Discontinuing or withholding primary prophylaxis against Mycobacterium avium in patients on successful antiretroviral combination therapy. The Swiss HIV Cohort Study

Incidence of disseminated Mycobacterium avium-complex infection in HIV patients receiving antiretroviral therapy with use of Mycobacterium avium-complex prophylaxis

The incidence of disseminated Mycobacterium avium complex (MAC) infection in HIV patients has fallen markedly since the introduction of effective antiretroviral therapy (ART). However, current guidelines still recommend primary prophylaxis. We conducted a retrospective cohort study in a university-affiliated hospital from January 1998 to January 2014. During that period, HIV patients who had at least one CD4 cell count below 50 cells/mm³ and had been treated with ART were enrolled. We compared incidence of disseminated MAC infection in the 12 months after the first CD4 cell count below 50 cells/mm³ between prophylaxis and nonprophylaxis groups. A total of 157 patients were enrolled and the total observation period was 144 patient-years (PY). Thirty-three patients (21%) received primary MAC prophylaxis. The initial CD4 cell count of the prophylaxis group was lower than that of the nonprophylaxis group ( P = 0.024), but the proportion of patients who reached a CD4 cell count >100 cells/mm³ ( P = 0.234) and were virologically suppressed ( P = 0.513) 12 months after ART commencement was not different in the prophylaxis and nonprophylaxis groups. The incidence of MAC did not differ significantly between the groups (3.4/100 PY versus 0.8/100 PY, P = 0.368). Routine MAC prophylaxis may be not required in the era of effective ART.

Drug efficacy by direct and adjusted indirect comparison to placebo: An illustration by Mycobacterium avium complex prophylaxis in HIV

Background

Our goal was to illustrate a method for making indirect treatment comparisons in the absence of head-to-head trials, by portraying the derivation of published efficacies for prophylaxis regimens of HIV-related opportunistic infections.

Results

We identified published results of randomized controlled trials from the United States in which HIV-infected patients received rifabutin, azithromycin, clarithromycin, or placebo for prophylaxis against Mycobacterium avium complex (MAC). We extracted the number of subjects, follow-up time, primary MAC events, mean CD4 count, and proportion of subjects on mono or dual antiretroviral therapy (ART) from each study. We derived the efficacy of each drug using adjusted indirect comparisons and, when possible, by direct comparisons. Five articles satisfied our inclusion criteria. Using direct comparison, we estimated the efficacies of rifabutin, clarithromycin, and azithromycin compared to placebo to be 53% (95% CI, 48-61%), 66% (95% CI, 61-74%), and 66% (95% CI, 60-81%), respectively. Using adjusted indirect calculations, the efficacy of rifabutin compared to placebo ranged from 41% to 44%. The adjusted indirect efficacies of clarithromycin and azithromycin were estimated to be 73% and 72%, respectively.

Conclusions

Accurate estimates of specific drug dosages as compared to placebo are important for policy and implementation research. This study illustrates a simple method of adjusting for differences in study populations by using indirect comparisons in the absence of head-to-head HIV clinical trials.

Long-term outcome of AIDS-associated cryptococcosis in the era of combination antiretroviral therapy

BACKGROUND

Immune restoration following combination antiretroviral therapy (cART) questions the maintenance of prophylaxis among HIV-infected patients with cryptococcosis.

OBJECTIVE

To describe the long-term outcome after the diagnosis of cryptococcosis at the cART era.

DESIGN

Multicentre cohort of patients with a diagnosis of cryptococcosis between 1996 and 2000, follow-up until December 2002. Comparison with a historical cohort (1990-1994) for survival.

SETTING

Eighty-four French AIDS clinical centres.

PATIENTS

Two-hundred and forty HIV-infected adult patients at the cART era and 149 at the pre-cART era experiencing a first episode of culture-confirmed cryptococcosis.

RESULTS

In the cART era, 82/189 patients surviving more than 3 months after initiation of antifungal therapy had their maintenance therapy interrupted with a subsequent median follow-up of 19 months. Their relapse rate per 100 person-years was 0.9 [95% confidence interval (CI),0.0-2.0]. When considering the whole cART cohort, probability of reaching negative serum cryptococcal antigen was 71% after 48 months of follow-up. A CD4 cell count < 100/microl [relative risk (RR), 5.5; 95% CI, 1.3-22.2], antifungal therapy < 3 months over the past 6 months [RR, 5.0; 95% CI, 1.1-22.3] and serum cryptococcal antigen titre > or = 1/512 [RR, 3.5; 95% CI, 1.1-10.8] were associated with a higher rate of cryptococcosis relapse. The mortality rate per 100 person-years was 15.3 [95% CI,12.2-18.4] in the cART era versus 63.8 [95% CI,53.0-74.9] in the pre-cART era although early mortality did not differ between the two periods.

CONCLUSION

Overall survival after cryptococcosis has dramatically improved at the cART era. Immune restoration and low serum cryptococcal antigen titres are associated with lower cryptococcosis relapse rates.

Discontinuation of Primary Prophylaxis against Mycobacterium avium Complex Infection in HIV-Infected Persons Receiving Antiretroviral Therapy: Observations from a Large National Cohort in the United States, 1992-2002

In a large, diverse cohort of human immunodeficiency virus (HIV)-infected persons receiving routine care, the proportion of eligible persons who discontinued primary prophylaxis against Mycobacterium avium complex (MAC) infection, according to guidelines of the US Public Health Service and the Infectious Diseases Society of America, increased from 16.7% (in 1996) to 84.9% (in 2002). The discontinuation of primary prophylaxis was not associated with an increased risk of disseminated MAC infection.

Disseminated mycobacterium avium-intracellulare complex (MAC) infection in the era of effective antiretroviral therapy: is prophylaxis still indicated?

Before highly active antiretroviral therapies (HAART) were available for the treatment of persons with HIV infection, disseminated Mycobacterium avium-intracellulare complex (MAC) infection was one of the most common opportunistic infections that affected people living with AIDS. Routine use of chemoprophylaxis with a macrolide has been advocated in guidelines for the treatment of HIV-infected individuals if they have a circulating CD4+ cell count of < or =50 cells/microL. In addition, lifelong prophylaxis for disease recurrence has been recommended for those with a history of disseminated MAC infection. The introduction of HAART has resulted in a remarkable decline in the incidence of opportunistic infections and death among persons living with AIDS. Considerable reconstitution of functional immune responses against opportunistic infections can be achieved with HAART. In the case of infection with MAC, there has been a substantial reduction in the incidence of disseminated infections in the HAART era, even in countries where the use of MAC prophylaxis was never widely accepted. Moreover, the clinical picture of MAC infections in patients treated with potent antiretroviral therapies has shifted from a disseminated disease with bacteraemia to a localised infection, presenting most often with lymphadenopathy and osteomyelitis. Data from several recently conducted randomised, double-blind, placebo-controlled trials led to the current practice of discontinuing primary and secondary prophylaxis against disseminated MAC infections at stable CD4+ cell counts >100 cells/microL. These recommendations are still conservative as primary or secondary disseminated MAC infections are only rarely seen in patients who respond to HAART, despite treatment initiation at very low CD4+ cell counts. Potential adverse effects of macrolide therapy and drug interactions with antiretrovirals also metabolised via the cytochrome P450 enzyme system must be critically weighed against the marginal benefit that MAC prophylaxis may provide in addition to treatment with HAART. These authors feel that, unless patients who initiate HAART at low CD4+ cell counts do not respond to HIV-treatment, routine MAC prophylaxis should not be recommended. Nevertheless, the patient population for whom MAC prophylaxis may still be indicated in the era of HAART needs to be identified in prospectively designed clinical trials.

A prospective multicentre study of discontinuing prophylaxis for opportunistic infections after effective antiretroviral therapy

OBJECTIVE

To assess the medium-term safety of discontinuing prophylaxis (primary or secondary) for opportunistic infections following an effective response to antiretroviral therapy.

METHODS

Participating clinical sites prospectively identified patients in whom the discontinuation of prophylaxis for any opportunistic infection was considered to be clinically indicated, although CD4 levels were not predefined. A follow-up report was subsequently sent every 6 months requesting information on changes in prophylaxis, antiretroviral drugs, new AIDS-defining events, and CD4 cell count results.

RESULTS

Prophylaxis for Pneumocystis carinii pneumonia (PCP) was withdrawn in 524 patients (426 primary and 98 secondary prophylaxis), prophylaxis for Mycobacterium avium complex (MAC) was withdrawn in 28 patients (13 primary and 15 secondary), and prophylaxis for cytomegalovirus (CMV) retinitis was withdrawn in 10 patients. CD4 counts were generally maintained above accepted prophylaxis threshold levels during the period of follow up (95-98% of the time). Total follow up to last report or re-continuation of prophylaxis was 680 and 144 person-years for patients discontinuing primary and secondary PCP prophylaxis, respectively. No cases of PCP were reported, giving incidence rates of 0.0 (upper 95% confidence limit 0.4) and 0.0 (2.1) per 100 person-years. No cases of MAC were reported, but one patient had a recurrence of CMV retinitis. PCP prophylaxis was restarted in 30 patients; no patients restarted MAC or CMV prophylaxis.

CONCLUSIONS

Previous studies have demonstrated a low risk of PCP in the short term following the withdrawal of prophylaxis in patients who have responded well to antiretroviral therapy. The present study suggests a continuing low level of risk with extended follow up, provided adequate CD4 count levels are maintained. The case of recurrent CMV retinitis in a patient with impressive immunological and virological response indicates the need for close monitoring of patients previously diagnosed with this condition.

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.

Long-term effects of protease-inhibitor-based combination therapy on CD4 T-cell recovery in HIV-1-infected children and adolescents

BACKGROUND

There is limited evidence about longer-term effects of combination antiretroviral therapy that includes protease inhibitors (PIs) on the immunological status of HIV-1-infected children. Better understanding might help to resolve questions on when to initiate treatment.

METHODS

The change in percentage of CD4-positive T lymphocytes (CD4%) was investigated in 1012 previously treated HIV-1-infected children (aged 0-17 years) who were enrolled in research clinics in the USA before 1996 and followed up to 2000. 702 started PI-based combination therapy. Data analyses ignored subsequent treatment changes.

FINDINGS

Among the 1012 children, the median CD4% increased from 22% to 28% between 1996, when PIs were first prescribed, and 2000. For the 702 who started PI-based therapy, the mean CD4% increase after 3 years was largest among participants with the greatest immunosuppression (15.7%, 10.6%, 5.1%, and 2.0% for participants with CD4% before therapy of <5%, 5-14%, 15-24%, and >25%; p<0.0001). After adjustment for pre-PI CD4%, the mean increase was largest among the youngest participants (9.2%, 8.0%, and 4.3% for ages <5 years, 5-9 years, and >10 years; p=0.001). However, only a minority of significantly immunocompromised participants (33%, 26%, and 49% of those with pre-PI CD4% of <5%, 5-14%, or 15-24%) achieved CD4% values above 25%, whereas 84% of those with pre-PI values above 25% maintained such values.

INTERPRETATION

Although PI-based therapy was associated with substantial improvements in CD4%, initiation before severe immunosuppression and at younger ages may be more effective for recovery or maintenance of normal CD4%. Randomised investigation of when to start combination therapy in children, particularly infants, is needed.

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.

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.

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.

Presence of macrolide resistance in respiratory flora of HIV-Infected patients receiving either clarithromycin or azithromycin for Mycobacterium avium complex prophylaxis

Clarithromycin 500 mg po bid or azithromycin 1200 mg po weekly is recommended as first line prophylaxis for Mycobacterium avium complex (MAC) in patients with HIV infection whose CD4 counts are <50 cells/microL. HIV-infected patients with CD4+ T-cell counts <200 cells/microL were randomized to receive either clarithromycin 500 mg po bid or azithromycin 1200 mg po weekly for 12 weeks. Nasopharyngeal swabs for Streptococcus pneumoniae and Haemophilus influenzae plus an anterior nare culture for Staphylococcus aureus were obtained at pretreatment, at 6 weeks, and at 12 weeks. A throat culture for oral flora was obtained for susceptibility testing against erythromycin. Minimum inhibitory concentrations (MICs) for clarithromycin and azithromycin were performed on all S. pneumoniae, H. influenzae, and S. aureus isolates. The study was terminated after respiratory flora, from all participants, revealed macrolide resistance. Because results of recent randomized trials indicate minimal efficacy of continuing MAC prophylaxis in patients who respond to potent combination antiretroviral therapy, the observed high incidence of macrolide-resistant bacterial colonization of the respiratory tract in this trial supports the discontinuation of macrolide prophylaxis in all AIDS patients whose CD4 counts have risen above 100 cells/microL.

Management and Prevention of Opportunistic Infections in the HIV-Infected Patient

With the introduction of potent antiretroviral therapy, the incidence of opportunistic infections (OIs) as well as death has dramatically decreased since 1996. Opportunistic infections are seen mainly in three groups: (1) newly diagnosed patients not receiving antiretroviral therapy and presenting with an OI, (2) patients nonadherent to antiretroviral and OI treatment regimens or (3) patients whose antiretroviral therapy has failed. This article will review the most common opportunistic infections (OIs) seen in the HIV-infected individual and their treatment. The current guidelines for the prophylaxis against these OIs will also be discussed.