Lytic to temperate switching of viral communities.

Microbial viruses can control host abundances via density-dependent lytic predator-prey dynamics. Less clear is how temperate viruses, which coexist and replicate with their host, influence microbial communities. Here we show that virus-like particles are relatively less abundant at high host densities. This suggests suppressed lysis where established models predict lytic dynamics are favoured. Meta-analysis of published viral and microbial densities showed that this trend was widespread in diverse ecosystems ranging from soil to freshwater to human lungs. Experimental manipulations showed viral densities more consistent with temperate than lytic life cycles at increasing microbial abundance. An analysis of 24 coral reef viromes showed a relative increase in the abundance of hallmark genes encoded by temperate viruses with increased microbial abundance. Based on these four lines of evidence, we propose the Piggyback-the-Winner model wherein temperate dynamics become increasingly important in ecosystems with high microbial densities; thus 'more microbes, fewer viruses'.

Treatment outcomes of integrase inhibitors, boosted protease inhibitors and nonnucleoside reverse transcriptase inhibitors in antiretroviral-naïve persons starting treatment.

OBJECTIVES: Although outcomes of antiretroviral therapy (ART) have been evaluated in randomized controlled trials, experiences from subpopulations defined by age, CD4 count or viral load (VL) in heterogeneous real-world settings are limited. METHODS: The study design was an international multicohort collaboration. Logistic regression was used to compare virological and immunological outcomes at 12 ± 3 months after starting ART with an integrase strand transfer inhibitor (INSTI), contemporary nonnucleoside reverse transcriptase inhibitor (NNRTI) or boosted protease inhibitor (PI/b) with two nucleos(t)ides after 1 January 2012. The composite treatment outcome (cTO) defined success as VL < 200 HIV-1 RNA copies/mL with no regimen change and no AIDS/death events. Immunological success was defined as a CD4 count > 750 cells/µL or a 33% increase where the baseline CD4 count was ≥ 500 cells/µL. Poisson regression compared clinical failures (AIDS/death ≥ 14 days after starting ART). Interactions between ART class and age, CD4 count, and VL were determined for each endpoint. RESULTS: Of 5198 ART-naïve persons in the International Cohort Consortium of Infectious Diseases (RESPOND), 45.4% started INSTIs, 26.0% PI/b and 28.7% NNRTIs; 880 (17.4%) were aged > 50 years, 2539 (49.4%) had CD4 counts < 350 cells/µL and 1891 (36.8%) had VL > 100 000 copies/mL. Differences in virological and immunological success and clinical failure among ART classes were similar across age groups (≤ 40, 40-50 and > 50 years), CD4 count categories (≤ 350 vs. > 350 cells/µL) and VL categories at ART initiation (≤ 100 000 vs. > 100 000 copies/mL), with all investigated interactions being nonsignificant (P > 0.05). CONCLUSIONS: Differences among ART classes in virological, immunological and clinical outcomes in ART-naïve participants were consistent irrespective of age, immune suppression or VL at ART initiation. While confounding by indication cannot be excluded, this provides reassuring evidence that such subpopulations will equally benefit from contemporary ART.

Euroguidelines in Central and Eastern Europe (ECEE) conference and the Warsaw Declaration - a comprehensive meeting report.

OBJECTIVES: The objective of this paper is to summarize the outcomes of the Euroguidelines in Central and Eastern Europe (ECEE) conference held in Warsaw in February 2016. The main aim of this conference was to facilitate a discussion on European AIDS Clinical Society (EACS) guidelines implementation across the region and neighbouring countries and to present the current obstacles in benchmarking HIV care in Europe. METHODS: During a 2-day meeting, there were country-based presentations using a predefined template so as to make the data comparable and focus the discussion. Areas covered were country epidemiology, surveillance, national strategy for treatment and prevention, standards of care, access to care and treatment availability. Each participant filled in a questionnaire investigating HIV guidelines usage per country. RESULTS: In total, 16 Central and Eastern Europe (CEE) and neighbouring countries were represented at the conference: Albania, Armenia, Belarus, Croatia, Czech Republic, Estonia, Georgia, Hungary, Lithuania, Moldova, Poland, Romania, Russia, Serbia, Slovakia and Turkey. EACS guidelines version 7.1 were used in 14 (87%) countries. In 11 (69%) countries, national guidelines were available, of which eight had been recently updated. Half of the countries declared that they use World Health Organization (WHO) and Department of Health and Human Services (DHHS) guidelines, over one-third the European Centre for Disease Prevention and Control (ECDC) HIV testing guidelines and one in five the International Antiviral Society-USA (IAS-USA) Panel guidelines from 2012. CONCLUSIONS: Participants declared their will to promote the widespread use of EACS guidelines for HIV infection in the CEE region and neighbouring countries by signing the Warsaw Declaration. They also emphasized the need to increase publishing of data from national cohorts in that region.

Cytochrome P450 2B6 516G-->T is associated with plasma concentrations of nevirapine at both 200 mg twice daily and 400 mg once daily in an ethnically diverse population.

OBJECTIVES: The aim of the study was to characterize the impact of the cytochrome P450 2B6 (CYP2B6), CYP3A4, CYP3A5 and ATP-binding cassette sub-family B member 1 (ABCB1) polymorphisms on nevirapine plasma concentrations. METHODS: A total of 104 patients (82% male; 26% non-Caucasian) were genotyped for eight single nucleotide polymorphisms at four loci (CYP2B6, CYP3A4, CYP3A5 and MDR1). Nevirapine plasma concentrations were determined using high-performance liquid chromatography. RESULTS: Non-Caucasian ethnicity [5609 ng/mL (n=27) for non-Caucasians vs. 3771 ng/mL (n=77) for Caucasians; P<0.0001] and CYP2B6 516G-->T [GG, 3574 ng/mL (n=50); GT, 4634 ng/mL (n=50); TT, 8170 ng/mL (n=4); P(analysis of variance (anova))=0.001] were significantly associated with a higher nevirapine trough concentration (C(trough)). The latter association was maintained with both 200 mg twice daily (bid) and 400 mg once daily (qd) dosing [GG, 3527 ng/mL (n=30); GT, 4525 ng/mL (n=32); TT, 7020 ng/mL (n=2); P(anova)=0.05 and GG, 3645 ng/mL (n=20); GT, 4861 ng/mL (n=17); TT, 9508 ng/mL (n=2); P(anova)=0.01, respectively]. In a multivariable analysis, CYP2B6 516G-->T and non-Caucasian ethnicity remained significant predictors of nevirapine C(trough) but CYP2B6 516G-->T homozygosity had the greatest effect (108% higher, 46% higher). No associations were found between nevirapine C(trough) and the remaining polymorphisms. CONCLUSION: In this population, both non-Caucasian ethnicity and carriage of the variant allele of CYP2B6 516G-->T were significant predictors of nevirapine C(trough). The association between CYP2B6 516G-->T and higher plasma nevirapine exposure was maintained at both bid and qd dosing.

Factors associated with viral rebound among highly treatment-experienced HIV-positive patients who have achieved viral suppression.

OBJECTIVE: More and more highly treatment-experienced patients are achieving viral suppression. However, the durability of suppression remains unclear. METHODS: Patients from Royal Free Hospital (London, UK) and JW Goethe University Hospital (Frankfurt, Germany) who had failed > or = 1 antiretroviral (ARV) regimen in all three main drug classes and > or = 3 previous ARV regimens and subsequently achieved viral load < 50 HIV-1 RNA copies/mL were included. They were followed until stopping pre-combination antiretroviral therapy, end of follow-up or viral rebound (two viral loads >400 copies/mL). RESULTS: Two hundred and forty-seven patients contributed 723 person-years and 114 viral rebounds [rate=15.8 per 100 person-years; 95% confidence interval (CI) 12.9-18.7]. More recent calendar years of viral suppression [relative risk (RR)=0.90 per year later; 95% CI 0.81-1.00; P=0.05] and greater number of ARVs in the regimen not previously failed (RR=0.78 per 1 ARV more; 95% CI 0.65-0.95; P=0.01) were associated with lower viral rebound rates. At 0-1, 1-2, 2-3 and > 3 years after achieving suppression, the rebound rates were 30.9, 9.2, 4.3 and 3.5 per 100 person-years, respectively. Compared to 0-1 years, the adjusted RRs (95% CIs) after 1-2, 2-3 and > 3 years were 0.33 (0.18-0.58), 0.21 (0.09-0.48) and 0.14 (0.06-0.33), respectively (P<0.0001). CONCLUSIONS: Although rebound rates are high, especially in the first year after viral suppression, this risk reduces substantially if highly treatment-experienced patients can maintain viral suppression.

Comparison of nucleoside reverse transcriptase inhibitor use as part of first-line therapy in a Serbian and a UK HIV clinic.

BACKGROUND: Use of dideoxynucleoside reverse transcriptase inhibitors (dNRTIs) may lead to increased mitochondrial toxicity. We compared nucleoside reverse transcriptase inhibitor (NRTI) use as part of antiretroviral therapy (ART) in two HIV clinics: one in a low-middle income (HIV Centre Belgrade [HCB], Serbia) and one a high income (ICDC, Royal Free Hospital, London, UK) country. METHODS: Antiretroviral naïve patients starting ART from 2003 to 2005 were included. Specific NRTIs were compared between centers, focusing on dNRTI use. Kaplan-Meier estimates of the percentage of patients making changes to their NRTI backbone (a) for any reason or (b) for mitochondrial toxicity (peripheral neuropathy, pancreatitis, lactic acidosis) were calculated. RESULTS: Of 287 HCB patients, 89 (31.0%) received didanosine (ddI)-containing, 39 (13.6%) stavudine (d4T)-containing, and 39 (13.6%) ddI+d4T-containing regimens; for 539 ICDC patients, these were 18 (3.3%), 66 (12.2%), and 0 (0.0%), respectively (p < .0001). After 12 months, 57.5% and 52.6% at HCB and ICDC had switched their NRTI backbone. This was reduced to 34.5% at HCB after excluding changes due to drug supply interruption and to 11.2% and 1.3% at HCB and ICDC after changes were made for mitochondrial-related reasons. At 6 months, 73/80 (91.3%) and 385/488 (78.9%) had viral load below 50 copies/mL at HCB and ICDC, respectively. CONCLUSION: Patients treated at HCB faced higher levels of mitochondrial-related toxicity, likely due to greater dNRTI use.

Long-term clinical and surrogate marker effects of subcutaneous intermittent interleukin-2 without antiretroviral therapy in HIV-infected patients.

OBJECTIVES: Subcutaneous administration of interleukin-2 (IL-2) has been shown to increase CD4 counts in HIV-infected patients. It remains unclear whether this effect is associated with a clinical benefit. PATIENTS AND METHODS: We conducted a long-term follow-up in the cohort of the UK-Vanguard study in which three groups of 12 antiretroviral-naive subjects with CD4 cell counts >350 cells/mm(3) received no treatment or IL-2 at either 4.5 or 7.5 MIU twice daily in 5 day cycles, respectively. RESULTS: Mean follow-up was 376 weeks. IL-2 therapy was associated with a higher area under the curve of CD4 cell count change from baseline at week 48 but not thereafter. HIV-RNA levels were unaffected. Highly active antiretroviral therapy (HAART) was initiated after a mean of 172, 175 and 152 weeks in the control group, low-dose and high-dose IL-2 treatment group, respectively, a statistically non-significant difference. There was a tendency to start HAART soon after discontinuation of IL-2 therapy which may have been triggered by the steep decay of CD4 counts. There were two serious adverse events in the control group, seven in the low-dose IL-2 group and eight in the high-dose IL-2 group. No pattern of disease was detected, making an association with IL-2 therapy unlikely. CONCLUSIONS: We could detect neither a benefit of IL-2 therapy after week 48 nor delayed initiation of HAART. This is currently the longest follow-up data comparing IL-2 therapy with no therapy in antiretroviral-naive HIV-infected patients and does not show a persistent benefit of the intervention.

Treatment outcome and cost-effectiveness of different highly active antiretroviral therapy regimens in the UK (1996-2002).

The aim of this study was to estimate the outcome and cost-effectiveness per life-year-gained (LYG) of first-, second- and third-line non-nucleoside reverse transcriptase inhibitors (NNRTI) versus protease inhibitor (PI) containing highly active antiretroviral therapy regimens. Hospital care costs (2002 US dollars discounted 3.5% per annum) were linked to treatment failure times. Results show that the median time-to-treatment failure for first-line (nucleoside reverse transcriptase inhibitors) 2NRTIs + NNRTI was substantially longer than that for 2NRTIs + PI(boosted), 2NRTIs + PI and 2NRTIs + 2PIs, whereas for second- and third-line they were similar. Comparing first-line 2NRTIs + NNRTI with 2NRTIs + PI(boosted) cost per LYG was US$ 12,375; US$ 12,139 per LYG when compared with 2NRTIs + PI and US$ 2948 per LYG when compared with 2NRTIs + 2PIs. For second-line cost per LYG comparing 2NRTIs + NNRTI with 2NRTIs + PI(boosted) was US$ 19,501; US$ 18,364 per LYG when compared with 2NRTIs + PI and cost-saving when compared with 2NRTIs + 2PIs. For third-line cost per LYG comparing 2NRTIs + NNRTI with 2NRTIs + PI(boosted) was US$ 2708; US$ 11,559 per LYG when compared with 2NRTIs + PI and cost-saving when compared with 2NRTIs + 2PIs. In conclusion, first-line 2NRTIs + NNRTI was cost-effective or cost-saving when compared with PI-containing regimens for all lines of therapy. Such information is required by clinicians and managers of HIV services to make appropriate treatment decisions based on clinical and financial grounds, and given the increasing number of people living with HIV, such information will become more important over time.

The incidence of AIDS-defining illnesses in 4883 patients with human immunodeficiency virus infection. Royal Free/Chelsea and Westminster Hospitals Collaborative Group.

BACKGROUND: Acquired immunodeficiency syndrome (AIDS)-defining illnesses are known to occur at different levels of immunosuppression, and the incidence of diagnoses may also vary according to the CD4 lymphocyte count strata. Information about the incidence of disease at different levels of immunosuppression would help clinicians monitoring patients and would allow prophylaxis to be targeted at the most appropriate population. METHODS: Between 1982 and July 1995, 4883 patients testing positive for the human immunodeficiency virus were seen at either the Royal Free or Chelsea and Westminster Hospitals in London, England. The incidence of each diagnosis, both overall and stratified by CD4 lymphocyte count, was calculated using a person-years analysis. Patients who had no CD4 lymphocyte counts measured during follow-up were excluded from the analysis. RESULTS: During a median follow-up period of 27.6 months, 3875 AIDS-defining illnesses were reported in 1713 patients. The incidence of AIDS-defining illnesses ranged from 6.22 per 100 person-years of follow-up for Pneumocystis carinii pneumonia (95% confidence interval, 5.74-6.70) to 0.37 for extrapulmonary tuberculosis (95% confidence interval, 0.26-0.48). The incidence of each AIDS-defining illness increased as the CD4 lymphocyte count declined; diagnoses such as cytomegalovirus and Mycobacterium avium-intracellulare complex infection had a low incidence at CD4 lymphocyte counts above 0.05x10(9)/L (50/mm3), while Kaposi sarcoma, P carinii pneumonia, and esophageal candidiasis had a high incidence throughout all CD4 lymphocyte count strata. CONCLUSIONS: This study provides important information about the risk of AIDS-defining illnesses at lower CD4 lymphocyte counts, enabling disease-specific prophylaxis to be targeted at the most appropriate population. In the future, as more prophylactic therapies are developed, this study will provide historical data of the incidence of diseases before specific prophylaxis was introduced.

Restriction of sensitivity of HIV-1-antigen ELISA by serum anti-core antibodies.

Addition of varying concentrations of HIV-1-seropositive plasma to purified virus particles and soluble viral antigen preparation inhibited the detection of HIV-1-antigen by ELISA. The degree of inhibition on p24 antigen ELISA depended on the relative concentrations of viral antigen and anti-p24 antibodies in the mixtures. The relevance of these observations to clinical specimens was demonstrated when serial plasma samples from nine AIDS-related complex (ARC) patients in a clinical trial of foscarnet therapy were assayed for p24 antigen. Six (66.6%) out of nine patients were negative on screening. However, when their plasma was centrifuged through a sucrose solution, virus particles were pelleted that were depleted of anti-p24 and virus-specific p24 antigen was detected in resuspended pellets obtained from samples from all six patients. Eight serial samples collected from a male homosexual over 50 weeks following seroconversion were also subjected to the separation procedure. HIV-1-antigen was detected in all eight samples. In the light of these observations, the application of the separation technique in monitoring the efficacy of zidovudine or other anti-retroviral therapy should reveal more precise antigen levels in patients who otherwise appear to be antigen-negative in HIV-antigen assays. We propose that the natural history of HIV infections follows a pattern of chronic viral infection with continuous shedding of virus particles circulating as immune complexes.

Rapid decline in detectability of HIV-1 drug resistance mutations after stopping therapy.

OBJECTIVE: To investigate the rate of decline of drug resistant viruses after stopping therapy. DESIGN: Twenty-five patients receiving multiple combination therapies (mean five; range three to nine drugs) for more than 3 months were tested for HIV-1 resistance on therapy and off therapy. The sample off therapy was tested 6-175 days after stopping therapy. METHODS: Patients were tested for genotypic changes associated with drug resistance using an in-house automated DNA sequencing assay to detect resistance in the protease and reverse transcriptase genes. RESULTS: All samples tested when patients were on therapy showed evidence of drug resistance (range 1-9 mutations). The patients were divided into three groups: <2 weeks after stopping therapy, median 1.1 weeks (n = 8, group A); 2 weeks-2 months, median 6.4 weeks (n = 7, group B) and 2 months-6 months, median 12.9 weeks (n = 10, group C). Of primary mutations (protease: 30N, 461/L, 82A, 90M; reverse transcriptase: 70R, 184I/V, 215 Y/F) detected on therapy 100% remained after stopping therapy in group A; 68% remained in group B and 15% remained in group C. For secondary mutations 98% remained in group A; 99% remained in group B and 57% in group C. CONCLUSIONS: This study showed a rapid decline in detectability of the majority of primary mutations within 13 weeks of stopping combination therapy. From this data, HIV-1 resistance testing to direct patients' therapy should only be carried out when on existing therapy, or < 2 weeks off therapy, if reliable decisions are to be made relating to future combinations.

Use of a stochastic model to develop understanding of the impact of different patterns of antiretroviral drug use on resistance development.

OBJECTIVE: To use a stochastic model to gain insights into the consequence for resistance development of different drug use patterns. METHODS: We consider use of three drugs (A, B and C) where for each drug one and only one viral mutation is associated with ability to replicate (effective reproductive ratio, R > 1) in the presence of that drug as monotherapy. For drug A mutation is a, etc. We define eight populations of short-lived infected cells that live 1 day: Vo with no mutations a, b, c; Va with mutation a only, Vab with mutations a and b, etc. A random number generator was used to determine whether mutations occur in any one round of replication and to sample from a Poisson distribution to determine for each cell the number of cells of the same population created in the next generation, using the R operative at that time. Values of R depended on drug exposure, cost of resistance and availability of target cells. RESULTS: Treatment strategies and the resulting percentage (over 100 runs) developing full "resistance" in 1500 days (Vabc not equal 0) were: (i) ABC 1500 days 0%; (ii) A 300 days, AB 300 days, ABC 900 days 100%; (iii) AB 300 days, ABC 1200 days 33%; (iv) ABC 2/3 1500 days 15%; (v) ABC 1/2 1500 days 100%; (vi) ABC 50 days, no drugs 50 days, for 1500 days 1%, where ABC 2/3 means on-drug for 2 days in every 3, ABC 1/2 represents on-drug for 1 day in every 2, and represents suboptimal adherence. CONCLUSIONS: This model helps to develop understanding of key principles concerning development of resistance under different patterns of treatment use.

The safety of intravenous chemotherapy and zidovudine when treating epidemic Kaposi's sarcoma.

Patients with epidemic Kaposi's sarcoma, who are often taking zidovudine, may be treated with cytotoxic chemotherapeutic agents. Both cytotoxic chemotherapy and zidovudine are myelotoxic and we have treated 16 patients with this combination. We report an acceptable rate of anaemia, leucopaenia, thrombocytopaenia and non-haematological side effects. This combination can be safely administered to this group of patients, although much of our experience is with the relatively non-myelotoxic chemotherapeutic agents, bleomycin and vincristine.

Anti-herpesvirus treatment and risk of Kaposi's sarcoma in HIV infection. Royal Free/Chelsea and Westminster Hospitals Collaborative Group.

OBJECTIVE: With the recent identification of a new herpesvirus in patients with Kaposi's sarcoma (human herpesvirus-8 or Kaposi's sarcoma-associated herpesvirus), there have been several reports on the use of anti-herpesvirus therapy (foscarnet, ganciclovir and aciclovir) and risk of developing Kaposi's sarcoma. We therefore investigated the association between use of anti-herpesvirus drugs and Kaposi's sarcoma in a large unselected group of patients with AIDS. PATIENTS AND METHODS: We studied a group of HIV-positive patients at the Chelsea and Westminster Hospital, for whom details on all AIDS-defining diagnoses made during follow-up, treatment and regular CD4 counts were available. Cox proportional hazards models with time-dependant covariates were used to assess the association between treatment with aciclovir, foscarnet and ganciclovir and risk of Kaposi's sarcoma. RESULTS: A total of 3688 patients have been followed up for a median period of 4.2 years, during which time 598 patients (16.2%) developed Kaposi's sarcoma. After adjustments for sex, exposure category, age, treatment with antiretrovirals or Pneumocystis carinii pneumonia prophylaxis, the development of AIDS-defining conditions (including separate adjustment for the development of cytomegalovirus and herpes simplex virus) and CD4 count, there was a decreased risk of developing Kaposi's sarcoma with foscarnet [relative hazard (RH), 0.38; 95% confidence interval (CI), 0.15-0.95; P = 0.038] and with ganciclovir (RH, 0.39; 95% CI, 0.19-0.84; P = 0.015), but not with aciclovir (RH, 1.10; 95% CI, 0.88-1.38; P = 0.40). CONCLUSIONS: These results suggest that both foscarnet and ganciclovir may have some activity in preventing the occurrence of Kaposi's sarcoma, but that aciclovir has no benefit. Further studies of the effect of these drugs on the risk of Kaposi's sarcoma is warranted.

Pneumocystis carinii pneumonia treated with eflornithine in AIDS patients resistant to conventional therapy.

Eflornithine (DFMO) was used to treat 31 AIDS patients with confirmed Pneumocystis carinii pneumonia who had clinically failed treatment with pentamidine, sulphamethoxazole-trimethoprim or both agents as their first-line therapy. Twenty-one of 31 (68%) responded to second-line treatment with 400mg/kg per day of eflornithine. Five patients discontinued treatment because of bone marrow toxicity. Eflornithine appears to be a useful salvage therapy in patients failing first-line treatments.

Anti-CD4 autoantibodies and screening for anti-idiotypic antibodies to anti-CD4 monoclonal antibodies in HIV-seropositive people.

The cell-surface antigen CD4 is the major receptor for HIV. Anti-CD4 autoantibodies and anti-idiotypic antibodies to murine monoclonal anti-CD4 antibodies have been described in HIV-infected people. Ninety-seven sera from HIV-infected people at all stages of disease were examined for the presence of anti-idiotypic antibodies to three anti-CD4 monoclonal antibodies. None were found. The same sera were screened for antibodies reactive with soluble CD4, and five (5.2%) were positive. These antibodies did not recognize native CD4, and it is thought unlikely that they arise as anti-idiotypes to anti-gp120 antibodies.

Changes in CD4 lymphocyte counts after interruption of therapy in patients with viral failure on protease inhibitor-containing regimens. Royal Free Centre for HIV Medicine.

OBJECTIVE: To describe the short-term changes in CD4 lymphocyte counts after the interruption of antiretroviral HIV therapy in order to increase the understanding of CD4 lymphocyte dynamics, and so that appropriate monitoring strategies can be designed. METHODS: We studied 35 HIV-infected patients with late-stage disease who had therapy interruptions leading to high viral load levels, median greater than 750 000 RNA log10 copies/ml, and in whom two CD4 cell counts (median 28 days apart) were available before beginning a salvage regimen. RESULTS: Overall, there was a substantial decline in CD4 cell counts from a median of 125 to 83 cells/mm3 in the average 28 day period, with median proportionate and absolute losses of 26% and 24 cells/mm3 per month, respectively (P < 0.008). This tended to be greater in individuals studied sooner after interrupting therapy (P = 0.03) and in those with CD4 cell counts above the pre-therapy baseline (P = 0.06). There was a strong negative correlation between the proportionate increase in viral load and the absolute change in CD4 cell count (-0.66, P = 0.0002). CONCLUSION: Patients with relatively advanced HIV infection interrupting antiretroviral therapy after failing a protease inhibitor-containing regimen require frequent monitoring because CD4 cell counts appear to fall quite rapidly, at least in the first few weeks after interruption.

Immunological, virological and clinical response to highly active antiretroviral therapy treatment regimens in a complete clinic population. Royal Free Centre for HIV Medicine.

BACKGROUND: Highly active antiretroviral therapy (HAART) is now widely used in clinical practice and gives rise to a range of immunological, virological and clinical responses. OBJECTIVES: To describe the immunological, virological and clinical response to HAART and to examine the frequency of modification of the HAART regimen among patients from a single treatment centre. METHODS: Kaplan-Meier estimation and incidence rates were used to describe responses to HAART (a protease inhibitor or non-nucleoside drug in addition to at least two nucleoside analogues) among 421 patients from the Royal Free Hospital in London. RESULTS: The median CD4 cell count at starting HAART was 186 x 10(6) cells/l [interquartile range (IQR) 76-310] and viral load was 5.13 log10 copies/ml (IQR 4.66-5.56). At 6 months after starting HAART, 51.1% of patients were estimated to have experienced a 100 x 10(6) cells/l increase in CD4 cell count; the median time for viral load to fall below 400 copies/ml was 3.7 months (95% confidence interval 3.2-4.4). At 6 months after the first viral load was < 400 copies/ml, 16.4% of patients were estimated to have failed on the basis of a single viral load > 400 copies/ml and 12.4% were estimated to have failed if the more stringent definition of two viral loads above the limit of detection was used. Compared with the pre-HAART era, the incidence of death among patients on HAART was one sixth of that level; new AIDS-defining illnesses was one seventh; and hospital admissions was one fifth. In total, 141 patients (33.5%) stopped at least one of the antiretroviral agents included as part of their HAART regimen; the occurrence of side effects was the most common reason (n = 63; 44.7%). CONCLUSION: A good response occurred to an initial HAART regimen. There was a high rate of virological relapse, which varied considerably according to the definition of failure used. Even so, the rates of clinical progression and hospital admissions observed to date were low. Further follow-up of these patients is required to determine their long-term immunological, virological and clinical outcome.

The changing pattern of admissions to a London hospital of patients with HIV: 1988-1997. Royal Free Centre for HIV Medicine.

OBJECTIVE: To describe the changes over time in incidence of hospital admissions among patients with HIV, reasons for hospital admission, duration of stay, relationship with CD4 T-cell count and with antiretroviral treatment. METHODS: The incidence of hospital admissions during each calendar year from 1988 to 1997 inclusive was calculated using a person-years analysis. In addition the proportion of patient follow-up spent in hospital and the impact of changing treatment regimens among all patients with HIV aged > or = 14 years and with at least one CD4 T-cell count seen at the Royal Free Hospital, London was also described. RESULTS: A total of 1806 patients were investigated with median follow-up of 21.1 months. Among all patients, the proportion of follow-up time spent as an in-patient decreased from 3.9% in 1988 to 1.3% in 1997 (P = 0.0015; test for trend). Hospital admissions for any cause peaked during 1989 at 72.0 per 100 patient years of follow-up (PYFU) and was 28.5 per 100 PYFU during 1997 (P < 0.0001; test for trend). There was a statistically significant decline in the proportion of follow-up time spent as an in-patient among patients with CD4 T-cell counts of < 50 x 10(6)/l from > 30% before 1990 to < 5% during 1997 (P = 0.026; test for trend). Hospital admissions varied greatly according to treatment regimen; in 1996 and 1997 just 0.1% of follow-up time of patients on triple antiretroviral treatment regimens was spent as a hospital admission. CONCLUSIONS: Admissions to hospital began falling before the introduction of combination therapy and declined strikingly during 1996 and 1997 following the introduction of highly active antiretroviral therapy. These results have important implications for future allocation of resources and for patient management.