LIVIVO - Search results -

Search results

Result 1 - 10 of total 361

Search options

Article ; Online: Correction: Sample Size Calculations for Stepped Wedge Designs with Treatment Effects that May Change with the Duration of Time under Intervention.

Hughes, James P / Lee, Wen-Yu / Troxel, Andrea B / Heagerty, Patrick J

Prevention science : the official journal of the Society for Prevention Research

2024

Language	English
Publishing date	2024-01-06
Publishing country	United States
Document type	Published Erratum
ZDB-ID	2251270-6
ISSN	1573-6695 ; 1389-4986
ISSN (online)	1573-6695
ISSN	1389-4986
DOI	10.1007/s11121-024-01645-2
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 6466: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
ab Jg. 2022: Lesesaal (EG)

Order via subito

This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

Details ▾
- See ZB MED holdings
- Order with fees

Article ; Online: Correction: Sample Size Calculations for Stepped Wedge Designs with Treatment Effects that May Change with the Duration of Time under Intervention.

Hughes, James P / Lee, Wen-Yu / Troxel, Andrea B / Heagerty, Patrick J

Prevention science : the official journal of the Society for Prevention Research

2024

Language	English
Publishing date	2024-02-16
Publishing country	United States
Document type	Published Erratum
ZDB-ID	2251270-6
ISSN	1573-6695 ; 1389-4986
ISSN (online)	1573-6695
ISSN	1389-4986
DOI	10.1007/s11121-024-01652-3
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Zs.A 6466: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article ; Online: Sample Size Calculations for Stepped Wedge Designs with Treatment Effects that May Change with the Duration of Time under Intervention.

Hughes, James P / Lee, Wen-Yu / Troxel, Andrea B / Heagerty, Patrick J

Prevention science : the official journal of the Society for Prevention Research

2023

Abstract: The stepped wedge design is often used to evaluate interventions as they are rolled out across schools, health clinics, communities, or other clusters. Most models used in the design and analysis of stepped wedge trials assume that the intervention ... ...

Abstract	The stepped wedge design is often used to evaluate interventions as they are rolled out across schools, health clinics, communities, or other clusters. Most models used in the design and analysis of stepped wedge trials assume that the intervention effect is immediate and constant over time following implementation of the intervention (the "exposure time"). This is known as the IT (immediate treatment effect) assumption. However, recent research has shown that using methods based on the IT assumption when the treatment effect varies over exposure time can give extremely misleading results. In this manuscript, we discuss the need to carefully specify an appropriate measure of the treatment effect when the IT assumption is violated and we show how a stepped wedge trial can be powered when it is anticipated that the treatment effect will vary as a function of the exposure time. Specifically, we describe how to power a trial when the exposure time indicator (ETI) model of Kenny et al. (Statistics in Medicine, 41, 4311-4339, 2022) is used and the estimand of interest is a weighted average of the time-varying treatment effects. We apply these methods to the ADDRESS-BP trial, a type 3 hybrid implementation study designed to address racial disparities in health care by evaluating a practice-based implementation strategy to reduce hypertension in African American communities.
Language	English
Publishing date	2023-09-20
Publishing country	United States
Document type	Journal Article
ZDB-ID	2251270-6
ISSN	1573-6695 ; 1389-4986
ISSN (online)	1573-6695
ISSN	1389-4986
DOI	10.1007/s11121-023-01587-1
Database	MEDical Literature Analysis and Retrieval System OnLINE

Full text online

Accessible to users with ZB MED library card

In stock of ZB MED Cologne/Königswinter

Zs.A 6466: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾

Article ; Online: Factors and Challenges in Understanding SARS-CoV-2 RNA Levels, Symptoms, and Transmissibility-Reply.

Chung, Erin / Hughes, James P / Chu, Helen Y

JAMA pediatrics

2021 Volume 175, Issue 12, Page(s) 1293–1294

MeSH term(s)	COVID-19 ; Humans ; RNA, Viral/genetics ; SARS-CoV-2
Chemical Substances	RNA, Viral
Language	English
Publishing date	2021-09-20
Publishing country	United States
Document type	Journal Article ; Comment
ZDB-ID	2701223-2
ISSN	2168-6211 ; 2168-6203
ISSN (online)	2168-6211
ISSN	2168-6203
DOI	10.1001/jamapediatrics.2021.3579
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Cologne/Königswinter

Um IV Zs.74: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾
- See ZB MED holdings
- Order with fees

Article ; Online: A multiview model for relative and absolute microbial abundances.

Williamson, Brian D / Hughes, James P / Willis, Amy D

Biometrics

2021 Volume 78, Issue 3, Page(s) 1181–1194

Abstract: The absolute abundance of bacterial taxa in human host-associated environments plays a critical role in reproductive and gastrointestinal health. However, obtaining the absolute abundance of many bacterial species is typically prohibitively expensive. In ...

Abstract	The absolute abundance of bacterial taxa in human host-associated environments plays a critical role in reproductive and gastrointestinal health. However, obtaining the absolute abundance of many bacterial species is typically prohibitively expensive. In contrast, relative abundance data for many species are comparatively cheap and easy to collect (e.g., with universal primers for the 16S rRNA gene). In this paper, we propose a method to jointly model relative abundance data for many taxa and absolute abundance data for a subset of taxa. Our method provides point and interval estimates for the absolute abundance of all taxa. Crucially, our proposal accounts for differences in the efficiency of taxon detection in the relative and absolute abundance data. We show that modeling taxon-specific efficiencies substantially reduces the estimation error for absolute abundance, and controls the coverage of interval estimators. We demonstrate the performance of our proposed method via a simulation study, a study of the effect of HIV acquisition on microbial abundances, and a sensitivity study where we jackknife the taxa with observed absolute abundances.
MeSH term(s)	Bacteria/genetics ; High-Throughput Nucleotide Sequencing/methods ; Humans ; RNA, Ribosomal, 16S/genetics
Chemical Substances	RNA, Ribosomal, 16S
Language	English
Publishing date	2021-06-08
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	213543-7
ISSN	1541-0420 ; 0099-4987 ; 0006-341X
ISSN (online)	1541-0420
ISSN	0099-4987 ; 0006-341X
DOI	10.1111/biom.13503
Database	MEDical Literature Analysis and Retrieval System OnLINE

Full text online

Accessible to users with ZB MED library card

In stock of ZB MED Cologne/Königswinter

Zs.B 72: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾

Article ; Online: A multiview model for relative and absolute microbial abundances

Williamson, Brian D. / Hughes, James P. / Willis, Amy D.

Biometrics. 2022 Sept., v. 78, no. 3 p.1181-1194

2022

Abstract: The absolute abundance of bacterial taxa in human host‐associated environments plays a critical role in reproductive and gastrointestinal health. However, obtaining the absolute abundance of many bacterial species is typically prohibitively expensive. In ...

Abstract	The absolute abundance of bacterial taxa in human host‐associated environments plays a critical role in reproductive and gastrointestinal health. However, obtaining the absolute abundance of many bacterial species is typically prohibitively expensive. In contrast, relative abundance data for many species are comparatively cheap and easy to collect (e.g., with universal primers for the 16S rRNA gene). In this paper, we propose a method to jointly model relative abundance data for many taxa and absolute abundance data for a subset of taxa. Our method provides point and interval estimates for the absolute abundance of all taxa. Crucially, our proposal accounts for differences in the efficiency of taxon detection in the relative and absolute abundance data. We show that modeling taxon‐specific efficiencies substantially reduces the estimation error for absolute abundance, and controls the coverage of interval estimators. We demonstrate the performance of our proposed method via a simulation study, a study of the effect of HIV acquisition on microbial abundances, and a sensitivity study where we jackknife the taxa with observed absolute abundances.
Keywords	gastrointestinal system ; genes ; humans ; models
Language	English
Dates of publication	2022-09
Size	p. 1181-1194.
Publishing place	John Wiley & Sons, Ltd
Document type	Article ; Online
Note	JOURNAL ARTICLE
ZDB-ID	213543-7
ISSN	0099-4987 ; 0006-341X
ISSN	0099-4987 ; 0006-341X
DOI	10.1111/biom.13503
Database	NAL-Catalogue (AGRICOLA)

In stock of ZB MED Bonn / Germany

Z 58/144: Show issues
I/354: Show issues

Order via subito

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Details ▾
- See ZB MED holdings
- Order with fees

Article ; Online: Power and sample size calculation for stepped-wedge designs with discrete outcomes.

Xia, Fan / Hughes, James P / Voldal, Emily C / Heagerty, Patrick J

Trials

2021 Volume 22, Issue 1, Page(s) 598

Abstract: Background: Stepped-wedge designs (SWD) are increasingly used to evaluate the impact of changes to the process of care within health care systems. However, to generate definitive evidence, a correct sample size calculation is crucial to ensure such ... ...

Abstract	Background: Stepped-wedge designs (SWD) are increasingly used to evaluate the impact of changes to the process of care within health care systems. However, to generate definitive evidence, a correct sample size calculation is crucial to ensure such studies are properly powered. The seminal work of Hussey and Hughes (Contemp Clin Trials 28(2):182-91, 2004) provides an analytical formula for power calculations with normal outcomes using a linear model and simple random effects. However, minimal development and evaluation have been done for power calculation with non-normal outcomes on their natural scale (e.g., logit, log). For example, binary endpoints are common, and logistic regression is the natural multilevel model for such clustered data. Methods: We propose a power calculation formula for SWD with either normal or non-normal outcomes in the context of generalized linear mixed models by adopting the Laplace approximation detailed in Breslow and Clayton (J Am Stat Assoc 88(421):9-25, 1993) to obtain the covariance matrix of the estimated parameters. Results: We compare the performance of our proposed method with simulation-based sample size calculation and demonstrate its use on a study of patient-delivered partner therapy for STI treatment and a study that assesses the impact of providing additional benchmark prevalence information in a radiologic imaging report. To facilitate adoption of our methods we also provide a function embedded in the R package "swCRTdesign" for sample size and power calculation for multilevel stepped-wedge designs. Conclusions: Our method requires minimal computational power. Therefore, the proposed procedure facilitates rapid dynamic updates of sample size calculations and can be used to explore a wide range of design options or assumptions.
MeSH term(s)	Computer Simulation ; Humans ; Research Design ; Sample Size
Language	English
Publishing date	2021-09-06
Publishing country	England
Document type	Journal Article
ZDB-ID	2040523-6
ISSN	1745-6215 ; 1468-6694 ; 1468-6708
ISSN (online)	1745-6215 ; 1468-6694
ISSN	1468-6708
DOI	10.1186/s13063-021-05542-9
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Article: Sample size calculation for active-arm trial with counterfactual incidence based on recency assay.

Gao, Fei / Glidden, David V / Hughes, James P / Donnell, Deborah J

Statistical communications in infectious diseases

2021 Volume 13, Issue 1, Page(s) 20200009

Abstract: Objectives: The past decade has seen tremendous progress in the development of biomedical agents that are effective as pre-exposure prophylaxis (PrEP) for HIV prevention. To expand the choice of products and delivery methods, new medications and ... ...

Abstract	Objectives: The past decade has seen tremendous progress in the development of biomedical agents that are effective as pre-exposure prophylaxis (PrEP) for HIV prevention. To expand the choice of products and delivery methods, new medications and delivery methods are under development. Future trials of non-inferiority, given the high efficacy of ARV-based PrEP products as they become current or future standard of care, would require a large number of participants and long follow-up time that may not be feasible. This motivates the construction of a counterfactual estimate that approximates incidence for a randomized concurrent control group receiving no PrEP. Methods: We propose an approach that is to enroll a cohort of prospective PrEP users and aug-ment screening for HIV with laboratory markers of duration of HIV infection to indicate recent infections. We discuss the assumptions under which these data would yield an estimate of the counterfactual HIV incidence and develop sample size and power calculations for comparisons to incidence observed on an investigational PrEP agent. Results: We consider two hypothetical trials for men who have sex with men (MSM) and transgender women (TGW) from different regions and young women in sub-Saharan Africa. The calculated sample sizes are reasonable and yield desirable power in simulation studies. Conclusions: Future one-arm trials with counterfactual placebo incidence based on a recency assay can be conducted with reasonable total screening sample sizes and adequate power to determine treatment efficacy.
Language	English
Publishing date	2021-11-10
Publishing country	United States
Document type	Journal Article
ISSN	2194-6310
ISSN	2194-6310
DOI	10.1515/scid-2020-0009
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Bayesian validation framework for dynamic epidemic models.

Dasgupta, Sayan / Moore, Mia R / Dimitrov, Dobromir T / Hughes, James P

Epidemics

2021 Volume 37, Page(s) 100514

Abstract: Complex models of infectious diseases are used to understand the transmission dynamics of the disease, project the course of an epidemic, predict the effect of interventions and/or provide information for power calculations of community level ... ...

Abstract	Complex models of infectious diseases are used to understand the transmission dynamics of the disease, project the course of an epidemic, predict the effect of interventions and/or provide information for power calculations of community level intervention studies. However, there have been relatively few opportunities to rigorously evaluate the predictions of such models till now. Indeed, while there is a large literature on calibration (fitting model parameters) and validation (comparing model outputs to data) of complex models based on empirical data, the lack of uniformity in accepted criteria for such procedures for models of infectious diseases has led to simple procedures being prevalent for such steps. However, recently, several community level randomized trials of combination HIV intervention have been planned and/or initiated, and in each case, significant epidemic modeling efforts were conducted during trial planning which were integral to the design of these trials. The existence of these models and the (anticipated) availability of results from the related trials, provide a unique opportunity to evaluate the models and their usefulness in trial design. In this project, we outline a framework for evaluating the predictions of complex epidemiological models and describe experiments that can be used to test their predictions.
MeSH term(s)	Bayes Theorem ; Communicable Diseases/epidemiology ; Epidemics ; Humans
Language	English
Publishing date	2021-10-30
Publishing country	Netherlands
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	2467993-8
ISSN	1878-0067 ; 1755-4365
ISSN (online)	1878-0067
ISSN	1755-4365
DOI	10.1016/j.epidem.2021.100514
Database	MEDical Literature Analysis and Retrieval System OnLINE

Order via subito

Article ; Online: Diverging Neisseria gonorrhoeae Morbidity in Non-Hispanic Black and White Females: Application of Group-Based Trajectory Modeling to Trends in County-Level Morbidity 2003-2018.

Rowlinson, Emily / Hughes, James P / Stenger, Mark R / Khosropour, Christine M / Golden, Matthew R

Journal of urban health : bulletin of the New York Academy of Medicine

2022 Volume 100, Issue 1, Page(s) 215–226

Abstract: National trends in gonorrhea rates may obscure informative local variations in morbidity. We used group-based trajectory models to identify groups of counties with similar gonorrhea rate trajectories among non-Hispanic White (NHW) and non-Hispanic Black ( ...

Abstract	National trends in gonorrhea rates may obscure informative local variations in morbidity. We used group-based trajectory models to identify groups of counties with similar gonorrhea rate trajectories among non-Hispanic White (NHW) and non-Hispanic Black (NHB) females using county-level data on gonorrhea cases in US females from 2003 to 2018. We assessed models with 1-15 groups and selected final models based on fit statistics and identification of divergent trajectory groups with distinct intercepts and/or slopes. We mapped counties by assigned trajectory group and examined the association of county characteristics with group membership. We identified 7 distinct gonorrhea trajectory groups for NHW females and 9 distinct trajectory groups for NHB females. All identified groups for NHW female morbidity experienced increasing gonorrhea rates with a limited range (11.6-183.3/100,000 NHW females in 2018); trajectories of NHB female morbidity varied widely in rates (146.6-966.0/1000 NHB females in 2018) and included 3 groups of counties that experienced a net decline in gonorrhea rates. Counties with higher NHW female morbidity had lower adult sex ratios, lower health insurance coverage, and lower marital rates among NHW adults. Counties with higher NHB female morbidity were more urban, experienced higher rates of poverty, and had lower rates of marriage among NHB adults. Morbidity patterns did not always follow geographic proximity, which could be explained by variation in social determinants of health. Our results demonstrated a highly heterogenous gonorrhea epidemic among NHW and NHB US females, which should prompt further analysis into the differential drivers of gonorrhea morbidity.
MeSH term(s)	Adult ; Female ; Humans ; Gonorrhea/epidemiology ; Gonorrhea/ethnology ; Morbidity ; Neisseria gonorrhoeae ; United States/epidemiology ; White ; Black or African American
Language	English
Publishing date	2022-12-29
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	1435288-6
ISSN	1468-2869 ; 1099-3460
ISSN (online)	1468-2869
ISSN	1099-3460
DOI	10.1007/s11524-022-00702-x
Database	MEDical Literature Analysis and Retrieval System OnLINE

Full text online

Accessible to users with ZB MED library card

In stock of ZB MED Cologne/Königswinter

Ua VI Zs.28: Show issues

Location:
Je nach Verfügbarkeit (siehe Angabe bei Bestand)
bis Jg. 2021: Bestellungen von Artikeln über das Online-Bestellformular
ab Jg. 2022: Lesesaal (EG)

Order via subito

Details ▾

To top

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

Full text online

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

Full text online

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito

More links

Kategorien

In stock of ZB MED Bonn / Germany

Order via subito

Inter-library loan at ZB MED

More links

Kategorien

Order via subito

More links

Kategorien

Order via subito

Inter-library loan at ZB MED

More links

Kategorien

Order via subito

Full text online

More links

Kategorien

In stock of ZB MED Cologne/Königswinter

Order via subito