Biostatistics Commons^™

Improving Power In Group Sequential, Randomized Trials By Adjusting For Prognostic Baseline Variables And Short-Term Outcomes, Tianchen Qian, Michael Rosenblum, Huitong Qiu

Johns Hopkins University, Dept. of Biostatistics Working Papers

In group sequential designs, adjusting for baseline variables and short-term outcomes can lead to increased power and reduced sample size. We derive formulas for the precision gain from such variable adjustment using semiparametric estimators for the average treatment effect, and give new results on what conditions lead to substantial power gains and sample size reductions. The formulas reveal how the impact of prognostic variables on the precision gain is modified by the number of pipeline participants, analysis timing, enrollment rate, and treatment effect heterogeneity, when the semiparametric estimator uses correctly specified models. Given set prognostic value of baseline variables and …

Stochastic Optimization Of Adaptive Enrichment Designs For Two Subpopulations, Aaron Fisher, Michael Rosenblum

Johns Hopkins University, Dept. of Biostatistics Working Papers

An adaptive enrichment design is a randomized trial that allows enrollment criteria to be modified at interim analyses, based on a preset decision rule. When there is prior uncertainty regarding treatment effect heterogeneity, these trial designs can provide improved power for detecting treatment effects in subpopulations. We present a simulated annealing approach to search over the space of decision rules and other parameters for an adaptive enrichment design. The goal is to minimize the expected number enrolled or expected duration, while preserving the appropriate power and Type I error rate. We also explore the benefits of parallel computation in the …

An Examination Of The Neural Unreliability Thesis Of Autism, John Butler, Sophie Molholm, Gizely Andrade, John J. Foxe

Articles

An emerging neuropathological theory of Autism, referred to here as “the neural unreliability thesis,” proposes greater variability in moment-to-moment cortical representation of environmental events, such that the system shows general instability in its impulse response function. Leading evidence for this thesis derives from functional neuroimaging, a methodology ill-suited for detailed assessment of sensory transmission dynamics occurring at the millisecond scale. Electrophysiological assessments of this thesis, however, are sparse and unconvincing. We conducted detailed examination of visual and somatosensory evoked activity using high-density electrical mapping in individuals with autism (N = 20) and precisely matched neurotypical controls (N = 20), recording …

Very Rapid Onset Cannabis Dependence Risk In Relation To Co-Occurring Use Of Other Psychoactive Drugs, Olga A. Vsevolozhskaya, Fernando A. Wagner, James C. Anthony

Biostatistics Presentations

Background: Epidemiological estimates for lifetime cumulative incidence indicate that for every 9-11 who start using cannabis, one becomes a case of the cannabis dependence syndrome (CDS) – i.e., roughly 9%-11%. More recent estimates clarify that CDS risk might be much lower among ’cannabis only’ users, due in part to the fact that many ’cannabis only’ users try the drug a few times and never again. We turned to Hill functional analysis in order to study CDS probability soon after 1st cannabis use, estimated across strata defined by the number of recent days of cannabis use, with an acknowledgment that a …

Pertussis-Associated Pneumonia In Infants And Children From Low- And Middle-Income Countries Participating In The Perch Study., Breanna Barger-Kamate, Maria Deloria Knoll, E Wangeci Kagucia, Christine Prosperi, Henry C Baggett, Daniel E. Park, +31 Additional Authors

Epidemiology Faculty Publications

BACKGROUND:  Few data exist describing pertussis epidemiology among infants and children in low- and middle-income countries to guide preventive strategies.

METHODS:  Children 1-59 months of age hospitalized with World Health Organization-defined severe or very severe pneumonia in 7 African and Asian countries and similarly aged community controls were enrolled in the Pneumonia Etiology Research for Child Health study. They underwent a standardized clinical evaluation and provided nasopharyngeal and oropharyngeal swabs and induced sputum (cases only) for Bordetella pertussis polymerase chain reaction. Risk factors and pertussis-associated clinical findings were identified.

RESULTS:  Bordetella pertussis was detected in 53 of 4200 (1.3%) cases …

Analysis Of Hiv Diversity In Hiv-Infected Black Men Who Have Sex With Men (Hptn 061), Iris Chen, Gordon Chau, Jing Wang, William Clarke, Mark A. Marzinke, Manya Magnus, +14 Additional Authors

Epidemiology Faculty Publications

Background

HIV populations often diversify in response to selective pressures, such as the immune response and antiretroviral drug use. We analyzed HIV diversity in Black men who have sex with men who were enrolled in the HIV Prevention Trials Network 061 study.

Methods

A high resolution melting (HRM) diversity assay was used to measure diversity in six regions of the HIV genome: two in gag, one in pol, and three in env. HIV diversity was analyzed for 146 men who were HIV infected at study enrollment, including three with acute infection and 13 with recent infection (identified …

Genomics And Csf Analyses Implicate Thyroid Hormone In Hippocampal Sclerosis Of Aging, Peter T. Nelson, Yuriko Katsumata, Kwangsik Nho, Sergey C. Artiushin, Gregory A. Jicha, Wang-Xia Wang, Erin L. Abner, Andrew J. Saykin, Walter A. Kukull, Alzheimer’S Disease Neuroimaging Initiative (Adni), David W. Fardo

Sanders-Brown Center on Aging Faculty Publications

We report evidence of a novel pathogenetic mechanism in which thyroid hormone dysregulation contributes to dementia in elderly persons. Two single nucleotide polymorphisms (SNPs) on chromosome 12p12 were the initial foci of our study: rs704180 and rs73069071. These SNPs were identified by separate research groups as risk alleles for non-Alzheimer’s neurodegeneration. We found that the rs73069071 risk genotype was associated with hippocampal sclerosis (HS) pathology among people with the rs704180 risk genotype (National Alzheimer’s Coordinating Center/Alzheimer’s Disease Genetic Consortium data; n = 2113, including 241 autopsy-confirmed HS cases). Furthermore, both rs704180 and rs73069071 risk genotypes were associated with widespread brain …

Characterizing The Effects Of Repetitive Head Trauma In Female Soccer Athletes For Prevention Of Mild Traumatic Brain Injury, Diana Otero Svaldi

Open Access Dissertations

As participation in women’s soccer continues to grow and the longevity of female athletes’ careers continues to increase, prevention of mTBI in women’s soccer has become a major concern for female athletes as the long-term risks associated with a history of mTBI are well documented. Among women’s sports, soccer exhibits the highest concussion rates, on par with those of men’s football at the collegiate level. Head impact monitoring technology has revealed that “concussive hits” occurring directly before symptomatic injury are not predictive of mTBI, suggesting that the cumulative effect of repetitive head impacts experienced by collision sport athletes should be …

Inter-Relationships Linking Probability Of Becoming A Case Of Nicotine Dependence With Frequency Of Tobacco Cigarette Smoking, Olga A. Vsevolozhskaya, James C. Anthony

Biostatistics Faculty Publications

INTRODUCTION: Once smoking starts, some tobacco cigarette smokers (TCS) can make very rapid transitions into tobacco dependence syndromes (TCD). With adjustment for smoking frequency, we posit female excess risk for this rapid-onset TCD. In a novel application of functional analysis for tobacco research, we estimate four Hill function parameters and plot TCD risk against a gradient of smoking frequency, as observed quite soon after smoking onset.

METHODS: In aggregate, the National Surveys of Drug Use and Health, 2004-2013, identified 1546 newly incident TCS in cross-sectional research, each with standardized TCD assessment.

RESULTS: Hill function estimates contradict our apparently over-simplistic hypothesis. …

Self-Reported Sleep Apnea And Dementia Risk: Findings From The Prevention Of Alzheimer's Disease With Vitamin E And Selenium Trial, Xiuhua Ding, Richard J. Kryscio, Joshua Turner, Gregory A. Jicha, Gregory E. Cooper, Allison M. Caban-Holt, Frederick A. Schmitt, Erin L. Abner

Sanders-Brown Center on Aging Faculty Publications

OBJECTIVES: To investigate the association between baseline sleep apnea and risk of incident dementia in the Prevention of Alzheimer's Disease with Vitamin E and Selenium (PREADViSE) study and to explore whether the association depends on apolipoprotein E (APOE) ɛ4 allele status.

DESIGN: Secondary analysis based on data collected during PREADViSE.

SETTING: Participants were assessed at 128 local clinical study sites during the clinical trial phase and later were followed by telephone from a centralized location.

PARTICIPANTS: Men enrolled in PREADViSE (without dementia or other active neurological conditions that affect cognition such as major psychiatric disorders, including depression; N = …

Gathering Steam In Health Care: A Student History, Michael J. Leach

The Transdisciplinary STEAM+ Journal

In this reflection, I demonstrate STEAM in health care by outlining my 15 years as a university student engaged in formal education, extracurricular learning, research, and employment.

Efficiency Of Two Sample Tests Via The T-Mean Survival Time For Analyzing Event Time Observations, Lu Tian, Haoda Fu, Stephen J. Ruberg, Hajime Uno, Lj Wei

Harvard University Biostatistics Working Paper Series

In comparing two treatments with the event time observations, the hazard ratio (HR) estimate is routinely used to quantify the treatment difference. However, this model dependent estimate may be difficult to interpret clinically especially when the proportional hazards (PH) assumption is violated. An alternative estimation procedure for treatment efficacy based on the restricted means survival time or t-year mean survival time (t-MST) has been discussed extensively in the statistical and clinical literature. On the other hand, a statistical test 1 via the HR or its asymptotically equivalent counterpart, the logrank test, is asymptotically distribution-free. In this paper, we assess the …

The Risk Of Pneumonia Among Toddlers In Lambatee, Aceh, Rapitos Sidiq, Ritawati Ritawati, Roma Sitio, Siti Hajar

Kesmas

Pneumonia merupakan salah satu masalah kesehatan global yang sangat penting pada anak bawah lima tahun (balita), khususnya pada negara-negara berkembang. Saat ini, pneumonia merupakan salah satu kasus penyebab kematian pada anak terbesar, terutama pada periode baru lahir. Di Provinsi Aceh, penyakit pneumonia merupakan penyakit urutan ke-8 dari 25 penyakit terbesar yang ditemukan di puskesmas dengan jumlah 1.112 kasus. Sedangkan besarnya kasus pneumonia pada penderita rawat jalan di Aceh mencapai 434 kasus (29,03%). Penelitian ini bertujuan untuk mengetahui faktor-faktor yang berhubungan dengan kejadian pneumonia pada balita. Penelitian bersifat analitik dengan desain potong lintang. Sampel penelitian adalah ibu dan balita yang berjumlah …

Motivation Variables To Use Contraceptive Among Male In Yogyakarta, Susiana Sariyati, Febrina Suci Hati, Fatimah Fatimah

Kesmas

Program Keluarga Berencana (KB) merupakan salah satu program pembangunan nasional yang sangat penting dalam rangka mewujudkan keluarga Indonesia yang sejahtera. Peran program KB sangat besar pengaruhnya terhadap kesehatan reproduksi seseorang, baik untuk kesehatan reproduksi perempuan maupun kesehatan reproduksi laki-laki. Penelitian ini bertujuan untuk mengetahui faktor-faktor yang berhubungan dengan motivasi laki-laki pasangan usia subur dalam menggunakan kontrasepsi di Desa Bumijo, Kecamatan Jetis, Kota Yogyakarta. Jenis penelitian ini bersifat kuantitatif dengan analisis regresi logistik. Hasil penelitian menunjukkan hubungan pengetahuan dengan motivasi yaitu nilai p = 0,368. Hubungan sosial budaya dengan motivasi yaitu nilai p = 0,147. Hubungan pendidikan dengan motivasi yaitu nilai …

Family Planning Information, Education And Communication With Contaceptive Use, Endah Winarni, Muhammad Dawam

Kesmas

Komunikasi Informasi dan Edukasi (KIE) berperan penting dalam meningkatkan pencapaian prevalensi kesertaan Keluarga Berencana (KB). Namun, prevalensi KB di Indonesia selama satu dekade terakhir (2002-2012) tidak meningkat secara signifikan, walaupun pelbagai kegiatan KIE KB telah dilaksanakan. Penelitian ini bertujuan untuk mengetahui faktor sosio ekonomi demografi yang berkaitan dengan KIE KB, pelbagai unsur KIE yang berkaitan dengan pemakaian KB, dan unsur KIE yang berpengaruh terhadap pemakaian KB. Analisis menggunakan sumber data Survei Demografi dan Kesehatan Indonesia 2012 dengan unit analisis perempuan berstatus kawin usia 15-49 tahun. Jumlah sampel yang dianalisis 33.465 perempuan berstatus kawin. Analisis menggunakan odds ratio atau rasio kecenderungan …

Social Determinant Of Health Of Adults Smoking Behavior: Differences Between Urban And Rural Areas In Indonesia, Fitri Kurnia Rahim, Thunwadee Suksaroj, Isareethika Jayasvasti

Kesmas

Indonesia memiliki prevalensi perilaku merokok tertinggi di antara negara-negara di Asia Tenggara. Penelitian ini bertujuan untuk mengetahui prediktor terhadap perilaku merokok antara wilayah pedesaan dan perkotaan. Data diambil dari Global Adult Tobacco Survey. Penelitian menggunakan studi analitik potong lintang dan analisis regresi logistik ganda. Sampel berjumlah 8.305 orang dewasa Indonesia berusia ≥ 15 tahun. Penelitian menunjukkan bahwa perokok di wilayah pedesaan lebih tinggi dibandingkan di wilayah perkotaan, masing-masing 36,8% dan 31,9%. Prediktor signifikan terhadap perilaku merokok di wilayah pedesaan dan perkotaan adalah usia, pekerjaan, jenis kelamin, tingkat pendidikan, status ekonomi serta aturan merokok di dalam rumah. Di wilayah perkotaan, usia …

Effectivity Of Foot Care Education Program In Improving Knowledge, Self-Efficacy And Foot Care Behavior Among Diabetes Mellitus Patients In Banjarbaru, Indonesia, Mahdalena Mahdalena, Endang Sri Purwanti Ningsih

Kesmas

Masalah kaki diabetik di Indonesia masih merupakan masalah besar dan masih memerlukan perhatian yang optimal. Edukasi perawatan kaki adalah salah satu upaya yang harus dilakukan dalam mencegah masalah kaki untuk pasien diabetes melitus. Penelitian ini bertujuan untuk menganalisis efektivitas program pendidikan perawatan kaki dalam meningkatkan pengetahuan, efikasi diri, dan perilaku perawatan kaki pasien diabetes di wilayah Banjarbaru. Jenis penelitian yang digunakan adalah quasi experimental dengan prepost test, dilakukan di puskesmas wilayah Banjarbaru tahun 2013. Kelompok intervensi diberikan program pendidikan perawatan kaki. Sampel berjumlah 48 pasien (32 orang kelompok intervensi dan 16 orang kelompok kontrol) menggunakan teknik purposive sampling. Variabel yang …

Lack Of Exclusive Breastfeeding Among Working Mothers In Indonesia, Yulia Sari

Kesmas

Keberlangsungan proses menyusui pada saat ibu kembali bekerja merupakan isu serius yang harus segera ditindaklanjuti agar program pemberian Air Susu Ibu (ASI) eksklusif selama enam bulan pertama kehidupan dapat tercapai. Selain memberikan banyak manfaat bagi bayi, ASI juga bermanfaat bagi ibu dan pengusaha. Penelitian ini bertujuan untuk mengetahui hubungan ibu bekerja terhadap pemberian ASI eksklusif. Desain penelitian yang digunakan adalah potong lintang dengan data sekunder Survei Demografi dan Kesehatan Indonesia (SDKI) tahun 2012 dengan sampel berjumlah 1.193 ibu berusia 15 – 49 tahun yang memiliki bayi berusia 0-5 bulan. Berdasarkan analisis multivariat, ibu bekerja dapat menurunkan peluang pemberian ASI eksklusif …

Coronary Heart Disease Risk Factors Among Women Aged Older Than 45 Years Old In Makassar, Masriadi Masriadi, Hasta Handayani Idrus, Arman Arman

Kesmas

Penyakit kardiovaskuler menyebabkan 8.6 juta kematian pada perempuan setiap tahun, yang merupakan penyebab kematian terbanyak, yaitu sepertiga dari seluruh kematian perempuan di seluruh dunia. Setengah dari seluruh kematian perempuan berusia di atas 50 tahun disebabkan oleh penyakit jantung dan stroke. Penelitian ini bertujuan untuk menganalisis faktor yang berhubungan dengan penyakit jantung koroner pada perempuan usia > 45 tahun di Rumah Sakit TNI AU Dody Sarjoto Makassar. Besar sampel sebanyak 76 sampel yang terdiri dari 64 kasus penyakit jantung koroner dan 12 kasus non penyakit jantung koroner. Penentuan sampel menggunakan metode purposive sampling. Data primer diperoleh melalui wawancara terhadap responden dengan menggunakan …

Basis For Development Of Business Strategic Plan Primary Health Care With Local Public Service Entity Status In Gianyar District, Putu Ayu Indrayathi, Luh Putu Sinthya Ulandari

Kesmas

Puskesmas yang berbentuk Badan Layanan Umum Daerah (BLUD) perlu membuat rencana strategi bisnis yang tepat. Penyusunan rencana strategi bisnis perlu memerhatikan pesaing yang beroperasi di sekitar wilayah kerja. Penelitian ini bertujuan untuk mempelajari aspek lingkungan internal dan eksternal di Puskesmas Ubud 1 dan Tegallalang 1 serta mengembangkan model pengembangan rencana strategi bisnis di kedua puskesmas yang berstatus BLUD tersebut. Penelitian ini merupakan penelitian deskriptif eksploratif yang dilakukan pada tahun 2014. Data dikumpulkan melalui penyebaran kuesioner dan studi dokumentasi. Sampel penelitian ditentukan secara purposif dan diambil secara non proporsional, terdiri dari kepala dan staf Puskesmas Ubud 1 dan Tegallalalng 1. Data …