Discontinuation of primary prophylaxis against Pneumocystis carinii pneumonia in HIV-1-infected adults treated with combination antiretroviral therapy. Swiss HIV Cohort Study

Endemic fungal infections caused by Cryptococcus neoformans and Penicillium marneffei in patients infected with human immunodeficiency virus and treated with highly active anti-retroviral therapy

This study compared the clinical presentations of 58 episodes of cryptococcosis in 50 patients and 26 episodes of penicillosis in 25 patients infected with human immunodeficiency virus (HIV) between June 1994 and June 2004, and assessed the safety of discontinuation of secondary prophylaxis for endemic fungal infections in those patients responding to highly active anti-retroviral therapy (HAART). Neurological symptoms were seen more commonly in patients with cryptococcosis, whereas respiratory symptoms, lymphadenopathy, hepatomegaly and/or splenomegaly, and non-thrush-related oral presentations were seen more commonly in patients with penicillosis. Patients with penicillosis were more likely to have abnormal chest radiography results and radiographic presentations of interstitial lesions, cavitations, fibrotic lesions and mass lesions. At the end of the study, maintenance antifungal therapy had been discontinued in 27 patients with cryptococcosis and in 18 patients with penicillosis in whom the median CD4 count had increased to 186 cells/microL (range, 9-523 cells/microL) and 95 cells/microL (range, 15-359 cells/microL), respectively, after HAART. Only one episode of penicillosis recurred (a relapse rate of 1.72/100 person-years; 95% CI, 1.44-2.10/100 person-years) after a median follow-up duration of 35.3 months (range, 2.6-91.6 months). No relapses occurred in patients with cryptococcosis after a median follow-up duration of 22.3 months (range, 1-83.4 months). These findings suggest that there are differences in the clinical presentations between endemic cryptococcosis and penicillosis in patients with HIV infection, and that it is safe to discontinue secondary antifungal prophylaxis for cryptococcosis and penicillosis in patients responding to HAART.

Immunological recovery and antiretroviral therapy in HIV-1 infection

Potent antiretroviral therapy has dramatically improved the prognosis of patients infected with HIV-1. Primary and secondary prophylaxis against Pneumocystis carinii, Mycobacterium avium, cytomegalovirus, and other pathogens can be discontinued safely once CD4 cell counts have increased beyond pathogen-specific thresholds. Approximately one-third of individuals receiving antiretroviral therapy will not reach CD4 cell counts above 500 cells per muL after 5 years despite continuous suppression of plasma HIV-1 RNA. Whether this failure represents a risk factor for the long-term incidence of opportunistic diseases--eg, tuberculosis or malignancies--remains uncertain. We describe the time course of CD4 cell concentrations in patients whose plasma HIV-1 RNA is durably suppressed by antiretroviral therapy, in patients with incomplete suppression of plasma HIV-1 RNA, and during treatment interruptions. In addition, immune reconstitution disease, an inflammatory syndrome associated with immunological recovery occurring days to weeks after the start of antiretroviral therapy, is briefly described.

Withdrawal of Pneumocystis jirovecii prophylaxis in HIV-infected children under highly active antiretroviral therapy

OBJECTIVE

In HIV-infected adults Pneumocystis jirovecii pneumonia (PCP) prophylaxis can be safely withdrawn after immune reconstitution due to the introduction of highly active antiretroviral therapy (HAART). With regard to children only a small amount of data has been published. The present study investigated whether the withdrawal of PCP prophylaxis after immune reconstitution is safe in HIV-infected children.

METHODS

A retrospective analysis at 10 European centers belonging to the Pediatric European Network on the treatment of AIDS (PENTA) using a standardized questionnaire.

RESULTS

A total of 113 questionnaires were received. In 82 children the indication for PCP prophylaxis was provided following Centers for Disease Control (CDC) guidelines (72 primary and 10 secondary). Prophylaxis was withdrawn after the CD4 cell count increased above the age-related CDC thresholds. The observation period off prophylaxis was 335 years (300 years for primary and 35 years for secondary prophylaxis) and the median time per patient off prophylaxis was 4.1 years (range, 0.3-7.7 years). No episode of PCP occurred during the study period. In comparison with the incidence rate from historical data before the introduction of PCP prophylaxis and HAART, this was a significant reduction (P < 0.05).

CONCLUSIONS

The increase in CD4 cell count provides functional reconstitution of the immune system in children. Our data suggests that the risk of developing a PCP after immune reconstitution is sufficiently low to withdraw PCP prophylaxis.

The rate of serious bacterial infections among HIV-infected children with immune reconstitution who have discontinued opportunistic infection prophylaxis

OBJECTIVE

Receipt of highly active antiretroviral therapy is associated with a decrease in the incidence of opportunistic infections (OIs) among HIV-infected adults. The goal of Pediatric AIDS Clinical Trials Group protocol 1008 was to evaluate prospectively the incidence of serious bacterial infections (SBIs) and other OIs after discontinuation of OI and/or Pneumocystis jiroveci pneumonia (PCP) prophylaxis among HIV-infected pediatric subjects who experienced immune reconstitution while receiving stable antiretroviral therapy.

METHODS

HIV-infected children and adolescents, 2 to 21 years of age, who had received OI and/or PCP prophylaxis for > or =6 months were enrolled if they had sustained responses (>16 weeks before study entry) to antiretroviral therapy, with CD4+ cell percentages of > or =20% for patients >6 years of age or > or =25% for patients 2 to 6 years of age. Prophylaxis was discontinued at entry. To identify whether any correlation existed between functional immune reconstitution and protection from OIs, subjects were immunized with the hepatitis A virus vaccine. The association between the humoral immune response and the likelihood of developing an OI was evaluated.

RESULTS

A total of 235 HIV-infected subjects from 43 participating sites had a median follow-up period of 132 weeks, yielding 547 person-years of observation. Twenty SBIs were observed among 19 subjects, resulting in an incidence rate of 3.66 SBIs per 100 person-years (95% confidence interval: 2.24-5.66 SBIs per 100 person-years). Sixteen of the events were presumed bacterial pneumonia, with 4 proven SBIs. One participant experienced 2 separate pneumonia episodes, of presumed bacterial cause. Ten subjects who developed SBIs had baseline CD4+ cell counts of > or =750 cells per mm3, and 15 had CD4+ cell percentages of > or =25% at the time of their SBIs. Two subjects died as a result of non-SBI-related causes. There were no statistically significant differences in changes over time in CD4+ cell counts or CD4+ cell percentages between subjects who experienced primary end points and those who did not. There was no evidence that baseline protease inhibitor use, gender, race/ethnicity, age, or CD4+ cell count or percentage affected the time to development of a SBI.

CONCLUSIONS

OI or PCP prophylaxis can be withdrawn safely for HIV-infected pediatric patients who experience CD4+ cell recovery while receiving stable antiretroviral therapy. More studies are needed to assess the association between antibody responses to neoantigens and the development of SBIs.

[Effectiveness of antiretroviral therapy in HIV-1 infected children. A cross-sectional study]

INTRODUCTION

There are few cross-sectional studies describing the current situation of HIV-1-infected children. Such studies would be useful to determine patients' clinical and immunologic and virologic status, currently prescribed therapies and their associated toxicity.

OBJECTIVES

To perform a descriptive analysis of the clinical, immunological and virological status of HIV-1-infected children followed-up in the pediatric unit of a tertiary hospital and describe the current antiretroviral therapies used to treat them.

MATERIAL AND METHODS

A cross-sectional study was performed. Data were collected from all HIV-1-infected children followed-up until January 2002 in a large pediatric referral hospital (Hospital 12 de Octubre in Madrid). Clinical evaluation and laboratory investigations were scheduled to be performed every 3 months. The most recent CD4 and plasma viral loads were evaluated. Viral loads were considered undetectable when there were less than 300 copies/ml at the last evaluation.

RESULTS

Sixty-six HIV-1-infected children who were followed-up to January 2002 were analyzed. All the children acquired the infection through vertical transmission except one, in whom the mode of transmission was unknown. The median age was 111 months (18-216). Twenty children were category C. The median CD4 cell count was 953 cells/mm3 (276-3137), 28 % +/- 8 (12.42). One child was receiving no therapy, four were on combination therapy with two nucleoside reverse transcriptase inhibitors (NRTI) and 61 were receiving highly active anti-retroviral therapy (HAART). Twenty-seven children (44 %) were receiving the first HAART regimen, 23 the second, and 11 had already been switched more than twice. Overall, 37 of the 61 patients receiving HAART had an undetectable plasma viral load.

CONCLUSIONS

Most children in our study had gone through several antiretroviral regimens, although not all children were being treated with HAART. Fifty-six percent of the patients with HAART had an undetectable plasma viral load. However, new complications associated with this therapy have begun to appear.

Long-term antifungal prophylaxis in high-risk hematopoietic stem cell transplant recipients

The risks for invasive fungal infections, particularly mould infections such as invasive aspergillosis, among hematopoietic stem cell transplant (HSCT) recipients are linked to the duration and severity of myelosuppression and immunosuppression. Strategies to prevent invasive fungal infections have focused primarily on the use of orally administered azole antifungal agents during the neutropenic period rather than on the more prolonged post-engraftment period. The major limitations of these studies included the heterogeneity among the subjects studied for fungal infection risk factors, the agents administered, the dosing, and duration of prophylaxis. More recent studies have attempted to examine the efficacy of antifungal prophylaxis strategies among allogeneic HSCT recipients to day 100 and beyond. It is clear that a variety of products have efficacy in preventing invasive candidiasis, including imidazole and triazole antifungals, low-dose amphotericin B, and the echinocandin, micafungin; however, only the extended spectrum azole, itraconazole, has been shown to impact the incidence of proven invasive aspergillosis. Other extended spectrum azole antifungal agents, voriconazole and posaconazole, are being studied as long-term prophylaxis in high-risk HSCT recipients. While clinical trials have suggested that a duration of prophylaxis against moulds of six months or more may be required, it remains unclear if this is required in all cases. The prophylactic efficacy over time may be linked to the degree of immunosuppression as measured by markers such as the numbers of circulating CD4 T lymphocytes. Concerns about selection for resistant moulds among long-term recipients of these drugs are emerging. The cumulative experience to date suggests that long-term antifungal chemoprophylaxis is feasible and effective when applied in defined circumstances. The concerns about treatment-related toxicities, resistance, and costs are valid.

Long-Term Follow-Up of HIV-Infected Individuals Who Have Significant Increases in CD4+ Cell Counts during Antiretroviral Therapy

BACKGROUND

Descriptions of the durability and consequences of immune reconstitution in patients who start highly active antiretroviral therapy (HAART) while severely immunosuppressed are limited.

METHODS

Patients with previous CD4+ cell counts <50 cells/mm3, all of whom had HAART-induced increases in CD4+ cell counts of >100 cells/mm3 on 2 separate occasions (measured sequentially at least 4 weeks apart), were enrolled in a prospective trial and observed every 16-32 weeks. Evaluations included assessments for new opportunistic complications, virologic (human immunodeficiency virus [HIV] RNA load) and immunologic (CD4+ cell count) responses, or death.

RESULTS

The median follow-up duration for 612 subjects was 184 weeks (range, 8-216 weeks). The rate of increase in CD4+ cell counts was approximately 5.9 cells/mm3 every 8 weeks, with the degree of increase associated with the baseline HIV RNA load (<500 vs. > or =500 copies/mL). Subsequent measurements of virologic suppression based on HIV RNA levels were also associated with predicted CD4+ cell responses. Thirty-three AIDS-defining illnesses were reported (1.75 events per 100 person-years of follow-up); >40% (14 cases) occurred with higher than expected CD4+ cell counts.

CONCLUSIONS

CD4+ cell count increases are related to virological control, with continuing increases seen in individuals who are immunosuppressed. Opportunistic illnesses and/or complications are infrequent but can occur at any time, even in patients who maintained an elevated CD4+ cell count.

Impact of highly active antiretroviral therapy on incidence and management of human immunodeficiency virus-related opportunistic infections

We review the changes in incidences of HIV-related opportunistic infections and the safety of discontinuation of primary and secondary prophylaxis for HIV-related opportunistic infections in patients achieving immune restoration after the introduction of highly active antiretroviral therapy (HAART). HIV-related opportunistic infections continue to occur in patients who are newly diagnosed with HIV infection, those in the early course of HAART or non-adherent to HIV care and HAART, and those in whom non-HIV-related infections have emerged as a significant cause of morbidity and mortality in the post-HAART era. Clinical studies of patients with tuberculosis and HIV co-infection are reviewed to provide appropriate regimen combinations of rifamycins and antiretrovirals, which have varying degrees of drug-drug interactions that have posed challenges in the management of tuberculosis as well as HIV infection.

Long-term safety of discontinuation of secondary prophylaxis against Pneumocystis pneumonia: prospective multicentre study

OBJECTIVES

To assess the long-term safety of discontinuation of secondary anti-Pneumocystis prophylaxis in HIV-infected adults treated with antiretroviral combination therapy and who have a sustained increase in CD4 cell counts.

DESIGN

Prospective observational multicentre study.

PATIENTS AND METHODS

The incidence of P. jirovecii pneumonia after discontinuation of secondary prophylaxis was studied in 78 HIV-infected patients on antiretroviral combination therapy after they experienced a sustained increase in CD4 cell counts to at least 200 x 10(6) cells/l and 14% of total lymphocytes measured twice at least 12 weeks apart.

RESULTS

Secondary prophylaxis was discontinued at a median CD4 cell count of 380 x 10(6) cells/l. The median follow-up period after discontinuation of secondary prophylaxis was 40.2 months, yielding a total of 235 person-years of follow-up. No cases of recurrent P. jirovecii pneumonia occurred during this period. The incidence was thus 0 per 100 person-years with a 95% upper of confidence limit of 1.3 cases per 100 patient-years.

CONCLUSIONS

Discontinuation of secondary prophylaxis against P. jirovecii pneumonia is safe even in the long term in patients who have a sustained immunologic response on antiretroviral combination therapy.

Immune reconstitution in HIV-infected patients

The prognosis of patients infected with human immunodeficiency virus (HIV) type 1 has dramatically improved since the advent of potent antiretroviral therapies (ARTs), which have enabled sustained suppression of HIV replication and recovery of CD4 T cell counts. Knowledge of the function of CD4 T cells in immune reconstitution was derived from large clinical studies demonstrating that primary and secondary prophylaxis against infectious agents, such as Pneumocystis jirovecii (Pneumocystis carinii), Mycobacterium avium complex, cytomegalovirus, and other pathogens, can be discontinued safely once CD4 T cell counts have increased beyond pathogen-specific threshold levels (usually >200 CD4 T cells/mm3) for 3-6 months. The downside of immune reconstitution is an inflammatory syndrome occurring days to months after the start of ART, with outcomes ranging from minimal morbidity to fatal progression. This syndrome can be elicited by infectious and noninfectious antigens. Microbiologically, the possible pathogenic pathways involve recognition of antigens associated with ongoing infection or recognition of persisting antigens associated with past (nonreplicating) infection. Specific antimicrobial therapy, nonsteroidal anti-inflammatory drugs, and/or steroids for managing immune reconstitution syndrome should be considered.

Prevention of opportunistic infections in adult and adolescent patients with HIV infection. GESIDA/National AIDS Plan guidelines, 2004 [correction]

OBJECTIVE

To provide an update of guidelines from the Spanish AIDS Study Group (GESIDA) and the National AIDS Plan (PNS) committee on the prevention of opportunistic infections in adult and adolescent HIV-infected patients.

METHODS

These consensus recommendations have been produced by a group of experts from GESIDA and/or the PNS after reviewing the earlier document and the scientific advances in this field in the last years. The system used by the Infectious Diseases Society of America and the United States Public Health Service has been used to classify the strength and quality of the data.

RESULTS

This document provides a detailed review of the measures for the prevention of infections caused by viruses, bacteria, fungi and parasites in the context of HIV infection. Recommendations are given for preventing exposure and for primary and secondary prophylaxis for each group of pathogens. In addition, criteria are established for the withdrawal of prophylaxis in patients who respond well to highly active antiretroviral therapy (HAART).

CONCLUSIONS

HAART is the best strategy for the prevention of opportunistic infections in HIV-positive patients. Nevertheless, prophylaxis is still necessary in countries with limited economic resources, in highly immunodepressed patients until HAART achieves beneficial effects, in patients who refuse to take or who cannot take HAART, in those in whom HAART is not effective, and in the small group of infected patients with inadequate recovery of CD4+ T lymphocyte counts despite good inhibition of HIV replication.

Discontinuation of maintenance therapy for cryptococcal meningitis in patients with AIDS treated with highly active antiretroviral therapy: an international observational study

We conducted a retrospective, multicenter study evaluating the safety of discontinuing maintenance therapy for cryptococcal meningitis after immune reconstitution. Inclusion criteria were a previous definitive diagnosis of cryptococcal meningitis, a CD4 cell count of >100 cells/microL while receiving highly active antiretroviral therapy (HAART), and the subsequent discontinuation of maintenance therapy for cryptococcal meningitis. The primary end point was relapse of cryptococcal disease. As of July 2002, 100 patients were enrolled. When maintenance therapy was discontinued, the median CD4 cell count was 259 cells/microL and the median plasma virus load was <2.30 log10 copies/mL, and serum cryptococcal antigen was undetectable in 56 patients. During a median follow-up period of 28.4 months (range, 6.7-64.5; 262 person-years), 4 events were observed (incidence, 1.53 events per 100 person-years; 95% confidence interval, 0.42-3.92). Three of these patients had a CD4 cell count of >100 cells/microL and a positive serum cryptococcal antigen test result during the recurrent episode. In conclusion, discontinuation of maintenance therapy for cryptococcal meningitis is safe if the CD4 cell count increases to >100 cells/microL while receiving HAART. Recurrent cryptococcal infection should be suspected in patients whose serum cryptococcal antigen test results revert back to positive after discontinuation of maintenance therapy.

Pneumocystis jiroveci Pneumonia in Adult Patients with AIDS

Pneumocystis jiroveci (P. carinii) is an opportunistic pathogen that has gained particular prominence since the onset of the AIDS epidemic. Among several important advances in diagnosis and management, appropriately targeting chemoprophylaxis to HIV-infected patients at high clinical risk for P. jiroveci pneumonia and the introduction of effective combination anti-retroviral therapy (including highly active antiretroviral therapy [HAART]) have contributed to the reduced incidence of P. jiroveci pneumonia. Despite the success of these clinical interventions, P. jiroveci pneumonia remains the most common opportunistic pneumonia and the most common life-threatening infectious complication in HIV-infected patients. Trimethoprim/sulfamethoxazole (cotrimoxazole) remains the first-line agent for effective therapy and chemoprophylaxis, and corticosteroids represent an important adjunctive agent in the treatment of moderate-to-severe P. jiroveci pneumonia. However, problems of chemoprophylaxis and treatment failures, high rates of adverse drug reactions and drug intolerance to first-line antimicrobials, high rates of relapse or recurrence with second-line agents, and newer concerns about the development of P. jiroveci drug resistance represent formidable challenges to the management and treatment of AIDS-related P. jiroveci pneumonia. With the expanding global problem of HIV infection, the intolerance or unavailability of HAART to many individuals and limited access to healthcare for HIV-infected patients, P. jiroveci pneumonia will remain a major worldwide problem in the HIV-infected population. New drugs under development as anti-Pneumocystis agents such as echinocandins and pneumocandins, which inhibit beta-glucan synthesis, or sordarins, which inhibit fungal protein synthesis, show promise as effective agents. Continued basic research into the biology and genetics of P. jiroveci and host defense response to P. jiroveci will allow the development of newer antimicrobials and immunomodulatory therapeutic agents to more effectively treat life-threatening pneumonia caused by this organism.

Recurrence of Pneumocystis carinii pneumonia in an HIV-infected patient: apparent selective immune reconstitution after initiation of antiretroviral therapy

Although several studies have reported that it is safe to discontinue secondary Pneumocystis carinii pneumonia (PCP) prophylaxis in patients infected with HIV who experience a sustained immune response as a result of antiretroviral therapy, we describe a patient who developed recurrent PCP <3 months after discontinuing trimethoprim-sulfamethoxazole prophylaxis. He developed disease despite a sustained CD4 T-cell count above 200 cells/microL for more than 3 years while on antiretroviral therapy, as well as an apparent immune reconstitution against disseminated Mycobacterium avium complex (MAC) and Histoplasma capsulatum, for which he also discontinued therapy but without adverse effects. Thus, although increasing evidence continues to indicate that HIV-infected patients receiving combinations of antiretroviral therapies may regain specific immunity against opportunistic infections, our patient's experience suggests that this immune recovery may be selective and incomplete.

Atypical toxoplasmic manifestation after discontinuation of maintenance therapy in a human immunodeficiency virus type 1-infected patient with immune recovery

We describe an HIV-infected man with recurrence of a toxoplasmic manifestation, despite immune reconstitution during highly active antiretroviral therapy. This atypical recurrence was more likely to be a reinfection than a reactivation, as attested by the genotypic analysis of the Toxoplasma gondii strain recovered from the patient.

Restoration of human immunodeficiency virus-1-specific responses in patients changing from protease to non-nucleoside reverse transcriptase inhibitor-based antiretroviral therapy

The effect of altering antiretroviral therapy (ART) on responses to viral, recall and human immunodeficiency virus (HIV)-1-specific recombinant antigens and interleukin-2 (IL-2) in HIV-1-infected patients was assessed. A longitudinal cohort study in eight HIV-1 infected individuals following a clinically indicated therapy change (seven for drug intolerance and one for virological failure) from protease inhibitor (PI) to non-nucleoside reverse transcriptase inhibitor (NNRTI)-based antiretroviral regimens was performed. CD4 T-cell counts, viral loads, lymphoproliferative responses, cytokine production and latent proviral deoxyribonucleic acid (DNA) were measured at baseline and at weeks 12 and 24 after therapy substitution. Following therapy-switch there was a 33% proportional increase in mitogen response (95% confidence interval (CI), 3-33%) and a 31% increase (95% CI, 15-48%) in viral and recall-antigen responses. Six patients developed proliferative responses to low concentration IL-2 stimulation. All patients demonstrated an increase in median HIV-1-specific responses, as three had detectable virus at baseline (two being viral rebound); this may reflect an autovaccination effect. Proviral DNA changes largely reflected plasma HIV-1 ribonucleic acid (RNA). In conclusion, NNRTI substitution for a PI may favour immune reconstitution with an improvement in HIV-1-specific responses, which may reflect differential effects on antigen processing and presentation, an autovaccination effect or alternatively a potential suppressive effect of the PI.

Low incidence of community-acquired pneumonia among human immunodeficiency virus-infected patients after interruption of Pneumocystis carinii pneumonia prophylaxis

We compared the incidence of bacterial pneumonia among 336 patients who discontinued trimethoprim-sulfamethoxazole (TMP-SMX) as prophylaxis against Pneumocystis carinii pneumonia (PCP) with that among 75 patients who fulfilled the criteria for discontinuation but continued receiving prophylaxis. The difference in the overall incidence rates for the 2 groups (1.2 events per 100 person-years) was not statistically significant. Discontinuation of TMP-SMX prophylaxis against PCP is not associated with a significant increase in the incidence of bacterial pneumonia among patients with a sustained CD4 cell count increase to >200 cells/microL.

Human immunodeficiency virus-associated dementia: an evolving disease

This article reviews the changing epidemiology of HIV-associated dementia, current concepts of the different patterns of dementia under the influence of highly active antiretroviral therapy, and reviews therapeutic aspects.

Discontinuation of secondary prophylaxis for Pneumocystis carinii pneumonia in human immunodeficiency virus-infected patients: a randomized trial by the CIOP Study Group

This subgroup analysis assessing secondary prophylaxis for Pneumocystis carinii pneumonia (PCP) describes a multicenter, open-labeled, randomized, controlled trial evaluating the discontinuation of PCP prophylaxis. The main inclusion criterion was a history of PCP and an increase in the CD4 cell count to >200 cells/microL associated with receipt of highly active antiretroviral therapy for >or=3 months. The primary end point was the development of definitive or presumptive PCP. A total of 146 patients were enrolled (77 in the treatment discontinuation arm). After >2 years, 1 definitive and 1 presumptive case of PCP were observed, both of which occurred in patients who discontinued therapy. In most patients, secondary prophylaxis for PCP can be safely discontinued after potent antiretroviral therapy is initiated, but the threshold of >200 CD4 cells/microL may not be considered absolutely safe. Patients who present with symptoms after discontinuation of secondary prophylaxis should be evaluated for PCP despite high CD4 count and complete virus suppression.

Low versus High CD4 Cell Count as Starting Point for Introduction of Antiretroviral Treatment in Resource-Poor Settings: A Scenario-Based Analysis

Objective

To evaluate CD4 cell count-driven strategies for the initiation of highly active antiretroviral therapy (HAART) in terms of the reduction of the incidence of AIDS-defining events in resource-poor settings.

Methods

Data from the Amsterdam Cohort Study on HIV infection and AIDS were used to estimate the hazard of AIDS in untreated HIV-1 infection and after initiation of HAART, respectively, conditional on CD4 cell count. Different strategies for initiating therapy were compared by calculating the expected HAART administration rate and 1-year cumulative AIDS incidence in three different population settings, varying in the stage of HIV-1 infection at the time of presentation.

Results

Among 695 HIV-1-infected cohort participants, the 1-year AIDS incidence density (ID) ranged from 3.2 per 100 person-years for CD4 cell counts 600–700 cells/mm3, to 31.9 per 100 person-years for CD4 cell counts 100–200 cells/mm3 and 77.9 per 100 person-years for CD4 cell counts below 100 cells/mm3. Upon initiation of HAART, the ID in the lowest CD4 strata declined to 13.3 and 16.3 per 100 person-years, respectively. Extrapolated to developing countries, supply of HAART to patients presenting with HIV-1 infection below 200 CD4 cells/mm3 is expected to give an administration rate of 67%, while the AIDS incidence will drop from over 30% to almost 10%.

Conclusions

Introduction of HAART in populations with advanced HIV-1 infection can accomplish a threefold reduction of the AIDS incidence when HAART is administered to patients with CD4 cell counts below 200 cells/mm3. In a hospital-based setting in resource-poor environments this ensures an efficient treatment allocation.

Treatment for primary HIV infection: projecting outcomes of immediate, interrupted, or delayed therapy

With limited data available on the optimal treatment of primary HIV infection, disease modeling can be used to project clinical outcomes and inform decision makers. The authors developed a simulation model to evaluate the clinical outcomes and life expectancy projections for three primary HIV infection treatment strategies: 1) continuous antiretroviral therapy (ART) initiated at CD4 count <350 cells/mm(3); 2) continuous ART initiated immediately on diagnosis of primary HIV infection; and 3) ART initiated on diagnosis followed by structured treatment interruption. Projected life expectancies for the three strategies were 23.92, 24.46, and 26.07 years, respectively. The impact of key variables was assessed in sensitivity analysis, with the structured treatment interruption strategy remaining the most effective over a broad range of inputs. The immunologic benefit associated with immediate therapy and the potential for antiretroviral resistance due to structured treatment interruption have the most important impact on the optimal strategy. Based on current data, immediate treatment on diagnosis of primary HIV infection followed by structured treatment interruption will likely yield the best outcome. These results can assist decision makers and those planning clinical trials in defining evidence-based performance measures for primary HIV infection treatment and future trials.

Features of 'CD4-exploders', HIV-positive patients with an optimal immune reconstitution after potent antiretroviral therapy

OBJECTIVE

To identify crucial immunological characteristics of a group of patients, defined 'CD4-exploders', who were able to fully reconstitute their immune system after receiving highly active antiretroviral therapy (HAART).

PATIENTS

Among a population of 540 HIV-positive patients treated with HAART, six individuals were identified who experienced a nadir of less than 85 x 106 CD4+ cells/l, had major opportunistic infections (four out of six), started HAART in 1996 or 1997, and showed a rapid and relevant CD4+ lymphocyte increase (mainly due to virgin cells), in some cases regardless of virological control.

METHODS

Enzyme-linked immunosorbent assay for the determination of interleukin (IL)-7 plasma levels; flow cytometry to analyse surface antigens and CD127 (IL-7 receptor alpha-chain) expression; quantitative-competitive (QC) PCR for detecting cells containing T-cell receptor rearrangement excision circles (TREC); chest-computed tomography (CT) to analyse thymus volume and content.

RESULTS

In 'CD4-exploders', high levels of TREC+ lymphocytes were found among CD4+ T cells, which also contained a high percentage of naive cells. However, CT revealed a dramatic depletion of intrathymic lymphoid tissue. Plasma levels of IL-7 were significantly high. Most CD4+ and CD8+ T lymphocytes expressed CD127, whose level was similar to that of healthy donors. CD127 expression on CD8+ lymphocytes was markedly higher than in HIV-positive individuals treated with the same therapy or in patients with AIDS.

CONCLUSION

In 'CD4-exploders', HAART-induced reconstitution of the T-cell compartment is independent from thymus volume, and is favoured by the upregulation of the IL-7/IL-7 receptor system.

The relationship of preventable opportunistic infections, HIV-1 RNA, and CD4 Cell counts to chronic mortality

BACKGROUND

Both HIV-1 RNA and absolute CD4 cell counts have been identified as important predictors of HIV-1 disease progression and mortality. The independent impact of opportunistic infections on the risk of chronic mortality, defined as death beyond 30 days of an opportunistic infection, has not been studied when controlling for HIV-1 RNA. Our objective was to determine the relationship between a history of any of five preventable opportunistic infections (Pneumocystis carinii pneumonia, Mycobacterium avium complex, toxoplasmosis, cytomegalovirus, and candida esophagitis) and chronic mortality.

METHODS

Using the Multicenter AIDS Cohort Study (MACS) public use data set of 2193 HIV-infected men in four U.S. cities, we employed a Cox regression model to estimate the impact of a history of preventable opportunistic infection on chronic mortality while controlling for maximum HIV-1 RNA, CD4 cell count, use of antiretroviral drugs, and age.

FINDINGS

The chronic mortality rate among individuals with a history of preventable opportunistic infection was 66.7 per 100 person-years compared with 2.3 per 100 person-years for those without a history of preventable opportunistic infection (RR = 28.4, 95% CI: 24.7-32.8). In the adjusted analysis, the relative hazard of death for those with a history of preventable opportunistic infections was 7.0 (5.8-8.3), whereas antiretroviral therapy was associated with a decreased risk of death (0.37 [0.30-0.44]). We found no association between maximum HIV-1 RNA and chronic mortality. There was statistically significant effect modification between preventable opportunistic infections and CD4 cell count (p <.0001).

INTERPRETATION

Preventable opportunistic infections cause not only short-term mortality in HIV-1 disease but appear to have a major impact on chronic mortality.

Goals and milestones during treatment of HIV-1 infection with antiretroviral therapy: a pathogenesis-based perspective

Highly active antiretroviral therapy (HAART) has reduced the morbidity and mortality related to infection with the human immunodeficiency virus-1 (HIV-1) through its ability to suppress viral replication and preserve and reconstitute specific immune responses in many infected individuals. However, the complete eradication of HIV-1 with current HAART regimens is not considered possible by most experts. Moreover, many current antivirals have metabolic complications and limiting side effects. Consequently, the treatment paradigm has shifted from 'hit hard and early' to delaying the initiation of therapy until later in the course of HIV-1-related disease, with corresponding modifications of consensus treatment guidelines. Factors that need to be considered in deciding when to initiate therapy and with what regimen include the patient's risk of disease progression, the possible adverse drug effects, the patient's ability to adhere to the prescribed therapy, and the need to preserve future therapeutic options. In this article, we discuss the issues surrounding the initiation of HAART, and describe the virologic and immunologic milestones that may be achieved with effective antiretroviral therapy.

Predictive value of HIV-1 viral load on risk for opportunistic infection

OBJECTIVE

The relationship between HIV-1 viral load and the risk for opportunistic infection (OI) was examined in Adult AIDS Clinical Trial Group (AACTG) 722, a virology substudy of AACTG 323: a phase 4 randomized study designed to examine the use of chronic suppressive versus episodic fluconazole therapy.

METHODS

The primary analysis used a case-control sampling scheme with two controls per "case" (subjects that developed an OI) matched by gender, age, and time on study. Forty-five cases and matched controls were identified and used in the analysis.

RESULTS

Study 722 accrued 518 subjects between 5/97 and 11/99. Forty-five subjects developed serious OIs or refractory candidiasis. Median baseline CD4 count was 24 cell/mm3 for cases and 46 for controls (p =.003). Median viral load (VL) was 5.02 log10 copies/mL for cases and 4.08 for controls (p =.002). Multivariate analysis found four independent variables associated with time to OI: baseline VL and CD4 (RR = 2.2 per log increment and 6.0 per 50-cell increment, respectively), a one log increase in VL at any time (RR = 15), and history of an OI (RR = 5.2).

CONCLUSIONS

VL and changes in VL were independently associated with risk of development of OIs in a prospective study and should be considered by clinicians when assessing patients for risk of OI.

Lifetime Cost of HIV Care in France during the Era of Highly Active Antiretroviral Therapy

Objective

To estimate the treatment and health care costs of HIV infection or AIDS in France during the era of highly active antiretroviral therapy (HAART).

Design

We used a clinical database of HIV-infected patients to calculate the resource use and cost of care for different stages of HIV infection. Costs were incorporated into a computer-based, probabilistic simulation model of the natural history and treatment of HIV infection to estimate the lifetime cost of treating patients with HIV disease.

Setting

A northern France HIV clinical cohort.

Participants

1232 HIV-infected patients followed from January 1994 through July 1998.

Results

In the absence of an AIDS-defining event, the average total cost of care ranged from 670 euros (1 euro=US $1.19) per person-month in the highest CD4 stratum (>500/μl) to 1060 euros per person-month in the lowest CD4 stratum (≤50/μl). The mean cost of care was estimated at 3370 euros per person-month during the initial months around the occurrence of an AIDS-defining event; at 1750 euros per person-month during the period spanning from 2 months after the diagnosis of specific AIDS-defining event to 1 month prior to death; and at 13 010 euros per person-month in the final month prior to death. If clinical management of HIV infection began at a CD4 cell count of 378/μl, as in this cohort, the discounted lifetime cost of treating an HIV-infected French patient was estimated at 214 000 euros. The undiscounted costs were 309 000 euros over a projected life expectancy of 16.4 years.

Conclusion

The cost of HIV disease varies widely depending upon the stage of illness. These estimates of stage-specific and lifetime costs of HIV care will assist health policy planners in assessing the burden of disease in the era of HAART and projecting future resource requirements.

Management of Opportunistic Infection Prophylaxis in the Highly Active Antiretroviral Therapy Era

Prophylaxis and maintenance therapy against opportunistic infections are a mainstay of management of HIV-infected patients and have led to a significant improvement in quality of life and survival. Antiretroviral combination therapy (ART) has markedly changed the natural course of HIV infection. Incidence of opportunistic infections (OIs) has declined and survival after an OI has improved. Achieving a CD4 count of 200 cells/L after 6 months of ART is a valuable marker for low risk of OI afterwards. Therefore, recommendations on prophylaxis and maintenance therapy need to be redefined. Criteria for discontinuation, such as a CD4 count rise above threshold values and time above threshold values as response to ART, should be evaluated for the most frequent OIs. Reliable data in favor of discontinuation of primary prophylaxis against Pneumocystis carinii pneumonia, toxoplasmic encephalitis, and Mycobacterium avium infection have been published. Discontinuation of maintenance therapy against P. carinii pneumonia is possible, and may be safe against cytomegalovirus retinitis, M. avium, and cryptococcosis and toxoplasmosis in selected patients. Pharmacologic interactions between drugs used for OI prophylaxis and antiretroviral drugs need to be taken into account.

HIV-related morbidity and mortality in patients starting protease inhibitors in very advanced HIV disease (CD4 count of < 50 cells/microL): an analysis of 338 clinical events from a randomized clinical trial

BACKGROUND

AIDS defining events occur infrequently in the presence of CD4 counts above 200 cells/microL. It is, however, uncertain for most of the AIDS defining conditions whether this threshold can be considered equally safe in patients with a previously very low CD4 nadir.

METHODS

We evaluated in detail all the AIDS defining events observed during a 48-week clinical trial in 1251 nucleoside reverse transcriptase inhibitor-experienced patients who started protease inhibitors (PIs) at CD4 counts below 50 cells/microL. The type of event, immunological status at the moment of event and time between start of PI treatment and event occurrence were analysed cumulatively and by event type; event rates were calculated.

RESULTS

Concomitant data on CD4 counts were available for 338 AIDS defining events (81% of total events). Median time between start of treatment with PI and event was 94.5 days and median absolute CD4 value at the occurrence of event was 20 per microL. Only 14 events (in 12 patients) were observed above the threshold of 200 CD4 cells/microL. An analysis of the 67 deaths with concomitantly available CD4 counts (57%) showed a median CD4 count of 10 cells/microL, with only four deaths occurring in the presence of a CD4 count above 100 cells/microL.

CONCLUSIONS

Very few clinical AIDS defining conditions were observed in patients who start PIs at very low CD4 counts and with treatment restore absolute values in CD4 counts above 200 cells/microL. This threshold can therefore be considered a clinically effective goal of treatment with respect to occurrence of all AIDS defining conditions in patients starting PIs in very advanced HIV disease.

Discontinuation of secondary prophylaxis against disseminated Mycobacterium avium complex infection and toxoplasmic encephalitis

We retrospectively studied outcomes for patients infected with human immunodeficiency virus who received highly active antiretroviral therapy (HAART) and had stopped receiving secondary prophylaxis against toxoplasmic encephalitis (TE) or disseminated Mycobacterium avium complex (MAC) infection. Nineteen patients had a history of TE, and 26 had a history of disseminated MAC infection. The median duration of secondary prophylaxis was 27 months, and the median duration of HAART before discontinuation of secondary prophylaxis was 22 months. Median CD4(+) cell counts at the time of cessation of secondary prophylaxis against TE or disseminated MAC infection were 404 and 105 cells/mm(3), respectively. Plasma virus load was undetectable in 68% of the patients who had a history of TE and in 31% of patients who had a history of disseminated MAC infection. Patients were followed up for a median of 29 months after discontinuation of secondary prophylaxis; no relapses occurred in patients with a history of TE, and 3 relapses occurred in patients with a history of disseminated MAC infection (incidence, 4 relapses per 100 person-years).

The extent of HIV-1-related immunodeficiency and age predict the long-term CD4 T lymphocyte response to potent antiretroviral therapy

OBJECTIVE

To study the long-term immunological recovery in HIV-1-infected individuals receiving potent antiretroviral therapy (ART).

DESIGN

Prospective, observational study.

METHODS

Plasma HIV-1 RNA, CD4 and CD8 T lymphocyte counts were determined at 3-6 monthly intervals in 95 HIV-1-infected subjects receiving ART who suppressed plasma HIV-1 RNA to levels below 400 copies/ml during a median observation period of 45 months.

RESULTS

The median CD4 cell count rose from 325 to 624 cells/microl at 48 months, increasing by 22.6 cells/microl per month in the first 3 months, 8.1 cells/microl per month from months 3 to 12, 6.8 cells/microl per month in the second year, 3.3 cells/microl per month in the third, and 1.7 cells/microl per month in the fourth year. At 48 months, 98% of subjects reached CD4 cell counts > 200 cells/microl, 86% > 350 cells/microl, and 74% > 500 cells/microl. A higher nadir CD4 cell count and younger age were independently associated with greater increases in CD4 cell counts, and higher absolute CD4 cell counts at 48 months. Poor immunological responders who did not reach 500 CD4 lymphocytes/microl at 48 months showed lower nadir and baseline CD4 cell counts than good responders (99 versus 300 cells/microl and 160 versus 373 cells/microl, respectively).

CONCLUSION

The recovery of CD4 T lymphocytes occurs mainly in the first 2 years after the initiation of ART, and is associated with age and the pre-existing degree of HIV-1-related immunodeficiency, suggesting that the long-term exposure to HIV-1 infection has caused damage to the immune system that is difficult to correct.

CD4+ T-lymphocyte nadir and the effect of highly active antiretroviral therapy on phenotypic and functional immune restoration in HIV-1 infection

To evaluate the effects of the timing of highly active antiretroviral therapy (HAART) on immune reconstitution, we compared lymphocyte subpopulations and lymphocyte proliferation (LP) in response to Candida albicans, cytomegalovirus, HIV p24, Mycobacterium avium complex, pokeweed mitogen, streptokinase, and tetanus toxoid in 43 patients with pretherapy advanced, moderately advanced, and early chronic HIV-1 infection. All patients had recent CD4+ T-cell counts >450/microl and HIV RNA <400 copies/ml for >12 months. CD4+ nadirs were positively correlated with recent numbers of CD4+ T-cells (P < 0.001), memory cells (P < 0.001), and naïve CD4+ T-cells (P < 0.05) and CD4+ CD28+ T-lymphocytes (P < 0.05) and were negatively correlated with recent CD8+ T-lymphocyte counts (P < 0.05). Only CD4+ naïve T-cells normalized when HAART was initiated at lower CD4+ T-cell levels. Fifty-three percent of patients had LP responses to HIV p24 antigen. While LP responses to prevalent antigens were usually present, responses to tetanus toxoid were more common with higher CD4+ T-lymphocyte nadirs (P < 0.05). Delaying HAART may limit phenotypic and functional immune restoration in HIV-1 infection.

Evaluation of a cyclic GMP-dependent protein kinase inhibitor in treatment of murine toxoplasmosis: gamma interferon is required for efficacy

The trisubstituted pyrrole 4-[2-(4-fluorophenyl)-5-(1-methylpiperidine-4-yl)-1H-pyrrol-3-yl]pyridine (compound 1) is a potent inhibitor of cyclic GMP-dependent protein kinases from Apicomplexan protozoa and displays cytostatic activity against Toxoplasma gondii in vitro. Compound 1 has now been evaluated against T. gondii infections in the mouse and appeared to protect the animals when given intraperitoneally at 50 mg/kg twice daily for 10 days. However, samples from brain, spleen, and lung taken from infected treated mice revealed the presence of parasites after cessation of administration of compound 1, indicating that a transient asymptomatic parasite recrudescence occurs in all survivors. The ability of mice to control Toxoplasma infection after compound 1 treatment has been terminated suggested that the mouse immune system plays a synergistic role with chemotherapy in controlling the infection. To explore this possibility, gamma interferon (IFN-gamma)-knockout mice were infected with parasites and treated with compound 1, and survival was compared to that of normal mice. IFN-gamma-knockout mice were protected against T. gondii throughout the treatment phase but died during the posttreatment phase in which peak recrudescence was observed in treated immunocompetent mice. These data suggest that an IFN-gamma-dependent immune response was essential for controlling and resolving parasite recrudescence in mice treated with compound 1. In addition, when compound 1-cured immunocompetent mice were rechallenged with a lethal dose of T. gondii, all survived (n = 32). It appears that the cytostatic nature of compound 1 provides an "immunization" phase during chemotherapy which allows the mice to survive the recrudescence and any subsequent challenge with a lethal dose of T. gondii.

Clinical indicators of immune restoration following highly active antiretroviral therapy

The course of human immunodeficiency virus (HIV) disease is characterized by a progressive decline in immune function. The advent of highly active antiretroviral therapy (HAART) has allowed patients to experience a significant degree of immune restoration when compared with the era before the availability of HAART. Multiple studies, which have employed sophisticated in vitro measures of immune function, have demonstrated improvement in CD4(+) lymphocyte (T4) responses to various opportunistic pathogens. In addition, for patients treated during acute HIV infection, HIV-specific T4 responses have been restored. By contrast, there are a limited number of in vivo measures of T4 function available to assess immune recovery following initiation of HAART. The primary measurement is an increase in CD4 lymphocyte count, the significance of which may be underappreciated. Delayed-type hypersensitivity testing to recall antigens and serological response to prophylactic vaccines may also have a role. This review discusses available markers of immune function and offers suggestions regarding their use in HAART recipients.

Durability of HIV-1 viral suppression over 3.3 years with multi-drug antiretroviral therapy in previously drug-naive individuals

BACKGROUND

Relatively little is known about the long-term durability of viral suppression in individuals initially achieving a viral load of less than 50 copies/ml within 24 weeks of starting antiretroviral therapy, nor the extent to which therapy interruption accounts for the loss of suppression.

METHODS

We intensely followed all 336 antiretroviral-naive patients attending the Goethe Universitat Clinic who began multi-drug combination regimens and in whom a viral load of less than 50 copies/ml was achieved within 24 weeks, in order to assess the risk of viral load rebound. Inspection of case notes allowed the distinction of viral rebound according to whether there was an associated complete interruption of therapy.

RESULTS

A total of 61 patients experienced viral rebound during 543.1 person-years of follow-up, giving a 25.3% risk of rebound by 3.3 years from first achieving viral suppression. However, for 47 of the patients with viral rebound there was an associated documented complete interruption of antiretroviral therapy, mostly as a result of co-morbidities, leaving 14 who appear to represent a failure of the virological efficacy of therapy (viral breakthrough; 5.2% risk by 3.3 years). The risk of viral breakthrough declined with the increased duration of suppression (P = 0.01).

CONCLUSION

The intrinsic virological effectiveness of multi-drug antiretroviral therapy in previously drug-naive individuals appears to be such that viral suppression, once achieved, can be maintained for several years in patients not interrupting therapy. The major challenge is to develop regimens that can be taken consistently and safely for such long periods of time.

Immune reconstitution in HIV-1-infected individuals treated with potent antiretroviral therapy

Potent combination antiretroviral therapy that was introduced in the mid-1990s for treatment of HIV-1 infection has resulted in unprecedented decreases in HIV-1 replication and increases in CD4+ T cell counts in many individuals. Coincident with the introduction of potent combination antiretroviral therapy, substantial declines in AIDS-related morbidity and mortality have been observed. Although these declines strongly suggest that significant immune reconstitution is occurring, increasing evidence suggests that immune reconstitution is neither uniform nor complete in all treated individuals. Clinical data suggest that some HIV-1-associated malignancies have not declined despite the new therapies, and that not all treated individuals reconstitute CD4+ T cell numbers to normal values. Laboratory studies reveal that immune responses to ubiquitous antigens are reconstituted, but that responses to rarely encountered antigens, such as tetanus, are not reconstituted without repeat vaccination. Many questions remain concerning the extent and clinical significance of the immune reconstitution that occurs in the setting of antiretroviral drug therapy. A better understanding of the nature of the immune reconstitution that results from potent antiretroviral therapy is critical to the optimal clinical management of HIV-1-infected individuals, and may provide important insights into the immunopathogenesis of HIV-1 infection as well.

Discontinuation of Pneumocystis carinii prophylaxis in patients infected with human immunodeficiency virus: a meta-analysis and decision analysis

We performed a meta-analysis and a decision analysis on the discontinuation of prophylaxis for Pneumocystis carinii pneumonia (PCP) in patients infected with human immunodeficiency virus who had adequate immune recovery while receiving highly active antiretroviral therapy. In the meta-analysis (14 studies with 3584 subjects who had discontinued prophylaxis), 8 cases of PCP occurred during 3449 person-years (0.23 cases per 100 person-years [95% confidence interval, 0.10-0.46]). In the decision analysis, mortality and time spent alive without immunodeficiency in the modeled discontinuation strategy were similar to those in the continuation strategy. For patients who received primary prophylaxis, the discontinuation strategy led to slightly fewer episodes of PCP and fewer toxicity-related prophylaxis withdrawals (e.g., 8.6 vs. 34.5 cases per 100 patients during a 10-year period). Patients on the discontinuation strategy were more likely to be receiving trimethoprim-sulfamethoxazole when they became immunodeficient. Comparative results were similar for patients with prior PCP. Discontinuation of PCP prophylaxis in patients with adequate immune recovery is a useful strategy that should be widely considered.

Highly active antiretroviral therapy responders exhibit a phenotypic lymphocyte pattern comparable to that of long-term nonprogressors

BACKGROUND

The implementation of highly active antiretroviral therapy (HAART) in patients with progressive HIV-1 disease has resulted in a marked reduction of HIV-1-associated morbidity and mortality. In fact, the risk of HAART responders to develop opportunistic infections becomes similar to that of long-term nonprogressors (LTNPs).

METHODS

Reasoning that HAART may ultimately have consequences on both the quantity and quality of immune responses of a HIV-1-infected person, we assessed CD4+ and CD8+ T cell subsets in HAART recipients over a time period of 15 months and compared them to the lymphocyte phenotype of LTNPs and healthy controls. Evaluations included quantitative determinations of memory (CD45RO+CD62L-), naive (CD45RO-CD62L+), effector (CD27-, CD28-) and activated (HLA-DR+, CD38+, CD95+) CD4+ and CD8+ lymphocytes. The T cell function was assayed by skin tests.

RESULTS

Compared to healthy persons, treatment-naive patients with progressive disease exhibited a considerable reduction of CD4+ T cells with many of the remaining T cells showing signs of activation at baseline. CD8+ T cells were greatly increased in number, mainly because of an expansion of CD28- effector and memory CD8+ T cells. LTNPs, in contrast, had stable CD4+ and elevated CD8+ T cell counts, the latter being mainly due to a marked increase in CD27- effector cells. Essentially, the same immunophenotype was seen in HAART responders after 15 months of treatment when compared to LTNPs.

CONCLUSIONS

It is tempting to speculate that a HAART-induced reduction in viral load may influence the immune system's capacity to mount protective responses to pathogenic microorganisms.

Prevention of infection caused by Pneumocystis carinii in transplant recipients

Pneumocystis carinii remains an important pathogen in patients who undergo solid-organ and hematopoietic transplantation. Infection results from reactivation of latent infection and via de novo acquisition of infection from environmental sources. The risk of infection depends on the intensity and duration of immunosuppression and underlying immune deficits. The risk is greatest after lung transplants, in individuals with invasive cytomegalovirus disease, during intensive immunosuppression for allograft rejection, and during periods of neutropenia. Prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMZ) prevents many opportunistic infections, including infection with P. carinii, Toxoplasma gondii, and community-acquired respiratory, gastrointestinal, and urinary tract pathogens. Intolerance of TMP-SMZ is common; desensitization is useful less often in transplant patients than in patients with AIDS. Alternative agents provide a narrower spectrum of protection than does TMP-SMZ and less adequate protection against Pneumocystis species. Clinically, the diagnosis of breakthrough Pneumocystis pneumonia often requires invasive procedures. Strategies for the prevention of Pneumocystis infection must be individualized on the basis of a stratification of risk for each patient.

Viral load as an independent risk factor for opportunistic infections in HIV-infected adults and adolescents

OBJECTIVE

We investigated whether HIV plasma RNA (viral load; VL) predicts risk for opportunistic infections (OI) in HIV-infected persons, independent of CD4 lymphocyte count and other factors that might affect disease outcome.

METHODS

Among persons who had initiated antiretroviral therapy (ART), we studied the risk for OI following a VL measurement in the Centers for Disease Control and Prevention Adult and Adolescent Spectrum of HIV Disease (ASD) Project, a medical record review study of HIV-infected persons in 11 US cities. Analysis was limited to persons who had initiated ART and who had VL data, primarily from the period 1996-1999. Persons were considered at risk for OI for 1 to 6 months after a given VL; risk for OI was assessed using a Poisson multiple regression model controlling for CD4 lymphocyte count, ART, and other variables potentially associated with development of OI: history of AIDS OI, age, sex, race, HIV risk category, OI prophylaxis, and calendar year.

RESULTS

Although decreasing CD4 count was the strongest predictor of risk for OI [relative risk (RR), 13.3 for persons with CD4 lymphocyte count < 50 x 10(6)/l compared with persons with CD4 lymphocyte count > or = 500 x 10(6)/l], increasing VL was independently associated with increased risk [RR, 1.6, 1.9, 2.7, and 3.5 for VL of 7000-19 999, 20 000-54 999, 55 000-149 999, and > or = 150 000 copies/ml (by reverse transcription-PCR), respectively, compared with VL < 400]. Similar results were obtained when the risk period was reduced to 5, 4, 3, and 2 months after VL measurement.

CONCLUSIONS

VL is an independent risk factor for OI and should be considered in special situations, such as in decisions to discontinue primary or secondary OI prophylaxis after CD4 lymphocyte counts have increased in response to ART.