National Institute on Drug Abuse
Director's Report to the National Advisory Council on Drug Abuse
September, 1999
Research Findings
AIDS Research
Micronutrients and Survival among HIV-Infected Children
New insights on the role of nutrition in improving survival among individuals with HIV have been gained from studies on micronutrient deficiencies among drug abusers with HIV infection. Baum and her colleagues at the University of Miami School of Medicine have found that low levels of selenium may be related to decreased survival of HIV-infected children. The study population consisted of 24 children who were exposed perinatally to HIV and who were symptomatic. They were recruited between October and December 1990 from the Jackson Memorial Pediatric Immunology Clinic, Miami, and were observed for 5 years. The children were assessed for their immune status by their CD4 cell count; and nutritional status by serum albumin level and plasma levels of trace elements (iron, zinc, selenium). Twelve children died of HIV-related causes. Cox multivariate analyses showed that only CD4 cell count below 200 (RR=7.05, CI=1.87-26.5, p<0.004), and low levels of selenium (RR=5.96, CI=1.32-26.8, p<0.02) were significantly and independently related to mortality. Among the children who died, those with low selenium levels (<85 ug/l) died at a younger age, suggesting more rapid disease progression. These data in children concur with the Baum's earlier findings of increased mortality with low levels of selenium in HIV infected adults. Campa, A., Shor-Posner, G., Indacochea, F., Zhang, G., Lai, H., Asthana, D., Scott, G., and Baum, M. Mortality Risk in Selenium-Deficient HIV-Positive Children. Journal of Acquired Immune Deficiency and Human Retrovirology, 20, pp. 508-513, 1999.
Highly Active Antiretroviral Therapy in a Large Urban Clinic: Risk Factors for Virologic Failure and Adverse Drug Reactions
In a retrospective cohort study, Lucas and his colleagues from Johns Hopkins University School of Medicine identified demographic, behavioral, and clinical features that correlated with failure to suppress viral load outside of the clinical trial setting. In clinical trials, highly active antiretroviral therapy (HAART) reduces HIV-1 viral load to undetectable levels (500 copies/ml or less) in 60% to 90% of patients. The researchers' hypothesis was that the virologic response to HAART would be less efficient among unselected patients in an inner-city clinic than among patients enrolled in clinical trials. The study population was composed of 273 protease inhibitor-na•ve patients who began taking a protease inhibitor regimen containing at least one other antiretroviral drug to which the patient had not previously been exposed. Levels of HIV-1 RNA were undetectable in 42% of the cohort at 1 to 90 days, 44% at 3 to 7 months, and 37% at 7 to 14 months. Missed clinic visits was the most important factor associated with failure to suppress the HIV-1 viral load. Other factors associated with failure to suppress viral load were nonwhite ethnicity, age 40 years or younger, injection drug use, lower baseline CD4 lymphocyte count, and higher baseline viral load. Lucas, G.M., Chaisson, R.E., Moore, R.D. Ann Int Med, 131, pp. 222-229, 1999.
Comparison of Clinical Manifestations of HIV Infections Among Women by Risk Group, CD4 Cell Count, and HIV-1 Plasma Viral Load
This cross-sectional analysis was conducted on data available for 724 HIV infected women. The women were participants of the HIV Epidemiology Research Study (HERS), a multi-center prospective study of HIV infection in women. In this study the authors compared the prevalence of HIV-related symptoms, physical examination findings and hematologic variables among women whose risk for HIV was injection drug use (n=387) since 1985 as opposed to sexual contact (n=337). The researchers also evaluated the influence of HIV plasma viral load and CD4 cell count on clinical manifestations according to risk. In analyses adjusting for CD4 cell level alone and for plasma viral load combined with CD4 cell level, injection drug users (IDUs) were more likely to report: recent memory loss and weight loss, but not recent episodes of genital herpes. IDUs were also more likely to have enlarged livers, a body mass index (BMI) less than 24, and low hematocrit (<34%) and platelet count (<150,000/ml). After adjusting for CD4 cell count and risk group, high and medium HIV-1 plasma viral load levels were associated with the presence of oral leukoplakia on examination, and only the highest level of plasma viral load was associated with recent histories of fever and thrush, oral hairy leukoplakia, pseudomembranous candidiasis, and BMI less than 24 on examination, and low hematocrit. This study demonstrated some differences in frequency of signs, symptoms and laboratory values between risk groups, but this may be due to effects of injections drug use rather than HIV infection. The fact that the difference in signs and symptoms found associated with increasing levels of viral load was not different across risk groups indicates a more direct association of these findings with HIV infection. Rompalo, A.M., Astemborski, J., Schoenbaum, E., Schuman, P., Carpenter, C. Holmberg, S.D., Warren, D.L., Farzadegan, H., Vlahov, D., Smith, D.K. JAIDS & HR 20(5), pp. 448-454, 1999.
Gender Differences at Admission and Follow-Up in a Sample of Methadone Maintenance Clients
Although one-third of clients enrolled in methadone treatment (MMT) in the United States are female, few studies have looked at gender differences at admission and follow-up. An understanding of these differences can lead to improved treatment strategies. The investigation reported is based on data collected as part of the Drug Abuse Treatment and AIDS-Risk Reduction (DATAR) project. Using interview data from 435 opioid dependent clients (31% female) collected at admission and approximately one year after discharge, females were found to have more dysfunctional families of origin and greater prior and current psychological and medical problems. Both genders showed significant improvement from admission to follow-up in terms of reduced drug use, criminal activity and HIV/AIDS-risky behaviors. In some areas such as improved family relationships and improved psychosocial status, females seemed to benefit more from treatment than did the males. In addition, females were more likely to seek further help for both drug misuse and psychological problems subsequent to discharge. Chatham, L.R., Hiller, M.L., Rowan-Sal, G.A., Joe, G.W., and Simpson D.D. Substance Use & Misuse, June 1999, 34(8), pp. 1137-1165, 1999.
Cocaine Use and High Risk Sexual Behavior Among STD Clinic Patients
This study examined the effect of cocaine use and other correlates on participation in high-risk sexual behavior among STD clinic patients. This was a cross-sectional study of 1,490 consecutive patients attending three Los Angeles County STD clinics between 1992 and 1994. Male patients number 892 and females, 598. Analyses found high-risk sexual activity was associated with being male and being of younger age. Among women, high-risk sexual behavior was associated with crack cocaine use and a perceived need for help. Among the men in the study, ethnicity (being black) and having an arrest history were associated with high-risk behavior. The present study confirmed findings from other studies that showed an association between cocaine use and high-risk sexual practices among STD clinic patients and identified several important gender differences that may be considered in planning AIDS and drug prevention programs. These gender differences also suggest that programs might employ different outreach and intervention strategies for women and men. Hser, Y., Chou, C., Hoffman, V., and Anglin, M.D. Sexually Transmitted Diseases, 26(2), February 1999.
An Institutional Analysis of HIV Prevention Efforts by the Nation's Outpatient Drug Abuse Treatment Units
This paper examines the use of human immunodeficiency virus (HIV) prevention practices by the nation's outpatient substance abuse treatment units during the period 1988 to 1995. Using an institutional perspective that argues that organizations adopt new practices not only for technical reasons, but also because external factors actively promote or model the use of particular practices, the researchers examine the extent to which treatment units use several practices to prevent HIV infection among their clients and among drug-users not in treatment. Results from random-effects regression analyses of national survey data show that treatment units significantly increased their use of HIV prevention practices during the study period. Both the number of units engaged in the prevention efforts and the intensity of their efforts increased. Those efforts included HIV testing and counseling with clients and outreach to intravenous drug users not in treatment. Further, the results show that treatment units' use of prevention practices was related to clients' risks for HIV infection, unit resources available to support these practices, and organizational support for the practices. D'Aunno, T., Vaughn, T., and McElroy, P. Journal of Health and Social Behavior, Vol. 40, pp. 175-192, 1999.
Relationship Between Substance Use During Adolescence and HIV Risk Behavior Among Young Adults
Young men (N=400) and women (N= 552) 19-21 years of age, some with, some without college experience represented a targeted sample of 2,071 who completed a questionnaire while in the sixth grade in 1987-88. Questionnaires to assess current substance use and sex behavior were mailed to the study participants. Early substance use (as reported in the 1987-88 questionnaire) placed study participants in one of three categories: Frequent users (n=148), experimental users (n=603), or abstainers (n=200). ANOVA with post hoc analyses was used. Results indicate that frequent users of both genders were younger than experimenters and female experimenters were younger than female abstainers at first intercourse. There was a significant interaction between gender and educational level and a significant main effect for number of sexual partners with college experience serving as a protective factor. Overall, the results of the study support the hypothesis that substance use at an early age is related to earlier initiation of sexual activity. Staton, M., Leukefeld, C., et al. Risky Sex Behavior and Substance Use Among Young Adults. Health & Social Work, 24 (2), 1999.
HIV Risk is Higher for Puerto Rican Drug Users Compared to Other Hispanic Subgroups
Researchers estimated and compared the HIV risks among three Hispanic subpopulations (N= 3,660) chronic drug users who participated in NIDA's Cooperative Agreement intervention study on drug use. Interview data were collected regarding drug use and sexual behavior. HIV risk was estimated using information about individuals' HIV-relevant behaviors, the social context (i.e., city) in which such behaviors occur, and published estimates of HIV transmission for various risk behaviors. Multiple linear regression analysis was used to investigate differences in estimated HIV risk between Puerto Rican, Mexican-American, and Mexican drug users, accounting for sociodemographic factors, sexual preference, and geographic region. Puerto Ricans were found to have significantly greater estimated overall HIV risk, estimated injection risk, and in general, significantly greater estimated sexual risk than Mexican Americans and Mexicans. No significant differences were found among any of the subgroups for estimated risk from having unprotected high-risk sex. These findings suggest that Puerto Ricans who use drugs experience a higher risk of HIV infection than other Hispanic drug users.
Research is needed to identify which economic, social, and cultural components account for this increased risk. Montoya, I., Bell, D., Richard, A., Carlson, J., et al. Estimated HIV Risk Among Hispanics in a National Sample of Drug Users. J AIDS Hum Retroviol, 21, pp. 42-50, 1999.
Risk Network Cohesion is Dynamically Linked to Infectious Disease Transmission
In this study, researchers sought to relate dynamic changes in risk-network (sex and/or injecting drug) structure to observe STD/HIV transmission. They analyzed macro- and micro-structural elements in two heterosexual networks, augmented by ethnographic observations. In a Colorado cohort of injecting drug users (N = 595), measures of subgroup formation and of density of activity showed a decrease of network cohesion over time; only one HIV transmission was observed in three years. In a group of adolescent heterosexuals in Georgia (N = 99), the reverse process (increase in structural cohesion) was associated with efficient syphilis transmission: 10 cases were observed. Changes in personal risk behaviors over time were modest. STD/HIV transmission patterns were associated with intensification or diminution of network cohesion. Network and ethnographic data suggest that enhanced connectivity facilitates transmission while segmentation impedes it, suggesting opportunities for interventions. These data also emphasize the need to re-evaluate purely behavioral explanations of STD/HIV transmission. Potterat , J., Rothenberg, R., Muth, S.Q. Network Structural Dynamics and Infectious Disease Propagation. Int J STD AIDS, 10(3), pp. 182-185, 1999.
"Shotgunning" is Linked to Both Sexual Risk Behaviors and Risks of Infection
A series of ethnographic observations were conducted to characterize more fully the practice of "shot gunning," an illicit drug smoking practice in which smoked drugs are exhaled or blown by one user into the mouth of another user. Inhalation drug use such as this is implicated in the transmission of a variety of pathogens by the respiratory route. In addition, crack smoking has been associated with an increased risk of HIV infection, particularly through the exchange of sex for drugs. This study also sought to characterize the range of behaviors associated with the shot gunning drug use practice, and the settings and contexts in which the practice occurs. Shot gunning is a form of drug use that is closely linked to high risk sexual behaviors. It is associated with the potential for both direct and indirect risk of disease transmission by sexual, blood-borne and respiratory routes, making the development and evaluation of comprehensive risk reduction interventions essential. Perlman, D., Henman, A., Kochems, L., Paone, D., et al. Doing a Shotgun: A Drug Use Practice and Its Relationship to Sexual Behaviors and Infection Risk. Soc Sci Med, 48(10), pp. 1441-1448, 1999.
Forgetting is a Factor in Incomplete Reporting of Sexual and Drug Use Partners
Partner notification and social network studies of infectious disease often involve interviewing people to elicit their sexual and/or drug injection partners. Incomplete reporting of partners in these contexts would significantly hamper efforts to understand and control the spread of sexually transmitted diseases, HIV, and other infections. There are many reasons why individuals might not name their partners in interviews. This study provides a comprehensive assessment of forgetting as a cause of incomplete reporting of sexual and injection partners. One hundred fifty-six persons in Seattle, Washington, at presumed high risk for HIV recalled their sexual and/or injection partners in two interviews separated by 1 week or 3 months. Repeated, nonspecific prompting elicited, on average, 10% of all partners recalled in an interview. Subjects displayed substantial forgetting of partners across partner types, recall periods, and four independent measurement approaches, with up to 72% of partners forgotten. The number of partners recalled and subjective assessment of forgetting are moderate to good predictors of the number of partners forgotten. Recalled and forgotten partners do not differ dramatically on any of several partner variables. Forgetting is a primary factor in the incomplete reporting of sexual and injection partners. Interviewers should prompt repeatedly to maximize recall of partners. Re-interviewing is currently the best method available for identifying partners as completely as possible and should be focused on individuals who report many partners and/or sense they have other partners they cannot recall. Brewer D., Garrett S., and Kulasingam S. Forgetting as a Cause of Incomplete Reporting of Sexual and Drug Iinjection Partners. Sex Transm Dis, 26(3), pp. 166-76, 1999.
Simulation Estimates HIV Transmission Probabilities In a Network of Cocaine Injectors
In a simulation study, researchers addressed the applicability of various network measures for the analysis of a disease transmission network. A simulation was conducted to estimate HIV transmission probabilities within an empirical network of cocaine injectors. The results of the simulation were then used as a criterion to evaluate network measures of disease vulnerability and infectivity. For the type of disease transmission studied, the analysis showed that relatively simple network measures can be adequate to the measurement of vulnerability to disease and infectivity. Vulnerability (the probability of being infected) and infectivity (the probability that an important or prominent network member or "actor" will infect others) are of most concern in the consideration of HIV transmission networks. The findings will help investigators in understanding disease processes and particularly, the dynamic propagation of HIV in drug use and sexual risk networks. Bell, D., Atkinson, J., and Carlson, J. Centrality Measures for Disease Transmission Networks. Social Networks, 21, pp. 1-21, 1999.
How Tucson IDUs Appropriate and Internalize HIV Prevention Concepts
In this study, researchers illuminate how social categorizations, concepts, and procedures that are a valuable part of HIV prevention efforts are reportedly enacted by IDUs within certain social contexts. The categories and concepts circulated by AIDS prevention programs have a direct if not always apparent influence on the regulation of relations within IDU social networks. Ideas regarding risk groups, safer sex, and HIV test results are actualized in specific interactions and often serve to structure the patterns of relationships IDUs share with specific people around them. Ultimately, this study points to some of the parameters governing the regulation of relationships among people by illustrating how macro-communications are enacted in micro-contexts. Estrada, A. and G. Quintero. Redefining Categories of Risk and Identity: The Appropriation of AIDS Prevention Information and Constructions of Risk. In Elwood, W. (ed.) Power in the Blood: A Handbook of AIDS, Politics, and Communication. Mahwah, N.J.: Lawrence Erlbaum Associates, 1999.
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