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Biomedical subjects

S M Gore

Publications and source records attributed to S M Gore.

At least 55 records · Page 3Linked to original sources
PubMed1996

Statistical analysis of zidovudine (AZT) effect on CD4 cell counts in HIV disease.

We fit a class of random effects linear growth curve models for the square root of CD4 count to serial marker data from 164 HIV-positive individuals with known (or accurately estimated) dates of seroconversion and at least 10 CD4 measurements each (median 16). We do so by adopting a Bayesian viewpoint and using the Markov chain Monte Carlo technique Gibbs sampling. In particular, we examine the effect of the antiretroviral treatment zidovudine on the square root of CD4 series for the 136 patients who took the drug. Treatment effects are modelled by positing recoveries in square root of CD4 level proportional to current immuno-competence and changes in slope proportional to current rate of square root of CD4 loss. Both fixed and random treatment effects are considered and models are criticized and compared using Bayesian predictive methodology and checking data which comprise 424 new observations. Results indicate re-elevation of square root of CD4 level is associated with treatment but the effect, though significant, is mostly of small magnitude and is possibly transient; models neglecting consideration of treatment fit the checking data almost as well. Best overall model estimates mean rate of square root of CD4 loss per annum to be 2.1 (standard error 0.12); mean seroconversion value of square root of CD4 is 28.4 (SE 0.65). The estimated variance of individual slopes is 1.9 (SE 0.28), there being considerable individual variation in rate of CD4 loss, and a recovery in level of 0.047 (SE 0.014) times current square root of CD4 level is estimated at treatment uptake.

Antiviral Agents↗
PubMed1996

Clinical and surgical factors influencing corneal graft survival, visual acuity, and astigmatism. Corneal Transplant Follow-up Study Collaborators.

PURPOSE: To quantify clinical and operative factors that influence corneal graft outcome. METHODS: A multifactorial analysis was done on 2242 corneal grafts registered by the United Kingdom Transplant Service from July 1987 to June 1991. RESULTS: There was an increased risk of graft failure in patients with preoperative diffuse and other noncentral stromal edema, less-common eye diseases, small trephine size, difference in donor and recipient sizes greater than 0.25 mm, and use of mixed continuous and interrupted sutures. Visual acuity 3 months after surgery was poorer in patients who had glaucoma and low visual acuity preoperatively, small trephine size, and combined vitreous surgery. Use of interrupted sutures resulted in higher astigmatism at 3 months. CONCLUSIONS: After allowing for the effects of recipient factors, surgical factors significantly affected corneal graft outcome. No factors that showed significant benefits for graft survival also adversely affected visual performance. Details of medical history, clinical condition, and surgical method failed to predict more than a small proportion of observed variability in visual performance of functioning grafts.

Astigmatism↗
PubMed1996

The epidemiology of HIV infection in Edinburgh related to the injecting of drugs: an historical perspective and new insight regarding the past incidence of HIV infection derived from retrospective HIV antibody testing of stored samples of serum.

The pattern of sudden explosive outbreaks of HIV infection among drug users has been seen in several countries but is as yet incompletely understood. The epidemic of injecting drugs in Edinburgh was associated with at least four overlapping epidemics of blood-borne viruses (hepatitis B, C, D and HIV). Only hepatitis B was initially recognized, being followed by HIV and latterly hepatitis C. Retrospective HIV testing of stored samples of serum from clinically diagnosed patients with HIV has allowed the HIV epidemic to be delineated and more accurate seroconversion dates identified for most of the patients. There is evidence to suggest that the explosive drug-related Edinburgh HIV epidemic may have been self-terminating and that the epidemic in male drug users preceded that in female drug users by around 3 months. We suggest that the self-terminating nature of this epidemic may have been related to changes in drug injecting behaviour or to varying infectivity of the virus. This latter possibility should be explored in future studies of HIV transmission.

Adult↗
PubMed1996

Association of HLA types A1-B8-DR3 and B27 with rapid and slow progression of HIV disease.

We examined how HLA types A1-B8-DR3 and B27 were related to progression of clinical disease and rate of loss of CD4 lymphocytes in the Edinburgh City Hospital cohort of HIV-positive patients, mainly injection drug users. Patients (n = 692) were prospectively followed from 1985 through March 1994. Accurately estimated seroconversion times were determined retrospectively for a subgroup of 313 (45%). Of 262 patients (39%) who were fully or partially HLA typed, 155 (50%) had known seroconversions. Of 34 patients typed positive for A1-B8-DR3, 29 progressed to CDC stage IV, 22 to AIDS and 20 died. Twelve patients were typed positive for B27; six of these progressed to CDC stage IV, one to AIDS and none died. In a proportional hazards analysis of the 313 patients with known seroconversions, A1-B8-DR3 was significantly associated with covariate-adjusted relative risks of 3.7 (95% CI 1.9-7.2), 3.1 (1.6-6.0) and 1.9 (1.1-3.2) for progression from seroconversion to death, AIDS and CDC stage IV, respectively. Events for B27 were too rare to include B27 in analyses to death and AIDS, but B27 was significantly associated with slower progression to CDC stage IV (0.3, CI 0.1-0.9). Random effects growth curve models were used to estimate individual rates of loss of square root CD4 count and loss of CD4 percentage, for 603 and 617 patients, respectively. A1-B8-DR3 was associated with rapid loss of both markers (p = 0.02 and p = 0.01, respectively); B27 was associated with slow loss of both markers (p = 0.04 and p < 0.005).

Acquired Immunodeficiency Syndrome↗
PubMed1996

United Kingdom AIDS survival in adults.

OBJECTIVE: To examine the impact of age, year and region of AIDS diagnosis on early (up to 12 months) and late survival of AIDS patients in different exposure categories; to describe the hazard pattern from 12 months after AIDS diagnosis. PATIENTS: A total of 4577 UK adult AIDS diagnoses to the end of 1991 in men who have sex with men, 273 AIDS cases in injecting drug users, 411 AIDS patients infected by blood products, and 535 other adult AIDS cases, mainly ascribed to heterosexual transmission. Deaths have been recorded for 4739 of these 5796 AIDS patients. RESULTS: The influence of calendar year and region of AIDS diagnosis on survival were short-term, for the most part operative only within the first year of follow-up. The monthly death-rate was roughly constant from 12 to 48 months post-AIDS [pooled estimate, 0.055 with 95% confidence interval (CI), 0.053-0.057] but was more than halved for 4-year survivors (pooled estimate, 0.022; 95% CI, 0.017-0.027). About 7% of AIDS cases diagnosed in 1990-1991 survive for at least 48 months. Survival after AIDS diagnosis shortens with advancing age at AIDS diagnosis: the relative hazard per decade of age (1.35; 95% CI, 1.29-1.41 in the first year after AIDS) is significantly greater (P < 0.001) in the first year after AIDS diagnosis than from 12 to 48 months (1.19; 95% CI, 1.13-1.25 in the second epoch). CONCLUSIONS: The influence of covariates, including age, is strongest in the first year of follow-up after AIDS diagnosis. Monthly death-rate is roughly constant at 0.055 from 12 to 48 months post-AIDS and at 0.022 thereafter.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Progression of HIV: follow-up of Edinburgh injecting drug users with narrow seroconversion intervals in 1983-1985.

OBJECTIVE: To describe progression and survival of individuals infected with HIV by injecting drug use in Edinburgh. DESIGN AND METHODS: From 313 HIV-infected patients with retrospectively estimated narrow seroconversion intervals, 260 infected via injecting drug use in the years 1983-1985 were selected for the study group. MAIN OUTCOME MEASURES: The effects of gender, age, human leukocyte antigen (HLA) type and zidovudine (ZDV) treatment on progression and survival from seroconversion; Weibull estimates of the AIDS incubation distribution and the overall survival distribution; slopes of absolute CD4 lymphocyte loss (on the square root scale) and loss of CD4 percentage. RESULTS: The cumulative progression rates at 10 years were 68% to CDC stage IV and 31% to AIDS with a mortality rate of 25%. Three-year survival rates for AIDS and CDC stage IV cases were 25 and 72%, respectively. Gender and age effects on progression or overall survival were not found, although those aged over 30 years experienced poorer survival from AIDS. A strong HLA (A1, B8, DR3) association with faster progression and poorer survival was found. Median survival was estimated by Weibull distribution to be 12.6 years; median AIDS-free time was estimated to be 11.6 years. CD4 cell loss was approximately linear when transformed to the square root scale as was the decline in CD4 percentage. Only HLA effects on slopes were found: A1,B8, DR3 was significantly associated with faster loss of both absolute CD4 cells and CD4 percentage (P < 0.001) and B27 was significantly associated with slower loss of CD4 percentage (P = 0.01). CONCLUSIONS: Edinburgh IDU do not seem to progress more rapidly than other cohorts with predominantly different risk activities. Older age was associated with poorer survival from AIDS but no gender effect was found for progression or overall survival. The clearest significant association with AIDS progression, mortality and loss of CD4 cells was the phenotype HLA A1,B8,DR3. In contrast HLA B27 was associated with slower loss of CD4 cells.

Adult↗
PubMed1995

Heterosexual transmission of HIV analysed by generalized estimating equations.

A longitudinal analysis of a partner study is compared with a cross-sectional analysis which identify behavioural and biological risk factors for heterosexual transmission of HIV. Using generalized estimating equations (GEEs) a random effects logistic model is used for the longitudinal analysis. These approaches are illustrated by the Edinburgh heterosexual partner study. The longitudinal analysis finds that 'high-risk' sexual practices, unprotected intercourse for HIV and a low CD4 count in the index case significantly increase the risk of HIV transmission. The cross-sectional analysis, however, only indicates 'high-risk' sexual practices as favourable for HIV transmission.

Adolescent↗
PubMed1995

Drug injection and HIV prevalence in inmates of Glenochil prison.

OBJECTIVE: To determine prevalence of HIV infection and drug injecting behaviour among inmates of Glenochil Prison on a specified date a year after an outbreak of hepatitis B and HIV infection. DESIGN: Cross sectional: voluntary, anonymous HIV salivary antibody surveillance and linked self completion questionnaire on risk factors. SETTING: Glenochil prison, Scotland, a year after an outbreak of hepatitis B and HIV transmission related to drug injection. SUBJECTS: 352 prisoners, of whom 295 (84%) took part; 284 questionnaires (96%) passed logical checks. MAIN OUTCOME MEASURES: HIV prevalence; proportion of all inmates who had ever injected drugs, had ever injected inside prison, had started injecting drugs while inside prison. RESULTS: More than half (150/284) the current inmates were also in Glenochil Prison during the critical period of January to June 1993, when hepatitis B and HIV were transmitted. Similar proportions of current inmates and men who were also in Glenochil during the critical period were drug users (27% (75/278) v 30% (44/149)). A quarter of injecting drug users (18/72) had first injected inside prison, irrespective of whether they were in Glenochil in January to June 1993 and regardless of the calendar period when they first injected. Significantly more inmates from Glasgow (41%; 56/138) than from Edinburgh (21%; 7/34) or elsewhere (11%; 12/106) were injecting drug users. On testing for HIV, seven saliva samples out of 293 gave positive results--four were presumed to be from inmates known to be infected with HIV, and the others from injecting drug users from Glasgow, all of whom had been in Glenochil during January to June 1993, when two of the three had injected drugs and had been tested for HIV, with negative results. The ratio of overall (2.4%) to disclosed (1.4%) HIV prevalence was 1.7. For men who had injected drugs in Glenochil during January to June 1993, HIV prevalence was estimated at 29%. CONCLUSION: Between a quarter and a third of prisoners who injected drugs in Glenochil in January to June 1993 were infected with HIV. There is widespread ongoing risk of bloodborne virus infection within prisons, which is probably long standing but demands urgent attention.

Adult↗
PubMed1995

Anonymous HIV surveillance with risk factor elicitation at Scotland's largest prison, Barlinnie.

OBJECTIVE: To determine prevalence of HIV infection and risk behaviours among male inmates of Her Majesty's Prison (HMP) Barlinnie, Glasgow, Scotland on 8-9 September 1994. DESIGN: Cross-sectional study: voluntary, anonymous HIV surveillance (using saliva samples) of all inmates and linked self-completion risk-factor questionnaire. SUBJECTS: Of 1073 prisoners available to participate, 985 (92%) completed a risk-factor questionnaire and 982 salivettes were received for testing, of which 978 were tested for HIV antibodies (four were dry samples); 928 questionnaires passed logical checks for consistency. MAIN OUTCOME MEASURES: HIV prevalence on saliva testing, related risk behaviours and ratio of overall-to-disclosed HIV prevalence. Proportion of all inmates who have ever injected drugs, ever injected inside prison, started injecting inside, ever had acute hepatitis, had a recent personal HIV test (since January 1993). RESULTS: Nine saliva samples [eight injecting drug users (IDU), one recognized other risk] out of 978 were HIV-antibody-positive (three presumptively from known HIV-infected inmates). Overall HIV prevalence was estimated at 1% compared with a known prevalence of 0.4%, giving an overall-to-disclosed HIV prevalence ratio of 2.6 in HMP Barlinnie in September 1994. A higher proportion of prisoners from Glasgow (48%) than elsewhere (19%) were IDU. Year of first injection was also different by residence with 23% of Glasgow IDU having first injected after 1988 compared with 45% of IDU from elsewhere, mainly West and South Scotland. Half the IDU inmates reported having injected while incarcerated and 6% had started to inject while incarcerated. Ten per cent of all prisoners and 20% of IDU inmates had had a personal HIV test since January 1993. Logistic regression showed that there was a significant deficit of recent HIV test uptake by Glasgow residents (odds ratio, 0.5; 95% confidence interval, 0.27-0.89), that IDU were more likely to have had treatment for a sexually transmitted disease, and that IDU who had injected inside and those whose injecting career began prior to 1989 were more likely to have had acute hepatitis. CONCLUSION: A consistent harm-reduction policy is needed across prisons in the United Kingdom to avoid transmission of blood-borne viral infections. Drug injecting inside prison is common, a proportion of IDU inmates having first injected drugs while in prison, and much higher rates of hepatitis have been reported in association with injecting while incarcerated compared with that for IDU who only injected outside prison.

Adult↗