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Articles 151 - 180 of 186

Full-Text Articles in Clinical Epidemiology

Economic Evaluation Of Fungal Meningitis Outbreak Response In New River Valley: Local Health Department Perspective, Kaja M. Abbas, Nargesalsadat Dorratoltaj, Margaret L. O’Dell, Paige Bordwine, Thomas M. Kerkering, Kerry J. Redican Aug 2015

Economic Evaluation Of Fungal Meningitis Outbreak Response In New River Valley: Local Health Department Perspective, Kaja M. Abbas, Nargesalsadat Dorratoltaj, Margaret L. O’Dell, Paige Bordwine, Thomas M. Kerkering, Kerry J. Redican

Frontiers in Public Health Services and Systems Research

Background: The multi-state fungal meningitis outbreak started in September 2012 in Tennessee. The cause of the outbreak was injection of contaminated lots of methylprednisolone acetate used in epidural spinal injections. Roanoke and New River Valley were the epicenter of this outbreak in Virginia, with two clinical centers having administered the contaminated injections to their patients. New River Health District, in coordination with hospitals, and state and federal agencies, deployed its resources to control the local impact of the outbreak.

Purpose: The objective of this study was to conduct an economic evaluation of the fungal meningitis outbreak response in New River …


Know Your Status: Alleviating Stigma From The Hiv Positive Community Of San Luis Obispo California, Mario Alberto Viveros Espinoza Jun 2015

Know Your Status: Alleviating Stigma From The Hiv Positive Community Of San Luis Obispo California, Mario Alberto Viveros Espinoza

Ethnic Studies

The purpose of this project is to alleviate stigma from the HIV community in San Luis Obispo, CA by creating an outreach program, “Know Your Status,” that raises awareness of HIV education and prevention. Research on HIV stigma and on ideologies for program development and implementation shows that HIV positive individuals face both internalized and externalized stigma. Program development and implementation can be effective by assessing and addressing the specific needs of those living within the community. This project includes the data needed for program development and implementation, collected through anonymous surveys from HIV positive community members, interviews with professionals …


"Nursing Contamination: Wearing Scrubs In Public", Kemble Green May 2014

"Nursing Contamination: Wearing Scrubs In Public", Kemble Green

Undergraduate Honors Theses

Nurses are frequently seen in public in their “scrubs,” which could mean that contaminated clothing is being brought into the community, thereby posing an infection risk. The purpose of this study is to investigate if and which contaminants are present on the fabrics and the actions nurses are taking to eliminate contamination risks.

Eleven scrub tops were worn on hospital units over one twelve-hour shift. The contaminated scrubs and three control tops were then swabbed and used to inoculate agar plates. After incubation, colonies were counted, streaked onto nutrient and Mannitol-salt agar for isolation, and incubated. Using API Staph strips …


Performance Of The Oraquick Hcv Rapid Antibody Test For Screening Exposed Patients In A Hepatitis C Outbreak Investigation, Fengxiang Gao, Elizabeth A. Talbot, Carol H. Loring, Jill J. Power, Jodie Dionne-Odom Apr 2014

Performance Of The Oraquick Hcv Rapid Antibody Test For Screening Exposed Patients In A Hepatitis C Outbreak Investigation, Fengxiang Gao, Elizabeth A. Talbot, Carol H. Loring, Jill J. Power, Jodie Dionne-Odom

Dartmouth Scholarship

During a nosocomial hepatitis C outbreak, emergency public clinics employed the OraQuick HCV rapid antibody test on site, and all results were verified by a standard enzyme immunoassay (EIA). Of 1,157 persons, 1,149 (99.3%) exhibited concordant results between the two tests (16 positive, 1,133 negative). The sensitivity, specificity, positive predictive value, and negative predictive value were 94.1%, 99.5%, 72.7%, and 99.9%, respectively. OraQuick performed well as a screening test during an outbreak investigation and could be integrated into future hepatitis C virus (HCV) outbreak testing algorithms.


Forecasting The Spread Of Raccoon Rabies Using A Purpose-Specific Group Decision-Making Process., Aaron M. Anderson, Stephanie A. Shwiff, Richard B. Chipman, Todd C. Atwood, Tyler Cozzens, Frank Fillo, Robert Hale, Brody Hatch, Joanne Maki, Olin E. Rhodes Jr., Erin E. Rees, Charles E. Rupprecht, Rowland Tinline, Kurt C. Vercauteren, Dennis Slate Apr 2014

Forecasting The Spread Of Raccoon Rabies Using A Purpose-Specific Group Decision-Making Process., Aaron M. Anderson, Stephanie A. Shwiff, Richard B. Chipman, Todd C. Atwood, Tyler Cozzens, Frank Fillo, Robert Hale, Brody Hatch, Joanne Maki, Olin E. Rhodes Jr., Erin E. Rees, Charles E. Rupprecht, Rowland Tinline, Kurt C. Vercauteren, Dennis Slate

United States Department of Agriculture Wildlife Services: Staff Publications

The Centers for Disease Control (CDC) and USDA Wildlife Services (WS) have been involved in an oral rabies vaccination (ORV) program for raccoons (Procyon lotor) that has slowed the westward spread of raccoon rabies. The objective of this study was to forecast the spread of the disease if an ORV zone was not maintained. A group decision-making process was designed to address the forecasting problem and was implemented using a group of 15 experts and 4 support personnel at a meeting at the USDA National Wildlife Research Center. Ten expansion regions were constructed that described the spread of …


Computational Model For Survey And Trend Analysis Of Patients With Endometriosis : A Decision Aid Tool For Ebm, Salvo Reina, Vito Reina, Franco Ameglio, Mauro Costa, Alessandro Fasciani Feb 2014

Computational Model For Survey And Trend Analysis Of Patients With Endometriosis : A Decision Aid Tool For Ebm, Salvo Reina, Vito Reina, Franco Ameglio, Mauro Costa, Alessandro Fasciani

COBRA Preprint Series

Endometriosis is increasingly collecting worldwide attention due to its medical complexity and social impact. The European community has identified this as a “social disease”. A large amount of information comes from scientists, yet several aspects of this pathology and staging criteria need to be clearly defined on a suitable number of individuals. In fact, available studies on endometriosis are not easily comparable due to a lack of standardized criteria to collect patients’ informations and scarce definitions of symptoms. Currently, only retrospective surgical stadiation is used to measure pathology intensity, while the Evidence Based Medicine (EBM) requires shareable methods and correct …


The Associations Between Homa-Ir And Muscular Strengthening Activity In Euglycemic U.S. Adults, William Robert Boyer Ii Jan 2014

The Associations Between Homa-Ir And Muscular Strengthening Activity In Euglycemic U.S. Adults, William Robert Boyer Ii

UNF Graduate Theses and Dissertations

Background: Muscular strengthening activity (MSA) has been shown to be inversely associated with insulin resistance (IR). The associations between quartiles of the homeostatic model assessment of insulin resistance (HOMA-IR) and self-reported MSA in a nationally representative sample of euglycemic U.S. adults were examined.

Methods: Sample included adult participants (≥20 years of age [n=2,543]) from the 1999-2004 National Health and Nutrition Examination Survey (NHANES). HOMA-IR was categorized into quartiles based on every 25th percentile. No MSA was the dependent variable.

Results: Following adjustment for covariates, those with HOMA-IR values in third (p

Conclusions: Having a higher HOMA-IR value is associated …


Using Quantitative Disease Dynamics As A Tool For Guiding Response To Avian Influenza In Poultry In The United States Of America, K. M. Pepin, E. Spackman, J. D. Brown, K. L. Pabilonia, Lindsey P. Garber, J. Todd Weaver, D. A. Kennedy, Kelly A. Patyk, K. P. Huyvaert, Ryan S. Miller, Alan B. Franklin, Kerri Pedersen, T. L. Bogich, P. Rohani, Susan A. Shriner, Colleen T. Webb, S. Riley Jan 2014

Using Quantitative Disease Dynamics As A Tool For Guiding Response To Avian Influenza In Poultry In The United States Of America, K. M. Pepin, E. Spackman, J. D. Brown, K. L. Pabilonia, Lindsey P. Garber, J. Todd Weaver, D. A. Kennedy, Kelly A. Patyk, K. P. Huyvaert, Ryan S. Miller, Alan B. Franklin, Kerri Pedersen, T. L. Bogich, P. Rohani, Susan A. Shriner, Colleen T. Webb, S. Riley

United States Department of Agriculture Wildlife Services: Staff Publications

Wild birds are the primary source of genetic diversity for influenza A viruses that eventually emerge in poultry and humans. Much progress has been made in the descriptive ecology of avian influenza viruses (AIVs), but contributions are less evident from quantitative studies (e.g., those including disease dynamic models). Transmission between host species, individuals and flocks has not been measured with sufficient accuracy to allow robust quantitative evaluation of alternate control protocols. We focused on the United States of America (USA) as a case study for determining the state of our quantitative knowledge of potential AIV emergence processes from wild hosts …


Empowerment-Based Positive Youth Development: A New Understanding Of Healthy Development For African American Youth, Raphael Travis Jr., Tamara Leech Jun 2013

Empowerment-Based Positive Youth Development: A New Understanding Of Healthy Development For African American Youth, Raphael Travis Jr., Tamara Leech

Department of Public Health Scholarship and Creative Works

A shift occurred in research about adolescents in the general population. Research is moving away from deficits toward a resilience paradigm and understanding trajectories of positive youth development. This shift has been less consistent in research and practice with African American youth. A gap also exists in understanding whether individual youth development dimensions generate potential in other dimensions. This study presents an empowerment-based positive youth development model. It builds upon existing research to present a new vision of healthy development for African American youth that is strengths-based, developmental, culture-bound, and action-oriented. It emphasizes the relationship between person and environment, the …


Associations Between Alcohol Consumption And Fasting Blood Glucose In Young Adults, Julie Ann Lucca Jun 2013

Associations Between Alcohol Consumption And Fasting Blood Glucose In Young Adults, Julie Ann Lucca

Master's Theses

Current research shows moderate alcohol consumption is associated with decreased risk of diabetes and excessive consumption or binge drinking can cause insulin resistance and diabetes. In 2010, diabetes was the seventh leading cause of death in the United Statesand was responsible for significant health complications: blindness, kidney failure, and limb amputations, and is a large national economic burden. Fasting blood glucose (FBG) is a tool used to help diagnose diabetes. Abnormally high FBG, ≥100 mg/dl, is indicative of diabetes and pre-diabetes. Few studies have observed diabetic prevalence among young adults or college students. Studying young adults can help provide added …


Comparing Two-Year Community College And Four-Year University Student Social And Behavioral Sexually Transmitted Infection Risk Factors, Oswald M. Attin Jan 2013

Comparing Two-Year Community College And Four-Year University Student Social And Behavioral Sexually Transmitted Infection Risk Factors, Oswald M. Attin

Faculty Dissertations

Sexually transmitted infections (STIs) could cause ectopic, cervical cancer, infertility, and organ damage to the heart, kidneys, and brain. This study compared several behavioral risk factors of STIs (condom use, number of sexual partners, type of sex (anal or vaginal) and drinking habits) between two distinct educational settings and their association with socioeconomic risk factors such as low income and parent’s lower level of education that are known to increase the incidence of STIs among college-aged students. This study was based on the precautionary-health-behavior model, where individuals act regardless of consequences, and the health-behavior-change model, where individual behaviors either increase …


Epidemiology Of Tuberculosis In Ohio, Usha Bala Vayuvegula Oct 2012

Epidemiology Of Tuberculosis In Ohio, Usha Bala Vayuvegula

Master of Public Health Program Student Publications

Background: Tuberculosis (TB) is a global infectious disease often associated with HIV. Study of the distribution and epidemiologic trends may help target prevention and control measures towards high risk areas and groups.

Objective: To determine TB trends in four counties in Ohio, i.e. Franklin, Cuyahoga, Hamilton and Montgomery counties, and to explore differences in distribution of cases across gender, age groups and races.

Methods: TB surveillance data was collected from the Ohio Department of Health website for 12 years (1999-2011). Mean TB rates across gender were compared using the two sample t-test. One way ANOVA was used to compare means …


A Mathematical Model For Dengue Fever In A Virgin Environment, Jason K. Bowman May 2012

A Mathematical Model For Dengue Fever In A Virgin Environment, Jason K. Bowman

Senior Honors Projects

Dengue is a mosquito-borne viral infection found in tropical and subtropical regions around the world. The disease was named in 1779 and the first recorded epidemic of it occurred simultaneously on three continents within the following decade. Dengue is characterized by flu-like symptoms and, while its symptoms are generally reported as quite unpleasant, is rarely fatal. However, in some cases patients can contract a more serious form of the disease, known as Dengue Hemorrhagic Fever, which is far more dangerous. The World Health Organization estimates that today over 2.5 billion people are at risk for Dengue (over 40% of the …


Evaluating Retention In Medical Care And Its Impact On The Health Outcomes Of Individuals Living With Human Inmmunodeficiency Virus, Timothy N. Crawford Jan 2012

Evaluating Retention In Medical Care And Its Impact On The Health Outcomes Of Individuals Living With Human Inmmunodeficiency Virus, Timothy N. Crawford

Theses and Dissertations--Epidemiology and Biostatistics

In the last few years, engagement in medical care among individuals living with HIV has become a major priority among HIV medical providers and public health researchers. Engagement in medical care is an important concept as it involves the process of linking newly diagnosed individuals into medical care and retaining those individuals in care throughout the course of their infection. Although there have been major advances in the management of HIV, like the advent of Highly Active Antiretroviral Therapy, morbidity and mortality due to HIV cannot be fully reduced if the individual does not optimally retain in care. Retention in …


Political Competition, Relative Deprivation, And Perceived Threat: A Research Note On Anti- Christian Violence In India, Chad Bauman, Tamara Leech Dec 2011

Political Competition, Relative Deprivation, And Perceived Threat: A Research Note On Anti- Christian Violence In India, Chad Bauman, Tamara Leech

Department of Public Health Scholarship and Creative Works

A preliminary subnational statistical analysis of violence against Christians in contemporary India, this article suggests that whereas the data provide very little support for simple, demographic explanations of this violence, they do more robustly support theories emphasizing the relative status of ethnic and religious minorities (vis-à-vis majorities) and the perception, among Hindus, that Christians (and other minorities) represent a threat to their numerical, political and economic strength.


An Investigation Of The Subtype Diversity Of Clinical Isolates Of Irish Clostridium Difficile Ribotypes 027 And 078 By Repetitive-Extragenic Palindromic Pcr, Denise Drudy, K. Solomon, S. Murray, L. Scott, S. Mcdermott,, A. Martin, C. O’Donoghue, M. Skally, K. Burns, L. Fenelon, F. Fitzpatrick,, L. Kyne, S. Fanning Jan 2011

An Investigation Of The Subtype Diversity Of Clinical Isolates Of Irish Clostridium Difficile Ribotypes 027 And 078 By Repetitive-Extragenic Palindromic Pcr, Denise Drudy, K. Solomon, S. Murray, L. Scott, S. Mcdermott,, A. Martin, C. O’Donoghue, M. Skally, K. Burns, L. Fenelon, F. Fitzpatrick,, L. Kyne, S. Fanning

Articles

A repetitive-extragenic palindromic PCR (rep-PCR) subtyping method (DiversiLab) in conjunction with ribotyping, toxinotyping and antimicrobial-susceptibility testing was used to detect subtypes within Clostridium difficile ribotypes 027 and 078. Clinical isolates of ribotypes 027 (toxinotype III) (n530) and 078 (toxinotype V) (n523) were provided by health-care facilities across the Republic of Ireland over 2 months in 2006 and 1 month in 2009. Ribotype 027 isolates were significantly more related to each other (9 different subtype profiles) when compared to ribotype 078 isolates (14 different profiles) (P50.001; cut-off .90 % similarity). Almost half of ribotype 078 isolates (45.5 %) showed no relationship …


Everything's Better In Moderation: Young Women's Gender Role Attitudes And Risky Sexual Behavior, Tamara Leech May 2010

Everything's Better In Moderation: Young Women's Gender Role Attitudes And Risky Sexual Behavior, Tamara Leech

Department of Public Health Scholarship and Creative Works

Purpose This study examines the association between gender role attitudes and risky sexual behavior among young women. Previous studies have posed seemingly contradictory arguments: that either traditional attitudes or egalitarian attitudes are associated with riskier behavior. Methods Data are based on the children of the National Longitudinal Survey of Youth, representing 520 sexually active 18–19-year-old women. Propensity radius matching was used to assess differences in rates of multiple sexual partners and sex outside of a committed relationship. Results Relative to moderate gender role attitudes, both egalitarian gender role attitudes and traditional gender role attitudes are associated with higher rates of …


Nonparametric Regression With Missing Outcomes Using Weighted Kernel Estimating Equations, Lu Wang, Andrea Rotnitzky, Xihong Lin Apr 2010

Nonparametric Regression With Missing Outcomes Using Weighted Kernel Estimating Equations, Lu Wang, Andrea Rotnitzky, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.


The Cradle Of The Deltaf508 Mutation, Danish Saleheen, Philippe M Frossard Oct 2008

The Cradle Of The Deltaf508 Mutation, Danish Saleheen, Philippe M Frossard

Department of Biological & Biomedical Sciences

Cystic fibrosis (CF) is the most common autosomal recessive disorder caused due to mutation/s in the CFTR gene. The most common mutation in CFTR worldwide is deltaF508 and cystic fibrosis genetic analysis consortium revealed that this mutation is responsible for approximately 66% of all CF chromosomes in the world. Studies looking at the DNA polymorphic haplotypes created by CF linked markers suggest that deltaF508 has a single origin as this mutation has been found associated exclusively with one marker haplotype. Despite a high prevalence of this mutation in CF patients in northern parts of Europe, findings suggest that this mutation …


A Comparison Of Methods For Estimating The Causal Effect Of A Treatment In Randomized Clinical Trials Subject To Noncompliance, Rod Little, Qi Long, Xihong Lin Jun 2008

A Comparison Of Methods For Estimating The Causal Effect Of A Treatment In Randomized Clinical Trials Subject To Noncompliance, Rod Little, Qi Long, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.


A Cohort Study Of Reproductive And Hormonal Factors And Renal Cell Cancer Risk In Women, Gc Kabat, Stephanie A. Navarro Silvera, Ab Miller, Te Rohan Feb 2007

A Cohort Study Of Reproductive And Hormonal Factors And Renal Cell Cancer Risk In Women, Gc Kabat, Stephanie A. Navarro Silvera, Ab Miller, Te Rohan

Department of Public Health Scholarship and Creative Works

We examined the association of reproductive and hormonal factors with renal cell cancer risk in a cohort study of 89 835 Canadian women. Compared with nulliparous women, parous women were at increased risk (hazard ratio (HR) 1.78, 95% confidence interval (CI) 1.02–3.09), and there was a significant gradient of risk with increasing levels of parity: relative to nulliparous women, women who had X5 pregnancies lasting 4 months or more had a 2.4-fold risk (HR 1⁄4 2.41, 95% CI 1⁄4 1.27–4.59, P for trend 0.01). Ever use of oral contraceptives was associated with a modest reduction in risk. No associations were …


Girls' Perception Of Physical Environmental Factors And Transportation: Reliability And Association With Physical Activity And Active Transport To School, Kelly R. Evenson, Amanda Birnbaum, Ariane L. Bedimo-Rung, James Sallis, Carolyn C. Voorhees, Kimberly Ring, John P. Elder Sep 2006

Girls' Perception Of Physical Environmental Factors And Transportation: Reliability And Association With Physical Activity And Active Transport To School, Kelly R. Evenson, Amanda Birnbaum, Ariane L. Bedimo-Rung, James Sallis, Carolyn C. Voorhees, Kimberly Ring, John P. Elder

Department of Public Health Scholarship and Creative Works

Background

Preliminary evidence suggests that the physical environment and transportation are associated with youth physical activity levels. Only a few studies have examined the association of physical environmental factors on walking and bicycling to school. Therefore, the purpose of this study was (1) to examine the test-retest reliability of a survey designed for youth to assess perceptions of physical environmental factors (e.g. safety, aesthetics, facilities near the home) and transportation, and (2) to describe the associations of these perceptions with both physical activity and active transport to school.

Methods

Test and retest surveys, administered a median of 12 days later, …


Perceived Smoking Environment And Smoking Initiation Among Multi-Ethnic Urban Girls, Tracy R. Nichols, Amanda Birnbaum, Sara Birnel, Gilbert J. Botvin Apr 2006

Perceived Smoking Environment And Smoking Initiation Among Multi-Ethnic Urban Girls, Tracy R. Nichols, Amanda Birnbaum, Sara Birnel, Gilbert J. Botvin

Department of Public Health Scholarship and Creative Works

Purpose

To examine associations between the perceived smoking environment and smoking initiation among urban multi-ethnic adolescent girls in New York City.

Methods

Self-report surveys completed in grades 7, 8, and 9 assessed girls’ (n = 858) smoking initiation, and perceived smoking environment (family smoking, friends’ smoking, smoking norms, and cigarette availability). Carbon monoxide breath samples were collected from girls using a variation of the bogus pipeline procedure.

Results

Differences were found in smoking prevalence with white girls reporting the highest prevalence of smoking at baseline and the greatest increase in smoking prevalence from seventh to eighth grade. Black girls reported …


Need For Cognition And Message Complexity In Motivating Fruit And Vegetable Intake Among Callers To The Cancer Information Service, Pamela Williams-Piehota, Judith Pizarro, Stephanie A. Navarro Silvera, Linda Mowad, Peter Salovey Jan 2006

Need For Cognition And Message Complexity In Motivating Fruit And Vegetable Intake Among Callers To The Cancer Information Service, Pamela Williams-Piehota, Judith Pizarro, Stephanie A. Navarro Silvera, Linda Mowad, Peter Salovey

Department of Public Health Scholarship and Creative Works

This field experiment examined the impact of an individual's need for cognition (NFC; the tendency to enjoy thinking deeply about issues), complex versus simple messages, and the interaction of NFC and message type on encouraging fruit and vegetable consumption. Callers to the Cancer Information Service of the National Cancer Institute (N = 517) were asked to participate in the experiment at the end of their call. Individual NFC was assessed, and participants were assigned randomly to receive a telephone message promoting fruit and vegetable consumption that was either complex and multifaceted or simple and straightforward. Similarly constructed brochures were mailed …


Secular Trends In Life Expectancy By Diet Status Among Never Smoking Seventh-Day Adventists, Noha Salim Daher Jun 2005

Secular Trends In Life Expectancy By Diet Status Among Never Smoking Seventh-Day Adventists, Noha Salim Daher

Loma Linda University Electronic Theses, Dissertations & Projects

To evaluate how life expectancy changed by age and secular time from 1960 through 1988, two cohort studies, the Adventist Mortality Study (AMS, 1960-1985, n = 27,530) and the Adventist Health Study (AHS, 1976-1988, n = 34,192) were combined. The life expectancy of omnivores was compared to vegetarians separately in never-smoking males and females for all-cause mortality, and where the cause of death was cardiovascular disease or all site-cancer. Life expectancies were calculated for subjects who had survived to ages 30, 50, 70, and 80 during six calendar periods: 1960- 1964, 1965-1969, 1970-1974, 1975-1979, 1980-1984, and 1985-1988. Ten-year calendar periods …


Insights Into Latent Class Analysis, Margaret S. Pepe, Holly Janes Jan 2005

Insights Into Latent Class Analysis, Margaret S. Pepe, Holly Janes

UW Biostatistics Working Paper Series

Latent class analysis is a popular statistical technique for estimating disease prevalence and test sensitivity and specificity. It is used when a gold standard assessment of disease is not available but results of multiple imperfect tests are. We derive analytic expressions for the parameter estimates in terms of the raw data, under the conditional independence assumption. These expressions indicate explicitly how observed two- and three-way associations between test results are used to infer disease prevalence and test operating characteristics. Although reasonable if the conditional independence model holds, the estimators have no basis when it fails. We therefore caution against using …


Standardizing Markers To Evaluate And Compare Their Performances, Margaret S. Pepe, Gary M. Longton Jan 2005

Standardizing Markers To Evaluate And Compare Their Performances, Margaret S. Pepe, Gary M. Longton

UW Biostatistics Working Paper Series

Introduction: Markers that purport to distinguish subjects with a condition from those without a condition must be evaluated rigorously for their classification accuracy. A single approach to statistically evaluating and comparing markers is not yet established.

Methods: We suggest a standardization that uses the marker distribution in unaffected subjects as a reference. For an affected subject with marker value Y, the standardized placement value is the proportion of unaffected subjects with marker values that exceed Y.

Results: We apply the standardization to two illustrative datasets. In patients with pancreatic cancer placement values calculated for the CA 19-9 marker are smaller …


Combining Predictors For Classification Using The Area Under The Roc Curve, Margaret S. Pepe, Tianxi Cai, Zheng Zhang, Gary M. Longton Jan 2005

Combining Predictors For Classification Using The Area Under The Roc Curve, Margaret S. Pepe, Tianxi Cai, Zheng Zhang, Gary M. Longton

UW Biostatistics Working Paper Series

No single biomarker for cancer is considered adequately sensitive and specific for cancer screening. It is expected that the results of multiple markers will need to be combined in order to yield adequately accurate classification. Typically the objective function that is optimized for combining markers is the likelihood function. In this paper we consider an alternative objective function -- the area under the empirical receiver operating characteristic curve (AUC). We note that it yields consistent estimates of parameters in a generalized linear model for the risk score but does not require specifying the link function. Like logistic regression it yields …


Combining Predictors For Classification Using The Area Under The Roc Curve, Margaret S. Pepe, Tianxi Cai, Zheng Zhang Jun 2004

Combining Predictors For Classification Using The Area Under The Roc Curve, Margaret S. Pepe, Tianxi Cai, Zheng Zhang

UW Biostatistics Working Paper Series

We compare simple logistic regression with an alternative robust procedure for constructing linear predictors to be used for the two state classification task. Theoritical advantages of the robust procedure over logistic regression are: (i) although it assumes a generalized linear model for the dichotomous outcome variable, it does not require specification of the link function; (ii) it accommodates case-control designs even when the model is not logistic; and (iii) it yields sensible results even when the generalized linear model assumption fails to hold. Surprisingly, we find that the linear predictor derived from the logistic regression likelihood is very robust in …


Survival Model Predictive Accuracy And Roc Curves, Patrick Heagerty, Yingye Zheng Dec 2003

Survival Model Predictive Accuracy And Roc Curves, Patrick Heagerty, Yingye Zheng

UW Biostatistics Working Paper Series

The predictive accuracy of a survival model can be summarized using extensions of the proportion of variation explained by the model, or R^2, commonly used for continuous response models, or using extensions of sensitivity and specificity which are commonly used for binary response models.

In this manuscript we propose new time-dependent accuracy summaries based on time-specific versions of sensitivity and specificity calculated over risk sets. We connect the accuracy summaries to a previously proposed global concordance measure which is a variant of Kendall's tau. In addition, we show how standard Cox regression output can be used to obtain estimates of …