (IVA) telah digunakan untuk program skrining sejak tahun 2014 tetapi hanya 2,45 % perempuan yang melakukan pemeriksaan pada tahun 2015. Di tempat penelitian, cakupan skrining metode IVA kurang dari 1%. Penelitian sebelumnya menyebutkan faktor psikososial sebagai satu faktor penting, tetapi sedikit penelitian yang menganalisis peran dukungan suami dan pengalaman langsung dengan penderita kanker serviks. Penelitian ini bertujuan mempelajari hubungan antara pengalaman langsung dengan penderita kanker serviks, dukungan suami, persepsi diri dan keinginan perempuan melakukan skrining IVA. Penelitian potong lintang dilakukan secara acak pada perempuan berusia 25-55 tahun …

Web-Based Application To Support Physical Fitness Information Of Elderly People, Yudhy Dharmawan, Suroto Suroto, Priguna Septia Putra

Kesmas

Penduduk lanjut usia (lansia) semakin banyak seiring meningkatnya usia harapan hidup. Banyak upaya yang harus dilakukan untuk mencegah kesakitan di lansia, salah satunya dari aspek preventif dengan menjaga kebugaran para lansia. Untuk memonitor status kebugaran lansia, maka diperlukan aplikasi pemantauan kebugaran jasmani berbasis teknologi web karena tidak ada sistem yang merekam data kebugaran para lansia. Aplikasi ini ditujukan untuk merekam data kebugaran jasmani para lansia untuk merekomendasikan gym yang sesuai berdasarkan kondisi kesehatan yang dapat diakses di mana saja. Aplikasi ini dibuat dengan bahasa pemrograman PHP dan MYSQL sebagai pengolahan basis data yang dilengkapi dengan grafik untuk memantau kebugaran jasmaninya. …

The Implementation Of Documentation By Midwives In Pekanbaru, Wan Anita

Kesmas

Dokumentasi kebidanan adalah suatu bukti pencatatan dan pelaporan yang dimiliki oleh bidan dalam melakukan catatan perawatan yang berguna untuk kepentingan pasien, bidan, dan tim kesehatan. Pendokumentasian dapat diterapkan dengan metode Subjektif, Objektif, Analisa dan Perencanaan (SOAP). Penelitian ini bertujuan mengetahui faktor-faktor yang berhubungan dengan pelaksanaan dokumentasi SOAP oleh bidan di Kota Pekanbaru tahun 2016. Penelitian bersifat kuantitatif analitik observasional dengan desain penelitian potong lintang analitik. Sampel penelitian adalah seluruh populasi bidan yang praktik mandiri atau di rumah bersalin di Kota Pekanbaru dengan jumlah sampel sebanyak 191 bidan yang diambil dengan prosedur systematic random sampling. Data dikumpulkan melalui wawancara langsung dengan …

Adolescent’S Knowledge And Skill To Refuse Drugs, Lucky Herawati, Johan Arief Budiman, Haryono Haryono

Kesmas

Berbagai upaya telah dilakukan untuk mencegah remaja dari penggunaan narkoba, kendatipun evaluasi pengetahuan dan keterampilan remaja menolak narkoba belum pernah dilakukan. Penelitian ini dilakukan pada 300 remaja, siswa kelas 7 atau setara usia 12-15 tahun di dua kota di Provinsi Daerah Istimewa Yogyakarta. Penelitian analitik bertujuan mengetahui gambaran pengetahuan, keterampilan remaja menolak narkoba, dan hubungan keduanya dengan karakteristik remaja. Variabel yang diteliti adalah pengetahuan remaja tentang narkoba, keterampilan menolak narkoba, dan karakteristik remaja, yang dikumpulkan dengan menggunakan kuesioner (self-reported questionnaire). Data dianalisis dengan uji korelasi Pearson dan Spearman rho, dengan tingkat signifikansi 95 persen. Hasil penelitian menunjukkan bahwa rata-rata nilai …

Dietary Inflammatory Index And Biomarkers Of Lipoprotein Metabolism, Inflammation And Glucose Homeostasis In Adults, Catherine Phillips, Nitin Shivappa, James R. Hébert, Ivan Perry

Faculty Publications

Accumulating evidence identifies diet and inflammation as potential mechanisms contributing to cardiometabolic risk. However, inconsistent reports regarding dietary inflammatory potential, biomarkers of cardiometabolic health and metabolic syndrome (MetS) risk exist. Our objective was to examine the relationships between a food frequency questionnaire (FFQ)-derived dietary inflammatory index (DII®), biomarkers of lipoprotein metabolism, inflammation and glucose homeostasis and MetS risk in a cross-sectional sample of 1992 adults. Energy-adjusted DII (E-DII) scores derived from an FFQ were calculated. Lipoprotein particle size and subclass concentrations were measured using nuclear magnetic resonance (NMR) spectroscopy. Serum acute-phase reactants, adipocytokines, pro-inflammatory cytokines and white blood cell (WBC) …

Robust Inference For The Stepped Wedge Design, James P. Hughes, Patrick J. Heagerty, Fan Xia, Yuqi Ren

UW Biostatistics Working Paper Series

Based on a permutation argument, we derive a closed form expression for an estimate of the treatment effect, along with its standard error, in a stepped wedge design. We show that these estimates are robust to misspecification of both the mean and covariance structure of the underlying data-generating mechanism, thereby providing a robust approach to inference for the treatment effect in stepped wedge designs. We use simulations to evaluate the type I error and power of the proposed estimate and to compare the performance of the proposed estimate to the optimal estimate when the correct model specification is known. The …

Bubble Stream Production By Belugas (Delphinapterus Leucas), Megan Slack

Theses

Bubble stream production in belugas has been poorly characterized and its function is not well understood. I examined behavioral states when producing bubble streams (“bubbling”), and when bubbling calls, to determine whether bubbling was significantly associated with a particular call category or behavioral state. Using 19 hours of video and audio recordings collected over a two-day period, I quantified bubble streams of a 4-month old calf and an unrelated adult female housed together. Based on the overall activity budgets and pool of vocalizations for both animals, I calculated the expected counts of bubble streams with and without vocalizations, assuming that …

Bayesian Analytical Approaches For Metabolomics : A Novel Method For Molecular Structure-Informed Metabolite Interaction Modeling, A Novel Diagnostic Model For Differentiating Myocardial Infarction Type, And Approaches For Compound Identification Given Mass Spectrometry Data., Patrick J. Trainor

Electronic Theses and Dissertations

Metabolomics, the study of small molecules in biological systems, has enjoyed great success in enabling researchers to examine disease-associated metabolic dysregulation and has been utilized for the discovery biomarkers of disease and phenotypic states. In spite of recent technological advances in the analytical platforms utilized in metabolomics and the proliferation of tools for the analysis of metabolomics data, significant challenges in metabolomics data analyses remain. In this dissertation, we present three of these challenges and Bayesian methodological solutions for each. In the first part we develop a new methodology to serve a basis for making higher order inferences in metabolomics, …

Generalized Spatiotemporal Modeling And Causal Inference For Assessing Treatment Effects For Multiple Groups For Ordinal Outcome., Soutik Ghosal

Electronic Theses and Dissertations

This dissertation consists of three projects and can be categorized in two broad research areas: generalized spatiotemporal modeling and causal inference based on observational data. In the first project, I introduce a Bayesian hierarchical mixed effect hurdle model with a nested random effect structure to model the count for primary care providers and understand their spatial and temporal variation. This study further enables us to identify the health professional shortage areas and the possible impacting factors. In the second project, I have unified popular parametric and nonparametric propensity score-based methods to assess the treatment effect of multiple groups for ordinal …

Design, Development And Construct Validation Of The Children’S Dietary Inflammatory Index, Samira Khan, Micheal D. Wirth, Andrew Ortaglia, Christian R. Alvarado, Nitin Shivappa, Thomas Hurley, James R. Hébert

Faculty Publications

Objective: To design and validate a literature-derived, population-based Children’s Dietary Inflammatory Index (C-DII)TM. Design: The C-DII was developed based on a review of literature through 2010. Dietary data obtained from children in 16 different countries were used to create a reference database for computing C-DII scores based on consumption of macronutrients, vitamins, minerals, and whole foods. Construct validation was performed using quantile regression to assess the association between C-reactive protein (CRP) concentrations and C-DII scores. Data Sources: All data used for construct validation were obtained from children between six and 14 years of age (n = 3300) who participated in …

A Math Research Project Inspired By Twin Motherhood, Tiffany N. Kolba

Journal of Humanistic Mathematics

The phenomenon of twins, triplets, quadruplets, and other higher order multiples has fascinated humans for centuries and has even captured the attention of mathematicians who have sought to model the probabilities of multiple births. However, there has not been extensive research into the phenomenon of polyovulation, which is one of the biological mechanisms that produces multiple births. In this paper, I describe how my own experience becoming a mother to twins led me on a quest to better understand the scientific processes going on inside my own body and motivated me to conduct research on polyovulation frequencies. An overview of …

Investigations Of Biotremors In The Veiled Chameleon (Chamaeleo Calyptratus), Kathryn C. Laslie

Masters Theses & Specialist Projects

While substrate-borne vibrations are utilized by different reptile species, true conspecific communication via biotremors has not yet been demonstrated in reptiles. This study follows a preliminary report that the veiled chameleon (Chamaeleo calyptratus) could produce biotremors in communicative contexts. I tested chameleon behavioral sensitivity to vibrations by placing them on a dowel attached to a shaker emitting vibrations of 25, 50, 150, 300, and 600 Hz and then measured their changes in velocity before and after the stimulus. I then paired chameleons in various social contexts [anthropogenic disturbance (human disruption of animal); dominance (malemale; female-female C. calyptratus); courtship (male-female C. …

Association Tests For Genetic Effect And Its Interaction With Environmental Factors, Zhengyang Zhou

Statistical Science Theses and Dissertations

My research is in the area of statistical genetics, and it contains three projects: (1) Differentiating the Cochran-Armitage (CA) trend test and Pearson’s chi-square test: location and dispersion; (2) Decomposing Pearson’s chi-square test: a linear regression and its departure from linearity; (3) Testing nonlinear gene-environment (GxE) interaction through varying coefficient and linear mixed models.

(1) In genetic case-control association studies, a standard practice is to perform the CA trend test with 1 degree-of-freedom (df) under the assumption of an additive model. However, when the true genetic model is recessive or near recessive, it is outperformed by Pearson’s chi-square test with …

Presence Of Antibiotic-Resistant Escherichia Coli In Wastewater Treatment Plant Effluents Utilized As Water Reuse For Irrigation, Asli Aslan, Zach A. Coles, Anunay Bhattacharya, Oghenekpaobor Oyibo

Biostatistics, Epidemiology & Environmental Health Sciences: Faculty Publications

Providing safe water through water reuse is becoming a global necessity. One concern with water reuse is the introduction of unregulated contaminants to the environment that cannot be easily removed by conventional wastewater treatment plants (WWTP). The occurrence of ampicillin, sulfamethoxazole, ciprofloxacin, and tetracycline-resistant Escherichia coli through the treatment stages of a WWTP (raw sewage, post-secondary, post-UV and post-chlorination) was investigated from January to May 2016. The highest concentrations of antibiotic resistant E. coli in the effluent were detected in April after rainfall. Ampicillin-resistant E. coli was the most common at the post UV and chlorination stages comprising 63% of …