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Biomedical subjects

E J van Ameijden

Publications and source records attributed to E J van Ameijden.

At least 19 recordsLinked to original sources
PubMed2001

Evaluation of hepatitis C antibody testing in saliva specimens collected by two different systems in comparison with HCV antibody and HCV RNA in serum.

Two different ELISA assays, the Ortho HCV 3.0 ELISA (Ortho Diagnostics Systems) and the Mono-Lisa anti-HCV Plus (Sanofi Diagnostics Pasteur) were evaluated for the detection of hepatitis C virus (HCV) antibody in saliva samples. Specimens were collected from 152 individuals who participated in a longitudinal cohort study on HIV infection, and who used illicit drugs. Saliva specimens were collected using two different systems: Salivette (Sarstedt) and Omni-Sal (Saliva Diagnostic Systems). Saliva specimens were tested following modified protocols by both ELISAs, and the results were compared with serum specimens that were tested according to the instructions of the manufacturer. Serum samples of 102 (67%) participants were positive by both assays, and 50 persons were negative for HCV antibody. A total of 99 of the 102 serum specimens were confirmed as positive using Ortho Riba HCV 3.0 (Ortho Diagnostics System) and Deciscan HCV (Sanofi Diagnostics Pasteur), and 3 yielded discrepant results. As no cut-off level is known for testing saliva samples by ELISA, 3 different levels were chosen: mean (M) + 1 standard deviation (SD), M + 2 SD, and M + 3 SD of the optical densities of saliva tests of the 50 HCV serum antibody negative persons. At a level of M + 1 SD and M + 2 SD the Salivette/Mono-Lisa combination gave the greatest proportion of HCV antibody positive saliva specimens obtained from the 102 HCV serum antibody positive participants, 88% and 79%, respectively. Differences between the various collection systems and assay combinations were not significant statistically. In 76 of the 102 persons with HCV antibodies in serum, HCV RNA was detected in serum. Salivary presence of HCV RNA, however, could not be demonstrated. The results show that the assays compared are unsuitable for diagnostic use, but the sensitivities of the assays are acceptable for use in epidemiological studies.

Adult↗
PubMed2001

Risk factors of HIV infection and needle sharing among injecting drug users in Ho Chi Minh City, Vietnam.

OBJECTIVE: We sought to identify risk factors for needle sharing and HIV infection among injecting drug users (IDUs) in Ho Chi Minh City (HCMC), Vietnam. METHODS: Three cross-sectional surveys among IDUs, both on the street (in 11 urban districts) and in the rehabilitation center for IDUs in HCMC, were carried out in April of 1995, 1997, and 1998. Outreach workers interviewed IDUs about socio-demographic characteristics, drug use and sexual practices, and HIV knowledge and perceptions. The IDUs were also tested for seropositivity to HIV. Independent predictors for HIV positivity and needle sharing were determined by univariate and multivariate logistic regression for the study sample within the rehabilitation center in 1997 and for that on the street in 1998. RESULTS: The HIV prevalence in 1998 among IDUs was 44% for those on the street and 38.5% for those in the rehabilitation center. Independent predictors for HIV infection in IDUs were being injected by drug dealers (for the 1997 sample), injecting on the street, and sharing the drug pots (for the 1998 sample). The reported rate of needle sharing was low and decreased significantly from 20% in 1995 to 12% in 1998 for the sample of IDUs at the street. In the multivariate analysis, predictors for needle sharing for both study samples were injecting on the street, injecting at shooting galleries, and having shared needles in the past. Adequate and easy access to sterile needles and syringes, and a supportive environment of behavior change, especially in street and shooting gallery could reduce risks of virus transmission in the Vietnamese IDU community.

Adult↗
PubMed2001

Large decline in injecting drug use in Amsterdam, 1986-1998: explanatory mechanisms and determinants of injecting transitions.

OBJECTIVES: To study community wide trends in injecting prevalence and trends in injecting transitions, and determinants. DESIGN: Open cohort study with follow up every four months (Amsterdam Cohort Study). Generalised estimating equations were used for statistical analysis. SETTING: Amsterdam has adopted a harm reduction approach as drug policy. PARTICIPANTS: 996 drug users who were recruited from 1986 to 1998, mainly at methadone programmes, who paid 13620 cohort visits. MAIN RESULTS: The prevalence of injecting decreased exponentially (66% to 36% in four to six monthly periods). Selective mortality and migration could maximally explain 33% of this decline. Instead, injecting initiation linearly decreased (4.1% to 0.7% per visit), cessation exponentially increased (10.0% to 17.1%), and relapse linearly decreased (21.3% to 11.8%). Non-injecting cocaine use (mainly pre-cooked, comparable to crack) and heroin use strongly increased. Trends were not attributable to changes in the study sample. CONCLUSIONS: Harm reduction, including large scale needle exchange programmes, does not lead to an increase in injecting drug use. The injecting decline seems mainly attributable to ecological factors (for example, drug culture and market). Prevention of injecting is possible and peer-based interventions may be effective. The consequences of the recent upsurge in crack use requires further study.

Adult↗
PubMed2001

The impact of harm-reduction-based methadone treatment on mortality among heroin users.

OBJECTIVES: The purpose of this study was to investigate the impact of harm-reduction-based methadone programs on mortality among heroin users. METHODS: A prospective cohort investigation was conducted among 827 participants in the Amsterdam Cohort Study. Poisson regression was used to identify methadone maintenance treatment characteristics (dosage, frequency of program attendance, and type of program) that are significantly and independently associated with mortality due to natural causes and overdose. RESULTS: From 1985 to 1996, 89 participants died of natural causes, and 31 died as a result of an overdose. After adjustment for HIV and underweight status, there was an increase in natural-cause mortality among subjects who left methadone treatment (relative risk [RR] = 2.38, 95% confidence interval [CI] = 1.28, 4.55). Leaving treatment was also related to higher overdose mortality, but only among injection drug users (RR = 4.55, 95% CI = 1.89, 10.00). CONCLUSIONS: Harm-reduction-based methadone treatment, in which the use of illicit drugs is tolerated, is strongly related to decreased mortality from natural causes and from overdoses. Provision of methadone in itself, together with social-medical care, appears more important than the actual methadone dosage.

Adult↗
PubMed2000

Prevalence, incidence and risk factors of anaemia in HIV-positive and HIV-negative drug users.

AIMS: To determine the prevalence of anaemia among HIV-positive and -negative drug users, estimate the incidence of anaemia among HIV-positive drug users and study risk factors for prevalent anaemia with emphasis on HIV infection, gender and drug use behaviour. DESIGN, SETTING AND PARTICIPANTS: Cross-sectional study among HIV-positive and HIV-negative drug users (n = 360) and a longitudinal study among HIV-positive drug users (n = 175, 860 visits) participating in a cohort study of drug users in Amsterdam. MEASUREMENTS: Self-reported data on socio-demographics, drug use behaviour and zidovudine and protease inhibitor therapy on regular cohort visits. Laboratory determinations of haemoglobin concentration, CD4(+)-cell counts and HIV-1 RNA. FINDINGS: The prevalence of anaemia was 21.1% among participating drug users according to the WHO definition. The incidence of anaemia in HIV-positive individuals was 33.0/100 person-years. The main risk factor for anaemia was high frequency of injecting drugs. A Quetelet body mass index < or = 20 and female gender were also positively and significantly related to anaemia in the cross-sectional study. In the longitudinal study among HIV-positive drug users progression of HIV infection indicated by low CD4(+)-cell count and AIDS diagnosis were predictive of anaemia. CONCLUSION: The results indicate that drug users in the Amsterdam cohort study have a high prevalence of anaemia, which can be explained mainly by high frequency of injecting drugs and HIV infection progression. Reduction or cessation of injecting drug use should reduce anaemia.

Adult↗
PubMed2000

Methadone maintenance and cessation of injecting drug use: results from the Amsterdam Cohort Study.

AIMS: To assess relationships between characteristics of methadone maintenance treatment and long-term cessation of injecting (> or = 1 year). DESIGN AND PARTICIPANTS: The incidence of cessation of injecting and relapse from non-injecting to injecting was estimated among 488 participants of the Amsterdam cohort study among drug users. We used a nested matched case-control design to identify methadone treatment characteristics significantly and independently related to cessation of injecting. To ensure detailed and valid assessment of methadone treatment, data of the Central Methadone Register were linked with cohort data. For 339 of 488 subjects of the initial study group methadone data were available. FINDINGS: The incidence of cessation of injecting increased from 2.2/100 person years in 1985-89 to 5.5/100 per year in 1995-97 (Ptrend = 0.005). Relapse to injecting was high: 17.2/100 person years (no trend). Methadone dosage and frequency of methadone programme attendance in themselves were not significantly related to cessation of injecting. However, an individual increase of 5 mg or more per year (OR 4.20, 95% CI 1.54-11.46) and receiving methadone mainly via the outpatient clinic for drug-abusing prostitutes and foreigners (OR 0.18, 95% CI 0.05-0.59) were independent predictors of cessation of injecting. After cessation of injecting, there were no HIV-seroconversions during the period of non-injecting (129 person years). After relapse to injecting there was one seroconverter; however, follow-up was small (23 person years). The HIV-incidence of those who continued injecting was 3.2/100 per year. CONCLUSIONS: Steadily increasing the methadone dosage in a harm reduction setting may be useful in supporting injecting drug users in the process of cessation of injecting and reducing the spread of HIV-infection.

Adolescent↗
PubMed2000

How does tuberculosis relate to HIV positive and HIV negative drug users?

OBJECTIVES: (1) To compare the incidence of active tuberculosis in HIV positive and HIV negative drug users. (2) To describe the main characteristics of the tuberculosis cases. DESIGN: A prospective study was performed from 1986 to 1996 as part of an ongoing cohort study of HIV infection in Amsterdam drug users. METHODS: Data from the cohort study, including HIV serostatus and CD4-cell numbers, were completed with data from the tuberculosis registration of the tuberculosis department of the Amsterdam Municipal Health Service. Analyses were carried out with person time and survival methods. RESULTS: Of 872 participants, 24 persons developed culture confirmed tuberculosis during a total follow up period of 4000 person years (0.60 per 100 py, 95% CI: 0.40, 0.90). Nineteen cases were HIV positive (1.54 per 100 py, 95% CI: 0.86, 2.11) and five HIV negative (0.18 per 100 py, 95% CI: 0.08, 0.43). Multivariately HIV infection (relative risk: 12.9; 95% CI: 3.4, 48.8) and age above 33 years (RR: 6.8; 95% CI: 1.3, 35.0, as compared with age below 27) increased the risk for tuberculosis substantially. Additional findings were: (1) 13 of 22 pulmonary tuberculosis cases (59%) were detected by half yearly radiographic screening of the chest; (2) tuberculosis occurred relatively early in the course of HIV infection at a mean CD4 cell number of 390/microliter; (3) an estimated two thirds of the incidence of tuberculosis observed among HIV positive cases was caused by reactivation; (4) all but one patient completed the tuberculosis treatment. CONCLUSION: HIV infection increases the risk for active tuberculosis in Amsterdam drug users 13-fold. The incidence of tuberculosis in HIV negative drug users is still six times higher than in the overall Amsterdam population. In the absence of contact tracing and screening with tuberculin skin tests, periodic chest radiographic screening contributes substantially to early casefinding of active tuberculosis in Amsterdam drug users.

AIDS-Related Opportunistic Infections↗
PubMed1999

Methadone maintenance treatment modalities in relation to incidence of HIV: results of the Amsterdam cohort study.

STUDY OBJECTIVE: To evaluate methadone maintenance treatment modalities, prescribed within the concept of harm reduction, in relation to incidence of HIV infection among drug users with a history of methadone treatment in Amsterdam, The Netherlands. DESIGN: Prospective observational cohort study among 582 HIV-negative drug users. To ensure valid and detailed assessment of methadone treatment, data from the Central Methadone Register in Amsterdam were linked to the Amsterdam cohort study among drug users. METHODS: Poisson regression analysis was used to identify independent and significant predictors of incidence of HIV. MAIN RESULTS: During 1906 person years, 58 drug users seroconverted, the overall incidence of HIV being 3.0 per 100 person years with a declining trend for current injectors. An increase in frequency of methadone programme attendance [relative risk (RR), 2.4; 95% confidence interval (CI), 1.2-4.6, compared with no change] and increase in methadone dosage (RR, 0.8; 95% CI, 0.6-1.0, per category of change of 10 mg/day) were significantly associated with incidence of HIV in multivariate analysis. Methadone dosage and frequency of programme attendance in itself were not significant predictors. Other multivariate significant risk factors were homelessness, current injecting and in-patient hospital care. CONCLUSIONS: Among drug users who receive methadone maintenance treatment in a harm-reduction setting, which includes ancillary services such as needle-exchange programmes and HIV testing and counselling, prescription of high methadone dosages is not sufficient to stop the spread of HIV. However, an individual increase of the methadone dosage and measures to achieve high treatment retention could contribute to the prevention of HIV among drug users.

Adolescent↗
PubMed1999

HIV monitoring in Vietnam: system, methodology, and results of sentinel surveillance.

OBJECTIVE: To measure the prevalence of and trends in HIV infections in populations defined by sentinel surveillance in Vietnam. METHODS: Surveillance was conducted in eight provinces in 1994, expanded to 12 in 1995 and to 20 in 1996. Sentinel populations were sexually transmitted disease (STD) patients, female sex workers (FSW), injecting drug users (IDU), tuberculosis (TB) patients, pregnant women, and military conscripts. Samples were collected twice yearly for high-risk populations and once yearly for low-risk populations. RESULTS: The overall HIV epidemic in Vietnam comprises several different smaller epidemics. It is primarily associated with injecting drug use, but its extent varies widely throughout the country. In 1998, HIV prevalence rates ranged from 0 to 85% (median, 13.1%), with an aggregate prevalence rate (APR; i.e., the sum of HIV-positive study subjects divided by the sum of all study subjects tested in sentinel provinces) of 17% among IDUs; this ranged from 0 to 14.7% (median, 0.8%), with the APR of 2.4% among FSWs; and from 0 to 6% (median, 0%), with the APR of 0.9% among STD patients. The APRs among antenatal women and army conscripts were less than 0.15%. APRs increased significantly from 1994 to 1998 among STD patients (p < .001), FSWs (p < .001), TB patients (p < .001), and pregnant women (p < .05) in original sentinel provinces. HIV prevalence also increased significantly among younger age groups of IDUs and FSWs. CONCLUSION: Vietnam's HIV epidemic is increasing predominantly and most rapidly among IDUs. However, prevalence rates among FSWs and STD patients are rising but are still low among pregnant women and army conscripts. Vietnam, at present, is still in the early phase of the HIV epidemic and has time to take effective and appropriate actions.

Adolescent↗
PubMed1999

New evidence to reconcile in vitro and epidemiologic data on the possible role of heroin on CD4+ decline among HIV-infected injecting drug users.

Long-term effects of drug type and other drug use related risk factors on CD4+ cell decline were assessed in 224 HIV-infected injecting drug users (IDUs) from Baltimore (ALIVE), USA, and 63 IDUs from Amsterdam, The Netherlands. Higher frequencies of borrowing used injection equipment since 1980 resulted in a higher CD4+ count already present before seroconversion (P = 0.049). Use of mainly heroin in the seroconversion interval resulted in a sharper CD4+ decline until the first 6 months after seroconversion (P = 0.004), but CD4+ values converged later on. This finding might reconcile earlier discordant epidemiological and laboratory study results regarding the possible effects of heroin.

Adult↗
PubMed1999

The validity of drug users' self-reports in a non-treatment setting: prevalence and predictors of incorrect reporting methadone treatment modalities.

BACKGROUND: Epidemiological studies among drug users are often based on retrospective self-reports. However, among others, memory failure, being under the influence of drugs, psychopathology, misunderstanding of questions and socially desirable answering may generate inaccurate reporting. METHODS: This study validated self-reported current (methadone dosage) and medium-term (main location of methadone dispensing and frequency of methadone programme attendance over the previous 4-6 months) aspects of methadone treatment in the Amsterdam AIDS cohort study among drug users, using data of the Central Methadone Register. In addition to descriptive measures, logistic regression analysis was used (adjusted for intra-individual correlation) to identify subgroups with incorrect reporting. Data collected at 4406 visits of 505 cohort participants were analysed. RESULTS: Current methadone dosage was accurately reported (unweighted kappa [kappa]: 0.94, weighted kappa [kappa W]: 0.97). A low methadone dosage, short duration of school education and depressive or euphoric mood during the interview were significant and independent predictors of incorrect reporting of methadone dosage. For main location of dispensing kappa was 0.82, for frequency of programme attendance kappa was 0.53 and kappa W 0.87. There was a tendency to reporting the extreme answering categories. Infrequent programme attendance was the only significant predictor of incorrectly reporting frequency of programme attendance. CONCLUSIONS: Drug users are able to give valid self-reports in a setting where social desirability does not play an important role. The main reasons of incorrect reporting were impaired cognitive functioning, memory failure and misunderstanding of questions.

Adult↗
PubMed1999

Pre-AIDS mortality and morbidity among injection drug users in Amsterdam and Baltimore: an ecological comparison.

Mortality and morbidity between injecting drug users in Amsterdam (n = 624) and Baltimore (n = 2,185) are compared to generate a hypothesis about the role of different health care systems and drug user policies (universal care and harm reduction versus episodic care and criminalization, respectively). Overdose/suicide mortality was twofold higher in Amsterdam; no sufficient explanation was found. Other independent "risk factors" for overdose/suicide mortality were recent injecting, polydrug use, and HIV-seropositivity (especially with CD4 count < 200/mm3). High dose methadone maintenance was associated with lower mortality. Incidence of hospitalizations and emergency room visits was substantially lower in Amsterdam, suggesting that higher accessibility to primary care in Amsterdam lowers (inpatient) hospital visits and presumably societal costs.

Adult↗
PubMed1998

Body mass index course in asymptomatic HIV-infected homosexual men and the predictive value of a decrease of body mass index for progression to AIDS.

Weight loss is a common characteristic of advanced stages of HIV infection. Weight changes during the asymptomatic stage of HIV infection have not been well documented and the possible predictive value of early weight loss for progression to AIDS is unknown. In 122 HIV seroconverters, the natural course of body mass index (BMI) following seroconversion was studied. No BMI decline was seen immediately following seroconversion. In the 56 AIDS cases, however, a steep BMI decline of 1.14 kg/m2 occurred 6 months before AIDS. This BMI decline was more pronounced in those with low CD4+ T cell counts (<100 x 10(6)/L) at the time of AIDS diagnosis (1.8 kg/m2). The relative hazard for progression to AIDS of a BMI decline of 1.14 kg/m2 per 6 months was 3.1, which remained similar after adjustment for CD4 count and p24 antigenemia. We conclude that the course of BMI in HIV-1 infection is biphasic: a relatively stable period is followed by a rapid decline in the 6 months preceding onset of AIDS. Furthermore, we found that this steep BMI decline was associated with faster progression to AIDS.

Adult↗
PubMed1998

The incubation period to AIDS in injecting drug users estimated from prevalent cohort data, accounting for death prior to an AIDS diagnosis.

OBJECTIVE: To estimate the incubation-period distribution (time from seroconversion to AIDS) accounting for death before an AIDS diagnosis (DBAD) in a cohort of injecting drug users (IDU) in Amsterdam, The Netherlands and to compare these estimates with those previously obtained from a contemporaneous study of homosexual and bisexual men in Amsterdam carried out using the same facilities. DESIGN: Participants in a cohort study begun in Amsterdam at the end of 1985 have scheduled follow-up visits every 4 months. All participants of Dutch nationality and who had two or more follow-up visits before January 1996 from which CD4 measurements were available were included in this study. Data concerning AIDS diagnosis and death were verified through review of national and municipal registries. METHODS: Because time of seroconversion was unknown for study participants and because IDU are at substantial risk for DBAD, we used a Markov model with CD4-based stages that allows for DBAD. The parameters in this model were estimated using the method of maximum likelihood and confidence intervals were calculated using bootstrap methods. RESULTS: A total of 173 IDU (134 seroprevalent, 39 seroincident) made 1829 visits. Nearly 10% of the visits were non-consecutive. Forty-five IDU developed AIDS and 25 died without an AIDS diagnosis. We estimated that 24% [95% confidence interval (CI), 17-25%] of IDU die before an AIDS diagnosis. As a result, the median time from seroconversion to AIDS (10.5 years; 95% CI, 9.1-10.7 years) is considerably longer than the median time from seroconversion to death (8.3 years; 95% CI, 7.9-8.5 years). Conditional on survival to an AIDS diagnosis, the median time to AIDS is 8.2 years (95% CI, 7.7-8.7 years). The median survival time after a diagnosis of AIDS is estimated to be 1.0 years. CONCLUSION: The high occurrence of DBAD in IDU has a considerable influence on estimates of the incubation-period distribution. Progression from seroconversion to death was faster in the IDU cohort than in a cohort of homosexual men in Amsterdam (median, 8.3 years and 9.6 years, respectively). However, progression to AIDS conditional on survival to an AIDS diagnosis seems to be similar in both the IDU cohort and in the cohort of homosexual men (median, 8.2 years and 8.3 years, respectively).

Acquired Immunodeficiency Syndrome↗