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Biomedical subjects

David Vlahov

Publications and source records attributed to David Vlahov.

At least 55 records · Page 3Linked to original sources
PubMed2005

Period and birth-cohort effects on age of first phencyclidine (PCP) use among drug users in New York City, 1960 to 2000.

PURPOSE: The aim of the study is to determine period and birth-cohort effects in the early initiation of phencyclidine (PCP) use in drug users in New York City (NYC). METHODS: We analyzed data collected from two surveys of street-recruited drug users in NYC. We used survival analysis and proportional hazards modeling to assess period and birth-cohort effects on risk for early initiation of PCP use. RESULTS: Of 787 participants, 292 (37.1%) had used PCP by the age of 23 years. Before 1987, there was a greater risk for initiation of PCP use through the age of 23 years (hazard ratio [HR] = 34.77; 95% confidence interval [CI], 21.45-56.36). Proportional hazards modeling showed that those born in the 1971 to 1975 birth cohort compared with those born in 1976 to 1980 had a lower risk for initiation of PCP use through age 23 years (HR = 0.58; 95% CI, 0.37-0.91). Other significant predictors of PCP use by age 23 included white race and having been in a juvenile detention center. CONCLUSIONS: There are period and birth-cohort differences in the likelihood of early initiation of PCP use. Changes in drug culture and social norms may influence the likelihood of initiation of PCP use. This may have implications for interventions aimed at slowing the nationwide increase in use of PCP.

Adult↗
PubMed2005

Effect of zinc and vitamin A supplementation on antibody responses to a pneumococcal conjugate vaccine in HIV-positive injection drug users: a randomized trial.

HIV-infected individuals have impaired immune responses to vaccines and high rates of pneumococcal disease. The effect of vitamin A and zinc supplementation on the immunogenicity of a 7-valent pneumococcal CRM-197 conjugate vaccine (PC-7) was evaluated in 118 HIV+ injection drug users. Subjects were randomized to oral 400,000 IU vitamin A, 300 mg zinc, vitamin A + zinc, or placebo, then immunized. Geometric mean titer increased 1.3-3.3-fold for all pneumococcal serotypes. PC-7 elicited an immune response in HIV-infected adults but neither vitamin A nor zinc altered the immunogenicity of the evaluated vaccines.

Adult↗
PubMed2005

Injection drug use is an independent risk factor for iron deficiency and iron deficiency anemia among HIV-seropositive and HIV-seronegative women.

The risk factors for iron deficiency and iron deficiency anemia among female injection drug users are not well characterized. We measured hemoglobin and plasma ferritin and obtained demographic information and injection drug use history in the last 6 months in a cross-sectional study of 200 female injection drug users (134 HIV-positive and 66 HIV-negative). The women were participants in a natural history study, the AIDS Linked to Intravenous Experiences study in Baltimore, Maryland. In multivariate analyses adjusting for age, hepatitis C virus status, and HIV status, injection drug use within the last 6 months was associated with iron deficiency (odds ratio [OR] = 2.61, 95% confidence interval [CI]: 1.33 to 5.09) and iron deficiency anemia (OR = 6.65, 95% CI: 2.33 to 18.9). Among 134 HIV-positive women, injection drug use in the last 6 months was associated with iron deficiency (OR = 2.43, 95% CI: 1.08 to 5.48) and iron deficiency anemia (OR = 6.05, 95% CI: 1.82 to 20.1) in multivariate analyses adjusting for hepatitis C virus status and CD4 lymphocyte count. Injection drug use seems to be associated with iron deficiency and iron deficiency anemia. Further longitudinal studies are needed to gain insight into the nature of this association.

Adult↗
PubMed2005

Community incidence of hepatitis B and C among reincarcerated women.

BACKGROUND: The incarceration rate has increased 239% in the United States over the past 2 decades. This increase in incarceration has been fueled by the movement towards a criminal, rather than medical, response to the problem of drug dependence. For women in particular, incarceration and drug use are interdependent epidemics. Given that incarceration is common among drug-dependent persons, infectious diseases--including hepatitis B virus (HBV) and hepatitis C virus (HCV) infection--are prevalent among incarcerated persons. We sought to determine the incidence of HBV and HCV infection among recidivist women prisoners. METHODS: From 1996 through 1997, excess from serum samples collected during HIV testing of female admittees to a state Department of Corrections facility were tested for HBV and HCV. Multiple samples obtained from women incarcerated multiple times during the study period were compared for incidence. RESULTS: Baseline prevalences of markers of HBV and HCV were 36% and 34%, respectively. Incidence rates for HBV and HCV infection among reincarcerated women were 12.2 and 18.2 per 100 person-years, respectively. The majority of the time spent between serial intakes was not spent in the correctional facility; thus, incident infections likely occurred in the community. CONCLUSIONS: Incidences of HBV and HCV infection among reincarcerated women were high. Prisons and jails can be efficient locations for the diagnosis, treatment, and prevention of hepatitis B and C through programs such as testing, counseling, education, vaccination, and linkage to medical and drug treatment services.

Adult↗
PubMed2005

The role of substance abuse in HIV disease progression: reconciling differences from laboratory and epidemiologic investigations.

From the onset of the HIV/AIDS epidemic, the use of licit and illicit drugs has been investigated for its potential impact on HIV disease progression. Findings from a large number of laboratory-based studies indicate that drug abuse may exacerbate HIV disease progression; however, epidemiological studies have shown mixed results. This article presents a review of findings from both laboratory-based and epidemiologic investigations. In addition, we provide a careful evaluation of methodological strengths and limitations inherent to both study designs in order to provide a more nuanced understanding of how these findings may complement one another.

Animals↗
PubMed2005

Receptive syringe sharing among injection drug users in Harlem and the Bronx during the New York State Expanded Syringe Access Demonstration Program.

BACKGROUND: Effective on January 1, 2001, New York State enacted the Expanded Syringe Access Demonstration Program (ESAP), which allows syringes to be sold in pharmacies without a prescription or dispensed through doctors, hospitals, and clinics to persons 18 years of age or older and permits the possession of those syringes for the purposes of injecting drugs. OBJECTIVE: To assess changes in receptive syringe sharing since the inception of the ESAP. METHODS: Sociodemographic characteristics and syringe use data regarding the last injection episode were combined from 3 projects (n = 1181) recruiting injection drug users in ongoing studies in Harlem and the Bronx in New York City from January 2001 through June 2003. These data were analyzed as serial cross sections by calendar quarter. RESULTS: Receptive sharing decreased significantly over time, from 13.4% in the first quarter to 3.6% in the last quarter. Obtaining the last injection syringe from an ESAP source (mostly pharmacies) increased significantly over time, from 7.5% in the first quarter to 25.0% in the last quarter. In multiple logistic regression analysis, variables that were significantly associated with less receptive sharing were syringe exchange and ESAP syringe source as well as time since ESAP inception. Female gender and white race/ethnicity were significantly associated with greater receptive sharing. CONCLUSIONS: The increase in the use of pharmacies and other ESAP syringe sources in this sample has been accompanied by a decline in receptive sharing.

Adult↗
PubMed2005

The effect of HIV infection on overdose mortality.

OBJECTIVES: To quantify the association of HIV infection with overdose mortality and explore the potential mechanisms. DESIGN: A prospective cohort study. METHODS: A total of 1927 actively injecting drug users who were HIV seronegative at baseline, of whom 308 later HIV seroconverted, were followed semi-annually for death from 1988 to 2001. Survival analyses using marginal structural and standard Cox models were used to evaluate the effect of HIV infection on the risk of overdose mortality. RESULTS: Overdose death rates were higher in HIV-seropositive than HIV-seronegative drug users: 13.9 and 5.6 per 1000 person-years, respectively (P < 0.01). The hazard ratio (HR) was 2.54 [95% confidence interval (CI) 1.47, 4.38] for the marginal structural model and 2.06 (95% CI 1.25, 3.38) for the standard Cox model, both adjusted for demographics, drug injection characteristics, alcohol abuse, substance abuse treatment, and sexual orientation. Adjusting for possible time-varying mediators (i.e. drug use, medical conditions and healthcare access) in extended marginal structural models reduced the effect of HIV on overdose mortality by 30% (HR 1.82, 95% CI 1.01, 3.30). Abnormal liver function was associated with a higher risk of overdose mortality (HR 2.00, 95% CI 1.05, 3.84); adjustment for this further reduced the effect of HIV on overdose mortality. CONCLUSION: HIV infection was associated with a higher risk of overdose mortality. Drug use behavior, systematic disease and liver damage associated with HIV infection appeared to account for a substantial portion of this association. The data suggest a group to target with interventions to reduce overdose mortality rates.

Adult↗
PubMed2005

Effectiveness of highly active antiretroviral therapy among injection drug users with late-stage human immunodeficiency virus infection.

Highly active antiretroviral therapy (HAART) has been shown to be effective in different populations, but data among injection drug users are limited. Human immunodeficiency virus-infected injection drug users recruited into the Acquired Immunodeficiency Syndrome Link to Intravenous Experiences (ALIVE) Study as early as 1988 were tested semiannually to identify their first CD4-positive T-lymphocyte cell count below 200/microl; they were followed for mortality through 2002. Visits were categorized into the pre-HAART (before mid-1996) and the HAART eras and further categorized by HAART use. Survival analysis with staggered entry was used to evaluate the effect of HAART on acquired immunodeficiency syndrome-related mortality, adjusting for other medications and demographic, clinical, and behavioral factors. Among 665 participants, 258 died during 2,402 person-years of follow-up. Compared with survival in the pre-HAART era, survival in the HAART era was shown by multivariate analysis to be improved for both those who did and did not receive HAART (relative hazards = 0.06 and 0.33, respectively; p < 0.001). Inferences were unchanged after restricting analyses to data starting with 1993 and considerations of lead-time bias and human immunodeficiency viral load. The annual CD4-positive T-lymphocyte cell decline was less in untreated HAART-era participants than in pre-HAART-era participants (-10/microl vs. -37/microl, respectively), suggesting that changing indications for treatment may have contributed to improved survival and that analyses restricted to the HAART era probably underestimate HAART effectiveness.

Adult↗
PubMed2005

Perspectives on urban conditions and population health.

The majority of the world's population will live in cities in the next few years and the pace of urbanization worldwide will continue to accelerate over the coming decades. While the number of megacities is projected to increase, the largest population growth is expected to be in cities of less than one million people. Such a dramatic demographic shift can be expected to have an impact on population health. Although there has been historic interest in how city living affects health, a cogent framework that enables systematic study of urban health across time and place has yet to emerge. Four alternate but complementary approaches to the study of urban health today are presented (urban health penalty, urban health advantage, urban sprawl, and an integrative urban conditions model) followed by three key questions that may help guide the study and practice of urban health in coming decades.

Cities↗
PubMed2005

Association of sex, hygiene and drug equipment sharing with hepatitis C virus infection among non-injecting drug users in New York City.

BACKGROUND: Hepatitis C virus (HCV) rates are higher in non-injecting drug users (NIDUs) than general population estimates. Whether this elevated HCV rate is due to drug use or other putative risk behaviors remains unclear. METHODS: Recent non-injection drug users of heroin, crack and/or cocaine were street-recruited from 2000 to 2003 and underwent an interview and venipuncture for HCV antibody assays. Multiple logistic regression analyses were used to assess correlates for HCV infection. RESULTS: Of 740 enrollees, 3.9% were HCV positive. The median age (intraquartile range) was 30 (35-24) years, 70% were male and 90% were Black or Hispanic. After adjustment, HCV seropositives were significantly more likely than seronegatives to be older than 30 [adjusted odds ratio (AOR)=5.71], tattooed by a friend/relative/acquaintance [AOR=3.61] and know someone with HCV [AOR=4.29], but were less likely to have shared nail or hair clippers, razors or a toothbrush [AOR=0.32]. CONCLUSIONS: Non-commercial tattooing may be a mode of HCV transmission among NIDUs and education on the potential risk in using non-sterile tattooing equipment should be targeted toward this population. While no evidence was found for HCV transmission through NIDU equipment sharing or sexual risk behavior, further research is still warranted.

Adult↗
PubMed2005

The effect of RANTES chemokine genetic variants on early HIV-1 plasma RNA among African American injection drug users.

HIV-1 plasma RNA is a prognostic indicator of HIV-1, and increased levels of HIV-1 plasma RNA are associated with rapid progression to AIDS. Because chemokines and chemokine receptors are involved in the binding and entry of HIV-1, possible effects of host genetics on viral RNA levels should be visible in early infection. HIV-1 plasma RNA was measured within 2 years of seroconversion in 198 seroincident injection drug users followed in the AIDS Link to Intravenous Experience cohort. Genetic variants were identified in the chemokine receptors (CCR2, CCR5, and CCR5 promoter) and the chemokine RANTES using TaqMan and restriction fragment length polymorphism assays. Linear regression of RANTES haplotypes on early HIV-1 plasma RNA identified individuals homozygous for the RANTES R1 haplotype as having a lower viral load by almost one-half log10 unit compared with those bearing non-RANTES R1 haplotypes (-0.43, 95% confidence interval: -0.74, -0.12). Genetic variants in RANTES may downregulate RANTES gene expression and increase early HIV-1 plasma RNA. Because RANTES is a critical chemokine and competitively inhibits HIV-1 by binding to its receptor CCR5, treatment to enhance RANTES expression may assist in delaying the progression of AIDS by decreasing the initial viral load.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Human immunodeficiency virus 1 infection, cocaine, and coronary calcification.

BACKGROUND: Although cocaine use and human immunodeficiency virus (HIV) infection have been linked with clinical cardiovascular disease, the effects of cocaine use and HIV infection, especially the combination of the 2, on subclinical disease have rarely been reported. The objective of this study was to evaluate whether cocaine use alone, HIV infection alone, or a combination of the 2 is associated with coronary calcification, a marker of subclinical atherosclerosis. METHODS: Between May 20, 2000, and March 31, 2003, 224 black study participants from Baltimore were enrolled in an observational study of subclinical atherosclerosis as related to HIV and cocaine use. Interviews about sociodemographic characteristics and drug use behaviors, clinical examinations, echocardiographic examinations, lipid profiles, high-sensitivity C-reactive protein tests, and computed tomographic scans for coronary calcium were performed. Although the overall investigation is a cohort study, the data presented herein are cross sectional only. RESULTS: The highest proportion (37.6%) of presence of coronary calcification was in the HIV-positive and cocaine-positive group, followed by 29.8% in the HIV-negative and cocaine-positive group, 28.6% in the HIV-positive and cocaine-negative group, and 18.8% in the HIV-negative and cocaine-negative group. Univariate analysis showed that HIV, cocaine use, and both were associated with a higher number of lesions, calcified area, volume, and calcium score. In multiple regression analysis with adjustment for age, body mass index, low-density lipoprotein cholesterol level, triglyceride level, mean corpuscular volume, and systolic blood pressure, HIV, cocaine use, and both were independently associated with coronary calcification. CONCLUSION: These results suggest that HIV infection alone, cocaine use alone, or the 2 combined may contribute to early subclinical atherosclerotic cardiovascular disease.

Adult↗
PubMed2005

Prospective evaluation of community-acquired acute-phase hepatitis C virus infection.

BACKGROUND: More than two-thirds of hepatitis C virus (HCV) infections in Western countries are caused by injection drug use, but prospective clinical data regarding the most common mode of HCV acquisition are rare, in part because acute-phase HCV infection is usually asymptomatic. METHODS: To characterize acute-phase HCV infection, 179 HCV antibody-negative injection drug users were prospectively evaluated; 62 (34%) of these patients had seroconverted. Twenty of the participants who seroconverted had long-term follow-up with consistent monthly sampling before and after seroconversion, allowing detailed study. RESULTS: The first indication of HCV infection was the presence of HCV RNA in serum, which preceded elevation of alanine transaminase levels and total bilirubin levels to > or =2 times baseline in 45% and 77% of patients, respectively. No subjects had jaundice. The median time from initial viremia to seroconversion was 36 days (range, 32-46 days). In one instance, viremia was detected 434 days before seroconversion. However, in no other case was HCV RNA detected >63 days before seroconversion. In subjects with viral persistence, a stable level of HCV RNA in the blood was noted in some subjects within 60 days after the initial detection of viremia, but in others, it was not apparent until >1 year later. In subjects with long-term viral clearance, HCV became persistently undetectable as early as 94 and as late as 620 days after initial viremia. CONCLUSIONS: These data underscore the importance of nucleic acid screening of blood donations to prevent HCV transmission and of long-term follow-up to ascertain whether there is viral persistence, at least among injection drug users.

Acute Disease↗
PubMed2005

A comparison of HIV seropositive and seronegative young adult heroin- and cocaine-using men who have sex with men in New York City, 2000-2003.

The purpose of this analysis was to determine the prevalence and correlates of HIV infection among a street-recruited sample of heroin- and cocaine-using men who have sex with men (MSM). Injection (injecting <or=3 years) and non-injection drug users (heroin, crack, and/or cocaine use <10 years) between 18 and 40 years of age were simultaneously street-recruited into two cohort studies in New York City, 2000-2003, by using identical recruitment techniques. Baseline data collected among young adult men who either identified as gay/bisexual or reported ever having sex with a man were used for this analysis. Nonparametric statistics guided interpretation. Of 95 heroin/ cocaine-using MSM, 25.3% tested HIV seropositive with 75% reporting a previous HIV diagnosis. The majority was black (46%) or Hispanic (44%), and the median age was 28 years (range 18-40). HIV-seropositive MSM were more likely than seronegatives to be older and to have an HIV-seropositive partner but less likely to report current homelessness, illegal income, heterosexual identity, multiple sex partners, female partners, and sex for money/drug partners than seronegatives. These data indicate high HIV prevalence among street-recruited, drug-using MSM compared with other injection drug use (IDU) subgroups and drug-using MSM; however, lower risk behaviors were found among HIV seropositives compared with seronegatives. Large-scale studies among illicit drug-using MSM from more marginalized neighborhoods are warranted.

Adolescent↗
PubMed2005

Circumstances of witnessed drug overdose in New York City: implications for intervention.

Drug users frequently witness the nonfatal and fatal drug overdoses of their peers, but often fail to intervene effectively to reduce morbidity and mortality. We assessed the circumstances of witnessed heroin-related overdoses in New York City (NYC) among a predominantly minority population of drug users. Among 1184 heroin, crack, and cocaine users interviewed between November 2001 and February 2004, 672 (56.8%) had witnessed at least one nonfatal or fatal heroin-related overdose. Of those, 444 (67.7%) reported that they or someone else present called for medical help for the overdose victim at the last witnessed overdose. In multivariable models, the respondent never having had an overdose her/himself and the witnessed overdose occurring in a public place were associated with the likelihood of calling for medical help. Fear of police response was the most commonly cited reason for not calling or delaying before calling for help (52.2%). Attempts to revive the overdose victim through physical stimulation (e.g., applying ice, causing pain) were reported by 59.7% of respondents, while first aid measures were attempted in only 11.9% of events. Efforts to equip drug users to manage overdoses effectively, including training in first aid and the provision of naloxone, and the reduction of police involvement at overdose events may have a substantial impact on overdose-related morbidity and mortality.

Adolescent↗
PubMed2005

Sex-based differences in T lymphocyte responses in HIV-1-seropositive individuals.

Sex-based differences in the levels of human immunodeficiency virus 1 (HIV-1) RNA in plasma could be associated with differences in the strength of HIV-1-specific CD8(+) T cell responses. CD8(+) effector responses in 18 men and 15 women were measured 0-2 years (time A) and 5-7 years (time B) after seroconversion. CD8(+) effector responses were seen in 7 (39%) of 18 men and 2 (13%) of 15 women at time A (P=.13) and in 12 (67%) of 18 men and 10 (67%) of 15 women at time B (P=.99). At time B, the strength of CD8(+) effector responses correlated with the number of CD4(+) lymphocytes in women ( rho =-0.68; P=.005) but not in men ( rho =-0.14; P=.58). The level of HIV-1 RNA was not associated with the strength of CD8(+) effector responses according to sex, but there was a sex-based difference in the correlation between the strength of CD8(+) effector response and the number of CD4(+) lymphocytes.

Adult↗