Does drug abuse influence the microglial response in AIDS and HIV encephalitis?

OBJECTIVES: To investigate the pathological evidence for a possible interaction between drugs of abuse and HIV infection in terms of microglial responses in early and late HIV/AIDS, and to discuss the possible long-term consequences of microglial activation in chronic HIV infection. DESIGN: This brain pathology study compared age and sex-matched control patients with HIV-negative intravenous drug users, and with HIV-positive drug users both in the presymptomatic stage and with AIDS. A further group of non-drug-using AIDS patients was included. All the AIDS patients had HIV encephalitis (HIVE) but no other significant HIV-associated brain pathology. METHODS: Microglia/macrophages were identified in the grey and white matter of the frontal and temporal lobes and the thalamus, using antibodies to CD68 and MHCII. Objective quantitation was used to compare subjects in the different groups. RESULTS: AIDS patients showed a significant increase in activated microglia/macrophages in both the grey and white matter of all areas compared with non-AIDS patients. Drug users with HIVE tended to have more activated microglia than non-drug-using comparison groups, but this difference was not found in all brain areas studied. CONCLUSION: Drug misuse appears to enhance the microglial activation resulting from HIV infection in some individuals. Other factors such as the severity of HIVE, or systemic immune factors, are also likely to affect the degree of microglial activation. The implications for drug-using patients who survive long term with HIV/AIDS are discussed, particularly in relation to premature neurodegeneration.

Systemic non-Hodgkin lymphoma in individuals with known dates of HIV seroconversion: incidence and predictors.

OBJECTIVES: To investigate temporal changes in the risk of non-Hodgkin lymphoma (NHL) and estimate NHL incidence in risk groups and the prognostic role of these risks and current, nadir and time-weighted average CD4 cell count. METHODS: Secular trends in time from HIV seroconversion to an NHL diagnosis was estimated using Cox models from data pooled from the 22 seroconverter cohorts in the CASCADE collaboration for three periods (pre-1997, 1997-1998, 1999-2002), adjusting for age at seroconversion, exposure category and sex. RESULTS: Of 7103 seroconverters, 129 developed NHL. Compared with pre-1997, there was little reduction in NHL risk in 1997-1998 [relative risk (RR), 0.66; 95% confidence interval (CI), 0.37-1.17] then a substantial reduction in 1999-2002 (RR, 0.25, 95% CI, 0.12-0.53). Compared with individuals with CD4 cell count > 350 x 10 cells/l, the RR of NHL increased to 1.9 (95% CI, 1.0-3.6), 1.4 (95% CI, 0.6-3.5) and 11.2 (95% CI, 6.3-20.0) at CD4 cell counts 200-349, 100-199 and < 100 x 10 cells/l, respectively. There was no evidence that nadir (P = 0.41) or time-weighted average CD4 cell count (P = 0.38) contributed further to predicting NHL risk or were better predictors than current CD4 cell count. For individuals with CD4 cell count > 350 x 10 cells/l pre-HAART, an NHL incidence of 1.8 and 0.4/1000 person-years was estimated for those at highest and lowest risk, respectively, when classified by age and exposure category. CONCLUSION: There appears to be no justification for initiating HAART at CD4 cell counts > 100 x 10 cells/l based specifically on concerns over NHL. The risk of NHL is, however, greatly increased at lower CD4 cell counts.

Changes over calendar time in the risk of specific first AIDS-defining events following HIV seroconversion, adjusting for competing risks.

BACKGROUND: Although studies have reported large reductions in the risks of AIDS and death since the introduction of potent anti-retroviral therapies, few have evaluated whether this has been similar for all AIDS-defining diseases. We wished to evaluate changes over time in the risk of specific AIDS-defining diseases, as first events, using data from individuals with known dates of HIV seroconversion. METHODS: Using a competing risks proportional hazards model on pooled data from 20 cohorts (CASCADE), we evaluated time from HIV seroconversion to each first AIDS-defining disease (16 groups) and to death without AIDS for four calendar periods, adjusting for exposure category, age, sex, acute infection, and stratifying by cohort. We compared results to those obtained from a cause-specific hazards model. RESULTS: Of 6,941, 2,021 (29%) developed AIDS and 437 (6%) died without AIDS. The risk of AIDS or death remained constant to 1996 then reduced; relative hazard = 0.89 (95% CI: 0.77-1.03); 0.90 (95% CI: 0.81-1.01); and 0.32 (95% CI: 0.28-0.37) for 1979-1990, 1991-1993, and 1997-2001, respectively, compared to 1994-1996. Significant risk reductions in 1997-2001 were observed in all but two AIDS-defining groups and death without AIDS in a competing risks model (with similar results from a cause-specific model). There was significant heterogeneity in the risk reduction across events; from 96% for cryptosporidiosis, to 17% for death without AIDS (P < 0.0001). CONCLUSION: These findings suggest that studies reporting a stable trend for particular AIDS diseases over the period 1979-2001 may not have accounted for the competing risks among other events or lack the power to detect smaller trends.

Lower healthcare costs associated with the use of a single-pill ARV regimen in the UK, 2004-2008.

AIM: Investigate the cost and effects of a single-pill versus two- or three pill first-line antiretroviral combinations in reducing viral load, increasing CD4 counts, and first-line failure rate associated with respective regimens at 6 and 12 months. METHODS: Patients on first-line TDF+3TC+EFV, TDF+FTC+EFV, Truvada®+EFV or Atripla® between 1996-2008 were identified and viral load and CD4 counts measured at baseline, six and twelve months respectively. Factors that independently predicted treatment failure at six and twelve months were derived using multivariate Cox's proportional hazard regression analyses. Use and cost of hospital services were calculated at six and twelve months respectively. RESULTS: All regimens reduced viral load to below the limit of detection and CD4 counts increased to similar levels at six and twelve months for all treatment regimens. No statistically significant differences were observed for rate of treatment failure at six and twelve months. People on Atripla® generated lower healthcare costs for non-AIDS patients at £5,340 (£5,254 to £5,426) per patient-semester and £9,821 (£9,719 to £9,924) per patient-year that was £1,344 (95%CI £1,222 to £1,465) less per patient-semester and £1,954 (95%CI £1,801 to £2,107) less per patient-year compared with Truvada®+EFV; healthcare costs for AIDS patients were similar across all regimens. CONCLUSION: The single pill regimen is as effective as the two- and three-pill regimens of the same drugs, but if started as first-line induction therapy there would be a 20% savings on healthcare costs at six and 17% of costs at twelve months compared with Truvada®+EFV, that generated the next lowest costs.

The cost-effectiveness of early access to HIV services and starting cART in the UK 1996-2008.

AIM: To calculate use, cost and cost-effectiveness of people living with HIV (PLHIV) starting routine treatment and care before starting combination antiretroviral therapy (cART) and PLHIV starting first-line 2NRTIs+NNRTI or 2NRTIs+PI(boosted), comparing PLHIV with CD4≤200 cells/mm3 and CD4>200 cells/mm3. Few studies have calculated the use, cost and cost-effectiveness of routine treatment and care before starting cART and starting cART above and below CD4 200 cells/mm3. METHODS: Use, costs and cost-effectiveness were calculated for PLHIV in routine pre-cART and starting first-line cART, comparing CD4≤200 cells/mm3 with CD4>200 cells/mm3 (2008 UK prices). RESULTS: cART naïve patients CD4≤200 cells/mm3 had an annual cost of £6,407 (95%CI £6,382 to £6,425) PPY compared with £2,758 (95%CI £2,752 to £2,761) PPY for those with CD4>200 cells/mm3; cost per life year gained of pre-cART treatment and care for those with CD4>200 cells/mm3 was £1,776 (cost-saving to £2,752). Annual cost for starting 2NRTIs+NNRTI or 2NRTIs+PI(boosted) with CD4≤200 cells/mm3 was £12,812 (95%CI £12,685-£12,937) compared with £10,478 (95%CI £10,376-£10,581) for PLHIV with CD4>200 cells/mm3. Cost per additional life-year gained on first-line therapy for those with CD4>200 cells/mm3 was £4639 (£3,967 to £2,960). CONCLUSION: PLHIV starting to use HIV services before CD4≤200 cells/mm3 is cost-effective and enables them to be monitored so they start cART with a CD4>200 cells/mm3, which results in better outcomes and is cost-effective. However, 25% of PLHIV accessing services continue to present with CD4≤200 cells/mm3. This highlights the need to investigate the cost-effectiveness of testing and early treatment programs for key populations in the UK.

Cost-effectiveness of early treatment with first-line NNRTI-based HAART regimens in the UK, 1996-2006.

AIM: Calculate time to first-line treatment failure, annual cost and cost-effectiveness of NNRTI versus PIboosted first-line HAART regimens in the UK, 1996-2006. BACKGROUND: Population costs for HIV services are increasing in the UK and interventions need to be effective and efficient to reduce or stabilize costs. 2NRTIs + NNRTI regimens are cost-effective regimens for first-line HAART, but these regimens have not been compared with first-line PI(boosted) regimens. METHODS: Times to first-line treatment failure and annual costs were calculated for first-line HAART regimens by CD4 count when starting HAART (2006 UK prices). Cost-effectiveness of 2NRTIs+NNRTI versus 2NRTIs+PI(boosted) regimens was calculated for four CD4 strata. RESULTS: 55% of 5,541 people living with HIV (PLHIV) started HAART with CD4 count ≤ 200 cells/mm3, many of whom were Black Africans. Annual treatment cost decreased as CD4 count increased; most marked differences were observed between starting HAART with CD4 ≤ 200 cells/mm3 compared with CD4 count >200 cells/mm3. 2NRTI+PI(boosted) and 2NRTI+NNRTI regimens were the most effective regimens across the four CD4 strata; 2NRTI + NNRTI was cost-saving or cost-effective compared with 2NRTI + PI(boosted) regimens. CONCLUSION: To ensure more effective and efficient provision of HIV services, 2NRTI+NNRTI should be started as first-line HAART regimen at CD4 counts ≤ 350 cell/mm3, unless specific contra-indications exist. This will increase the number of PLHIV receiving HAART and will initially increase population costs of providing HIV services. However, starting PLHIV earlier on cost-effective regimens will maintain them in better health and use fewer health or social services, thereby generating fewer treatment and care costs, enabling them to remain socially and economically active members of society. This does raise a number of ethical issues, which will have to be acknowledged and addressed, especially in countries with limited resources.

Rising population cost for treating people living with HIV in the UK, 1997-2013.

BACKGROUND: The number of people living with HIV (PLHIV) is increasing in the UK. This study estimated the annual population cost of providing HIV services in the UK, 1997-2006 and projected them 2007-2013. METHODS: Annual cost of HIV treatment for PLHIV by stage of HIV infection and type of ART was calculated (UK pounds, 2006 prices). Population costs were derived by multiplying the number of PLHIV by their annual cost for 1997-2006 and projected 2007-2013. RESULTS: Average annual treatment costs across all stages of HIV infection ranged from £17,034 in 1997 to £18,087 in 2006 for PLHIV on mono-therapy and from £27,649 in 1997 to £32,322 in 2006 for those on quadruple-or-more ART. The number of PLHIV using NHS services rose from 16,075 to 52,083 in 2006 and was projected to increase to 78,370 by 2013. Annual population cost rose from £104 million in 1997 to £483 million in 2006, with a projected annual cost between £721 and £758 million by 2013. When including community care costs, costs increased from £164 million in 1997, to £683 million in 2006 and between £1,019 and £1,065 million in 2013. CONCLUSIONS: Increased number of PLHIV using NHS services resulted in rising UK population costs. Population costs are expected to continue to increase, partly due to PLHIV's longer survival on ART and the relative lack of success of HIV preventing programs. Where possible, the cost of HIV treatment and care needs to be reduced without reducing the quality of services, and prevention programs need to become more effective. While high income countries are struggling to meet these increasing costs, middle- and lower-income countries with larger epidemics are likely to find it even more difficult to meet these increasing demands, given that they have fewer resources.

Survival following HIV infection of a cohort followed up from seroconversion in the UK.

OBJECTIVES: To estimate changes over calendar time in survival following HIV seroconversion in the era of HAART and to provide updated survival estimates. METHODS: Using data from a UK cohort of persons with well estimated dates of HIV seroconversion, we analysed time from seroconversion to death from any cause using Cox models, adjusted for prognostic factors. Kaplan-Meier methods were then used to determine the expected survival in each calendar period. RESULTS: 2275 seroconverters were included with 18 695 person-years of follow up. A total of 444 (20%) died. The relative risk of death, compared with pre-1996, decreased over time to 0.63 [95% confidence interval (CI), 0.48-0.81], 0.24 (0.17-0.34), 0.14 (0.10-0.21), 0.08 (0.05-0.13) and 0.03 (0.02-0.06) in 1996-1997, 1998-1999, 2000-2001, 2002-2003 and 2004-2006, respectively. An elevated risk of death was associated with older age at seroconversion [hazard ratio (HR), 1.49; 95% CI, 1.34-1.66 per 10-year increase] and HIV infection through injecting drug use (HR, 1.53; 95% CI, 1.17-2.00). In 2000-2006, the proportion of individuals expected to survive 5, 10 and 15 years following seroconversion was 99%, 94% and 89%, respectively. CONCLUSIONS: Survival following HIV seroconversion has continued to improve over calendar time in our cohort, even in the more recent years of HAART availability. HIV seroconverters, by definition identified early in their infection, are likely to have the greatest opportunity for intervention; if similar high survival expectations are to be seen in the wider HIV-infected population, early diagnosis is likely to be crucial.

HIV and drug misuse in the Edinburgh cohort.

The Edinburgh cohort of intravenous drug users (IVDUs) became infected with HIV between 1983 and 1984. Before the era of effective therapy, many of these infected IVDUs displayed cognitive impairments on progressing to AIDS and were found to have HIV encephalitis (HIVE). Full autopsies were conducted on these patients, providing an opportunity to study the intersecting pathology of pure HIVE and drug use. High proviral load in the brain correlated well with the presence of giant cells and HIV p24 positivity. In presymptomatic HIV infection, IVDUs were found to have a lymphocytic infiltrate in the central nervous system (CNS). Apart from the expected microglial activation in the presence of HIV infection of the CNS, drug use in its own right was found to be associated with microglial activation. Examination of HIV-negative IVDUs revealed a number of neuropathologic features, including microglial activation, which may underpin HIV-related pathology in the CNS. HIV isolated from different regions of the brain was exclusively of R5-tropic type throughout the course of infection. Detailed studies of p17 and V3 sequences suggest that viral sequestration occurs in the CNS before the onset of AIDS and that increasing diversity of HIV variants within the brain is associated with increasing severity of HIVE. Because brain isolates have proved to be different from those in lymphoid tissue (and blood), it is likely that selective neuroadaptive pressures operate before HIVE supervenes. Drug abuse may be synergistic in this process through activation of microglia, breakdown of the blood-brain barrier, and direct neurotoxicity. Collections of clinically well-characterized HIV-infected tissues such as those in the Edinburgh Brain Bank are a vital resource to support ongoing studies of viral pathogenesis in the CNS and interactions with drug abuse.