Huiman Xie Barnhart

Journal article Kidney Int · February 2010 Featured Publication The CHOIR trial in anemic patients with chronic kidney disease compared epoetin-alfa treatment with low (11.3 g/l) and high (13.5 g/l) hemoglobin targets on the composite end point of death, hospitalization for heart failure, stroke, and myocardial infarct ... Full text Link to item Cite

Applications of the repeatability of quantitative imaging biomarkers: a review of statistical analysis of repeat data sets.

Journal article Transl Oncol · December 2009 Featured Publication Repeat imaging data sets performed on patients with cancer are becoming publicly available. The potential utility of these data sets for addressing important questions in imaging biomarker development is vast. In particular, these data sets may be useful t ... Full text Link to item Cite

Premature atherosclerosis in pediatric systemic lupus erythematosus: risk factors for increased carotid intima-media thickness in the atherosclerosis prevention in pediatric lupus erythematosus cohort.

Journal article Arthritis Rheum · May 2009 Featured Publication OBJECTIVE: To evaluate risk factors for subclinical atherosclerosis in a population of patients with pediatric systemic lupus erythematosus (SLE). METHODS: In a prospective multicenter study, a cohort of 221 patients underwent baseline measurements of caro ... Full text Link to item Cite

Use of concordance correlation coefficient in objective and subjective assessment of limb function.

Journal article Vet Surg · October 2008 Featured Publication Full text Link to item Cite

Secondary analysis of the CHOIR trial epoetin-alpha dose and achieved hemoglobin outcomes.

Journal article Kidney Int · September 2008 Featured Publication Trials of anemia correction in chronic kidney disease have found either no benefit or detrimental outcomes of higher targets. We did a secondary analysis of patients with chronic kidney disease enrolled in the Correction of Hemoglobin in the Outcomes in Re ... Full text Link to item Cite

A general approach to evaluating agreement between two observers or methods of measurement from quantitative data with replicated measurements.

Journal article Stat Methods Med Res · April 2008 Featured Publication We present a general approach to the definition and estimation of coefficients for evaluating agreement between two fixed methods of measurements or human observers. The measured variable is assumed to be continuous with a finite second moment. No other di ... Full text Link to item Cite

Ovulatory response to treatment of polycystic ovary syndrome is associated with a polymorphism in the STK11 gene.

Journal article J Clin Endocrinol Metab · March 2008 Featured Publication CONTEXT: Clomiphene and insulin sensitizers such as metformin are used to induce ovulation in polycystic ovary syndrome (PCOS), but the ovulatory response is variable, and the causes of this variation are poorly understood. OBJECTIVE: Our objective was to ... Full text Link to item Cite

Sample size for comparing correlated concordance rates.

Journal article J Biopharm Stat · 2008 Featured Publication We consider collecting the measurements of a gold standard and two methods with error from each site of subjects. We propose an asymptotic test statistic to compare the concordance rates of two methods with the gold standard and a closed-form sample size f ... Full text Link to item Cite

Computer programs for the concordance correlation coefficient.

Journal article Comput Methods Programs Biomed · October 2007 Featured Publication The CCC macro is presented for computation of the concordance correlation coefficient (CCC), a common measure of reproducibility. The macro has been produced in both SAS and R, and a detailed presentation of the macro input and output for the SAS program i ... Full text Link to item Cite

Clomiphene, metformin, or both for infertility in the polycystic ovary syndrome.

Journal article N Engl J Med · February 8, 2007 Featured Publication BACKGROUND: The polycystic ovary syndrome is a common cause of infertility. Clomiphene and insulin sensitizers are used alone and in combination to induce ovulation, but it is unknown whether one approach is superior. METHODS: We randomly assigned 626 infe ... Full text Link to item Cite

An overview on assessing agreement with continuous measurements.

Journal article J Biopharm Stat · 2007 Featured Publication Reliable and accurate measurements serve as the basis for evaluation in many scientific disciplines. Issues related to reliable and accurate measurement have evolved over many decades, dating back to the nineteenth century and the pioneering work of Galton ... Full text Link to item Cite

Comparison of concordance correlation coefficient and coefficient of individual agreement in assessing agreement.

Journal article J Biopharm Stat · 2007 Featured Publication In method comparison and reliability studies, it is often important to assess agreement between multiple measurements made by different methods, devices, laboratories, observers, or instruments. For continuous data, the concordance correlation coefficient ... Full text Link to item Cite

Assessing individual agreement.

Journal article J Biopharm Stat · 2007 Featured Publication Evaluating agreement between measurement methods or between observers is important in method comparison studies and in reliability studies. Often we are interested in whether a new method can replace an existing invasive or expensive method, or whether mul ... Full text Link to item Cite

Assessing observer agreement in studies involving replicated binary observations.

Journal article J Biopharm Stat · 2007 Featured Publication We propose a new approach to evaluating agreement between two observers making binary observations on a set of subjects. This approach compares the probability of disagreement (or discordance) between the observers to the probability of disagreement betwee ... Full text Link to item Cite

The Pregnancy in Polycystic Ovary Syndrome study: baseline characteristics of the randomized cohort including racial effects.

Journal article Fertil Steril · October 2006 Featured Publication OBJECTIVE: To report the baseline characteristics and racial differences in the polycystic ovary syndrome (PCOS) phenotype from a large multicenter clinical trial (PPCOS). DESIGN: Double-blind, randomized trial of three treatment regimens (with extended re ... Full text Link to item Cite

The weighted generalized estimating equations approach for the evaluation of medical diagnostic test at subunit level.

Journal article Biom J · August 2006 Featured Publication Sensitivity and specificity are common measures used to evaluate the performance of a diagnostic test. A diagnostic test is often administrated at a subunit level, e.g. at the level of vessel, ear or eye of a patient so that the treatment can be targeted a ... Full text Link to item Cite

Coefficients of agreement for fixed observers.

Journal article Stat Methods Med Res · June 2006 Featured Publication Agreement between fixed observers or methods that produce readings on a continuous scale is usually evaluated via one of several intraclass correlation coefficients (ICCs). This article presents and discusses a few related issues that have not been raised ... Full text Link to item Cite

Assay validation for left-censored data.

Journal article Stat Med · November 15, 2005 Featured Publication In laboratory validation studies, it is often important to assess agreement between two assays, based on different techniques. Oftentimes, both assays have lower limits of detection and thus measurements are left censored. For example, in studies of Human ... Full text Link to item Cite

Assessing intra, inter and total agreement with replicated readings.

Journal article Stat Med · May 15, 2005 Featured Publication In clinical studies, assessing agreement of multiple readings on the same subject plays an important role in the evaluation of continuous measurement scale. The multiple readings within a subject may be replicated readings by using the same method or/and r ... Full text Link to item Cite

Maternal and child nutritional supplementation are inversely associated with fasting plasma glucose concentration in young Guatemalan adults.

Journal article J Nutr · April 2004 Featured Publication Cardiovascular disease and diabetes may be programmed early in life by abnormal development associated with undernutrition. We investigated whether maternal nutritional status (MNS; height, pregnancy weight gain, nonpregnant BMI, and prenatal supplementati ... Full text Link to item Cite

Comparison of linear growth patterns in the first three years of life across two generations in Guatemala.

Journal article Pediatrics · March 2004 Featured Publication OBJECTIVE: The secular increase in height is assumed to result from long-term improvements in nutritional intakes and reductions in infectious disease burdens. Nutritional supplementation in early life reduces stunting in chronically undernourished populat ... Full text Link to item Cite

Selected as the best paper in the 1990s: Reducing frailty and falls in older persons: an investigation of tai chi and computerized balance training.

Journal article J Am Geriatr Soc · December 2003 Featured Publication OBJECTIVES: To evaluate the effects of two exercise approaches, tai chi (TC) and computerized balance training (BT), on specified primary outcomes (biomedical, functional, and psychosocial indicators of frailty) and secondary outcomes (occurrences of fall) ... Full text Link to item Cite

Effects of early childhood supplementation on the educational achievement of women.

Journal article Pediatrics · November 2003 Featured Publication OBJECTIVE: Malnutrition during early childhood has been suggested to cause functional disadvantages in adults, including reduced intelligence and lower educational achievement (EA). We assessed the effects of improved nutrition in early life on the EA of w ... Full text Link to item Cite

A global sensitivity analysis of performance of a medical diagnostic test when verification bias is present.

Journal article Stat Med · September 15, 2003 Featured Publication Current advances in technology provide less invasive or less expensive diagnostic tests for identifying disease status. When a diagnostic test is evaluated against an invasive or expensive gold standard test, one often finds that not all patients undergo t ... Full text Link to item Cite

Evaluating medical diagnostic tests at the subunit level in the presence of verification bias.

Journal article Stat Med · July 15, 2003 Featured Publication We advocate that medical diagnostic tests should be evaluated at the subunit level instead of the patient level if a disease can occur in multiple parts/units within a patient, for example, vessels, segments, ears, eyes etc. When a non-invasive test is com ... Full text Link to item Cite

Prospective study of protein-energy supplementation early in life and of growth in the subsequent generation in Guatemala.

Journal article Am J Clin Nutr · July 2003 Featured Publication BACKGROUND: The secular increase in height is assumed to result from long-term improvements in nutritional intakes and reductions in infectious disease burdens. Nutritional supplementation in early life reduces stunting in chronically undernourished popula ... Full text Link to item Cite

Accounting for nonignorable verification bias in assessment of diagnostic tests.

Journal article Biometrics · March 2003 Featured Publication A "gold" standard test, providing definitive verification of disease status, may be quite invasive or expensive. Current technological advances provide less invasive, or less expensive, diagnostic tests. Ideally, a diagnostic test is evaluated by comparing ... Full text Link to item Cite

Overall concordance correlation coefficient for evaluating agreement among multiple observers.

Journal article Biometrics · December 2002 Featured Publication Accurate and precise measurement is an important component of any proper study design. As elaborated by Lin (1989, Biometrics 45, 255-268), the concordance correlation coefficient (CCC) is more appropriate than other indices for measuring agreement when th ... Full text Link to item Cite

Weighted least-squares approach for comparing correlated kappa.

Journal article Biometrics · December 2002 Featured Publication In the medical sciences, studies are often designed to assess the agreement between different raters or different instruments. The kappa coefficient is a popular index of agreement for binary and categorical ratings. Here we focus on testing for the equali ... Full text Link to item Cite

Joint models for toxicology studies with dose-dependent number of implantations.

Journal article Risk Anal · December 2002 Featured Publication Many chemicals interfere with the natural reproductive processes in mammals. The chemicals may prevent the fertilization of an egg or keep a zygote from implanting in the uterine wall. For this reason, toxicology studies with pre-implantation exposure ofte ... Full text Link to item Cite

Modeling concordance correlation via GEE to evaluate reproducibility.

Journal article Biometrics · September 2001 Featured Publication Clinical studies are often concerned with assessing whether different raters/methods produce similar values for measuring a quantitative variable. Use of the concordance correlation coefficient as a measure of reproducibility has gained popularity in pract ... Full text Link to item Cite

Testing proportionality in the proportional odds model fitted with GEE.

Journal article Stat Med · June 15, 1999 Featured Publication Generalized estimating equations (GEE) methodology as proposed by Liang and Zeger has received widespread use in the analysis of correlated binary data. Miller et al. and Lipsitz et al. extended GEE to correlated nominal and ordinal categorical data; in pa ... Full text Link to item Cite

A regression model for multivariate random length data.

Journal article Stat Med · January 30, 1999 Featured Publication Multivariate random length data occur when we observe multiple measurements of a quantitative variable and the variable number of these measurements is also an observed outcome for each experimental unit. For example, for a patient with coronary artery dis ... Full text Link to item Cite

Goodness-of-fit tests for GEE modeling with binary responses.

Journal article Biometrics · June 1998 Featured Publication Analysis of data with repeated measures is often accomplished through the use of generalized estimating equations (GEE) methodology. Although methods exist for assessing the adequacy of the fitted models for uncorrelated data with likelihood methods, it is ... Link to item Cite

A generalized estimating equation approach for modeling random length binary vector data.

Journal article Biometrics · September 1997 Featured Publication A common measure in clinical trials and epidemiologic studies is the number of events such as seizures, hospitalizations, or bouts of disease. Frequently, a binary measure of severity for each event is available but is not incorporated in the analysis. Thi ... Link to item Cite

Angioplasty or surgery for multivessel coronary artery disease: comparison of eligible registry and randomized patients in the EAST trial and influence of treatment selection on outcomes. Emory Angioplasty versus Surgery Trial Investigators.

Journal article Am J Cardiol · June 1, 1997 Featured Publication The Emory Angioplasty versus Surgery Trial (EAST) showed that multivessel patients eligible for both percutaneous transluminal coronary angioplasty (PTCA) and coronary bypass surgery (CABG) had equivalent 3-year outcomes regarding survival, myocardial infa ... Full text Link to item Cite

The effect of Tai Chi Quan and computerized balance training on postural stability in older subjects. Atlanta FICSIT Group. Frailty and Injuries: Cooperative Studies on Intervention Techniques.

Journal article Phys Ther · April 1997 Featured Publication BACKGROUND AND PURPOSE: This study explored whether two exercise programs would affect the ability to minimize postural sway of 72 relatively inactive, older subjects who participated in the Atlanta FICSIT trial. SUBJECTS: Subjects were randomly assigned t ... Full text Link to item Cite

Natural history of human immunodeficiency virus disease in perinatally infected children: an analysis from the Pediatric Spectrum of Disease Project.

Journal article Pediatrics · May 1996 Featured Publication OBJECTIVE: To describe the progression of human immunodeficiency virus (HIV) disease through clinical stages from birth to death among a large number of perinatally infected children. METHODS: The Pediatric Spectrum of Disease (PSD) project, coordinated by ... Link to item Cite

Reducing frailty and falls in older persons: an investigation of Tai Chi and computerized balance training. Atlanta FICSIT Group. Frailty and Injuries: Cooperative Studies of Intervention Techniques.

Journal article J Am Geriatr Soc · May 1996 Featured Publication OBJECTIVE: To evaluate the effects of two exercise approaches, Tai Chi (TC) and computerized balance training (BT), on specified primary outcomes (biomedical, functional, and psychosocial indicators of frailty) and secondary outcomes (occurrence of falls). ... Full text Link to item Cite

Emory Angioplasty Versus Surgery Trial (EAST): design, recruitment, and baseline description of patients.

Journal article Am J Cardiol · March 23, 1995 Featured Publication In patients with multivessel coronary artery disease who require revascularization there is uncertainty as to the selection of the appropriate patients for percutaneous transluminal coronary angioplasty (PTCA) as opposed to coronary artery bypass grafting ... Link to item Cite

Multiple population models for multivariate random length data--with applications in clinical trials.

Journal article Biometrics · March 1995 Featured Publication This paper focuses on the development and study of multiple population models for multivariate random length data, of the type often encountered in clinical trials. If experimental outcomes per subject consist of multiple measurements of a quantitative var ... Link to item Cite

A randomized trial comparing coronary angioplasty with coronary bypass surgery. Emory Angioplasty versus Surgery Trial (EAST).

Journal article N Engl J Med · October 20, 1994 Featured Publication BACKGROUND: The clinical benefit of percutaneous transluminal coronary angioplasty (PTCA) as compared with coronary-artery bypass grafting (CABG) for patients with multivessel coronary artery disease has not been established. To determine the outcomes of t ... Full text Link to item Cite