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Biomedical subjects

O Noel Gill

Publications and source records attributed to O Noel Gill.

10 recordsLinked to original sources
PubMed2006

Does the recent increase in HIV diagnoses among men who have sex with men in the UK reflect a rise in HIV incidence or increased uptake of HIV testing?

OBJECTIVES: To determine whether the increase in HIV diagnoses since 1997 among men who have sex with men (MSM) in the UK reflects a rise in HIV incidence or an increase in HIV testing. METHODS: Estimates of HIV incidence were derived using data from UK HIV surveillance systems (HIV diagnoses; CD4 surveillance; unlinked anonymous surveys) for 1997-2004. Data on HIV testing were provided by KC60 statutory returns, voluntary testing and unlinked anonymous surveys in sentinel genitourinary medicine (GUM) clinics. RESULTS: HIV diagnoses among MSM in the UK rose by 54% between 1997 and 2004 (from 1382 to 2124), with variation by age and geographical location. The number of HIV diagnoses among MSM <35 years of age in London showed no increase, but in all other groups it increased. Throughout the UK, uptake of HIV testing increased significantly among MSM attending GUM clinics between 1997 and 2004, including "at-risk" MSM (p<0.001). Direct incidence estimates (serological testing algorithm for recent HIV seroconversion assay) provided no evidence of a statistically significant increase or decrease in HIV incidence. Indirect estimates suggested that there may have been a rise in HIV incidence, but these estimates were influenced by the increased uptake of HIV testing. CONCLUSIONS: The number of HIV diagnoses increased among MSM in the UK between 1997 and 2004, except among younger MSM in London, in whom there was no change. The increase in HIV diagnoses among MSM in the UK since 1997 seems to reflect an increase in HIV testing rather than a rise in HIV incidence.

Adult↗
PubMed2006

Estimating the cost-effectiveness of detecting cases of chronic hepatitis C infection on reception into prison.

BACKGROUND: In England and Wales where less than 1% of the population are Injecting drug users (IDUs), 97% of HCV reports are attributed to injecting drug use. As over 60% of the IDU population will have been imprisoned by the age of 30 years, prison may provide a good location in which to offer HCV screening and treatment. The aim of this work is to examine the cost effectiveness of a number of alternative HCV case-finding strategies on prison reception METHODS: A decision analysis model embedded in a model of the flow of IDUs through prison was used to estimate the cost effectiveness of a number of alternative case-finding strategies. The model estimates the average cost of identifying a new case of HCV from the perspective of the health care provider and how these estimates may evolve over time. RESULTS: The results suggest that administering verbal screening for a past positive HCV test and for ever having engaged in illicit drug use prior to the administering of ELISA and PCR tests can have a significant impact on the cost effectiveness of HCV case-finding strategies on prison reception; the discounted cost in 2017 being pound2,102 per new HCV case detected compared to pound3,107 when no verbal screening is employed. CONCLUSION: The work here demonstrates the importance of targeting those individuals that have ever engaged in illicit drug use for HCV testing in prisons, these individuals can then be targeted for future intervention measures such as treatment or monitored to prevent future transmission.

Adult↗
PubMed2005

HIV prevalence among injecting drug users in England and Wales 1990 to 2003: evidence for increased transmission in recent years.

OBJECTIVE: To describe trends in HIV prevalence among injecting drug users in England and Wales between 1990 and 2003. METHODS: Analysis of surveillance data from voluntary unlinked anonymous cross-sectional surveys collecting oral fluid samples and behavioural information from injecting drug users recruited from both drug agency (n = 24,304) and community settings (n = 3628). RESULTS: HIV prevalence in England and Wales declined from 5.9% in 1990 to 0.6% in 1996 and then remained stable until 1999, after which it increased to 1.4% in 2003. Few HIV infections were detected among short-term injectors between 1994 and 1999, but in recent years prevalence among this group has increased. Other factors associated with higher odds of HIV infection were being recruited in London and from community settings, and ever having had a voluntary confidential HIV test. Incidence estimated through a force of infection model was 2.8% per annum among those injecting for less than a year in London between 1998 and 2003. CONCLUSIONS: These data suggest that incidence and prevalence of HIV may have increased, whereas other indicators suggest an increase in risk behaviour. It is critical that harm reduction measures are reinvigorated, and evolve in response to changes in drug use risk behaviours and policy.

Adolescent↗
PubMed2004

Surveillance of HIV-1 subtypes among heterosexuals in England and Wales, 1997-2000.

The molecular diversity and demographic characteristics among 976 anti-HIV-1-positive heterosexuals attending 15 sexually transmitted infection (STI) clinics participating in an unlinked anonymous HIV prevalence serosurvey in England and Wales during 1997-2000 were investigated. Subtypes were assigned by heteroduplex mobility assay or sequencing of the p17/p24 region of gag and the V3/V4 region of env and by sequencing of the protease gene. Overall, there was no significant change in the subtype distribution, with subtype C accounting for the majority (32%) of subtyped infections. Subtypes B (29%), A (12%), circulating recombinant forms (CRFs, 9%), unique recombinant forms (URFs, 8%), and subtypes D-H (8%) were also detected. Thirty-nine percent of infections in men were with subtype B, whereas subtype C was most common (38%) in women. Logistic regression analyses showed the relative risk (RR) of infection with a non-B subtype, compared with subtype B, to be greater in African-born individuals (RR = 28.9, P < 0.01), among newly diagnosed infections (RR = 3.4, P < 0.01), and in women (RR = 2.4, P < 0.01). These findings indicate a high level of genetic diversity among HIV-infected heterosexual STI clinic attendees in England and Wales. Recently, subtype C has become most prevalent, particularly in younger age groups, suggesting recent acquisition of this viral strain. The high proportion of non-B, CRF, and URF infections among UK-born individuals is consistent with mixing between migrants and UK-born individuals in England and Wales. As migration patterns change, continued monitoring of HIV genetic diversity will aid understanding of transmission patterns.

Africa↗
PubMed2004

HIV incidence appears constant in men who have sex with men despite widespread use of effective antiretroviral therapy.

OBJECTIVE: To estimate the trend in HIV incidence between 1995 and 2001 in men who have sex with men (MSM) attending sexually transmitted infection (STI) clinics in the UK. DESIGN: The Serological Testing Algorithm for Recent HIV Seroconversion (STARHS) was applied to serum specimens from MSM attending 15 STI clinics collaborating in an HIV unlinked anonymous prevalence serosurvey. METHODS: STARHS was performed on anti-HIV-1 positive specimens and HIV incidence rates determined. Specimens from MSM with previously diagnosed HIV or an AIDS defining condition were excluded. National data on uptake of antiretroviral therapy (ART), AIDS mortality and diagnoses of gonorrhoea in MSM were used to aid interpretation of the HIV incidence findings. RESULTS: Of 43,100 specimens collected from MSM 3565 were anti-HIV-1 positive. Of these, 1645 were eligible and available for STARHS testing, of which 317 were deemed to come from recently acquired infections. The overall estimated annual incidence ranged from 1.5% (1999) to 3.3% (1996). In 2001 it was 2.45%, with a 3.1% incidence in London and 1.0% elsewhere. No significant trends in HIV incidence were found. CONCLUSIONS: Despite the widespread use of ART there was no significant decline in HIV incidence. Individuals whose HIV infection has been diagnosed should be less infectious. However, over 20% of infections in MSM remain undiagnosed, many with acute STI, and this pool of unmanaged HIV infection may be an important driver of the ongoing epidemic. Initiatives to diagnose and treat a greater proportion of HIV infections may be the key to reducing HIV incidence in MSM.

Adult↗
PubMed2004

Past it? HIV and older people in England, Wales and Northern Ireland.

The majority of those infected and affected by HIV are younger adults. The ability of highly active antiretroviral therapies (HAART) to extend survival means that those infected when younger may reach older age, and future increases in numbers of older individuals living with HIV in England, Wales and Northern Ireland (E,W&NI) are expected. Evidence that older individuals engage in risky sexual behaviours suggests potential for HIV transmission. Data from national HIV/AIDS surveillance systems were reviewed (1997-2001). An older individual is defined as aged 45 years or over. Between 1997 and 2001, 2290 older individuals were diagnosed with HIV; 361 in 1997, rising to 648 in 2001. Heterosexual acquisition accounted for 1073 (47%) infections; 662 were male. Where reported, 666 (65%) older heterosexuals were probably infected in Africa, 144 (14%) in the United Kingdom and 113 (11%) in Asia. There were 1020 (45%) new diagnoses acquired homosexually; white (92%), infected in the United Kingdom (78%). Numbers of older individuals accessing HIV-related services more than doubled between 1997 (2488) and 2001 (5175). In 2001, 2270 (53%) were London residents. Between 1997 and 2001, among HIV-infected older individuals attending genitourinary medicine (GUM) clinics, the proportions previously undiagnosed were 60% and 82% in heterosexual males and females respectively, and for men who have sex with men (MSM), 42%. Numbers of older individuals newly diagnosed with HIV have increased in recent years. The increase in numbers of older individuals accessing HIV-related services were in excess of younger adults. A significant proportion of older HIV-infected female heterosexuals and MSM were undiagnosed. Awareness must be raised among clinicians, and an 'aged response' to HIV is required.

Adolescent↗
PubMed2003

Reconciling HIV incidence results from two assays employed in the serological testing algorithm for recent HIV seroconversion (STARHS).

The Abbott HIVAB and Vironostika HIV-1 Microelisa assays have both been validated for use in the serological testing algorithm for recent HIV seroconversion (STARHS). This ability to identify recently-acquired infection provides valuable insight into the epidemic. The availability of each assay during different periods led to longitudinal studies of annual HIV incidence being based on a mixture of results from each. We investigated whether results from both assays could be reconciled. Using statistical methods, the correlation of the two assays' results and other performance characteristics were examined. Of 378 anti-HIV-1 positive specimens examined by both assays, the Abbott assay flagged 40 as from recent infections, whereas Vironostika flagged 50. The correlation coefficient between screening reactivities in each assay was 0.84, and 0.77 in confirmatory mode. Abbott screening results were significantly higher than its confirmatory results, and some specimens from recent infections may consequently have gone undetected by that assay. This problem was not found with the Vironostika assay. Observational data indicated that the estimated HIV incidence derived from HIVAB results increased as the assay threshold, with its pre-defined seroconversion window, was increased. For Vironostika, the estimated HIV incidence remained stable over a wide range of thresholds. Modelling of the observed relationship between the two assays allowed an estimate of the equivalent threshold in the alternative assay, thus providing a means of reconciling results. Our findings suggest that the Vironostika assay is more reliable than the HIVAB, is easier to use, and is able to allow processing of more specimens per run.

Algorithms↗
PubMed1991

BCG vaccination in the first year of life protects children of Indian subcontinent ethnic origin against tuberculosis in England.

STUDY OBJECTIVE: The aim was to assess the protection conferred by BCG given during the first year of life against tuberculosis among children of Asian ethnic origin born in England. DESIGN: This was a matched case-control study. SETTING: Cases were selected from notifications of tuberculosis and controls were selected from child health or school health records in 14 English health districts. PARTICIPANTS: 111 cases of childhood tuberculosis with Asian names were selected. For each case there were five controls with Asian names, matched for age, sex and district of birth. MEASUREMENTS AND MAIN RESULTS: Child health or school health records were searched to determine the proportions of cases and controls who had been vaccinated with BCG. Overall, BCG vaccination given in the first year of life was estimated to confer 49% protection against tuberculosis with 95% confidence interval 14-62%. CONCLUSIONS: BCG vaccination in infancy was found to be associated with a lower protective efficacy than has been found for the secondary school age BCG programme (80%) but nevertheless the protection is substantial and, in the United Kingdom, BCG vaccination of infants considered to be at relatively higher risk of tuberculosis is likely to reduce the incidence of childhood tuberculosis.

Asia, Western↗