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1.
Stat Med ; 2024 Jun 17.
Artículo en Inglés | MEDLINE | ID: mdl-38885949

RESUMEN

Emergency medical diseases (EMDs) are the leading cause of death worldwide. A time-to-death analysis is needed to accurately identify the risks and describe the pattern of an EMD because the mortality rate can peak early and then decline. Dose-ranging Phase II clinical trials are essential for developing new therapies for EMDs. However, most dose-finding trials do not analyze mortality as a time-to-event endpoint. We propose three Bayesian dose-response time-to-event models for a secondary mortality analysis of a clinical trial: a two-group (active treatment vs control) model, a three-parameter sigmoid EMAX model, and a hierarchical EMAX model. The study also incorporates one specific active treatment as an active comparator in constructing three new models. We evaluated the performance of these six models and a very popular independent model using simulated data motivated by a randomized Phase II clinical trial focused on identifying the most effective hyperbaric oxygen dose to achieve favorable functional outcomes in patients with severe traumatic brain injury. The results show that the three-group, EMAX, and EMAX model with an active comparator produce the smallest averaged mean squared errors and smallest mean absolute biases. We provide a new approach for time-to-event analysis in early-phase dose-ranging clinical trials for EMDs. The EMAX model with an active comparator can provide valuable insights into the mortality analysis of new EMDs or other conditions that have changing risks over time. The restricted mean survival time, a function of the model's hazards, is recommended for displaying treatment effects for EMD research.

2.
J Biopharm Stat ; 34(2): 276-295, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37016726

RESUMEN

Detection of safety signals based on multiple comparisons of adverse events (AEs) between two treatments in a clinical trial involves evaluations requiring multiplicity adjustment. A Bayesian hierarchical mixture model is a good solution to this problem as it borrows information across AEs within the same System Organ Class (SOC) and modulates extremes due merely to chance. However, the hierarchical model compares only the incidence rates of AEs, regardless of severity. In this article, we propose a three-level Bayesian hierarchical non-proportional odds cumulative logit model. Our model allows for testing the equality of incidence rate and severity for AEs between the control arm and the treatment arm while addressing multiplicities. We conduct simulation study to investigate the operating characteristics of the proposed hierarchical model. The simulation study demonstrates that the proposed method could be implemented as an extension of the Bayesian hierarchical mixture model in detecting AEs with elevated incidence rate and/or elevated severity. To illustrate, we apply our proposed method using the safety data from a phase III, two-arm randomized trial.


Asunto(s)
Modelos Logísticos , Humanos , Teorema de Bayes , Simulación por Computador , Incidencia , Probabilidad , Ensayos Clínicos Fase III como Asunto , Ensayos Clínicos Controlados Aleatorios como Asunto
3.
J Biopharm Stat ; : 1-15, 2024 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-38847351

RESUMEN

Bayesian adaptive designs with response adaptive randomization (RAR) have the potential to benefit more participants in a clinical trial. While there are many papers that describe RAR designs and results, there is a scarcity of works reporting the details of RAR implementation from a statistical point exclusively. In this paper, we introduce the statistical methodology and implementation of the trial Changing the Default (CTD). CTD is a single-center prospective RAR comparative effectiveness trial to compare opt-in to opt-out tobacco treatment approaches for hospitalized patients. The design assumed an uninformative prior, conservative initial allocation ratio, and a higher threshold for stopping for success to protect results from statistical bias. A particular emerging concern of RAR designs is the possibility that time trends will occur during the implementation of a trial. If there is a time trend and the analytic plan does not prespecify an appropriate model, this could lead to a biased trial. Adjustment for time trend was not pre-specified in CTD, but post hoc time-adjusted analysis showed no presence of influential drift. This trial was an example of a successful two-armed confirmatory trial with a Bayesian adaptive design using response adaptive randomization.

4.
J Nutr ; 152(12): 2708-2715, 2023 01 14.
Artículo en Inglés | MEDLINE | ID: mdl-35953431

RESUMEN

BACKGROUND: DHA is an essential omega-3 (ω-3; n-3) fatty acid that has well-established benefits for the fetus. DHA also has the potential to influence the health of the mother, but this area is understudied. OBJECTIVES: The objective of this secondary analysis was to determine if DHA was related to maternal heart rate (HR) and heart rate variability (HRV) metrics in a large cohort of pregnant women. METHODS: In the parent trial (1R01HD086001) eligible participants (≥18 y old, English speaking, carrying a singleton pregnancy, 12-20 wk of gestation) were randomly assigned to consume 200 mg/d or 800 mg/d DHA for the duration of their pregnancy (n = 300). Weight, blood pressure, and magnetocardiograms (MCGs) were collected at 32 wk and 36 wk of gestation (n = 221). Measures of HR and HRV in time-, frequency-, and nonlinear-domains were determined from the isolated maternal MCG. Treatment group and timepoint were examined as predictors in association with HR and HRV metrics using random-intercept mixed-effects ANOVA unadjusted and adjusted models accounting for weight and dietary DHA intake. RESULTS: Women receiving the higher dose of DHA (800 mg/d) during pregnancy had lower HR, lower sympathetic index, higher vagally mediated HRV indices, and greater HRV complexity when compared with the women who received the lower dose (200 mg/d; all P < 0.05). All the dose relations remained significant even after controlling for the effect of time, maternal weight, and dietary DHA intake. CONCLUSIONS: DHA supplementation increases vagal tone in pregnant women. Longitudinal studies examining the potential link between DHA, enhanced vagal tone, and reported reduction in early preterm birth are warranted.


Asunto(s)
Ácidos Grasos Omega-3 , Nacimiento Prematuro , Humanos , Femenino , Embarazo , Recién Nacido , Ácidos Docosahexaenoicos , Suplementos Dietéticos , Madres
5.
Stat Med ; 42(25): 4582-4601, 2023 11 10.
Artículo en Inglés | MEDLINE | ID: mdl-37599009

RESUMEN

The Glasgow outcome scale-extended (GOS-E), an ordinal scale measure, is often selected as the endpoint for clinical trials of traumatic brain injury (TBI). Traditionally, GOS-E is analyzed as a fixed dichotomy with favorable outcome defined as GOS-E ≥ 5 and unfavorable outcome as GOS-E < 5. More recent studies have defined favorable vs unfavorable outcome utilizing a sliding dichotomy of the GOS-E that defines a favorable outcome as better than a subject's predicted prognosis at baseline. Both dichotomous approaches result in loss of statistical and clinical information. To improve on power, Yeatts et al proposed a sliding scoring of the GOS-E as the distance from the cutoff for favorable/unfavorable outcomes, and therefore used more information found in the original GOS-E to estimate the probability of favorable outcome. We used data from a published TBI trial to explore the ramifications to trial operating characteristics by analyzing the sliding scoring of the GOS-E as either dichotomous, continuous, or ordinal. We illustrated a connection between the ordinal data and time-to-event (TTE) data to allow use of Bayesian software that utilizes TTE-based modeling. The simulation results showed that the continuous method with continuity correction offers higher power and lower mean squared error for estimating the probability of favorable outcome compared to the dichotomous method, and similar power but higher precision compared to the ordinal method. Therefore, we recommended that future severe TBI clinical trials consider analyzing the sliding scoring of the GOS-E endpoint as continuous with continuity correction.


Asunto(s)
Lesiones Traumáticas del Encéfalo , Humanos , Teorema de Bayes , Lesiones Traumáticas del Encéfalo/terapia , Escala de Consecuencias de Glasgow , Probabilidad , Pronóstico , Ensayos Clínicos como Asunto
6.
J Biopharm Stat ; : 1-13, 2023 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-37417836

RESUMEN

Clinical trials powered to detect subgroup effects provide the most reliable data on heterogeneity of treatment effect among different subpopulations. However, pre-specified subgroup analysis is not always practical and post hoc analysis results should be examined cautiously. Bayesian hierarchical modelling provides grounds for defining a controlled post hoc analysis plan that is developed after seeing outcome data for the population but before unblinding the outcome by subgroup. Using simulation based on the results from a tobacco cessation clinical trial conducted among the general population, we defined an analysis plan to assess treatment effect among American Indians and Alaska Natives (AI/AN) enrolled in the study. Patients were randomized into two arms using Bayesian adaptive design. For the opt-in arm, clinicians offered a cessation treatment plan after verifying that a patient was ready to quit. For the opt-out arm, clinicians provided all participants with free cessation medications and referred them to a Quitline. The study was powered to test a hypothesis of significantly higher quit rates for the opt-out arm at one-month post randomization. Overall, one-month abstinence rates were 15.9% and 21.5% (opt-in and opt-out arm, respectively). For AI/AN, one-month abstinence rates were 10.2% and 22.0% (opt-in and opt-out arm, respectively). The posterior probability that the abstinence rate in the treatment arm is higher is 0.96, indicating that AI/AN demonstrate response to treatment at almost the same probability as the whole population.

7.
J Biopharm Stat ; 33(1): 43-52, 2023 01 02.
Artículo en Inglés | MEDLINE | ID: mdl-36411742

RESUMEN

We investigate the value of a two-armed Bayesian response adaptive randomization (RAR) design to investigate early preterm birth rates of high versus low dose of docosahexaenoic acid during pregnancy. Unexpectedly, the COVID-19 pandemic forced recruitment to pause at 1100 participants rather than the planned 1355. The difference in power between number of participants at the pause and planned was 87% and 90% respectively. We decided to stop the study. This paper describes how the RAR was used to execute the study. The value of RAR in two-armed studies is quite high and their use in the future is promising.


Asunto(s)
COVID-19 , Nacimiento Prematuro , Recién Nacido , Femenino , Humanos , Distribución Aleatoria , COVID-19/epidemiología , Teorema de Bayes , Pandemias , Proyectos de Investigación
8.
Matern Child Health J ; 27(10): 1811-1822, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37369811

RESUMEN

BACKGROUND: Latina women are less likely to start prenatal care in the first trimester and to attend the recommended amount of prenatal visits compared to their non-Latina white counterparts. OBJECTIVES: This study aimed to assess challenges and facilitators to first-trimester prenatal care (FTPNC) and prenatal care utilization (PNCU) in a Midwestern urban area with a growing immigrant Latino community. METHODS: This study used a mixed-method approach based on the Theoretical Domains Framework. Nine semi-structured interviews were conducted with healthcare professionals that worked in birth centers, clinics, or hospitals that provided prenatal care (PNC) services for Latina women. Eight focus groups and quantitative surveys were conducted with Latina women and their supporters in Kansas City metropolitan area. RESULTS: FTPNC was challenged by women's immigrant status, lack of healthcare coverage due to immigrant status, and complexity of Medicaid application. PNCU was challenged by the cost of PNC when diagnosed with gestational diabetes, lack of healthcare coverage, PNC literacy, late access to gynecologists/obstetricians, inadequate interpretation services, transportation, and mental health distress. Meanwhile, FTPNC was facilitated by social support and connectedness. PNCU was facilitated by Spanish-proficient providers and interpreters, effective nonverbal communication and education techniques, and pregnancy prevention access and education. CONCLUSIONS FOR PRACTICE: Results from this study highlight important targets to improve PNC for Latina women. Participants called for various types of support to address identified challenges, ranging from information on social media about PNC services to broader efforts such as building trust from the community toward PNC providers and making PNC services affordable for women with gestational diabetes.


Asunto(s)
Diabetes Gestacional , Atención Prenatal , Embarazo , Femenino , Humanos , Accesibilidad a los Servicios de Salud , Hispánicos o Latinos , Primer Trimestre del Embarazo
9.
Pediatr Res ; 92(1): 255-264, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-34552200

RESUMEN

INTRODUCTION: Maternal-infant equilibrium occurs when cord blood docosahexaenoic acid (DHA) is less than or equal to maternal DHA at delivery. Equilibrium may be an indicator of sufficient DHA for optimal fetal and infant neurodevelopment. The purpose of this study was to test the effect of maternal DHA supplementation on equilibrium status and fetal neurodevelopment. METHODS: Women enrolled between 12 and 20 weeks gestation and were randomized to 200 or 800 mg DHA/day until delivery. Maternal red blood cell (RBC) phospholipids were measured at enrollment, 32 weeks, delivery, and in cord blood at delivery. Fetal neurodevelopment was measured at 32 and 36 weeks gestation. Intent-to-treat analyses were conducted to test differences in equilibrium status by group. Fetal outcomes were assessed by equilibrium status and group. RESULTS: Three hundred women enrolled and 262 maternal-infant dyads provided blood samples at delivery. No maternal-infant dyads with maternal RBC-DHA ≤ 6.96% at delivery achieved equilibrium. The incidence of equilibrium was significantly higher in the 800 mg group. There was no effect of maternal group or equilibrium status on fetal neurodevelopment. CONCLUSION: The significance of maternal-infant DHA equilibrium remains unknown. Ongoing research will test the effect of treatment group, equilibrium, and nutrient status on infant behavior and brain function. IMPACT: Pregnant women who received a higher dose of docosahexaenoic acid (DHA) were more likely to achieve maternal-infant DHA equilibrium at delivery. Equilibrium status had no effect on fetal neurodevelopment in this sample. While DHA is crucial for early life neurodevelopment, the significance of achieving maternal-infant equilibrium above the lower threshold is uncertain. There is a lower threshold of maternal DHA status where maternal-infant DHA equilibrium never occurs. The lack of equilibrium associated with low maternal DHA status may indicate insufficient maternal status for optimal placental transfer.


Asunto(s)
Ácidos Docosahexaenoicos , Placenta , Suplementos Dietéticos , Femenino , Sangre Fetal , Humanos , Lactante , Embarazo , Atención Prenatal , Vitaminas
10.
BMC Med Res Methodol ; 22(1): 28, 2022 01 26.
Artículo en Inglés | MEDLINE | ID: mdl-35081912

RESUMEN

BACKGROUND: Although frequentist paradigm has been the predominant approach to clinical studies for decades, some limitations associated with the frequentist null hypothesis significance testing have been recognized. Bayesian approaches can provide additional insights into data interpretation and inference by deriving posterior distributions of model parameters reflecting the clinical interest. In this article, we sought to demonstrate how Bayesian approaches can improve the data interpretation by reanalyzing the Rural Engagement in Primary Care for Optimizing Weight Reduction (REPOWER). METHODS: REPOWER is a cluster randomized clinical trial comparing three care delivery models: in-clinic individual visits, in-clinic group visits, and phone-based group visits. The primary endpoint was weight loss at 24 months and the secondary endpoints included the proportions of achieving 5 and 10% weight loss at 24 months. We reanalyzed the data using a three-level Bayesian hierarchical model. The posterior distributions of weight loss at 24 months for each arm were obtained using Hamiltonian Monte Carlo. We then estimated the probability of having a higher weight loss and the probability of having greater proportion achieving 5 and 10% weight loss between groups. Additionally, a four-level hierarchical model was used to assess the partially nested intervention group effect which was not investigated in the original REPOWER analyses. RESULTS: The Bayesian analyses estimated 99.5% probability that in-clinic group visits, compared with in-clinic individual visits, resulted in a higher percent weight loss (posterior mean difference: 1.8%[95% CrI: 0.5,3.2%]), a greater probability of achieving 5% threshold (posterior mean difference: 9.2% [95% CrI: 2.4, 16.0%]) and 10% threshold (posterior mean difference: 6.6% [95% CrI: 1.7, 11.5%]). The phone-based group visits had similar result. We also concluded that including intervention group did not impact model fit significantly. CONCLUSIONS: We unified the analyses of continuous (the primary endpoint) and categorical measures (the secondary endpoints) of weight loss with one single Bayesian hierarchical model. This approach gained statistical power for the dichotomized endpoints by leveraging the information in the continuous data. Furthermore, the Bayesian analysis enabled additional insights into data interpretation and inference by providing posterior distributions for parameters of interest and posterior probabilities of different hypotheses that were not available with the frequentist approach. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT02456636 ; date of registry: May 28, 2015.


Asunto(s)
Teléfono , Pérdida de Peso , Teorema de Bayes , Humanos , Probabilidad , Proyectos de Investigación
11.
Subst Abus ; 43(1): 1035-1042, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35435813

RESUMEN

Background: Enrollment in smoking cessation trials remain sub-optimal. The aim of this analysis was to determine the effectiveness of a modified Zelen's design in engaging hospitalized patients who smoke in a pragmatic OPT-IN versus OPT-OUT tobacco treatment trial. Methods: At bedside, clinical staff screened smokers for eligibility, randomized eligible into study arms, and delivered the appropriate treatment approach. Study staff called randomized patients at one-month post-discharge, debriefed patients on the study design, and collected consent to participate. We used frequencies and percentages for categorical variables and means and standard deviations for quantitative variables to describe the characteristics of those who consented and were enrolled versus those who did not enroll. We also compared the characteristics of participants who consented and those who were reached and explicitly refused consent at one-month follow-up. We used the Cohen's d measure of effect size to evaluate differences. Results: Of the 1,000 randomized, 741 (74.1%) consented to continue in the study at one-month follow-up. One hundred and twenty-seven (12.7%) refused consent and 132 (13.2%) were unreachable. Cohen's d effect size differences between those who consented/enrolled (n = 741) and those who were not enrolled (n = 259) were negligible (<0.2) for age, gender, race/ethnicity, and most forms of insurance. The effect size was small for Medicaid (0.36), and other public insurance (0.48). After excluding those unreached at 1 month (12.7%), there were medium Cohen's d effect size differences between those who consented to participate (n = 741) and those who explicitly refused (n = 127) with respect to age (0.55) and self-pay or no insurance (0.51). There were small to negligible effect size differences with respect to sex, race/ethnicity, and other forms of health insurance. Conclusions: The modified Zelen's design resulted in successful enrollment of most participants who were initially randomized into the trial, including those not motivated to quit.


Asunto(s)
Cuidados Posteriores , Nicotiana , Humanos , Consentimiento Informado , Alta del Paciente , Distribución Aleatoria , Resultado del Tratamiento
12.
Pharm Stat ; 20(3): 573-596, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-33463906

RESUMEN

Patients with different characteristics (e.g., biomarkers, risk factors) may have different responses to the same medicine. Personalized medicine clinical studies that are designed to identify patient subgroup treatment efficacies can benefit patients and save medical resources. However, subgroup treatment effect identification complicates the study design in consideration of desired operating characteristics. We investigate three Bayesian adaptive models for subgroup treatment effect identification: pairwise independent, hierarchical, and cluster hierarchical achieved via Dirichlet Process (DP). The impact of interim analysis and longitudinal data modeling on the personalized medicine study design is also explored. Interim analysis is considered since they can accelerate personalized medicine studies in cases where early stopping rules for success or futility are met. We apply integrated two-component prediction method (ITP) for longitudinal data simulation, and simple linear regression for longitudinal data imputation to optimize the study design. The designs' performance in terms of power for the subgroup treatment effects and overall treatment effect, sample size, and study duration are investigated via simulation. We found the hierarchical model is an optimal approach to identifying subgroup treatment effects, and the cluster hierarchical model is an excellent alternative approach in cases where sufficient information is not available for specifying the priors. The interim analysis introduction to the study design lead to the trade-off between power and expected sample size via the adjustment of the early stopping criteria. The introduction of the longitudinal modeling slightly improves the power. These findings can be applied to future personalized medicine studies with discrete or time-to-event endpoints.


Asunto(s)
Ensayos Clínicos como Asunto , Medicina de Precisión , Proyectos de Investigación , Teorema de Bayes , Humanos , Inutilidad Médica , Tamaño de la Muestra
13.
BMC Med Res Methodol ; 20(1): 194, 2020 07 20.
Artículo en Inglés | MEDLINE | ID: mdl-32690004

RESUMEN

BACKGROUND: Phase II clinical trials primarily aim to find the optimal dose and investigate the relationship between dose and efficacy relative to standard of care (control). Therefore, before moving forward to a phase III confirmatory trial, the most effective dose is needed to be identified. METHODS: The primary endpoint of a phase II trial is typically a binary endpoint of success or failure. The EMAX model, ubiquitous in pharmacology research, was fit for many compounds and described the data well, except for a single compound, which had nonmonotone dose-response (Thomas et al., Stat Biopharmaceutical Res. 6:302-317 2014). To mitigate the risk of nonmonotone dose response one of the alternative options is a Bayesian hierarchical EMAX model (Gajewski et al., Stat Med. 38:3123-3138 2019). The hierarchical EMAX adapts to its environment. RESULTS: When the dose-response curve is monotonic it enjoys the efficiency of EMAX. When the dose-response curve is non-monotonic the additional random effect hyperprior makes the hierarchical EMAX model more adjustable and flexible. However, the normal dynamic linear model (NDLM) is a useful model to explore dose-response relationships in that the efficacy at the current dose depends on the efficacy of the previous dose(s). Previous research has compared the EMAX to the hierarchical EMAX (Gajewski et al., Stat Med. 38:3123-3138 2019) and the EMAX to the NDLM (Liu et al., BMC Med Res Method 17:149 2017), however, the hierarchical EMAX has not been directly compared to the NDLM. CONCLUSIONS: The focus of this paper is to compare these models and discuss the relative merit for each of their uses for an ongoing early phase dose selection study.


Asunto(s)
Proyectos de Investigación , Teorema de Bayes , Relación Dosis-Respuesta a Droga , Humanos , Modelos Lineales , Estudios Longitudinales
14.
Stat Med ; 38(17): 3123-3138, 2019 07 30.
Artículo en Inglés | MEDLINE | ID: mdl-31070807

RESUMEN

A primary goal of a phase II dose-ranging trial is to identify a correct dose before moving forward to a phase III confirmatory trial. A correct dose is one that is actually better than control. A popular model in phase II is an independent model that puts no structure on the dose-response relationship. Unfortunately, the independent model does not efficiently use information from related doses. One very successful alternate model improves power using a pre-specified dose-response structure. Past research indicates that EMAX models are broadly successful and therefore attractive for designing dose-response trials. However, there may be instances of slight risk of nonmonotone trends that need to be addressed when planning a clinical trial design. We propose to add hierarchical parameters to the EMAX model. The added layer allows information about the treatment effect in one dose to be "borrowed" when estimating the treatment effect in another dose. This is referred to as the hierarchical EMAX model. Our paper compares three different models (independent, EMAX, and hierarchical EMAX) and two different design strategies. The first design considered is Bayesian with a fixed trial design, and it has a fixed schedule for randomization. The second design is Bayesian but adaptive, and it uses response adaptive randomization. In this article, a randomized trial of patients with severe traumatic brain injury is provided as a motivating example.


Asunto(s)
Ensayos Clínicos Fase II como Asunto , Relación Dosis-Respuesta a Droga , Oxigenoterapia Hiperbárica , Modelos Estadísticos , Ensayos Clínicos Controlados Aleatorios como Asunto , Proyectos de Investigación , Teorema de Bayes , Humanos , Estudios Multicéntricos como Asunto , Estudios Prospectivos
15.
Clin Trials ; 16(6): 657-664, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31451012

RESUMEN

BACKGROUND: Monitoring subject recruitment is key to the success of a clinical trial. Accordingly, researchers have developed accrual-monitoring tools to support the design and conduct of trials. At an institutional level, delays in identifying studies with high risk of accrual failure can lead to inefficient and costly trials with little chances of meeting study objectives. Comprehensive accrual monitoring is necessary to the success of the research enterprise. METHODS: This article describes the design and implementation of the University of Kansas Cancer Center Accrual Prediction Program, a web-based platform was developed to support comprehensive accrual monitoring and prediction for all active clinical trials. The Accrual Prediction Program provides information on accrual, including the predicted completion date, predicted number of accrued subjects during the pre-specified accrual period, and the probability of achieving accrual targets. It relies on a Bayesian accrual prediction model to combine protocol information with real-time trial enrollment data and disseminates results via web application. RESULTS: First released in 2016, the Accrual Prediction Program summarizes enrollment information for active studies categorized by various trial attributes. The web application supports real-time evidence-based decision making for strategic resource allocation and study management of over 120 ongoing clinical trials at the University of Kansas Cancer Center. CONCLUSION: The Accrual Prediction Program makes accessing comprehensive accrual information manageable at an institutional level. Cancer centers or even entire institutions can reproduce the Accrual Prediction Program to achieve real-time comprehensive monitoring and prediction of subject accrual to aid investigators and administrators in the design, conduct, and management of clinical trials.


Asunto(s)
Ensayos Clínicos como Asunto/métodos , Modelos Estadísticos , Neoplasias/terapia , Selección de Paciente , Teorema de Bayes , Instituciones Oncológicas , Ensayos Clínicos como Asunto/estadística & datos numéricos , Humanos , Internet , Kansas , Proyectos de Investigación
16.
Public Health Nutr ; 22(12): 2157-2169, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-31146797

RESUMEN

OBJECTIVE: To describe the relationship between adherence to distinct dietary patterns and nutrition literacy. DESIGN: We identified distinct dietary patterns using principal covariates regression (PCovR) and principal components analysis (PCA) from the Diet History Questionnaire II. Nutrition literacy was assessed using the Nutrition Literacy Assessment Instrument (NLit). Cross-sectional relationships between dietary pattern adherence and global and domain-specific NLit scores were tested by multiple linear regression. Mean differences in diet pattern adherence among three predefined nutrition literacy performance categories were tested by ANOVA. SETTING: Metropolitan Kansas City, USA. PARTICIPANTS: Adults (n 386) with at least one of four diet-related diseases. RESULTS: Three diet patterns of interest were derived: a PCovR prudent pattern and PCA-derived Western and Mediterranean patterns. After controlling for age, sex, BMI, race, household income, education level and diabetes status, PCovR prudent pattern adherence positively related to global NLit score (P < 0·001, ß = 0·36), indicating more intake of prudent diet foods with improved nutrition literacy. Validating the PCovR findings, PCA Western pattern adherence inversely related to global NLit (P = 0·003, ß = -0·13) while PCA Mediterranean pattern positively related to global NLit (P = 0·02, ß = 0·12). Using predefined cut points, those with poor nutrition literacy consumed more foods associated with the Western diet (fried foods, sugar-sweetened beverages, red meat, processed foods) while those with good nutrition literacy consumed more foods associated with prudent and Mediterranean diets (vegetables, olive oil, nuts). CONCLUSIONS: Nutrition literacy predicted adherence to healthy/unhealthy diet patterns. These findings warrant future research to determine if improving nutrition literacy effectively improves eating patterns.


Asunto(s)
Dieta Saludable/psicología , Conducta Alimentaria/psicología , Alfabetización en Salud , Trastornos Nutricionales/psicología , Cooperación del Paciente/psicología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Enfermedad Crónica , Estudios Transversales , Femenino , Humanos , Kansas , Masculino , Persona de Mediana Edad , Trastornos Nutricionales/dietoterapia , Análisis de Componente Principal , Análisis de Regresión , Adulto Joven
17.
Stat Med ; 37(19): 2900-2901, 2018 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-30294062

RESUMEN

This paper is the letter to the editor regarding several comments on 'Tutorial on statistical considerations on subgroup analysis in confirmatory clinical trials.'


Asunto(s)
Proyectos de Investigación , Tamaño de la Muestra
18.
BMC Med Res Methodol ; 18(1): 19, 2018 02 06.
Artículo en Inglés | MEDLINE | ID: mdl-29409450

RESUMEN

BACKGROUND: Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig's disease, is a rare disease with extreme between-subject variability, especially with respect to rate of disease progression. This makes modelling a subject's disease progression, which is measured by the ALS Functional Rating Scale (ALSFRS), very difficult. Consider the problem of predicting a subject's ALSFRS score at 9 or 12 months after a given time-point. METHODS: We obtained ALS subject data from the Pooled Resource Open-Access ALS Clinical Trials Database, a collection of data from various ALS clinical trials. Due to the typical linearity of the ALSFRS, we consider several Bayesian hierarchical linear models. These include a mixture model (to account for the two potential classes of "fast" and "slow" ALS progressors) as well as an onset-anchored model, in which an additional artificial data-point, using time of disease onset, is utilized to improve predictive performance. RESULTS: The onset-anchored model had a drastically reduced posterior predictive mean-square-error distributions, when compared to the Bayesian hierarchical linear model or the mixture model under a cross-validation approach. No covariates, other than time of disease onset, consistently improved predictive performance in either the Bayesian hierarchical linear model or the onset-anchored model. CONCLUSIONS: Augmenting patient data with an additional artificial data-point, or onset anchor, can drastically improve predictive modelling in ALS by reducing the variability of estimated parameters at the cost of a slight increase in bias. This onset-anchored model is extremely useful if predictions are desired directly after a single baseline measure (such as at the first day of a clinical trial), a feat that would be very difficult without the onset-anchor. This approach could be useful in modelling other diseases that have bounded progression scales (e.g. Parkinson's disease, Huntington's disease, or inclusion-body myositis). It is our hope that this model can be used by clinicians and statisticians to improve the efficacy of clinical trials and aid in finding treatments for ALS.


Asunto(s)
Esclerosis Amiotrófica Lateral/diagnóstico , Esclerosis Amiotrófica Lateral/terapia , Teorema de Bayes , Modelos Lineales , Adulto , Anciano , Algoritmos , Ensayos Clínicos como Asunto/estadística & datos numéricos , Bases de Datos Factuales/estadística & datos numéricos , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pronóstico , Reproducibilidad de los Resultados , Índice de Severidad de la Enfermedad
19.
BMC Neurol ; 18(1): 205, 2018 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-30547800

RESUMEN

BACKGROUND: To assess the feasibility of using automated capture of Electronic Medical Record (EMR) data to build predictive models for amyotrophic lateral sclerosis (ALS) outcomes. METHODS: We used an Informatics for Integrating Biology and the Bedside search discovery tool to identify and extract data from 354 ALS patients from the University of Kansas Medical Center EMR. The completeness and integrity of the data extraction were verified by manual chart review. A linear mixed model was used to model disease progression. Cox proportional hazards models were used to investigate the effects of BMI, gender, and age on survival. RESULTS: Data extracted from the EMR was sufficient to create simple models of disease progression and survival. Several key variables of interest were unavailable without including a manual chart review. The average ALS Functional Rating Scale - Revised (ALSFRS-R) baseline score at first clinical visit was 34.08, and average decline was - 0.64 per month. Median survival was 27 months after first visit. Higher baseline ALSFRS-R score and BMI were associated with improved survival, higher baseline age was associated with decreased survival. CONCLUSIONS: This study serves to show that EMR-captured data can be extracted and used to track outcomes in an ALS clinic setting, potentially important for post-marketing research of new drugs, or as historical controls for future studies. However, as automated EMR-based data extraction becomes more widely used there will be a need to standardize ALS data elements and clinical forms for data capture so data can be pooled across academic centers.


Asunto(s)
Esclerosis Amiotrófica Lateral , Progresión de la Enfermedad , Registros Electrónicos de Salud , Adulto , Anciano , Esclerosis Amiotrófica Lateral/mortalidad , Femenino , Humanos , Modelos Lineales , Masculino , Persona de Mediana Edad , Modelos de Riesgos Proporcionales
20.
BMC Pregnancy Childbirth ; 17(1): 62, 2017 02 13.
Artículo en Inglés | MEDLINE | ID: mdl-28193189

RESUMEN

BACKGROUND: Preterm birth contributes to 0.5 million deliveries in the United States (one of eight pregnancies) and poses a huge burden on public health with costs in the billions. Of particular concern is that the rate of earliest preterm birth (<34 weeks) (ePTB), which has decreased little since 1990 and has the greatest impact on the overall infant mortality, resulting in the greatest cost to society. Docosahexaenoic acid (DHA) supplementation provides a potential high yield, low risk strategy to reduce early preterm delivery in the US by up to 75%. We propose a Phase III Clinical Trial (randomized to low or high dose DHA, double-blinded) to examine the efficacy and safety of high dose DHA supplementation to reduce ePTB. We also plan for a secondary pregnancy efficacy analysis to determine if there is a subset of pregnancies most likely to benefit from DHA supplementation. METHODS: Between 900 and 1200 pregnant women who are ≥ 18 years old and between 12 and 20 weeks gestation will be recruited from three trial experienced academic medical institutions. Participants will be randomly assigned to two daily capsules of algal oil (totaling 800 mg DHA) or soybean and corn oil (0 mg DHA). Both groups will receive a commercially available prenatal supplement containing 200 mg DHA. Therefore, the experimental group will receive 1000 mg DHA/d and the control group 200 mg DHA/d. We will then employ a novel Bayesian response adaptive randomization design that assigns more subjects to the "winning" group and potentially allows for substantially smaller sample size while providing a stronger conclusion regarding the most effective group. The study has an overall Type I error rate of 5% and a power of 90%. Participants are followed throughout pregnancy and delivery for safety and delivery outcomes. DISCUSSION: We hypothesize that DHA will decrease the frequency of ePTB <34 weeks. Reducing ePTB is clinically important as these earliest preterm deliveries carry the highest risk of neonatal morbidity, as well as contribute significant stress for families and post a large societal burden. TRIAL REGISTRATION: This trial was registered with ClinicalTrials.gov (identifier: NCT02626299 ) on December 8, 2015. Additional summary details may be found in Table 1.


Asunto(s)
Suplementos Dietéticos , Ácidos Docosahexaenoicos/administración & dosificación , Nacimiento Prematuro/prevención & control , Atención Prenatal/métodos , Administración Oral , Adulto , Aceite de Maíz/administración & dosificación , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Femenino , Edad Gestacional , Humanos , Recién Nacido , Embarazo , Nacimiento Prematuro/epidemiología , Aceite de Soja/administración & dosificación
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