Hepatitis: Pals SL

Pals SL, Murray DM, Alfano CM, Shadish WR, Hannan PJ, Baker WL. · Division of HIV/AIDS Prevention, National Center for HIV, Viral Hepatitis, STD and TB Prevention, MS E-45, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA 30333, USA. · Am J Public Health. · Pubmed #18556603 No free full text.

Abstract: OBJECTIVES: We reviewed published individually randomized group treatment (IRGT) trials to assess researchers' awareness of within-group correlation and determine whether appropriate design and analytic methods were used to test for treatment effectiveness. METHODS: We assessed sample size and analytic methods in IRGT trials published in 6 public health and behavioral health journals between 2002 and 2006. RESULTS: Our review included 34 articles; in 32 (94.1%) of these articles, inappropriate analytic methods were used. In only 1 article did the researchers claim that expected intraclass correlations (ICCs) were taken into account in sample size estimation; in most articles, sample size was not mentioned or ICCs were ignored in the reported calculations. CONCLUSIONS: Trials in which individuals are randomly assigned to study conditions and treatments administered in groups may induce within-group correlation, violating the assumption of independence underlying commonly used statistical methods. Methods that take expected ICCs into account should be used in reexamining past studies and planning future studies to ensure that interventions are not judged effective solely on the basis of statistical artifacts. We strongly encourage investigators to report ICCs from IRGT trials and describe study characteristics clearly to aid these efforts.

Hardnett FP, Pals SL, Borkowf CB, Parsons J, Gomez C, O'Leary A. · Centers for Disease Control and Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Division of HIV/AIDS Prevention, Quantitative Sciences and Data Management Branch, Atlanta, USA. · Public Health Rep. · Pubmed #19320371 No free full text.

Abstract: OBJECTIVES: A mediator is a psychosocial construct that is targeted by an intervention to bring about behavior change. Recent literature suggests that a widely used approach for assessing mediation, namely the causal steps method, can be severely statistically underpowered. This article describes three standard methods for assessing mediation: causal steps, difference in coefficients, and product of coefficients. We also demonstrate the use of asymmetric confidence limits (ACLs) in testing mediation. METHODS: We compared the results obtained by ACL construction with results obtained based on the causal steps and product of coefficients approaches to analyze data from the Seropositive Urban Men's Intervention Trial. RESULTS: ACL construction uncovered previously unidentified mediating factors. We also identified a marginally significant suppressor, which means that, with regard to this factor, the intervention had effects that were opposite from the desired direction. CONCLUSIONS: ACLs are preferred for this type of analysis because of their statistical power and because they are informative regardless of whether the intervention has a significant effect on the outcome. Furthermore, ACLs present the size of the mediating effect rather than just a binary decision regarding significance.

Pals SL, Beaty BL, Posner SF, Bull SS. · Division of HIV/AIDS Prevention, National Center for HIV, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. · Health Educ Behav. · Pubmed #19188372 No free full text.

Abstract: Studies designed to evaluate HIV and STD prevention interventions often involve random assignment of groups such as neighborhoods or communities to study conditions (e.g., to intervention or control). Investigators who design group-randomized trials (GRTs) must take the expected intraclass correlation coefficient (ICC) into account in sample size estimation to have adequate power; however, few published ICC estimates exist for outcome variables related to HIV and STD prevention. The Prevention Options for Women Equal Rights (POWER) study was a GRT designed to evaluate a campaign to increase awareness and use of condoms among young African American and Hispanic women. The authors used precampaign and postcampaign data from the POWER study to estimate ICCs (unadjusted and adjusted for covariates) for a variety of sexual behavior and other variables. To illustrate the impact of ICCs on power, the authors present sample-size calculations and demonstrate how ICCs of differing magnitude will affect estimates of required sample size.

Kidder DP, Wolitski RJ, Pals SL, Campsmith ML. · Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, 1600 Clifton Road, Mailstop E-04, Atlanta, GA 30333, USA. · J Acquir Immune Defic Syndr. · Pubmed #19186357 No free full text.

Abstract: OBJECTIVES: To compare drug, alcohol, and sexual HIV transmission risk behaviors of homeless and housed people living with HIV/AIDS. METHODS: Data were from 8075 respondents in a cross-sectional, multisite behavioral survey of adults recently reported to have HIV infection. RESULTS: At interview, 310 respondents (4%) were homeless. Compared with homeless respondents, housed respondents were more likely to be sexually active (past 12 months). However, sexually active homeless respondents had more sex partners (lifetime and past 12 months), greater sex exchange for money or drugs (lifetime and past 12 months), and greater unprotected vaginal or anal sex with an unknown serostatus partner. Homeless respondents were more likely to have possible alcohol abuse (lifetime), used drugs (last 12 months), and injected drugs (lifetime and past 12 months). After controlling for potential confounding variables, housing status remained a significant predictor of number of sex partners (past 12 months), sex exchange (lifetime and past 12 months), unprotected sex with unknown status partner, and all drug and alcohol use variables. CONCLUSIONS: Homeless people living with HIV/AIDS are more likely to have ever or recently engaged in substance use and HIV transmission risk behaviors. Findings underscore the need to provide HIV prevention services to homeless persons and address their housing needs.

Courtenay-Quirk C, Pals SL, Colfax G, McKirnan D, Gooden L, Eroğlu D. · Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, 1600 Clifton Road, NE, Mailstop E-45, Atlanta, GA 30333, USA. · AIDS Behav. · Pubmed #17592764 No free full text.

Abstract: Factors associated with HIV transmission risk may differ between subgroups of persons living with HIV/AIDS (PLWHA). This study examined such factors in a sample of PLWHA recruited in 3 US metropolitan areas. Sexually active participants were categorized as gay or bisexual men (GBM) (n = 545), heterosexual men (HSM, n = 223), or women (n = 214). Of 982 participants, 27.1% reported serodiscordant unprotected anal or vaginal sex (SDUAV). SDUAV was associated with multiple (2 or more) partners, using poppers, and lower safer sex self-efficacy among GBM. SDUAV was associated with multiple partners among HSM. Among women, factors examined were not associated with SDUAV. These findings are consistent with prior research and facilitate our ability to target those who may be most at risk for transmitting HIV among HIV-positive GBM. More research must be conducted to identify factors associated with risk behavior among HSM and women.