The ability to measure centrality in social networks has been a particularly useful development in social network analysis. For researchers trying to decide which centrality measure is most meaningful and valid for their research purposes, various papers have explored the conceptual foundations of centrality measures. Less well documented is the empirical performance of centrality measures under different research scenarios or constraints. This study uses bootstrap sampling procedures to determine how sampling affects the stability of 11 different network centrality measures. Results indicate that some measures are more stable than others, and that stability is also a function of network and study properties.

Supplementary data are available at Bioinformatics online.

Many Demographic and Health Surveys (DHS) in the past decade have queried husbands and wives about their current contraceptive use. In this study, couples' concurrence on use and method used is compared by means of data from 23 countries, mostly in sub-Saharan Africa. Husbands report higher levels of use than do their wives in every country studied, with ranges from 2 percent higher (Brazil) to 150 percent higher (Mali). Many of the discrepancies are the result of husbands' sole reports of periodic abstinence and condom use. Couples with polygynous husbands show less concurrence than do monogamous couples, although the majority of these differences could result from a data-collection problem. Monogamous couples in which one or both spouses reported having extramarital sex partners show less concurrence than do monogamous couples reporting no other partners. Problems of validity of both husbands' and wives' reports are discerned, and in the few instances where a direct comparison is possible, wives' reports are shown to have greater validity. Logistic regression results show that spousal discussion about family planning and greater female education are consistent predictors of concurrence.

The findings from this study show that, over and above IDUs' baseline characteristics, changes in their personal networks are associated with changes in individuals' risky injection behaviors. They also suggest that interventions aimed at reducing HIV risk among IDUs might benefit from increasing IDUs' social contacts with individuals who are not drug users.

No abstract

Gay and bisexual men are often treated as a homogenous group; however, there may be important differences between them. In addition, behaviorally bisexual men are a potential source of HIV infection for heterosexual women. In this study, we compared 97 men who have sex with men only (MSM) to 175 men who have sex with men and women (MSMW). We also compared the 175 MSMW to 772 men who have sex with women only (MSW). Bivariate and multiple logistic regression analyses were performed to assess correlates of MSMW risk behaviors with men and with women as well as whether MSMW, compared with MSW, engaged in more risky behaviors with women. Compared with MSM, MSMW were less likely to be HIV-positive or to engage in unprotected receptive anal intercourse. In contrast, MSMW were more likely than MSW to be HIV-positive and to engage in anal intercourse with their female partners; however, rates of unprotected anal intercourse were similar. The study findings suggest that there may be important differences in HIV risk behaviors and HIV prevalence between MSM and MSMW as well as between MSMW and MSW.

Methamphetamine use during heterosexual encounters appears to increase sexual risk-taking, especially when both partners are using it.

Background-Heavy alcohol use, hepatitis C and illicit drug use each have been shown to have negative impacts on health-related quality of life (HRQL). To date, considerations of HRQL have not played a prominent role in the design and measurement of intervention strategies for out-oftreatment at-risk populations.Methods-Data were collected from out-of-treatment IDUs recruited through street outreach in North Carolina. Multiple linear regression analyses were used to examine the independent effects of HCV status, harmful drinking (AUDIT), and illicit drug use on HRQL (SF-36).Results-Fifty-one percent of 619 study participants tested HCV-positive; 57% met criteria for harmful or hazardous drinking and 63% reported daily use of hard drugs. HRQL scores for this population were significantly lower than those of the general population. Multiple linear regression analyses demonstrated that harmful levels of alcohol consumption and use of methamphetamine in the past month had the strongest associations with reduced HRQL.Conclusions-Given the high rates of HCV in most IDU communities, new harm reduction approaches are needed for these populations which focus beyond prevention to the functioning and well-being of those already infected. In particular, reducing heavy alcohol use in addition to slowing HCV progression shows promise for improving HRQL.