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Biomedical subjects

M Hickman

Publications and source records attributed to M Hickman.

At least 19 recordsLinked to original sources
PubMed2007

Modelling the impact on Hepatitis C transmission of reducing syringe sharing: London case study.

BACKGROUND: Hepatitis C virus (HCV) prevalence and incidence among injecting drug users (IDUs) has increased in London and rest of UK. To inform public health action, mathematical modelling is used to explore the possible impact of strategies to decrease syringe sharing. METHODS: A mathematical model was developed to simulate HCV transmission amongst IDUs in London. Because of parameter uncertainty, numerical search algorithms were used to obtain different model fits to HCV seroprevalence data from London for 2002-03. These simulations were used to explore the likely impact of HCV prevention activities that reduce syringe sharing amongst all IDUs, IDUs that have injected for greater than one year, or IDUs with lower or higher frequencies of syringe sharing. RESULTS: Key differences between model fits centred on how they simulated the high HCV incidence amongst new injectors, either through assuming increased HCV infectivity during acute infection, a large sub-group of high frequency syringe sharers, or increased sharing among new IDUs. Despite parameter uncertainty, the model projections suggest that modest reductions in syringe sharing frequency (<25%) will reduce the HCV seroprevalence in newly initiated IDUs (injecting less than four years) but much larger and sustained reductions (>50%) are required to reduce the HCV seroprevalence in long-term IDUs (injecting more than 8 years). Critically the model also suggested that large reductions in HCV seroprevalence will be achieved only if interventions target all IDUs and reach IDUs within 12 months of injecting. DISCUSSION: Public health interventions must reduce syringe sharing amongst all IDUs, including newly initiated IDUs, and be sustained for many years to reduce HCV infection. More accurate data on key behavioural (sharing frequency) and biological (percentage of infected IDUs that clear infection) parameters is required to improve model projections.

Female↗
PubMed2006

Modelling the force of infection for hepatitis B and hepatitis C in injecting drug users in England and Wales.

BACKGROUND: Injecting drug use is a key risk factor, for several infections of public health importance, especially hepatitis B (HBV) and hepatitis C (HCV). In England and Wales, where less than 1% of the population are likely to be injecting drug users (IDUs), approximately 38% of laboratory reports of HBV, and 95% of HCV reports are attributed to injecting drug use. METHODS: Voluntary unlinked anonymous surveys have been performed on IDUs in contact with specialist agencies throughout England and Wales. Since 1990 more than 20,000 saliva samples from current IDUs have been tested for markers of infection for HBV, HCV testing has been included since 1998. The analysis here considers those IDUs tested for HBV and HCV (n = 5,682) from 1998-2003. This study derives maximum likelihood estimates of the force of infection (the rate at which susceptible IDUs acquire infection) for HBV and HCV in the IDU population and their trends over time and injecting career length. The presence of individual heterogeneity of risk behaviour and background HBV prevalence due to routes of transmission other than injecting are also considered. RESULTS: For both HBV and HCV, IDUs are at greatest risk from infection in their first year of injecting (Forces of infection in new initiates 1999-2003: HBV = 0.1076 95% C.I: 0.0840-0.1327 HCV = 0.1608 95% C.I: 0.1314-0.1942) compared to experienced IDUs (Force of infection in experienced IDUs 1999-2003: HBV = 0.0353 95% C.I: 0.0198-0.0596, HCV = 0.0526 95% C.I: 0.0310-0.0863) although independently of this there is evidence of heterogeneity of risk behaviour with a small number of IDUs at increased risk of infection. No trends in the FOI over time were detected. There was only limited evidence of background HBV infection due to factors other than injecting. CONCLUSION: The models highlight the need to increase interventions that target new initiates to injecting to reduce the transmission of blood-borne viruses. Although from the evidence here, identification of those individuals that engage in heightened at-risk behaviour may also help in planning effective interventions. The data and methods described here may provide a baseline for monitoring the success of public health interventions.

England↗
PubMed2006

Estimates of injecting drug users at the national and local level in developing and transitional countries, and gender and age distribution.

OBJECTIVE: To present and update available national and subnational estimates of injecting drug users (IDUs) in developing/transitional countries, and provide indicative estimates of gender and age distribution. METHODS: Literature review of both grey and published literature including updates from previously reported estimates on estimates of IDU population and data sources giving age and gender breakdowns. The scope area was developing/transitional countries and the reference period was 1998-2005. RESULTS: Estimates of IDU numbers were available in 105 countries and 243 subnational areas. The largest IDU populations were reported from Brazil, China, India, and Russia (0.8 m, 1.9 m, 1.1 m, and 1.6 m respectively). Subnational areas with the largest IDU populations (35,000-79,000) are: Warsaw (Poland); Barnadul, Irtkustk, Nizhny-Novgorod, Penza, Voronez, St Petersburg, and Volgograd (Russia); New Delhi and Mumbai (India); Jakarta (Indonesia), and Bangkok (Thailand). By region, Eastern Europe and Central Asia have the largest IDU prevalence (median 0.65%) (min 0.3%; max 2.2%; Q1 0.39%; Q3 1.32%) [corrected] followed by Asia and Pacific: 0.24% (min 0.004%; max 1.47%; Q1 0.14%; Q3 1.47%) [corrected] In the Middle East and Africa the median value equals 0.2% (min 0.0003%; max 0.35%; Q1 0.11%; Q3 0.23%) [corrected] and in Latin America and the Caribbean: 0.12% (min 0.11%; max 0.69%; Q1 0.04%; Q3 0.13%) [corrected] Subnational areas with the highest IDU prevalence among adults (8-14.9%) were Shymkent (Kazakhstan), Balti (Moldova), Astrakhan, Barnadul, Irtkustk, Khabarovsk, Kaliningrad, Naberezhnyje Chelny, Penza, Togliatti, Volgograd, Voronez, and Yaroslavl (Russia), Dushanbe (Tajikistan), Ashgabad (Turkmenistan), Ivano-Frankivsk and Pavlograd (Ukraine) and Imphal, Manipur (India). 66% (297/447) of the IDU estimates were reported without technical information. Data on the IDU age/gender distributions are also scarce or unavailable for many countries. In 11 Eastern European and Central Asian countries the age group 50% of the total. The proportion of IDU men was 70%-90% in Eastern Europe and Central Asia, and there was a marked absence of data on women outside this region. CONCLUSION: Unfortunately data on IDU prevalence available to national and international policymakers is of an unknown and probably yet to be tested quality. This study provide baseline figures but steps need to be taken now to improve the reporting and assessment of these critical data.

Adult↗
PubMed2005

Prevalence of, and risk factors for, hepatitis C virus infection among recent initiates to injecting in London and Glasgow: cross sectional analysis.

Our aim was to compare the prevalence of antibody to hepatitis C virus (anti-HCV) among recently initiated injecting drug users (IDUs) in London and Glasgow, and to identify risk factors which could explain differences in prevalence between the cities. Complementary studies of community recruited IDUs who had initiated injection drug use since 1996 were conducted during 2001-2002. Data on HCV risk behaviours were gathered using structured questionnaires with identical core questions and respondents were asked to provide an oral fluid specimen which was tested anonymously for anti-HCV but was linked to the questionnaire. Sensitivities of the anti-HCV assays for oral fluid were 92-96%. Prevalence of anti-HCV was 35% (122/354) in London and 57% (207/366) in Glasgow (P < 0.001). Multifactorially, factors significantly associated with raised odds of anti-HCV positivity were increasing length of injecting career, daily injection, polydrug use, having had a needlestick injury, and having served a prison sentence. In addition lower odds of anti-HCV positivity were associated with non-injection use of crack cocaine and recruitment from drug agencies. After adjustment for these factors, the increased odds of anti-HCV associated with being a Glasgow IDU were diminished but remained significant. HCV continues to be transmitted among the IDU population of both cities at high rates despite the availability of syringe exchange and methadone maintenance. Effectiveness of harm reduction interventions may be compromised by inadequate coverage and failure to reduce sufficiently the frequency of sharing different types of injecting equipment, as well as the high background prevalence of HCV, and its high infectivity. Comprehensive action is urgently required to reduce the incidence of HCV among injectors.

Adult↗
PubMed2004

Wall thickening assessment with tissue harmonic echocardiography results in improved risk stratification for patients with non-ST-segment elevation acute chest pain.

OBJECTIVES: To demonstrate whether the improved imaging quality gained by using tissue harmonic echocardiography in place of fundamental echocardiography results in the improved risk stratification of patients presenting with non-ST-elevation acute chest pain. METHODS AND RESULTS: Eighty patients with over 30 min of non-ST-elevation chest pain that had lasted less than 6 h were recruited. All patients underwent resting tissue harmonic and fundamental echocardiographic scans. Diagnosis for acute myocardial infarction was made on a 24 h creatine kinase-MB sample. Echocardiographic images were reported by two experienced blinded observers. Patients were followed up at least 4 months after admission. Endpoints included all-cause mortality, non-fatal myocardial infarction and revascularisation procedures. Tissue harmonic echocardiography allowed assessment of all myocardial segments in all patients compared to 43/78 patients ( p<0.001 ) with fundamental echocardiography. A wall thickening abnormality demonstrated on tissue harmonic echocardiography and not fundamental echocardiography was a significant predictor of index myocardial infarction on admission ( p<0.007 ) and for an adverse cardiac event during follow up ( p=0.002 ). CONCLUSIONS: Tissue harmonic echocardiography is superior to fundamental echocardiography for accurate assessment of systolic wall thickening and hence risk stratification for patients presenting with acute chest pain and non-diagnostic electrocardiogram changes.

Acute Disease↗
PubMed2002

Heavy users of acute psychiatric beds: randomized controlled trial of enhanced community management in an outer London borough.

BACKGROUND: Heavy users of psychiatric services, often defined as the population that uses the most beds, consume a large part of the resources used by the whole service, despite being relatively small in number. Any intervention that reduces heavy use is therefore likely to lead to significant savings, and enhancement of standard care using a form of intensive case management akin to assertive community treatment was thought to be a pragmatic strategy for testing in this group. METHODS: The effectiveness of enhanced community management (ECM) was compared with standard care alone in heavy users, who represented the 10% of patients with the highest number of hospital admissions and occupied bed days over the previous 6.5 years in an outer London borough. One hundred and ninety-three patients were randomly assigned to ECM or standard care and their use of services was determined after 1 and 2 years, with assessments of costs, clinical symptoms, needs, and social function made before entry into the study and after 1 and 2 years. RESULTS: Despite a 24 fold increase in community contacts in the study group, there were no significant differences between the two groups in any of the main outcome measures. Small savings on in-patient and day-hospital service costs were counterbalanced by the increased costs of outpatient and community care for the subjects assigned to ECM. Clinical outcome data derived from interviews in two-thirds of the subjects were similar in both groups. CONCLUSIONS: Providing additional intensive community focused care to a group of heavy users of psychiatric in-patient services in an outer London borough does not lead to any important clinical gains or reduced costs of psychiatric care.

Adolescent↗
PubMed2001

Estimating the relative incidence of heroin use: application of a method for adjusting observed reports of first visits to specialized drug treatment agencies.

In this paper, the authors propose a method for estimating the incidence of heroin use by adjusting reported numbers of heroin users visiting drug treatment agencies for the time lag between onset of heroin use and first treatment request (lag distribution). The adjusted incidence is relative, since it represents the number of individuals beginning heroin use in each year whose cases will be reported within 8 years of starting use. Users with longer lag times or whose cases are never reported are excluded. Utilizing data from southeastern England (1991--1998), the authors analyzed the effects of covariates (sex, age group, ethnic group, route of consumption, and year of onset of drug use) on the lag distribution. Trends in the adjusted incidence of heroin use were very different for injectors and noninjectors: Incidence among injectors seemed to be stable, while in noninjectors it increased twofold between 1991 and 1996--1997. These results must be interpreted cautiously, especially in relation to the wider context of underlying trends in the population. Potential biases derive from underreporting and from changes in the proportion of heroin users in treatment. The lag correction method adds substantially to the value of routine treatment data, at least for heroin use, and is potentially the best method for obtaining estimates of incidence.

Adolescent↗
PubMed2001

Elite swimmers and the D allele of the ACE I/D polymorphism.

A polymorphism of the human angiotensin-1-converting enzyme (ACE) gene has been identified in which the presence (insertion, I allele) of a 287-bp fragment rather than the absence (deletion, D allele) is associated with lower ACE activity. Several recent studies have shown an association of the I allele with endurance performance, it being found with excess frequency in elite distance runners, rowers and mountaineers. Other workers using heterogeneous cohorts of athletes from mixed sporting disciplines have found no such association. An increasing linear trend of I allele frequency with the distance run amongst Olympic runners and an excess of the D allele amongst sprinters led us to examine whether the ratio of I and D alleles in swimmers competing over different distances would also vary. Swimmers (n=120) from the European and Commonwealth championships and an American college team had their ACE genotype determined and their gene and allele frequencies compared with several control groups, the most closely age-matched of which were 1,248 military recruits. Of the 103 Caucasians, there was a significant excess of the D allele compared with this control group only in the truly elite swimmers of the European and Commonwealth championships (P=0.004). This association remained in those competing over shorter distances (P=0.005 for 400 m and below) but not in the longer events. These findings were confirmed in three further large control groups. A population association study testing whether a genetic marker (the ACE I/D polymorphism) occurs more frequently in cases (elite athletes) than in controls therefore requires a homogeneous cohort of subjects from the same sporting discipline.

Adolescent↗
PubMed2001

Comparison of Light-Cycler PCR, enzyme immunoassay, and tissue culture for detection of herpes simplex virus.

A rapid PCR method was developed using the Roche LightCycler technology for detection of Herpes Simplex Virus I and II. The Lightcycler method was compared with tissue culture and direct HSV antigen detection using routine clinical samples. The LightCycler PCR was shown to be more sensitive than isolation by tissue culture (sensitivity of culture versus PCR 78%) and HSV antigen detection (sensitivity of EIA versus PCR 56%). The amplified product may be typed without additional tests. The LightCycler PCR method provides a rapid method for HSV detection that correlates well with established tests.

Animals↗
PubMed2001

A comparison of different methods for estimating the prevalence of problematic drug misuse in Great Britain.

AIMS: The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) has produced methodological guidelines for national drug prevalence estimation. This paper pilots the methods to estimate prevalence for Great Britain and provides a commentary on the methods and resulting estimates. DESIGN: Three types of methodology were used to estimate prevalence: (a) the multiple indicator (MI) method, (b) multipliers applied to (i) drug-treatment records (ii) HIV estimates and (iii) mortality statistics and (c) the British/Scottish Crime Surveys. SETTING: England, Scotland and Wales. PARTICIPANTS: Aggregated data on people recorded on databases and respondents in household surveys. MEASUREMENTS: Prevalence estimates of different forms of problematic drug use. FINDINGS: The estimates are 161,133 (range: 120,850-241,700) for people at risk of mortality due to drug overdose; 161,000-169,000 for people who have ever injected drugs; 202,000 (range: 162,000-244,000) problem opiate users and 268,000 problem drug users (all types). CONCLUSIONS: The multiple indicator method offers a comprehensive approach to estimating the prevalence of problematic drug use in the United Kingdom. Simple multiplier methods and household surveys also provide a range of estimates corresponding to different types of drug use in the United Kingdom. The current study suggests that previous national estimates of 100,000-200,000 were conservative. The new estimate of 161,000-266,000 should enable a more focused response. For further development of this method, reliable and timely estimates of anchor points are required for specific geographical areas such as cities or Drug Action Teams (DAT), as well as routine aggregation of drug indicators for these areas.

Epidemiologic Methods↗
PubMed2001

Costs and characteristics of heavy inpatient service users in outer London.

"Heavy users" is a new term often used to describe those who occupy a disproportionate number of psychiatric beds. In this study we identified the heaviest 10% (193) inpatient service users in one London borough over a 6 year period and compared these with a control group of 400 ordinary inpatient users. A weighting index was used to combine frequency of admission with duration. Heavy users were diagnostically and demographically similar to ordinary inpatient service users and only differed by their extensive use of services, about 3 times more than ordinary users in terms of health care costs, during the measured year. Their heavy use mainly depended on occupying hospital beds, and their use of outpatient, day patient and community services was relatively light.

Adult↗
PubMed2001

Prevalence of hepatitis C among injection drug users in England and Wales: is harm reduction working?

OBJECTIVES: This study sought to establish the prevalence of hepatitis C antibodies (anti-HCV) and hepatitis B antibodies (anti-HBc) among injection drug users in England and Wales. METHODS: A voluntary cross-sectional survey collected oral fluid samples and behavioral information; 2203 injectors were recruited through drug agencies, and 758 were recruited in the community. RESULTS: Prevalence was 30% for anti-HCV, 21% for anti-HBc, and 0.9% for HIV antibodies. Anti-HCV prevalence rates were significantly greater among those with longer injecting careers, those in older age groups, those residing in London, those recruited in drug agencies, those positive for anti-HBc, and those with a previous voluntary HIV test. CONCLUSIONS: Anti-HCV prevalence rates among injectors in England and Wales, where comprehensive harm reduction programs exist, are lower than rates in other industrialized countries.

Adult↗
PubMed2000

Measuring injecting risk behaviour in the second decade of harm reduction: a survey of injecting drug users in England.

AIMS: To measure risk behaviour among injecting drug users (IDUs) using the Injecting Risk Questionnaire (IRQ). METHODS: Data were analysed from the first multi-site survey of injecting risk behaviour among IDUs not in contact with drug services in England. A total of 1214 IDUs were recruited from community settings in seven sites. FINDINGS: Fifty-two per cent reported sharing injecting equipment in the previous 4 weeks in response to a single question on sharing. This rose to 78% when asked more detailed and multiple questions on injecting risk practices. Levels of injecting risk behaviour did not differ substantially by gender, age, length of injecting career, main drug of injection, previous treatment contact or geographical location. However, sharing partners were restricted to a median of two others. CONCLUSION: These data raise questions concerning the extent to which levels of injecting risk behaviour have increased over recent years, or the extent to which previous monitoring systems underestimated levels of risk. None the less, the data confirm that the promotion of safer injecting continues to be an important public health issue with regard to reducing blood-borne infections.

Adolescent↗
PubMed2000

A comparison of trends in problematic drug misuse from two reporting systems.

BACKGROUND: Regional Drug Misuse Databases (RDMDs) are considered the main source of intelligence on problem drug takers in England. Originally intended to provide trend data on visible drug use, a recent strategic review concluded that their purpose should be to monitor treatment targets for the Government's latest 10 year strategy to tackle drug misuse. The aim of this analysis was to explore whether the General Practice Research Database (GPRD) could supplement RDMDs. METHODS: A retrospective analysis was carried out using the GPRD and the RDMD in the West Midlands from 1993 to 1997. RESULTS: Extrapolation of GPRD data indicates 6,574 drug misusing or dependent diagnosed patients in primary care in 1997 compared with 3,643 clients reported by all agencies including general practitioners (GPs) to the RDMD. From 1993 to 1997, the RDMD notification rate fluctuated whereas the GPRD rate has increased steadily since 1995. Half of all drug misusing or dependent patients recorded on the GPRD had psychiatric co-morbidity and 10 per cent had been referred to hospital for a drug overdose. CONCLUSIONS: As the GPRD has been unaffected by the demise of statutory notification of drug dependence in 1997, interpretation of trends may be more reliable than on the RDMD. There is also considerable potential for analysis of prescribing patterns, co-morbidity and drug-related hospitalization. As the Department of Health's Strategic Review of RDMDs recommends GPs as 'core reporters' for providing data to the national system, there is a need for a strategy to ensure valid and comprehensive reporting from GPs.

Data Collection↗