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Biomedical subjects

D Vlahov

Publications and source records attributed to D Vlahov.

At least 19 recordsLinked to original sources
PubMed2006

Determinants of influenza vaccination in hard-to-reach urban populations.

OBJECTIVE: Influenza vaccination rates among disadvantaged minority and hard-to-reach populations are lower than in other groups. We assessed the barriers to influenza vaccination in disadvantaged urban areas. METHODS: We conducted a cross-sectional study, using venue-based sampling, collecting data on residents of eight neighborhoods throughout East Harlem and the Bronx, New York City. RESULTS: Of 760 total respondents, 461 (61.6%) had received influenza vaccination at some point in their life. In multivariable models, having access to routine medical care, receipt of health or social services, having tested positive for HIV, and current interest in receiving influenza vaccination were significantly associated with having received influenza vaccination in the previous year. Of participants surveyed, 79.6% were interested in receiving an influenza vaccination at the time of survey. Among participants who had never previously received influenza vaccination in the past, 73.4% were interested in being vaccinated; factors significantly associated with an interest in being vaccinated were minority race, lower annual income, history of being homeless, being uninsured/underinsured, and not having access to routine medical care. CONCLUSIONS: Participants who are unconnected to health or social services or government health insurance are less likely to have been vaccinated in the past although these persons are willing to receive vaccine if it were available.

Adolescent↗
PubMed2006

Physical activity in a cohort of HIV-positive and HIV-negative injection drug users.

Physical activity is beneficial for persons with HIV infection but little is known about the relationships between physical activity, HIV treatment and injection drug use (IDU). This study compared physical activity levels between HIV-negative and HIV-positive injection drug users (IDUs) and between HIV-positive participants not on any treatment and participants on highly active antiretroviral therapy (HAART). Anthropometric measurements were obtained and an interviewer-administered modified Paffenbarger physical activity questionnaire was administered to 324 participants in a sub-study of the AIDS Linked to Intravenous Experiences (ALIVE) cohort, an ongoing study of HIV-negative and HIV-positive IDUs. Generalized linear models were used to obtain univariate means and to adjust for confounding (age, gender, employment and recent IDU). Vigorous activity was lower among HAART participants than HIV-positive participants not on treatment (p=0.0025) and somewhat lower than HIV-negative participants (p=0.11). Injection drug use and viral load were not associated with vigorous activity. Energy expenditure in vigorous activity was also lower among HAART participants than both HIV-negative and HIV-positive participants not on treatment. Thus, HIV-positive participants on HAART spend less time on vigorous activity independent of recent IDU. More research is needed into the reasons and mechanism for the lack of vigorous activities, including behavioral, psychological and physiological reasons.

Adult↗
PubMed2006

Alcohol drinking problems among New York City residents after the September 11 terrorist attacks.

Recent studies have shown an increase in alcohol use in New York City in the months after the September 11 terrorist attacks; thus far there have been no studies documenting changes in drinking problems. In 2002, a random digit dial phone survey was conducted of residents of New York City. This study provided us with estimates of the prevalence of alcohol drinking problems among residents of New York City 6 months after September 11 compared with the 6 months before September 11. Among 1,570 adults, the prevalence of drinking problems was 3.7% in the 6 months before September 11 and 4.2% in the 6 months after September 11. The incidence of drinking problems among those without drinking problems before September 11 was 2.2%. Persons with incident drinking problems were more likely than those without to report symptoms consistent with posttraumatic stress disorder (17.4% vs. 0.4% in those without drinking problems and 1.4% in nondrinkers), and depression (23.5% vs 5.6% vs. 4.9%, respectively) after September 11. After a disaster, a link between drinking problems and posttraumatic stress disorder or depression should be assessed.

Adolescent↗
PubMed2005

Liver enzyme values in injection drug users with chronic hepatitis C.

BACKGROUND: Liver enzymes fluctuate in chronic hepatitis C virus infection. However, the range that can be attributed to the course of hepatitis C virus (versus an intercurrent cause of hepatitis) is unknown. AIMS: To characterise the range of liver enzyme values as a function of the upper limit of normal (ULN) of the assay among persons chronically infected with hepatitis C virus. PATIENTS: One thousand and fifty-nine hepatitis C virus chronically infected individuals with > or =5 semi-annual evaluations. METHODS: Alanine aminotransferase and aspartate aminotransferase levels were prospectively obtained. Potential causes of elevations were examined using serologic testing. RESULTS: Among 1059 individuals, 11,463 enzyme measurements were obtained over 6.5 years, of which 63.5% were <1.25x ULN, 26.5% were 1.25-2.5x ULN, 8.3% were 2.5-5x ULN, and 1.6% were 5-10x ULN; only 0.2% were >10x ULN. Elevations >10x ULN were transient, the alanine aminotransferase/aspartate aminotransferase ratio tended to be different at the time of the elevation compared to before and after and 24% were associated with acute viral hepatitis. On the other hand, subjects with elevations 5-10x ULN tended to have elevated levels throughout follow-up and only 8% were associated with acute viral hepatitis. CONCLUSIONS: Liver enzymes fluctuate up to 5x ULN in most hepatitis C virus-infected persons; clinicians should seek alternate explanations for those with higher alanine aminotransferase or aspartate aminotransferase levels, especially among hepatitis C virus-infected persons with greater than 10-fold elevations.

Adult↗
PubMed2005

The urban built environment and overdose mortality in New York City neighborhoods.

Accidental drug overdose continues to be a substantial cause of mortality for drug users. Characteristics of the neighborhood built environment may be important determinants of the likelihood of drug overdose mortality independent of individual-level factors. Using data from the New York City Office of the Chief Medical Examiner, we conducted a multilevel case control study using data on accidental overdose deaths as cases and non-overdose accidental deaths as controls. We used archival data from the New York City Housing and Vacancy Survey and the Mayor's Office of Operations to assess characteristics of neighborhood external (e.g. dilapidation of buildings) and internal (e.g. quality of utilities in houses) built environment. Multilevel analyses were used to assess the relations between the neighborhood built environment and the likelihood of overdose death. Six out of the eight characteristics of the external environment studied and three out of the six characteristics of the internal environment studied were significantly associated with the likelihood of fatal drug overdose in multilevel models after adjusting for individual-level (age, race, sex) and neighborhood-level (income, drug use) variables. Deterioration of the built environment, particularly the external environment, is associated with an increased likelihood of fatal accidental drug overdose. Disinvestment in social resources, psychosocial stressors, neighborhood differences in response to a witnessed overdose, and differences in vulnerability to the adverse consequences of drug use in different neighborhoods may explain the observed associations.

Adolescent↗
PubMed2005

Haplotype analysis of the SDF-1 (CXCL12) gene in a longitudinal HIV-1/AIDS cohort study.

The stromal-derived factor-1 (SDF-1) chemokine gene encodes the only natural ligand for CXCR4, the coreceptor for the pathogenic X4 HIV-1 strains. A single-nucleotide polymorphism (SNP) in the 3' untranslated region (SDF1-3'A=rs1801157) of SDF-1 was reported to be protective against infection and progression in some, but not other, epidemiological studies. To identify additional alleles that may influence HIV-1 infection and progression to AIDS, nine SNPs (including rs1801157) spanning 20.2 kb in and around the SDF-1 gene were genotyped in over 3000 African American (AA) and European American (EA) participants enrolled in five longitudinal HIV-1/AIDS natural cohort studies. Six or five haplotypes were present at frequencies greater than 5% in AA or EA, respectively. Six of the nine SNPs occur on only one common haplotype (>5%), while the remaining three SNPs were found on multiple haplotypes, suggesting a complex history of recombination. Among EA, rs754618 was associated with an increased risk of infection (OR=1.50, P=0.03), while rs1801157 (=SDF1-3'A) was associated with protection against infection (OR=0.63, P=0.01). In the MACS cohort, rs1801157 was associated with AIDS-87 (RH=0.31, P=0.02) and with death (RH=0.18, P=0.02). Significant associations to a single disease outcome were found for two SNPs and one haplotype in AA.

Acquired Immunodeficiency Syndrome↗
PubMed2004

MICA and recovery from hepatitis C virus and hepatitis B virus infections.

The polymorphic MHC class I chain-related A (MICA) gene encodes a ligand that has different binding affinities for the NKG2D activating receptor of CD8+ T cells and natural killer (NK) cells. We hypothesized that MICA heterogeneity would affect recovery from hepatitis C virus (HCV) and hepatitis B virus (HBV) infections. To test the hypothesis, we initially typed known MICA polymorphisms for 228 persons who cleared HCV infection and 442 persons with persistent hepatitis C matched on other factors affecting viral persistence. Although MICA(*)015 was detected more than two-fold more often in persons with viral clearance (odds ratio 0.36, 95% confidence interval=0.19, 0.80), it occurred in fewer than 5% of the study population. In a similar analysis of 442 persons with chronic hepatitis B and 768 matched controls who recovered, MICA(*)015 was detected in 2.0% of persons with chronic hepatitis B and only 0.9% of controls. No significant associations were detected with other MICA polymorphisms. While further investigation may reveal a structural basis of the MICA(*)015 associations, these data provide little support for the hypothesis that differential distribution of MICA alleles substantially affects recovery from HCV and HBV infections.

Hepacivirus↗
PubMed2004

An analysis of tumor necrosis factor alpha gene polymorphisms and haplotypes with natural clearance of hepatitis C virus infection.

The cytokine tumor necrosis factor alpha (TNF-alpha) is important in generating an immune response against a hepatitis C virus (HCV) infection. The functions of TNF-alpha may be altered by single-nucleotide polymorphisms (SNPs) in its gene, TNF. We hypothesized that SNPs in TNF may be important in determining the outcome of an HCV infection. To test this hypothesis, we typed nine TNF SNPs in a cohort of individuals with well-defined HCV outcomes. Three of these SNPs were typed in a second cohort. Data were analyzed using logistic regression stratifying by ethnicity, since rates of HCV clearance differ in black subjects versus white subjects. The SNP -863A was associated with viral clearance in black subjects (odds ratios (OR) 0.52, 95% confidence interval (CI) 0.29-0.93). Furthermore, the common wild-type haplotype -863C/-308G was associated with viral persistence in black subjects (OR 1.91, 95% CI 1.24-2.95). These findings were independent of linkage with human leukocyte antigen (HLA) alleles. Further study of this polymorphism and haplotype is needed to understand these associations and the role of TNF-alpha in determining outcomes of HCV infection.

Black or African American↗
PubMed2004

Overdose deaths attributed to methadone and heroin in New York City, 1990-1998.

AIMS: Methadone treatment has been shown to be an effective intervention that can lower the risk of heroin-induced overdose death. Recent reports have suggested increases in methadone-induced overdose deaths in several locations in the USA and in Europe. This study investigated the role of methadone and opiates in accidental overdose deaths in New York City. DESIGN: We analysed data from the Office of the Chief Medical Examiner to examine all accidental drug overdose deaths in New York City between 1990 and 1998. FINDINGS: Of 7451 total overdose deaths during this period, there were 1024 methadone-induced overdose deaths, 4627 heroin-induced overdose deaths and 408 overdose deaths attributed to both methadone and heroin. Fewer than a third as many accidental overdose deaths were attributed to methadone than were attributed to heroin during this period. The proportion of accidental overdose deaths attributed to methadone did not change appreciably (12.6-15.8% of total overdose mortality), while the proportion of overdose deaths attributed to heroin increased significantly (53.5-64.2%) during the period of study. CONCLUSIONS: There was no appreciable increase in methadone-induced overdose mortality in New York City during the 1990s. Both heroin-induced overdose mortality and prescriptions of methadone increased during the same interval.

Adolescent↗
PubMed2004

Acceptance and completion of hepatitis B vaccination among drug users in New York City.

Hepatitis B (HBV) vaccination rates remain low among drug users. We examined correlates of vaccine acceptance and completion in two ongoing prospective studies of young injecting and non-injecting drug users in New York City. Street recruited drug users were enrolled at one of two neighbourhood locations (Harlem and the Bronx) between 2000 and 2004 and completed risk behaviour questionnaires and HBV testing. Free HBV vaccination was offered. Among 1117 participants, 26.1% (275) had a previous HBV infection, 57.9% (610) were susceptible to HBV, and 16.0% (169) had serological evidence of previous vaccination. Of the 610 participants susceptible to HBV, 466 (76.4%) returned for their results and were offered vaccination; 53.9% (251) received at least one dose of the vaccine (acceptors). Correlates of vaccine acceptance included older age, public assistance as main income source, and being recruited in the Bronx. Daily crack users were significantly less likely to initiate the vaccine series. Among 240 vaccine acceptors, 98 (40.8%) completed all three doses. Daily injectors, Hispanics, and those recruited in Harlem were less likely to complete the vaccination series. HBV vaccination acceptance among drug users seems likely in programmes that are convenient and offer remuneration; however, extended efforts are needed to improve series completion.

Adult↗
PubMed2003

Retinoids and drugs of abuse: implications for neurological disease risk in human immunodeficiency virus type 1 infection.

Among injection drug users, human immunodeficiency virus (HIV) type 1 infection may be associated with an increased risk of nervous system disease. For HIV-infected drug users with vitamin A deficiency, the overall risk of HIV-related morbidity and mortality may also be higher. In previous studies, levels of retinol, retinol-binding protein, and transthyretin in samples from such individuals were examined and found to be lower than such levels in seronegative control subjects. Also, in studies using an activated mononuclear cell line, all-trans retinoic acid and 9-cis retinoic acid suppressed production of the tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma. However, simultaneous exposure of the cells to morphine at a concentration similar to that to which drug users are exposed resulted in increased production of these cytokines. Therefore, morphine may alter the immunomodulatory effects of retinoids, thereby potentially affecting the clinical outcome of studies involving retinoid administration to HIV-infected drug users and increasing the risk for the development of HIV-related complications, including neurological disease.

AIDS Dementia Complex↗
PubMed2003

Longitudinal patterns of drug injection behavior in the ALIVE Study cohort,1988-2000: description and determinants.

The objective of this study was to characterize longitudinal patterns of drug injection behavior for individuals and to identify their early determinants. Participants were 1,339 injection drug users recruited into the AIDS Link to Intravenous Experience (ALIVE) Study in Baltimore, Maryland, through community outreach efforts. The study was initiated in 1988, and follow-up continued through 2000, with semiannual visits. Patterns of self-reported drug injection (yes/no) were defined for each participant, based on the number of drug-use transitions. The effect of baseline factors was assessed using multinomial logistic regression models. Over the 12-year study period, four patterns were noted: 29% of participants remained persistent drug injectors, 20% ceased injection, 14% relapsed once, and 37% had multiple transitions. Persistent injectors had the shortest follow-up and the highest mortality. For persons who changed their behavior, 3.4 years elapsed before their first cessation attempt, on average. Factors differentiating the groups included history of incarceration, young age, participation in drug treatment programs, recent overdose, and commercial sex. The observed long-term injection patterns are consistent with the view of drug addiction as a chronic disease. This view emphasizes the need for prolonged efforts to sustain cessation and to prevent adverse health and social outcomes among injection drug users.

Adult↗
PubMed2003

Genetic influence of CXCR6 chemokine receptor alleles on PCP-mediated AIDS progression among African Americans.

CXCR6 is a chemokine receptor and the primary coreceptor in SIV infection. A single nucleotide polymorphism 1469G-->A, results in a nonconservative change in codon 3 (CXCR6-E3K) of the N-terminus of the coreceptor. To investigate the relation between the chemokine receptor CXCR6 genotype and progression to Pneumocystis carinii pneumonia (PCP) and from PCP to death, we clinically assessed and genotyped 805 individuals from an African-American injection drug-using cohort in Baltimore, MD, USA, for this CXCR6-E3K polymorphism. The allele frequency of CXCR6-3K was high (44%) in African Americans and rare in European Americans (f<1%). Although time to AIDS and PCP was similar for all CXCR6 genotypes, the median survival time from PCP to death for the CXCR6-3E/E and CXCR6-3E/K genotype was 1.5 years compared to 3.1 years for the CXCR6-K/K genotype. Individuals homozygous or heterozygous for the CXCR6-3E allele were 5.6 times more likely to die a PCP-mediated AIDS-related death than were individuals homozygous for CXCR6-3K. This study shows an association between CXCR6 genotype and progression from PCP to death among African-Americans with HIV. We suggest that CXCR6 may play a role in late-stage HIV-1 infection and may alter the progression to death after initial infection with PCP.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Regional variation in CCR5-Delta32 gene distribution among women from the US HIV Epidemiology Research Study (HERS).

The CCR5-Delta32 genotype is known to influence HIV-1 transmission and disease. We genotyped 1301 US women of various races/ethnicities participating in the HIV Epidemiologic Research Study. None was homozygous for CCR5-Delta32. The distribution of heterozygotes was similar in HIV-1 infected and uninfected women. Thirty-seven (11.8%) white, 28 (3.7%) blacks/African Americans (AA), seven (3.3%) Hispanics/Latinas, and one (6.6%) other race/ethnicity were heterozygous. The frequency of heterozygotes differed among sites for all races combined (P = 0.001). More heterozygotes were found in AA women in Rhode Island (8.9%) than in the other sites (3.1%) (P = 0.02), while heterozygosity in white women was most common in Maryland (28.6%) (P = 0.025). These regional differences could be accounted for by racial admixture in AAs, but not in whites. Regional variations should be considered when studying host genetic factors and HIV-1 in US populations.

Adolescent↗
PubMed2002

Highly active antiretroviral treatment does not increase sexual risk behaviour among French HIV infected injecting drug users.

STUDY OBJECTIVE: This study examined the impact of highly active antiretroviral therapies (HAART) on sexual risk behaviours of HIV infected injecting drug users (IDUs) included in the French MANIF 2000 cohort study. DESIGN: Longitudinal analysis including baseline and last follow up characteristics using generalised estimating equations (GEE). SETTING: Hospital departments for specialist AIDS care in south eastern France and inner suburbs of Paris. PATIENTS: All patients antiretrovial treatment naive, who reported being sexually active at enrollment, and who had at least one follow up visit in the cohort between October 1996 and May 1998 (n=188). MAIN RESULTS: Of the 188 HIV infected IDUs who were antiretroviral treatment naive at enrollment, 34 were prescribed HAART during follow up. Proportion of patients who reported at least one episode of unprotected sexual intercourse in the previous six months only significantly decreased in the HAART treated group (from 47.1% to 23.5%, p=0.008, compared with 43.5% to 35.7% in the rest of the sample, p=0.10). GEE multivariate model confirmed that prescription of HAART was associated with reduced sexual risk. CONCLUSIONS: The concern that HAART might result in clinical improvement leading to resumption of high risk activities that could inadvertently result in HIV transmission was not supported by these data. Reasons for further reductions in HIV risk with taking HAART remain to be clarified.

Adult↗
PubMed2001

Cancer incidence in women with or at risk for HIV.

The purpose of our study was to identify the types and rates of cancers seen in high-risk human immunodeficiency virus (HIV)-infected and HIV-uninfected women. From 1993 to 1995, 1,310 women enrolled at four urban U.S. research sites in the HIV Epidemiology Research Study and were interviewed biannually to identify interval diagnoses and hospitalizations until study closure in March 2000. Cancer incidence data were collected through abstraction of medical records and death certificates. Of 871 HIV-infected and 439 HIV-uninfected women, 85% had a history of smoking and 50% a history of injection drug use. For our analysis, 4,180 person-years were contributed by HIV-infected women, and 2,308 person-years by HIV-uninfected women. HIV-infected women had 8 non-Hodgkin's lymphomas, 5 invasive cervical cancers (ICC), 1 Kaposi's sarcoma and 12 non-AIDS defining cancers, including 4 lung cancers, compared with 4 cancers in HIV-uninfected women including 1 lung cancer (all cancers, 6.22/1000 person-years vs. 1.73/1000 person-years, p = 0.01). CD4+ cell counts were above 200/mm3 in all women with ICC. HIV-infected women with lung cancer were young smokers (mean age, 40 years), and all died within 6 months of diagnosis. Lung cancer occurred at twice the rate in HIV-infected vs. uninfected women in the cohort and severalfold above expected in age- and race-matched women in U.S. national data (incidence relative risk 6.39; 95% confidence interval 3.71, 11.02; p < 10(-7)). The frequent occurrence of cervical and lung cancers have important implications for the counseling (cigarette cessation), screening (PAP smears) and care of women with HIV infection, as they live longer because of current antiretroviral therapies.

Adolescent↗