Human immunodeficiency virus type 1 antibody status and changes in risk behavior among drug users

Sexual behaviors among methadone maintenance patients in a mountainous area in northern Vietnam

Background

Methadone maintenance treatment (MMT) improves patients’ ability to access HIV-related services and reduces needle sharing and other risky HIV-related behaviors. However, patients may continue to engage in risky sexual practices. In this study, we evaluate sexual behaviors of MMT patients in a mountainous province in Northern Vietnam.

Methods

We explored the health status, MMT and substance use history, and sexual practices of 241 male MMT patients in Tuyen Quang province. Health status was investigated using the EuroQOL-5 Dimensions-5 Levels (EQ-5D-5 L). Multivariate logistic regression was employed to assess associated factors.

Results

Most patients (66.4%) reported having at least one sexual partner within the previous twelve months. Most of these partners were spouses or primary partners (72.6%). About 8.3% of patients had casual partners, and 5.8% had visited sex workers; of those who engaged in casual sexual relationships, 90.9% reported using condoms. Current drug use and living in a remote area were associated with an increased odd of having two or more sexual partners, while anxiety or depression was associated with lower odds.

Conclusion

This study highlights a low proportion of having sexual risk behaviors among MMT patients in Vietnamese mountainous settings. Integrating education about safe sexual practices into MMT services, along with providing medical care and ensuring methadone treatment adherence, is an important component in HIV risk reduction for these patients who were at risk of unsafe sexual practices.

The Impact of Ignoring Population Heterogeneity when Markov Models are Used in Cost-Effectiveness Analysis

Many factors related to the spread and progression of diseases vary throughout a population. This heterogeneity is frequently ignored in cost-effectiveness analyses by using aver-age or representative values or by considering multiple risk groups. The author explores the impact that such simplifying assumptions may have on the results and interpretation of cost-effectiveness analyses when Markov models are used to calculate the costs and health impact of interventions. A discrete-time Markov model for a disease is defined, and 5 potential interventions are considered. Health benefits, costs, and incremental cost-effectiveness ratios are calculated for each intervention. It is assumed that the population is heterogeneous with respect to the probability of becoming sick. Ignoring this heterogeneity may lead to optimistic or pessimistic estimates of cost-effectiveness ratios, depending on the intervention and, in some cases, the parameter values. Implications are discussed of this finding on the use of league tables and on comparisons of cost-effectiveness ratios versus commonly accepted threshold values.

Semiparametric methods in the proportional odds model for ordinal response data with missing covariates

We consider the estimation problem of a proportional odds model with missing covariates. Based on the validation and nonvalidation data sets, we propose a joint conditional method that is an extension of Wang et al. (2002, Statistica Sinica 12, 555-574). The proposed method is semiparametric since it requires neither an additional model for the missingness mechanism, nor the specification of the conditional distribution of missing covariates given observed variables. Under the assumption that the observed covariates and the surrogate variable are categorical, we derived the large sample property. The simulation studies show that in various situations, the joint conditional method is more efficient than the conditional estimation method and weighted method. We also use a real data set that came from a survey of cable TV satisfaction to illustrate the approaches.

Drug use patterns over time among HIV-seropositive and HIV-seronegative women: the HER study experience

BACKGROUND

Drug use, particularly among women, is a public health issue given its health effects and its impact on HIV transmission. Becoming HIV seropositive could lead to differing patterns of drug use over time. HIV infection may decrease drug use due to an increased access to health services. Alternatively, increased drug use may occur due to depression associated with being HIV infected, leading to despair, hopelessness, and a lack of motivation to become drug free.

METHODS

We evaluated the potential association between HIV serostatus and drug use among a cohort of 1310 women who were part of a multicenter collaborative study on the natural history of HIV infection. Eight hundred seventy-one HIV-seropositive women and 439 HIV-seronegative women were enrolled at four sites (New York, Providence, Baltimore, and Detroit). We defined drug use as any heroin or cocaine use reported at the baseline visit (enrollment).

RESULTS

Drug use was found to decrease during earlier visits (months 1-24) and remained stable at 20% thereafter (months 30-84). No significant differences in change of drug use were noted by HIV serostatus, using generalized estimating equation-based logistic regression analyses.

CONCLUSIONS

HIV-seropositive status did not affect drug use patterns over time within our population of high-risk women.

HIV-positive notification and behavior changes in Montreal injection drug users

This study examined the effect of an HIV-positive notification on the sexual and injection behaviors, living conditions, and medical demands of injection drug users (IDUs) in Montreal. The behavior changes of 73 IDUs who received an HIV-positive test result, and 219 IDUs who tested negative were compared, and the net difference (ND) in the proportion of IDUs adopting the particular change was determined. No significant changes were found in drug use or needle sharing practices. A higher proportion of IDUs who received an HIV-positive notification acquired unstable living conditions, ND = 20.7% (95% CI = 3.3, 38.1), began medical follow up, ND = 34.4% (95% CI = 20.8, 48.7), and increased needle exchange program (NEP) utilization, ND = 20.5% (95% CI = 8.3, 32.8). Compared with HIV-negative males, more HIV-positive male IDUs stopped sexual relations, ND = 24.6% (95% CI = 0.4, 48.9), and sex work, ND = 31.8% (95% CI = 12.4, 51.3), and fewer began new relations, ND = -38.2% (95% CI = -52.6, -23.9). The medical community and NEPs have an important role in providing support for newly diagnosed IDUs.

Optimal investment in a portfolio of HIV prevention programs

OBJECTIVES

In this article, the authors determine the optimal allocation of HIV prevention funds and investigate the impact of different allocation methods on health outcomes.

METHODS

The authors present a resource allocation model that can be used to determine the allocation of HIV prevention funds that maximizes quality-adjusted life years (or life years) gained or HIV infections averted in a population over a specified time horizon. They apply the model to determine the allocation of a limited budget among 3 types of HIV prevention programs in a population of injection drug users and nonusers: needle exchange programs, methadone maintenance treatment, and condom availability programs. For each prevention program, the authors estimate a production function that relates the amount invested to the associated change in risky behavior.

RESULTS

The authors determine the optimal allocation of funds for both objective functions for a high-prevalence population and a low-prevalence population. They also consider the allocation of funds under several common rules of thumb that are used to allocate HIV prevention resources. It is shown that simpler allocation methods (e.g., allocation based on HIV incidence or notions of equity among population groups) may lead to alloctions that do not yield the maximum health benefit.

CONCLUSIONS

The optimal allocation of HIV prevention funds in a population depends on HIV prevalence and incidence, the objective function, the production functions for the prevention programs, and other factors. Consideration of cost, equity, and social and political norms may be important when allocating HIV prevention funds. The model presented in this article can help decision makers determine the health consequences of different allocations of funds.

HIV transmission and the cost-effectiveness of methadone maintenance

OBJECTIVES

This study determined the cost-effectiveness of expanding methadone maintenance treatment for heroin addiction, particularly its effect on the HIV epidemic.

METHODS

We developed a dynamic epidemic model to study the effects of increased methadone maintenance capacity on health care costs and survival, measured as quality-adjusted life-years (QALYs). We considered communities with HIV prevalence among injection drug users of 5% and 40%.

RESULTS

Additional methadone maintenance capacity costs $8200 per QALY gained in the high-prevalence community and $10,900 per QALY gained in the low-prevalence community. More than half of the benefits are gained by individuals who do not inject drugs. Even if the benefits realized by treated and untreated injection drug users are ignored, methadone maintenance expansion costs between $14,100 and $15,200 per QALY gained. Additional capacity remains cost-effective even if it is twice as expensive and half as effective as current methadone maintenance slots.

CONCLUSIONS

Expansion of methadone maintenance is cost-effective on the basis of commonly accepted criteria for medical interventions. Barriers to methadone maintenance deny injection drug users access to a cost-effective intervention that generates significant health benefits for the general population.

Drug abuse treatment as an HIV prevention strategy: a review

We review drug abuse treatment as a means of preventing infection with HIV. Thirty-three studies, with an aggregate of over seventeen thousand subjects, were published in peer-reviewed journals from 1988-1998. Research on the utility of drug abuse treatment as an HIV prevention strategy has focused primarily on methadone maintenance treatment (MMT) rather than other modalities such as residential or outpatient drug-free treatment. Recent research provides clear evidence that MMT reduces HIV risk behaviors, particularly needle-use, and strong evidence that MMT prevents HIV infection. There is less definitive evidence that MMT reduces needle-sharing and unsafe sexual behavior, or that other treatment modalities prevent HIV infection. Future research should take into account patient self-selection processes and investigate other treatment modalities for heroin and stimulant abuse to determine their effects on HIV risk behaviors and HIV infection.

Predictors and risk-taking consequences of drug use among HIV-infected women

OBJECTIVE

To determine rates of drug use among women with HIV, and to examine associations between drug use, health, risk behavior, and sexually transmitted diseases (STD).

DESIGN

A longitudinal cohort study of 260 women with confirmed HIV-positive serostatus.

METHODS

Each participant contributed a self-report interview, a clinical examination, laboratory testing of cultures for Trichomonas vaginalis, Chlamydia trachomatis, Neisseria gonorrhoeae, and urinalysis for the presence of metabolites of cocaine and opiates. Data were examined on 140 women at 1-year follow-up. Women were defined as drug users if they reported crack, cocaine, or heroin use in the 6 months before the interview or if they had a positive toxicologic test result for cocaine or opiates.

RESULTS

34% of those in the sample were classified as positive for drug use. Drug use was associated with the number of sexual partners, age at first intercourse, prevalence of STDs, and lower quality of life. STDs were present at baseline in 33.7% and 15.5% of drug users and nonusers, respectively. Drug use among this population was also associated at both baseline and follow-up with the likelihood of having a Karnofsky score below 80, and with overall perceived general health.

CONCLUSIONS

Drug users in this cohort were more likely to engage in behaviors that place them at risk for STDs, to have elevated STD prevalence, and to have lower perceived health across several indices. Identification of drug use and treatment for it need to be a central component of HIV care for women.

Sexual, contraceptive, and drug use behaviors of women with HIV and those at high risk for infection: results from the Women's Interagency HIV Study

OBJECTIVE

To document the sexual and contraceptive practices of women with HIV infection or who are at risk for infection.

DESIGN

Data on the baseline behaviors of 561 HIV-negative and 2040 HIV-positive women were collected as part of the Women's Interagency HIV Study (WIHS). WIHS is a multisite, longitudinal study following the natural history of HIV infection among women in the United States.

METHODS

Each participant contributed an interviewer administered, self-report interview including questions on sexual and contraceptive behavior.

RESULTS

Women with HIV were less likely to report heterosexual activity in the previous 6 months (65% HIV-positive, 76% HIV-negative). Among sexually active women, there were no differences in the proportion of those reporting vaginal (97% HIV-positive, 98% HIV-negative) or anal sex (12% HIV-positive, 10% HIV-negative), although women with HIV were less likely to report cunnilingus (41% HIV-positive, 70% HIV-negative) and fellatio (48% HIV-positive, 57% HIV-negative). Of women with HIV, 63% always used condoms during vaginal sex (versus 28% HIV-negative), with lower rates reported during other sexual activities. Crack, cocaine, or injecting drug use, reported by 27% of HIV-positive and 35% of HIV-negative women, was associated with inconsistent condom use, independent of serostatus. HIV-positive women who reported using condoms and another contraception method were less consistent condom users (57% consistent versus 67%).

CONCLUSIONS

The prevalence of sexual risk behavior in this sample suggests that, although women with HIV exhibit lower levels of sexual risk behavior than uninfected women, many have not been successfully reached with regard to implementing safer behaviors. These findings have implications for more widespread and effective behavioral intervention efforts.

Readmissions to drug abuse treatment and HIV risk behavior

The objectives of the study were (a) to investigate the characteristics of drug abuse treatment clients who return to treatment and (b) among those with readmissions, to describe changes over time in risk behavior for human immunodeficiency virus (HIV) infection and to identify factors associated with behavior change. Data were derived from a multisite HIV surveillance program in a single community; the program used a unique identifier to link HIV test results and behavioral information from multiple contacts. During a 30-month period, 1994 clients were admitted to three satellite facilities of a single treatment agency: detoxification, long-term residential, and outpatient. Of these clients, 574 (29%) had one or more readmissions to the same or a different facility during the 24 months following the index admission. Drug injectors, those tested for HIV, and those living in the community were more likely to be readmitted to treatment. There was little overall change in HIV risk behavior between the index admission and the readmission furthest in time from the index admission. Clients whose index visit was at the residential facility were more likely to reduce their injection risk behavior than those admitted to the other facilities. Clients readmitted to either the residential or the outpatient facility were more likely to have reduced their injection risk behavior than those readmitted to detoxification. Treatment facility was not associated with sexual risk behavior change. Men were more likely than women to reduce their high-risk sexual behaviors. The results underscore the need for treatment programs to make HIV testing readily available to their clients and to make special efforts to assist female clients to reduce their HIV risk.

Methadone maintenance and other factors associated with intraindividual temporal trends in injection-drug use

The objective of this study was to determine what sociodemographic, lifestyle, or drug-related characteristics predict temporal changes in self reported drug injection frequencies among HIV-seronegative injection-drug users (IDUs) who were being given HIV testing and risk reduction counseling. The 277 subjects were given 4-11 quarterly interviews including detailed history of drug use and other HIV risk factors, HIV risk reduction counseling, and venipuncture for HIV antibody testing. A regression slope of change over time in drug injection frequency was calculated for each subject, and categories were created of decreasing temporal slope, increasing slope, relapse (decrease initially, then increase), or no substantial change. Only 44% of subjects decreased their drug injection frequencies despite repetitive HIV testing and counseling. In multivariate logistic analyses, decreasing temporal trends were associated with consistent enrollment in methadone maintenance (p < .1), whereas increasing trends conversely were associated with inconsistent enrollment (p < .01) and also with an absence of crack use (p < .01). Relapses were significantly associated with needle sharing with multiple partners and a low frequency of smoking. The data suggest that methadone maintenance facilitates a positive response to HIV risk reduction counseling. However, the fact that only a minority of subjects displayed a decreasing temporal trend in drug injection frequencies emphasizes the need for improved therapeutic and counseling techniques.