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S A Strathdee

Publications and source records attributed to S A Strathdee.

At least 37 records · Page 2Linked to original sources
PubMed2001

Therapy naivete in the era of potent antiretroviral therapy.

Antiretroviral therapy (ART) use was examined in a cohort of homosexual men infected with HIV-1 for long periods. Multivariate logistic regression models, stratified by clinical indication (below and above 500 CD4 cells/microl or prior AIDS), were used to determine predictors of ART naivete. Of the 673 men seen at visit 28 (10/97-4/98), 89 (13.2%) never used ART and 548 (81.4%) were current users; 55% of the therapy-naive were ART eligible. Lower CD4 cell counts predicted (P <.001) ART use. Determinants of therapy naivete differed by clinical indication. African-American race and no prior ambulatory visit predicted (P <.05) ART naivete in men with > or =500 CD4 cells/microl. Among those with clinical indications, less education, younger age, multiple sexual partners, and no prior ambulatory visit significantly predicted ART naivete. In this era of effective ART, use was not universal. Besides disease markers, these nonclinical determinants need to be considered for promoting population therapy effectiveness.

Adult↗
PubMed2001

Factors associated with adolescent initiation of injection drug use.

OBJECTIVE: The purpose of this study was to evaluate the extent to which demographic, sexual, and non-injection drug use practices predict adolescent initiation of injection drug use. METHODS: Street recruited injection drug users 15-30 years of age in Baltimore, Maryland, who initiated injection within five years of study enrollment, completed a questionnaire that included a year-by-year history regarding the five years prior to initiation of injection. Factors associated with initiation during adolescence (< or = 21 years of age) versus young adulthood (>21 ) were determined using logistic regression. RESULTS: Of 226 participants, most were female (61%) and African American (64%). Median age of participants was 25; median age at initiation of injection was 23. Factors significantly associated with adolescent initiation in multivariate analysis included race other than African American, and practices prior to initiating injection including condom use, lack of cocaine use, exclusive crack smoking just prior to initiation, and smoking marijuana. Adolescent initiates also had shorter durations of illicit drug use prior to initiating injection. CONCLUSION: Short-term non-injection drug use, particularly exclusive crack smoking, was associated with adolescent initiation of injection drug use. Early prevention efforts targeting this high-risk group of younger drug users are warranted in order to delay or prevent onset of injection drug use.

Adolescent↗
PubMed2001

Human immunodeficiency virus seroconversion and evolution of the hepatitis C virus quasispecies.

When chronic hepatitis C virus (HCV) infections are complicated by acquisition of human immunodeficiency virus (HIV), liver disease appears to accelerate and serum levels of HCV RNA may rise. We hypothesized that HIV might affect the HCV quasispecies by decreasing both complexity (if HIV-induced immunosuppression lessens pressure for selecting HCV substitutions) and the ratio of nonsynonymous (d(N)) to synonymous (d(S)) substitutions, because d(N) may be lower (if there is less selective pressure). To test this hypothesis, we studied the evolution of HCV sequences in 10 persons with chronic HCV infection who seroconverted to HIV and, over the next 3 years, had slow or rapid progression of HIV-associated disease. From each subject, four serum specimens were selected with reference to HIV seroconversion: (i) more than 2 years prior, (ii) less than 2 years prior, (iii) less than 2 years after, and (iv) more than 2 years after. The HCV quasispecies in these specimens was characterized by generating clones containing 1 kb of cDNA that spanned the E1 gene and the E2 hypervariable region 1 (HVR1), followed by analysis of clonal frequencies (via electrophoretic migration) and nucleotide sequences. We examined 1,320 cDNA clones (33 per time point) and 287 sequences (median of 7 per time point). We observed a trend toward lower d(N)/d(S) after HIV seroconversion in 7 of 10 subjects and lower d(N)/d(S) in those with rapid HIV disease progression. However, the magnitude of these differences was small. These results are consistent with the hypothesis that HIV infection alters the HCV quasispecies, but the number of subjects and observation time may be too low to characterize the full effect.

Adult↗
PubMed2000

Prevalence of type 2 diabetes mellitus among persons with hepatitis C virus infection in the United States.

BACKGROUND: Hepatitis C virus (HCV) infection may contribute to the development of diabetes mellitus. This relationship has not been investigated at the population level, and its biological mechanism remains unknown. OBJECTIVE: To examine the prevalence of type 2 diabetes among persons with HCV infection in a representative sample of the general adult population of the United States. DESIGN: Cross-sectional national survey. SETTING: The Third National Health and Nutrition Examination Survey, 1988-1994. PARTICIPANTS: 9841 persons older than 20 years of age for whom data on HCV infection and diabetes were complete. MEASUREMENTS: The presence of diabetes was ascertained by using American Diabetes Association guidelines based on fasting plasma glucose measurement and medication history. Presence of HCV infection was assessed by testing for serum HCV-specific antibodies (anti-HCV). RESULTS: Of the 9841 persons evaluated, 8.4% had type 2 diabetes and 2.1% were anti-HCV positive. Type 2 diabetes occurred more often in persons who were older, were nonwhite, had a high body mass index, and had low socioeconomic status. Type 2 diabetes was less common in persons who acknowledged previous illicit drug use. After adjustment for these factors, persons 40 years of age or older with HCV infection were more than three times more likely than those without HCV infection to have type 2 diabetes (adjusted odds ratio, 3.77 [95% CI, 1.80 to 7.87]). None of the 19 persons with type 1 diabetes were anti-HCV positive. CONCLUSION: In the United States, type 2 diabetes occurs more often in persons with HCV infection who are older than 40 years of age.

Adult↗
PubMed2000

Correlates of enrollment in methadone maintenance treatment programs differ by HIV-serostatus.

OBJECTIVES: To identify correlates of enrollment in methadone maintenance treatment programs (MMTP) among a prospective cohort of injection drug users (IDUs) in Baltimore, Maryland. METHODS: A total of 1480 IDUs undergoing semi-annual HIV tests and interviews were studied between 1994 and 1998, during which time a needle exchange program was introduced. Longitudinal analysis using generalized estimating equations was used to identify correlates of MMTP participation over time. RESULTS: Although similar proportions of HIV-seropositive and -seronegative IDUs enrolled in MMTP during follow-up (26 versus 22%, respectively), correlates of enrollment differed by HIV-serostatus. Among HIV-seropositive participants, older age [adjusted odds ratio (AOR, 1.37)] was associated with enrollment in MMTP. Among HIV-seronegative IDUs, factors associated with not enrolling in MMTP were being African American (AOR, 0.22) and having been recently incarcerated (AOR, 0.62) or homeless (AOR, 0.72). In both groups, females were twice as likely to be enrolled in MMTP, and those with Medicaid were 1.5 times more likely to be enrolled. When behavioral factors were lagged one visit, needle exchange program attendance was positively associated with MMTP enrollment among HIV-negative IDUs (AOR, 2.10); however, this association diminished significantly over time as dedicated treatment slots for needle exchange program participants became saturated. CONCLUSIONS: These findings underscore the need to improve access to MMTP, especially to certain subgroups such as African-Americans, the homeless, incarcerated and uninsured. Our data suggest that health care providers and needle exchange programs can facilitate enrollment into MMTP provided that adequate treatment slots are consistently available to this particularly vulnerable population.

Adult↗
PubMed2000

Short tandem repeat methodology for genotypic identification of single-person versus multi-person use of syringes.

OBJECTIVE: To develop laboratory methods to differentiate between single- versus multi-person use of syringes by injection drug users. METHODS: Forensic short tandem repeat (STR) genetic analysis was undertaken to cross-validate a test panel of trace blood contents from syringes representing single- versus multi-person syringe use. Laboratory-simulated scenarios of needle sharing generated 34 syringe washes that were blinded for evaluation. Polymerase chain reaction was used to amplify the polymorphic STR locus D6S502 from blood trace contents in used syringes. Alleles were sized and quantified using a commercial gene sequencer. A statistical algorithm was developed to determine the number of alleles present in the amplified DNA fragments. Syringes with more than two expected alleles were considered to represent multi-person syringe use. Sensitivity, specificity and the kappa coefficient were calculated. RESULTS: Allelic matrix-based analysis of alleles from the single STR successfully characterized single-use (n = 12) and multiple-use (n = 22) syringes with 68% sensitivity and 100% specificity upon re-analysis. The extent of agreement over and above chance (kappa = 0.6; P < 0.0001) indicated good agreement for differentiating single- versus multi-person syringe use. CONCLUSIONS: These findings suggest that improved genotypic STR analysis of syringe material could be an adjunct to methods for validating self-reported needle sharing, conducting behavioral surveillance of needle-sharing behaviors, and evaluating interventions such as needle-exchange programs. Assays based on multiple STR loci will undoubtedly improve upon the promising results obtained from laboratory simulations of needle sharing.

Alleles↗
PubMed2000

The natural history of hepatitis C virus infection: host, viral, and environmental factors.

CONTEXT: Hepatitis C virus (HCV) infection may resolve (viral clearance), persist without complications, or cause end-stage liver disease (ESLD). The frequency and determinants of these outcomes are poorly understood. OBJECTIVE: To assess the incidence and determinants of viral clearance and ESLD among persons who acquired HCV infection from injection drug use. DESIGN AND SETTING: Community-based prospective cohort study with enrollment in 1988-1989 and a median follow-up of 8.8 years. SUBJECTS: A total of 1667 persons aged 17 years or older with a history of injection drug use and an HCV antibody-positive test result during follow-up. MAIN OUTCOME MEASURES: Viral clearance was assessed in a subset of 919 patients and defined as failure to detect HCV RNA in at least 2 consecutive samples collected 5 or more months apart. End-stage liver disease was assessed at semiannual visits and by review of medical records and death certificates and defined by the presence of ascites, esophageal varices, or hepatic encephalopathy, or when ESLD was stated as a cause of death. RESULTS: Viral clearance was observed in 90 persons who were compared with 722 with persistent viremia, while the viremia of 107 was not resolved. Viral clearance occurred more often in nonblacks (adjusted odds ratio [OR], 5.15; 95% confidence interval [CI], 2.60-10.17) and those not infected with human immunodeficiency virus (HIV) (adjusted OR, 2.19; 95% CI, 1.26-3.47). Forty cases of ESLD were observed throughout follow-up (incidence, 3.1 per 1000 person-years). In a multivariate model, risk of ESLD was higher for persons aged 38 years or older at enrollment (adjusted relative incidence, 3.67; 95% CI, 1.96-6.88) and who reported ingestion of more than 260 g of alcohol per week (adjusted relative incidence, 3.60; 95% CI, 1.73-7.52). Of 210 patients without ESLD randomly selected for biopsy, only 2 had cirrhosis. CONCLUSIONS: Our results indicate that although HCV infection can be self-limited or associated with ESLD, the majority of adults have persistent viremia without clinically demonstrable liver disease. Further research is needed to explain the less frequent clearance of HCV infection among black persons and to improve utilization of treatment for those infected in the context of injection drug use. JAMA. 2000;284:450-456

Adult↗
PubMed2000

Comparing new participants of a mobile versus a pharmacy-based needle exchange program.

OBJECTIVE: To compare characteristics of first-time needle exchange participants who enrolled at a mobile van-based exchange site versus a fixed pharmacy-based exchange site, in an area where both types of needle exchange programs were available. METHODS: Demographic and drug use data were collected on needle exchange program participants on enrollment. Participants were included if they were first-time participants at the Baltimore needle exchange program between December 1997 and March 1999, and if their first visit was at either one van-based site or at one of two pharmacy-based sites. Descriptive statistics and inferences were based on the type of needle exchange into which participants enrolled. RESULTS: Among 286 first-time participants, 92% were African American, 28% were women, 11% were currently employed, 55% completed high school, and the median age was 40 years. In multivariate analyses, van-based enrollment was more common among frequent injectors (odds ratio [OR] = 2.0), but less common among African American participants (OR = 0.21). CONCLUSIONS: Our data suggest that different venues for needle exchange program settings attract different types of drug injecting participants. This suggests that offering different venue types to reach participants with differing drug use patterns will be important to optimize risk reduction strategies.

Adult↗
PubMed2000

Comparison of sexual behaviors, unprotected sex, and substance use between two independent cohorts of gay and bisexual men.

OBJECTIVE: To compare demographic characteristics, sexual practices, unprotected receptive and insertive anal intercourse, substance use and rates of HIV-1 seroconversion between two prospective cohorts of HIV-negative men who have sex with men. DESIGN: Comparative analysis of two independent cohorts. METHODS: Between May 1995 and April 1996, 235 HIV-negative Vanguard Project (VP) participants were enrolled and between January and December 1985, 263 HIV-negative participants in the Vancouver Lymphadenopathy AIDS Study (VLAS) completed a follow-up visit. The VP participants were compared with VLAS participants with respect to self-reported demographic variables, sexual behaviors, unprotected sex, substance use and rates of HIV-1 seroconversion during follow-up. RESULTS: In comparison with the VLAS participants the VP participants were younger (median age, 26 versus 34 years; P< 0.001), more likely to be non-Caucasian (75 versus 97%; P< 0.001), and were less likely to have attended university/college (35 versus 46%; P = 0.014). The VP participants reported a higher mean number of male sex partners in the previous year (15 versus 12; P= 0.026) and a higher mean number of regular partners (1.7 versus 0.6; P < 0.001). The VP participants were more likely to report engaging in receptive (92 versus 60%; P< 0.001) and insertive (90 versus 69%; P < 0.001) anal intercourse with regular partners and receptive anal intercourse with casual partners (62 versus 38%; P< 0.001). The VLAS participants were more likely to report never using condoms during insertive and receptive anal intercourse with both regular and casual partners. The VP participants were less likely to report using nitrite inhalants (34 versus 43%; P= 0.033), but more likely to report the use of cocaine (30 versus 8%; P< 0.001), LSD (21 versus 3%; P < 0.001), amphetamine (11 versus 1%; P< 0.001), heroin (3 versus 0%; P= 0.010) and methyldiamphetamine (17 versus 10%; P= 0.034). The VLAS participants were nine times more likely to report high-risk sexual behavior, after controlling for differences in age, ethnicity, substance use, and method of recruitment between cohort members. After adjustment for differences in demographics, sexual behaviors, and level of substance use, the risk ratio for seroconversion among VLAS participants remained significantly elevated compared with VP participants. CONCLUSION: These data provide evidence that men who have sex with men who were enrolled in the VP were more sexually active than their VLAS counterparts were 10 years ago as measured by self-reported numbers of regular and casual partners and frequency of anal intercourse with these partners. However, condom use appears to be significantly higher among VP participants, which has contributed to a lower rate of HIV-1 infection.

Adolescent↗
PubMed2000

HIV infection and risk behaviours among young gay and bisexual men in Vancouver.

BACKGROUND: Young gay and bisexual men may perceive that the consequences of HIV infection have dramatically improved with the availability of highly active antiretroviral therapy. We therefore sought to identify trends in HIV infection rates and associated risk behaviours among young gay and bisexual men in Vancouver. METHODS: Prospective cohort study involving gay and bisexual men aged 18-30 years who had not previously tested HIV positive. Subjects were recruited through physicians, clinics and community outreach in Vancouver. Annually participants were tested for HIV antibodies and asked to complete a self-administered questionnaire pertaining to sociodemographic characteristics, sexual behaviours and substance use. Prevalence of HIV infection and risk behaviours were determined for eligible participants who completed a baseline questionnaire and HIV testing as of May 1998. The primary outcome was the proportion of men who reported having protected sex during the year before enrollment and who reported any episode of unprotected sex by the time of the first follow-up visit. RESULTS: A total of 681 men completed a baseline questionnaire and HIV testing as of May 1998. The median duration between baseline and the first follow-up visit was 14 months. The median age was 25 years. Most of the subjects were white and of high socioeconomic status. The majority (549 [80.6%]) reported having sex only with men; 81 (11.9%) reported bisexual activity. Of the 503 men who had one or more regular male partners, 245 (48.7%) reported at least one episode of unprotected anal sex in the year before enrollment; the corresponding number among the 537 who had one or more casual male partners was 140 (26.1%). The prevalence and incidence of HIV seropositivity were 1.8% (95% confidence interval [CI] 0.8%-2.8%) and 1.7 per 100 person-years [95% CI 0.7-2.7], respectively. Fifty-two (26.5%) of the 196 and 55 (29.7%) of the 185 men with regular partners who reported having practiced protected insertive and receptive anal sex in the year before the baseline visit reported engaging in these activities without a condom at the follow-up visit; the corresponding numbers among the 232 and 242 men with causal partners who had practiced protected insertive and receptive anal sex before the baseline visit were 43 (15.5%) and 26 (9.4%) respectively at follow-up. INTERPRETATION: The incidence of HIV infection is unacceptably high among this cohort of young gay and bisexual men. Preliminary results suggest a disturbing trend toward increasing levels of unprotected anal intercourse.

Adult↗
PubMed2000

The prevalence of homelessness among injection drug users with and without HIV infection.

Cross-sectional investigations of homelessness have many potential biases. Data from 2,452 individuals enrolled in a longitudinal cohort study of Baltimore, Maryland, residents recruited in 1988-1989 with a history of injection drug use were analyzed to identify the extent and determinants of homelessness. Proportions having ever experienced homelessness were compared across subgroups of injection drug users (IDUs) who were human immunodeficiency virus (HIV) negative, HIV positive, and HIV seroconverting. Logistic regression identified independent predictors of homelessness. In the cohort, 1,144 (46.7%) participants experienced homelessness during the course of the study. There were differences in prevalence of homelessness by serostatus: 42.4% (n = 621) of participants who remained HIV negative were ever homeless, while 50.6% (n = 346) of HIV-infected individuals and 58.9% (n = 178) of those who seroconverted during the study were ever homeless (P < .001). Participants who consistently denied active injection drug use during follow-up were unlikely to experience homelessness (19%). Independent predictors of homelessness were male sex, HIV seroprevalence, and HIV seroconversion. Following participants over time captures more experiences of homelessness than cross-sectional studies and more accurately identifies risk characteristics. Our data suggest that homelessness is a significant problem among IDUs, especially those with HIV/AIDS.

Adolescent↗
PubMed2000

Characteristics and utilization patterns of needle-exchange attendees in Chicago: 1994-1998.

The objectives of this study were to describe characteristics and utilization patterns of participants attending a needle-exchange program (NEP) in Chicago, Illinois. Since 1994, demographics of NEP attendees and program utilization data were collected systematically at 22 sites operated by the Chicago Recovery Alliance (CRA). Descriptive statistics were used to assess time trends, site variations, and characteristics of attendees in day sites versus evening sites. A total of 11,855 injection drug users (IDUs) visited the NEP at least once from 1994 to 1998. Median age was 41 years, and 74% were male. Overall race distribution was African-American 50%, Caucasian 38%, Puerto Rican 10%, other 2%. Over time, there was a proportional decrease in African-American users (55.4% to 39.9%, P < .001), a significant increase in Puerto Rican users (1.4% to 14.1%, P < .001), and a stable proportion of Caucasian users (42%). Each year, 15-20% of all clients were first-time attenders. Overall, participants attending evening versus day sites were younger (median age 39 years vs. 42 years, P < .001) and more ethnically diverse. Over a 4-year period, this NEP reached a diverse population of IDUs and recruited a stable proportion of first-time users. Compared to daytime NEP venues, evening NEP sites attracted younger clients and those who were more diverse ethnically. To maximize coverage of sterile syringes, NEPs should strive for diversification in terms of hours of operation and location.

Adult↗
PubMed2000

Evaluating effectiveness of syringe exchange programmes: current issues and future prospects.

Although a large body of international literature has found syringe exchange programmes (SEPs) to be associated with reduced incidence of blood borne pathogens among injection drug users, recent studies have fuelled controversy surrounding SEP effectiveness. Existing studies are observational in nature and have seldom considered ecologic aspects affecting SEP functioning and evaluation. The authors apply concepts from infectious disease epidemiology to discuss the direct and indirect effects of SEP upon the spread of blood borne pathogens in drug users, their social networks and the broader community. Further, the authors discuss social policies, particularly drug control policies, which have directly and/or indirectly limited SEP functioning at local and national levels. A critical review of the literature suggests that biases common to observational studies can account for higher HIV incidence among SEP attenders relative to non-attenders. Strong selection factors often lead high-risk drug users to be over-represented among SEP attenders. Failure to account for these factors and the indirect effects of SEPs can bias interpretations of programme effectiveness. Future SEP evaluations should consider behavioural data, the local ethnographic context, the prevalence of infectious disease in the groups under study and the structural components of SEP that are most and least effective at reducing incidence of blood borne pathogens. Hierarchical models that take into account the ecological dimensions of SEP are recommended as an approach for future studies. Beyond methodologic concerns, the authors discuss social, legal and programmatic obstacles that must be overcome in order to maximise SEP effectiveness.

Blood-Borne Pathogens↗
PubMed2000

Determinants of the quantity of hepatitis C virus RNA.

To test the hypothesis that person-to-person variability in blood levels of hepatitis C virus (HCV) RNA can be explained, the quantity of HCV RNA was assessed in 969 persons who acquired HCV infection in the context of injection drug use. Serum HCV RNA levels ranged from 200,000 to >120 million equivalents/mL (the linear range of the assay). The median log10 HCV RNA level was 0.46 higher in 468 human immunodeficiency virus (HIV)-positive persons than in 501 HIV-negative persons (P<.001). In addition, among HIV-negative persons, lower HCV RNA levels were independently associated with younger age (P<.001), ongoing hepatitis B infection (P=.005), and the absence of needle sharing (P=.02). However, >90% of the person-to-person HCV RNA level variability was not explained by these sociodemographic, environmental, and virologic factors. Additional research is necessary to ascertain what determines the level of HCV RNA in blood.

Adult↗