Predictors and moderators of outcomes of HIV/STD sex risk reduction interventions in substance abuse treatment programs: a pooled analysis of two randomized controlled trials

Crits‐Christoph, Paul; Gallop, Robert; Sadicario, Jaclyn S; Markell, Hannah M.; Calsyn, Donald A.; Tang, Wan; He, Hua; Tu, Xin; Woody, George

doi:10.1186/1747-597x-9-3

Cited by 12 publications

(20 citation statements)

References 46 publications

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“…15 Similar analyses have been successfully conducted in the areas of physical activity and HIV sexual risk reduction. 16–17 However, we are not aware of any previous research examining correlates of optimal outcomes for ART adherence for people with low health literacy.…”

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confidence: 99%

Optimal Treatment Adherence Counseling Outcomes for People Living with HIV and Limited Health Literacy

Pellowski

Kalichman

Grebler

2014

Behavioral Medicine

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Limited health literacy has been shown to contribute to poor health, including poor adherence to antiretroviral therapy (ART) in people living with HIV/AIDS, over and above other indicators of social disadvantage and poverty. Given the mixed results of previous interventions for people with HIV and low health literacy, investigating possible targets for improved adherence is warranted. The present study aims to identify the correlates of optimal and suboptimal outcomes among participants of a recent skills-based medication adherence intervention (Kalichman et al., 2013). Participants included in this secondary analysis were 188 men and women living with HIV who had low health literacy as determined by scoring ≤90% on a test of health literacy and had complete viral load data for baseline and follow-up. Participants completed physical, psychosocial and literacy measures using computerized interviews. Adherence was assessed by unannounced pill count and follow-up viral loads were assessed by blood draw. Results showed that higher levels of health literacy and lower levels of alcohol use were the strongest predictors of achieving HIV viral load optimal outcomes. The interplay between lower health literacy and alcohol use on adherence should be the focus of future research.

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confidence: 99%

Optimal Treatment Adherence Counseling Outcomes for People Living with HIV and Limited Health Literacy

Pellowski

Kalichman

Grebler

2014

Behavioral Medicine

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“…Shown in the lower panel of Table II under 'Main' model is the same information as in the upper panel, except under missing data, plus variable selection results ('Missing data model') for the missing data model in (21). As in the complete data case, the approach worked well in the presence of missing data.…”

Section: Shown In the Upper Panel Ofmentioning

confidence: 96%

“…The intervention integrates a component to provide skill training programs such as role plays to reduce sexual risk behaviors. Because the intervention is very detailed and personal, separate trials with identical study designs were conducted for men and women . Our analysis is based on the pooled sample from both studies.…”

Section: Applicationmentioning

confidence: 99%

“…Some of these methods have recently found their applications in ZIP [17][18][19]. However, the ZIP yields biased estimates when the count response is overdispersed [20,21]; even ZINB yields biased estimates when overdispersion does not follow the NB [22]. Tang et al recently proposed a distribution-free (semi-parametric) approach to address the limitations of ZIP and ZINB [22].…”

Section: Introductionmentioning

confidence: 99%

“…Some of these methods have recently found their applications in ZIP . However, the ZIP yields biased estimates when the count response is overdispersed ; even ZINB yields biased estimates when overdispersion does not follow the NB .…”

Section: Introductionmentioning

confidence: 99%

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Variable selection for distribution‐free models for longitudinal zero‐inflated count responses

Chen

Tang

et al. 2016

Statistics in Medicine

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Zero-inflated count outcomes arise quite often in research and practice. Parametric models such as the zero-inflated Poisson and zero-inflated negative binomial are widely used to model such responses. Like most parametric models, they are quite sensitive to departures from assumed distributions. Recently, new approaches have been proposed to provide distribution-free, or semi-parametric, alternatives. These methods extend the generalized estimating equations to provide robust inference for population mixtures defined by zero-inflated count outcomes. In this paper, we propose methods to extend smoothly clipped absolute deviation (SCAD)-based variable selection methods to these new models. Variable selection has been gaining popularity in modern clinical research studies, as determining differential treatment effects of interventions for different subgroups has become the norm, rather the exception, in the era of patent-centered outcome research. Such moderation analysis in general creates many explanatory variables in regression analysis, and the advantages of SCAD-based methods over their traditional counterparts render them a great choice for addressing this important and timely issues in clinical research. We illustrate the proposed approach with both simulated and real study data. Copyright © 2016 John Wiley & Sons, Ltd.

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On performance of parametric and distribution‐free models for zero‐inflated and over‐dispersed count responses

Tang

Chen

et al. 2015

Statistics in Medicine

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Summary Zero-inflated Poisson (ZIP) and negative binomial (ZINB) models are widely used to model zero-inflated count responses. These models extend the Poisson and Negative Binomial (NB) to address excessive zeros in the count response. By adding a degenerate distribution centered at 0 and interpreting it as describing a non-risk group in the population, the ZIP (ZINB) models a two-component population mixture. As in applications of Poisson and NB, the key difference between ZIP and ZINB is the allowance for overdispersion by the ZINB in its NB component in modeling the count response for the at-risk group. Overdispersion arising in practice too often does not follow the NB and applications of ZINB to such data yields invalid inference. If sources of overdispersion are known, other parametric models may be used to directly model the overdispersion. Such models too are subject to assumed distributions. Further, this approach may not be applicable if information about the sources of overdispersion is unavailable. In this paper, we propose a distribution-free alternative and compare its performance with these popular parametric models as well as a moment-based approach proposed by Yu et al. [Statistics in Medicine 2013; 32: 2390-2405]. Like the generalized estimating equations (GEE), the proposed approach requires no elaborate distribution assumptions. Compared with the approach of Yu et al., it is more robust to overdispersed zero-inflated responses. We illustrate our approach with both simulated and real study data.

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Predictors and moderators of outcomes of HIV/STD sex risk reduction interventions in substance abuse treatment programs: a pooled analysis of two randomized controlled trials

Cited by 12 publications

References 46 publications

Optimal Treatment Adherence Counseling Outcomes for People Living with HIV and Limited Health Literacy

Optimal Treatment Adherence Counseling Outcomes for People Living with HIV and Limited Health Literacy

Variable selection for distribution‐free models for longitudinal zero‐inflated count responses

On performance of parametric and distribution‐free models for zero‐inflated and over‐dispersed count responses

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