The impact of HIV on chronic kidney disease outcomes

Chronic kidney disease (CKD) is a known complication of the human immunodeficiency virus (HIV) but outcomes among HIV-infected patients with kidney disease are unknown. We studied a national sample of 202,927 patients with CKD (stage 3 or higher) for death, end-stage renal disease (ESRD) and the mean annual rate of decline in estimated glomerular filtration rate (eGFR) over a median period of 3.8 years. Within this sample, 0.3% of the patients were diagnosed with HIV, 43.5% were diabetic, whereas the remainder had neither disease. In this national CKD cohort, HIV-infected black patients were at higher risk of death, a similar risk for ESRD and loss of eGFR than black patients with diabetes. HIV-infected white patients experienced higher rates of death but a lower risk of ESRD than their counterparts with diabetes. Our results highlight a need to study mortality and mechanisms of ESRD in the HIV infected population.

Toward a definition of HIV expertise: a survey of experienced HIV physicians

Medical care for human immunodeficiency virus (HIV)-infected persons has grown increasingly complex, yet few studies have examined experienced HIV physicians' views about current HIV medical care. The objective of this study was to examine the relationship between physicians' HIV experience, self-perceived expertise, and confidence with providing 18 aspects of HIV medical care and between confidence in aspects of care and medical specialty. At geographically diverse, HIV continuing medical education programs conducted in the fall of 1999, 359 currently practicing HIV physicians completed a written survey measuring participants' demographic characteristics, experience, HIV expertise, and level of confidence providing essential aspects of HIV care. Participants currently managed a median of 50 HIV-infected patients with a career total of 300. Significant correlations were found between experience and expertise items and experience and 15 of 18 confidence items. Confidence levels varied from 11% to 85% highly confident across 18 aspects of HIV care. Physicians' confidence with providing aspects of HIV care varied by the three predominant specialty groups (infectious diseases, internal medicine, and family practice/general medicine). Physicians who have informally specialized in HIV care reported a range of self-perceived expertise and confidence, indicating the complexity of HIV medical care today. Our results suggest that even the most experienced HIV physicians in the United States continue to benefit from more experience and that each medical specialty examined in this study brings its own set of skills needed to provide optimal HIV care. This study constitutes a first step toward defining and formalizing HIV medical care.

Antiretroviral therapy in adults: updated recommendations of the International AIDS Society-USA Panel

OBJECTIVE

To update recommendations for antiretroviral therapy for adult human immunodeficiency virus type 1 (HIV-1) infection, based on new information and drugs that are available.

PARTICIPANTS

A 17-member international physician panel with antiretroviral research and HIV patient care experience initially convened by the International AIDS Society-USA in December 1995.

EVIDENCE

Available clinical and basic science data including phase 3 controlled trials; data on clinical, virologic, and immunologic end points; research conference reports; HIV pathogenesis data; and panel expert opinion. Recommendations were limited to therapies available (US Food and Drug Administration approved) in 1999.

CONSENSUS PROCESS

The panel assesses new research reports and interim results and regularly meets to consider how the new data affect therapy recommendations. Recommendations are updated via full-panel consensus. Guidelines are presented as recommendations if the supporting evidence warrants routine use in the particular situation and as considerations if data are preliminary or incomplete but suggestive.

CONCLUSIONS

The availability of new antiretroviral drugs has expanded treatment choices. The importance of adherence, emerging long-term complications of therapy, recognition and management of antiretroviral failure, and new monitoring tools are addressed. Optimal care requires individualized management and ongoing attention to relevant scientific and clinical information in the field.

Advances in the medical management of patients with HIV-1 infection: an overview

New guidelines for the management of patients with HIV-1 infection emphasize early aggressive treatment using multi-drug combination regimens. Accurate assessment of the effectiveness of these treatments and their potential (small as it now seems) to eradicate HIV-1 infection requires testing for viral levels in the blood, and in other compartments that may serve as long-term viral reservoirs, using the most sensitive assays. At present, most of our information regarding triple-drug combination therapies (usually two nucleosides and a protease inhibitor or a non-nucleoside reverse transcriptase inhibitor) has come from the assessment of viral levels in blood. Available results strongly support the virologic superiority of such treatments over monotherapy and two-drug combinations. There are important questions that remain to be answered regarding these highly effective therapies. Questions regarding the durability of these treatments in preventing the evolution of drug resistance can be addressed by using sensitive reverse transcription/polymerase chain reaction assays to assess treatment response. Others, such as how best to treat patients who have failed potent drug therapy, await results from new, large-scale, clinical trials. An important concern with respect to newer antiretroviral therapies is their complexity and thus the increased risk for non-compliance and resultant viral resistance. In addition, longer-term side-effects are increasingly recognized. Programs that enhance compliance with these treatments will increase the probability that they will provide durable suppression of viral replication and arrest the clinical progression of HIV disease.

Novel four-drug salvage treatment regimens after failure of a human immunodeficiency virus type 1 protease inhibitor-containing regimen: antiviral activity and correlation of baseline phenotypic drug susceptibility with virologic outcome

Twenty human immunodeficiency virus-infected patients experiencing virologic failure of an indinavir- or ritonavir-containing treatment regimen were evaluated in a prospective, open-label study. Subjects received nelfinavir, saquinavir, abacavir, and either another nucleoside analog (n=10) or nevirapine (n=10). Patients treated with the nevirapine-containing regimen experienced significantly greater virologic suppression at week 24 than those not treated with nevirapine (P=.04). Baseline phenotypic drug susceptibility was strongly correlated with outcome in both treatment arms. Subjects with baseline virus phenotypically sensitive to 2 or 3 drugs in the salvage regimen experienced significantly greater virus load suppression than those with baseline virus sensitive to 0 or 1 drug (median week-24 change=-2.24 log and -0.35 log, respectively; P=.01). In conclusion, non-nucleoside reverse transcriptase inhibitors may represent a potent drug in salvage therapy regimens after failure of an indinavir or ritonavir regimen. Phenotypic resistance testing may provide a useful tool for selecting more effective salvage regimens.

Antiretroviral therapy for HIV infection in 1998: updated recommendations of the International AIDS Society-USA Panel

OBJECTIVE

To provide recommendations for antiretroviral therapy based on information available in mid-1998.

PARTICIPANTS

An international panel of physicians with expertise in antiretroviral research and care of patients with human immunodeficiency virus (HIV) infection, first convened by the International AIDS Society-USA in December 1995.

EVIDENCE

The panel reviewed available clinical and basic science study results (including phase 3 controlled trials; clinical, virologic, and immunologic end point data; data presented at research conferences; and studies of HIV pathophysiology); opinions of panel members were also considered. Recommendations were limited to drugs available in mid-1998.

CONSENSUS PROCESS

Panel members monitor new clinical research reports and interim results. The full panel meets regularly to discuss how the new information may change treatment recommendations. Updated recommendations are developed through consensus of the entire panel at each stage of development.

CONCLUSIONS

Accumulating data from clinical and pathogenesis studies continue to support early institution of potent antiretroviral therapy in patients with HIV infection. A variety of combination regimens show potency, expanding choices for initial regimens for individual patients. Plasma HIV RNA assays with increased sensitivity are important in monitoring therapeutic response; however, more data are needed to determine precisely the HIV RNA levels that define treatment failure. Long-term adverse drug effects are beginning to emerge, requiring ongoing attention. Some issues regarding optimal long-term approaches to antiretroviral management are unresolved. The increased complexity in HIV management requires ongoing monitoring of new data for optimal treatment of HIV infection.

An aggressive approach to HIV antiretroviral therapy

The introduction of highly active antiretroviral therapy offers the first real hope of durable control of HIV infection and prevention of clinical sequelae. But success hinges on early and complete suppression of viral replication. That demands near-perfect adherence to a complex regimen involving three or more drugs, each with its own dosage and dietary requirements.

Predictors and impact of patients lost to follow-up in a long-term randomized trial of immediate versus deferred antiretroviral treatment

We studied predictors for losses to follow-up and the impact of such losses in the AIDS Clinical Trials Group 019 protocol, a long-term randomized trial of immediate versus deferred antiretroviral therapy in asymptomatic HIV-1-infected patients with >500 CD4 cells/mm3. The trial was selected because of its key importance in determining guidelines for antiretroviral therapy, and because it had the longest follow-up among all antiretroviral trials and the largest percentage of patients whose vital status was unknown at study end. Younger age, a history of parenteral drug use, and nonwhite race were associated with higher rates of loss to follow-up, but race was not an important predictor after adjusting for clinical site. There was large and statistically significant variability in the rates of losses among different clinical sites (p < 0.001). Patient retention was significantly better in clinical sites that enrolled many participants, with 25% of enrollees lost to follow-up in sites enrolling >100 patients and 44% in sites enrolling <33 patients each. As a group, patients lost to follow-up after the 2nd year had steeper declines of CD4 cell counts, and a significantly larger proportion had reached a CD4 cell count <300/mm3 in the year before being lost, compared with patients remaining in the study. Losses to follow-up probably decreased substantially the observed number of primary endpoints, curtailed the power of the trial to demonstrate any difference between immediate and deferred initiation of antiretroviral therapy, and may have introduced large bias in the estimated hazard ratio for the primary endpoint and its statistical significance.

Antiretroviral therapy for HIV infection in 1997. Updated recommendations of the International AIDS Society-USA panel

OBJECTIVE

To provide current recommendations for antiretroviral therapy for human immunodeficiency virus (HIV) disease.

PARTICIPANTS

The original International AIDS Society-USA 13-member panel representing international expertise in antiretroviral research and care of patients with HIV infection.

EVIDENCE

The following were considered: Newly available clinical and basic science study results, including phase 3 controlled trials; clinical, virological, and immunologic end-point data; interim analyses of studies presented at national and international research conferences; studies of HIV pathophysiology; and expert opinions of panel members. Recommendations were limited to the drugs available in mid 1997.

PROCESS

The full panel met on a regular basis (July 1996, September 1996, November 1996, January 1997, and April 1997) since the publication of its initial recommendations in mid 1996 to review new research reports and interim results. The panel discussed whether and how new information changed its initial recommendations. The recommendations contained herein were determined by group consensus.

CONCLUSIONS

New data have provided a stronger rationale for earlier initiation of more aggressive therapy than previously recommended and reinforce the importance of careful selection of initial drug regimen for each patient for optimal long-term clinical benefit and adherence. The plasma viral load is a crucial element of clinical management for assessing prognosis and the effectiveness of therapy, and such testing must be done properly. Treatment failure is most readily indicated by a rising plasma HIV RNA level and should be confirmed prior to a change of treatment. Therapeutic approaches must be updated as new data, particularly on the long-term clinical effect of aggressive antiretroviral treatment, continue to emerge.

Antiretroviral therapy for HIV infection in 1996. Recommendations of an international panel. International AIDS Society-USA

OBJECTIVE

To provide clinical recommendations for antiretroviral therapy for human immunodeficiency virus (HIV) disease with currently (mid 1996) available drugs. When to start therapy, what to start with, when to change, and what to change to were addressed.

PARTICIPANTS

A 13-member panel representing international expertise in antiretroviral research and HIV patient care was selected by the international AIDS Society-USA.

EVIDENCE

Available clinical and basic science data, including phase 3 controlled trials, clinical endpoint data, virologic and immunologic endpoint data, interim analyses, studies of HIV pathophysiology, and expert opinions of panel members were considered. Recommendations were limited to drugs available in mid 1996.

PROCESS

For each question posed, 1 or more member(s) reviewed and presented available data. Recommendations were determined by group consensus (January 1996); revisions as warranted by new data were incorporated by group consensus (February-May 1996).

CONCLUSIONS

Recent data on HIV pathogenesis, methods to determine plasma HIV RNA, clinical trial data, and availability of new drugs point to the need for new approaches to treatment. Therapy is recommended based on CD4+ cell count, plasma HIV RNA level, or clinical status. Preferred initial drug regimens include nucleoside combinations; at present protease inhibitors are probably best reserved for patients at higher progression risk. For treatment failure or drug intolerance, subsequent regimen considerations include reasons for changing therapy, available drug options, disease stage, underlying conditions, and concomitant medication(s). Therapy for primary (acute) infection, high-risk exposures to HIV, and maternal-to-fetal transmission are also addressed. Therapeutic approaches need to be updated as new data continue to emerge.

HIV viral load markers in clinical practice

Plasma HIV RNA determinations are an important prognostic marker of disease progression and, when used appropriately, provide a valuable tool for the management of individual patients. But what constitutes appropriate use?

Doxorubicin encapsulated in liposomes containing surface-bound polyethylene glycol: pharmacokinetics, tumor localization, and safety in patients with AIDS-related Kaposi's sarcoma

A study of the plasma pharmacokinetics, tumor localization, and safety of a single dose of doxorubicin encapsulated in liposomes containing surface-bound polyethylene glycol (PEG-liposomal doxorubicin) was conducted in patients with Kaposi's sarcoma (KS) as a manifestation of acquired immune deficiency syndrome (AIDS). Eighteen patients with AIDS-KS diagnosed by examination of biopsy specimens were randomly assigned to receive either standard doxorubicin or PEG-liposomal doxorubicin. Consecutive participants were entered at three dose levels (10, 20, and 40 mg/m2) in ascending fashion. Clearance of PEG-liposomal doxorubicin was 0.034 L/h/m2 to 0.108 L/h/m2, volume of distribution (Vd) was 2.2 L/m2 to 4.4 L/m2, and half-lives (t1/2) of the initial decline in the plasma concentration-time curve and of the terminal decline were 3.77 hours and 41.3 hours, respectively. Seventy-two hours after administration, doxorubicin levels observed in lesions of patients receiving PEG-liposomal doxorubicin were 5.2 to 11.4 times greater than those found in patients given comparable doses of standard doxorubicin. PEG-liposomal doxorubicin and standard doxorubicin were roughly equipotent in producing toxicity. Encapsulation in liposomes containing surface-bound PEG significantly limits the distribution and elimination of doxorubicin, results in greater accumulation of the drug in KS lesions 72 hours after dosing than does standard doxorubicin, and may improve drug efficacy and therapeutic index in the treatment of AIDS-KS.

A comparison of immediate with deferred zidovudine therapy for asymptomatic HIV-infected adults with CD4 cell counts of 500 or more per cubic millimeter. AIDS Clinical Trials Group

BACKGROUND

The clinical benefits of zidovudine remain unproved in patients with asymptomatic human immunodeficiency virus (HIV) infection when CD4 cell counts exceed 500 per cubic millimeter. We compared zidovudine therapy given immediately with deferred therapy in such subjects.

METHODS

Beginning in 1987, subjects with asymptomatic HIV infection and 500 or more CD4 cells per cubic millimeter were randomly assigned to receive placebo or zidovudine (either 500 or 1500 mg per day, starting immediately). In 1989, the study was modified so that open-label treatment with 500 mg of zidovudine per day (deferred therapy) was offered when CD4 cell counts fell below 500 per cubic millimeter. The study end points included overall survival, survival free of the acquired immunodeficiency syndrome (AIDS), toxic effects, and changes in CD4 cell counts.

RESULTS

There were 1637 subjects who could be evaluated: 547 in the deferred-therapy group, 549 in the group receiving 500 mg of zidovudine immediately, and 541 in the 1500-mg group. The subjects were followed for up to 6.5 years (group medians, 4.8, 4.8, and 4.9, respectively). There was no significant difference in AIDS-free survival in the deferred-therapy group as compared with the low-dose or high-dose groups (81 cases of progression to AIDS or death vs. 81 and 74, respectively; P = 0.95 and P = 0.13) or in overall survival (51 deaths vs. 47 and 46; P = 0.25 and P = 0.16). The decline in CD4 cells was slower in both immediate-therapy groups than in the deferred-therapy group (P < 0.001 for both). Adverse effects were uncommon, and before the study modification their incidence was similar among the treatment groups, but severe anemia and granulocytopenia were more frequent in the 1500-mg group than in the deferred-therapy group (P < 0.001).

CONCLUSIONS

In asymptomatic, HIV-infected adults with 500 or more CD4 cells per cubic millimeter, treatment with zidovudine slows the decline in the CD4 cell count but does not significantly prolong either AIDS-free or overall survival. These results do not encourage the routine use of zidovudine monotherapy in this population.

Influence of molecular characteristics on clinical outcome in human immunodeficiency virus-associated non-Hodgkin's lymphoma: identification of a subgroup with favorable clinical outcome

The relationship between clinical and molecular characteristics of 45 treated individuals with histologically-documented human immunodeficiency virus (HIV)-associated B-cell non-Hodgkin's lymphoma was examined to determine whether differences in molecular features of lymphoma were associated with differences in clinical outcome. Tissue specimens from these tumors were evaluated for evidence of Ig heavy-chain gene rearrangements using both Southern blot analysis and reverse transcriptase polymerase chain reaction (RT-PCR). Lymphomas were also evaluated for the presence of Epstein-Barr virus (EBV) DNA sequences and c-myc gene rearrangements. Twenty-five lymphomas were characterized as polyclonal and 20 as monoclonal. PCR amplification of expressed Ig variable (V)-region genes confirmed polyclonality in three extensively studied polyclonal lymphomas. The median CD4 count was significantly higher in the group with polyclonal disease (277/microL) than in the group with monoclonal disease (123/microL), P = .04. The complete response rate to therapy was significantly higher in patients with polyclonal disease (78%) and CD4 greater than 200/microL (81%) than in those with monoclonal disease (31%) and CD4 less than 200/microL (33%). CD4 count, clonality, and presence of EBV DNA sequences were the most important predictors of survival. Both Kaplan-Meier and Cox proportional hazards analyses showed a markedly prolonged survival in those patients with both CD4 > or = 200/microL and polyclonal disease. Histologically the polyclonal lymphomas were high grade in appearance and contained prominent macrophages. All seven surviving patients were in this group. Median survival for those individuals whose tumors contained EBV sequences was only 3.2 months (range, 0.4 to 19.5), whereas those with EBV- tumors survived for a median of 9.0 months (range, 0.7 to 65.2), P = .0007. These data indicate that molecular features of HIV-associated lymphomas may be important predictors of clinical outcome. These characteristics define a distinct subset of patients with polyclonal EBV- tumors and CD4 counts greater than 200/microL that appear to have a less aggressive clinical course.

The duration of zidovudine benefit in persons with asymptomatic HIV infection. Prolonged evaluation of protocol 019 of the AIDS Clinical Trials Group

OBJECTIVE

To determine the durability of zidovudine-induced delay in clinical progression of asymptomatic human immunodeficiency virus (HIV) disease and to assess the relationship between this effect and the entry CD4+ cell count.

DESIGN AND INTERVENTIONS

Extended follow-up data from subjects participating in protocol 019 of the AIDS [acquired immunodeficiency syndrome] Clinical Trials Group were examined. Subjects were offered a total daily dose of 500 mg of open-label zidovudine after the unblinding of the original randomized trial in 1989. Original treatment groups included placebo, 500 mg of zidovudine, or 1500 mg of zidovudine daily in divided doses. Three distinct analyses were conducted to assess the duration of zidovudine's effect on progression to AIDS or death: (1) analysis of all follow-up information from all subjects, (2) analysis of all subjects but with follow-up of original placebo-assigned subjects censored at the time open-label zidovudine was initiated, and (3) analysis of the effect of initiating zidovudine in subjects initially assigned to receive placebo.

SETTING

University-based and university-affiliated AIDS research clinics participating in AIDS Clinical Trials Group protocol 019.

PATIENTS

A total of 1565 asymptomatic HIV-infected subjects with entry CD4+ cell counts less than 0.50 x 10(9)/L (500/microL).

MAIN OUTCOME MEASURE

Time to progression to AIDS or death.

RESULTS

During follow-up of up to 4.5 years (mean, 2.6 years), 232 subjects progressed to AIDS or died. In each of the three analyses described herein, zidovudine was associated with a significant (P = .008, .004, .007) decrease in the risk of such progression. However, each of these analyses also indicated a decreasing placebo:zidovudine relative risk with duration of use (P = .002, .08, .04), suggesting a nonpermanent effect. The duration of benefit appeared to be related to entry CD4+ cell count, with greater benefit in those with higher counts at entry. No significant differences in survival were found between those originally randomized to zidovudine or placebo.

CONCLUSIONS

Zidovudine at 500 mg/d caused a significant delay in progression to AIDS or death, but its earlier use in asymptomatic disease was not associated with an additional prolongation of survival compared with delayed initiation. The delay in progression diminished over time especially in subjects with entry CD4+ cell counts less than 0.30 x 10(9)/L (300/microL). Treatment strategies that alter drug regimens before the loss of zidovudine benefit should be explored.

Treatment dilemmas in HIV infection

Recent trials of early treatment with the nucleoside analogues have produced conflicting data, raising fundamental questions about this therapy. Nevertheless, these drugs do lengthen clinical latency and delay the onset of AIDS, and for that reason alone should not be abandoned. The new treatment guidelines of the National Institute of Allergy and Infectious Diseases are discussed.

Evaluation of the quality of life associated with zidovudine treatment in asymptomatic human immunodeficiency virus infection. The AIDS Clinical Trials Group

BACKGROUND

Zidovudine therapy is recommended for asymptomatic patients infected with the human immunodeficiency virus (HIV) who have fewer than 500 CD4+ cells per cubic millimeter. An analysis of the quality of life associated with therapy that integrated both the effects of adverse events and the benefits of delayed disease progression might influence this recommendation.

METHODS

We applied a survival analysis adjusted for the quality of life to data from a randomized trial conducted by the AIDS Clinical Trials Group. The trial compared treatment with 500 mg of zidovudine per day, 1500 mg of zidovudine per day, and placebo (Protocol 019) in 1338 asymptomatic HIV-infected patients.

RESULTS

The average time with neither a progression of disease nor an adverse event (symptom or laboratory finding) was 15.7, 15.6, and 14.8 months for patients receiving placebo, 500 mg of zidovudine, and 1500 mg of zidovudine, respectively. The incidence of severe symptoms was 13.8 percent in the placebo group, 15.2 percent in the 500-mg group, and 19.9 percent in the 1500-mg group (P = 0.038). After 18 months, the 500-mg group gained an average of 0.5 months without disease progression, as compared with the placebo group, but had severe adverse events an average of 0.6 months sooner. The 500-mg group had more quality-of-life--adjusted time than the placebo group only if the time lived after the progression of disease was considered by a patient to have less value than the time after the occurrence of a severe symptom.

CONCLUSIONS

For asymptomatic patients treated with 500 mg of zidovudine, a reduction in the quality of life due to severe side effects of therapy approximately equals the increase in the quality of life associated with a delay in the progression of HIV disease.

Within-subject variation in CD4 lymphocyte count in asymptomatic human immunodeficiency virus infection: implications for patient monitoring

Changes in CD4 lymphocyte counts are widely used in monitoring human immunodeficiency virus (HIV)-infected patients for disease progression. However, random fluctuations may obscure clinically significant changes. CD4 cell counts from 1020 untreated subjects with asymptomatic HIV infection monitored by standardized methods for up to 2 years were assessed. The within-subject coefficient of variation averaged 25% but was higher in subjects with lower counts; in 6% of subjects the count was half or double the one obtained 8 weeks before. Proportionate rates of decline, which had negligible correlation with the baseline count, averaged 14.3%/year but varied considerably between subjects: An estimated 29% had increasing trends. Declines were greater in HIV p24-positive subjects and those with higher lymphocyte percentages or lower platelet counts or hemoglobin levels. With such high variation, changes between single counts should be interpreted cautiously. Using multiple counts and other markers may provide more precise assessment of immune status.

Combination therapy with zidovudine and didanosine compared with zidovudine alone in HIV-1 infection

OBJECTIVE

To assess safety, pharmacokinetics, and in-vivo virologic activity of five different combination regimens of zidovudine and didanosine compared with zidovudine alone in patients with human immunodeficiency virus type 1 (HIV-1) infection.

DESIGN

Open-label, partially randomized, dose-ranging study.

SETTING

University-affiliated, medical center clinics.

PATIENTS

A total of 69 patients with HIV-1 infection, CD4+ cell counts fewer than 400 cells/mm3, and fewer than 121 days of previous zidovudine treatment.

INTERVENTIONS

Fifty-five patients received combination therapy with zidovudine and didanosine, and 14 received zidovudine therapy alone (600 mg/d). Daily dosages in milligrams of zidovudine and didanosine, respectively, in the five combination groups were 150 and 90 mg, 300 and 334 mg, 600 and 334 mg, 300 and 500 mg, and 600 and 500 mg.

MEASUREMENTS

CD4+ cell counts, HIV-1 RNA titers in plasma, and toxic effects.

RESULTS

The combination regimens were associated with higher and more sustained increases in CD4+ cells than zidovudine alone, even after adjustment for initial CD4+ counts and previous zidovudine therapy (P < 0.001). The median increase in CD4+ cell counts was 166 cells/mm3 with combination therapy and 77 cells/mm3 with zidovudine alone (P = 0.001) and did not differ statistically among the five combination regimens. Human immunodeficiency virus type 1 RNA titers in plasma decreased in 15 (83%) of 18 combination-therapy recipients compared with 2 of 7 zidovudine-alone recipients (P = 0.017). No pharmacokinetic interactions were seen between zidovudine and didanosine. Toxicity rates were low among all treatment groups. A greater decrease in hemoglobin levels was seen with the regimen using zidovudine alone (-8 g/L) compared with combination regimens using the same zidovudine dose (-1.5 g/L, P = 0.03).

CONCLUSIONS

Combination therapy with zidovudine and didanosine produced larger and more sustained increases in CD4+ cell counts, more frequent decreases in plasma HIV-1 RNA titers, and more stable hematologic status than zidovudine therapy alone. The effects of this combination on the progression of HIV disease merit further study, to provide information about clinical outcome, because this was a relatively small study based on surrogate markers of HIV-1 infection.

CD4+ lymphocytes are an incomplete surrogate marker for clinical progression in persons with asymptomatic HIV infection taking zidovudine

OBJECTIVE

To determine the extent to which lymphocytes, particularly those with the CD4 surface antigen, are a surrogate marker for the development of the acquired immunodeficiency syndrome (AIDS) in persons with asymptomatic human immunodeficiency virus (HIV) infection.

DESIGN

Analysis of data from the AIDS Clinical Trials Group Protocol 019, a placebo-controlled, double-blind, randomized trial.

SETTING

University-based referral centers.

PATIENTS

Asymptomatic HIV-infected patients with 500 or fewer CD4+ cells/mm3 at baseline who were given placebo (350 patients) or one of two daily doses of zidovudine (725 patients).

MEASUREMENTS

Baseline and interim measurements of CD4+ and other leukocytes were assessed. Patients were followed for progression to AIDS.

RESULTS

Patients' lymphocyte levels were correlated with progression to AIDS (P < 0.001; relative risk for each depletion of 50 CD4+ cells/mm3, 1.75; 95% CI, 1.53 to 2.01); however, only a small portion (0% to 37%) of the effect of zidovudine on this progression was statistically explained by its effect on CD4+ lymphocyte levels. A substantial portion of zidovudine's effect on delaying progression to AIDS that was independent of the levels of these markers occurred within the first 16 weeks of therapy. In patients who had not progressed to AIDS by week 16, most of the subsequent zidovudine effect in reducing the risk for progression could be explained by its effect on net CD4+ percent (percentage of CD4+ lymphocytes among all leukocytes) for the first 16 weeks of therapy.

CONCLUSION

Levels of CD4+ lymphocytes are an incomplete surrogate marker for progression to AIDS, and the association is especially weak during the first 16 weeks of zidovudine therapy.

Weekly doxorubicin in the treatment of patients with AIDS-related Kaposi's sarcoma. AIDS Clinical Trials Group

Fifty-three patients with AIDS-related Kaposi's sarcoma and no previous treatment with cytotoxic chemotherapy enrolled in a phase II multicenter study to evaluate the safety and efficacy of weekly doxorubicin treatment. Doxorubicin was given intravenously at a dose of 15 mg/m2. Patients were stratified for purposes of analyses by tumor burden and coexistence of HIV-associated signs and symptoms; stratum I included patients with cutaneous disease alone and no symptoms, and stratum II included patients with visceral disease, tumor-associated edema, a previous opportunistic infection, or systemic symptoms. Fifty-one patients were evaluable for toxicity and 50 for tumor response. Five patients had a partial response (10%); 32, a minor response (64%); 12, no change (24%); and one, progression (2%) as the best measurable response. Partial response durations ranged from 4 to 14 weeks. Fifteen patients subsequently showed progression while on treatment. A significantly greater number of patients in stratum I (20.1%) had a partial response compared with those in stratum II (0%, p = 0.009). The major toxicities included nausea (37%), stomatitis (9.8%), mucositis (13.7%), and moderate to severe neutropenia (71%). Neutropenia was dose limiting and resulted in discontinuation of doxorubicin in 18% of the patients. Two patients developed cardiac toxicity. In conclusion, doxorubicin treatment induced relatively few tumor responses and remission durations were short. Treatment was limited by a high rate of toxicity.

Toxic effects of zidovudine in asymptomatic human immunodeficiency virus-infected individuals with CD4+ cell counts of 0.50 x 10(9)/L or less. Detailed and updated results from protocol 019 of the AIDS Clinical Trials Group

BACKGROUND

Protocol 019 of the AIDS Clinical Trials Group is a multicenter, double-blind, placebo-controlled trial of zidovudine (3'-azido-3'-deoxythymidine; formerly AZT) in human immunodeficiency virus-infected asymptomatic individuals. The initial results in the stratum of subjects entering with CD4+ cell counts of 0.50 x 10(9)/L or less have been reported, but without a detailed analysis of toxic effects.

METHODS

This detailed and updated report analyzes the toxic effects that occurred in 1567 subjects (91% men; 89% white) in this stratum of protocol 019 who received placebo (494 subjects), a 500-mg daily dose of zidovudine (544 subjects), or a 1500-mg daily dose of zidovudine (529 subjects). Hematologic, hepatic, and renal effects and patient-reported symptoms and clinical signs were monitored.

RESULTS

Severe anemia (hemoglobin level, < 80 g/L) was associated with both the 500-mg zidovudine group and the 1500-mg group compared with placebo. The estimated 18-month risks of severe anemia were 0.4%, 2.0%, and 9.7% for the placebo, 500-mg zidovudine, and 1500-mg zidovudine groups, respectively. Predictive baseline measures were lower hemoglobin level in the 1500-mg group and the two zidovudine groups combined and lower platelet count in the 500-mg zidovudine group. The risk of a first severe anemia developing was greatest in months 3 through 8 of treatment. Of the 44 subjects with severe anemia in the zidovudine groups, 18 (41%) progressed from mild anemia (hemoglobin level, 95 to 109 g/L) to severe anemia on consecutive visits (usually 2 to 4 weeks apart). Severe neutropenia (absolute neutrophil count, < 750 x 10(6)/L) did not occur significantly more often in the 500-mg zidovudine group but did in the 1500-mg zidovudine group. Moderate neutropenia (absolute neutrophil count, < 1300 x 10(6)/L) did develop significantly more often in the 500-mg zidovudine group (165 subjects) than in the placebo group (71 subjects). Mild (or worse) elevations of bilirubin levels were uncommon but occurred more often with zidovudine. Severe nausea (and/or vomiting) was rare (2.8% of subjects) but was associated with zidovudine. Milder patient-reported events were common, and a number were associated with zidovudine.

CONCLUSION

Zidovudine at the 500-mg/d dosage appears to be tolerable in many patients with asymptomatic human immunodeficiency virus infection and CD4+ cell counts of 0.50 x 10(9)/L or less. Increased clinical surveillance for anemia may be warranted in certain patients.

A controlled trial comparing continued zidovudine with didanosine in human immunodeficiency virus infection. The NIAID AIDS Clinical Trials Group

BACKGROUND

Although zidovudine is effective in patients with human immunodeficiency virus (HIV) infection, its efficacy may decline with prolonged use. Didanosine is another inhibitor of HIV reverse transcriptase. We evaluated the effectiveness of changing anti-HIV treatment from zidovudine to didanosine.

METHODS

This multicenter, double-blind study involved 913 patients who had tolerated zidovudine for at least 16 weeks. The patients had the acquired immunodeficiency syndrome (AIDS), AIDS-related complex with less than or equal to 300 CD4 cells per cubic milliliter, or asymptomatic HIV infection with less than or equal to 200 CD4 cells per cubic milliliter. They were randomly assigned to receive 600 mg per day of zidovudine, 750 mg per day of didanosine, or 500 mg per day of didanosine.

RESULTS

There were significantly fewer new AIDS-defining events and deaths among the 298 subjects assigned to 500 mg per day of didanosine than among the subjects who continued to receive zidovudine (relative risk, 1.39; 95 percent confidence interval, 1.06 to 1.82; P = 0.015). With 750 mg of didanosine, there was no clear benefit over zidovudine (relative risk, 1.10; 95 percent confidence interval, 0.86 to 1.42). The efficacy of didanosine was unrelated to the duration of previous zidovudine treatment. In the two didanosine groups, there were improvements in the number of CD4 cells (P less than 0.001 for both groups) and in p24 antigen levels (P = 0.03 in the 500-mg group; P = 0.005 in the 750-mg group), as compared with the zidovudine group.

CONCLUSIONS

Changing treatment from zidovudine to 500 mg per day of didanosine appears to slow the progression of HIV disease.

A phase I study of HGP-30, a 30 amino acid subunit of the human immunodeficiency virus (HIV) p17 synthetic peptide analogue sub-unit vaccine in seronegative subjects

HGP-30-KLH vaccine in alum at doses of 10, 25, 50, and 100 micrograms/kg administered intramuscularly at weeks 0, 4, and 10 appear well-tolerated clinically. Local pain at the injection site, appears to be the main clinical toxicity. Laboratory parameters are not affected by administration of the vaccine candidate except for perhaps mild urinalysis abnormalities at the highest dose. This vaccine candidate has no apparent immunotoxicity and does not appear to affect lymphocyte populations or T-cell functional studies. Low levels and transient antibodies develop in a minority of subjects early after immunization with the vaccine candidate. These responses were observed in the lowest dose range. Higher doses, and longer follow-up will be needed to confirm this observation. T-cell proliferative responses to KLH and KLH-HGP-30 are consistent and may not be dose dependent, but the proliferative responses are variable and more data need to be accumulated. Preliminary, there appears to be an HGP-30-induced CTL response of HGP-30-coated EBV-transformed autologous B cell lines. This study was approved under an IND for the California Department of Health Services' Food and Drug Branch. They have provided excellent support and regulatory guidelines for this project. Future work will extend and confirm these initial observations.

Phase 1 study of recombinant human CD4-immunoglobulin G therapy of patients with AIDS and AIDS-related complex

The safety and pharmacokinetics of recombinant CD4-immunoglobulin G (rCD4-IgG) were evaluated in a phase 1 study with dose escalation. A total of 16 patients, 6 with AIDS and 10 with AIDS-related complex, were evaluated at two university-affiliated hospital clinics. rCD4-IgG was administered once weekly for 12 weeks to four patients each at doses of 0.03, 0.1, 0.3, and 1.0 mg/kg of body weight. Dosing was intravenous for two patients in the 1.0-mg/kg dose group and intramuscular for the remaining patients. Dosing was intravenous for two patients in the 1.0-mg/kg dose group and intramuscular for the remaining patients. Pharmacokinetic, toxicity, and immunologic variables were monitored with all patients. Administration of rCD4-IgG was well tolerated, with no important clinical or immunologic toxicities noted. No subjects required dose reduction or discontinuation of therapy due to toxicity. No consistent changes were seen in human immunodeficiency virus antigen levels in serum or CD4 lymphocyte populations. The volume of distribution was small, and compared with that of rCD4, the half-life of the hybrid molecule was markedly prolonged following intramuscular or intravenous administration. The rate and extent of absorption following intramuscular dosing were variable. Intramuscular administration of rCD4-IgG appears to be inferior to intravenous dosing from a pharmacokinetic standpoint, with lower peak concentrations and variable absorption. After intravenous administration, peak concentrations of rCD4-IgG in serum (20 to 24 micrograms/ml) that have shown antiviral activity in vitro against more sensitive clinical isolates of human immunodeficiency virus were achieved. The peak concentrations in serum after intramuscular administration were below these levels. Treatment with rCD4-IgG was well tolerated at the doses administered to patients in this study but did not result in significant changes in CD4 lymphocyte counts or p24 antigen levels in serum.

Pharmacokinetics of GLQ223 in rats, monkeys, and patients with AIDS or AIDS-related complex

The pharmacokinetics of GLQ223 administered as a single short intravenous infusion to rats, monkeys, and patients with AIDS or AIDS-related complex (ARC) are presented. GLQ223 was given at a dose of 3,500 micrograms/kg of body weight to five Sprague-Dawley rats; a dose of 300 micrograms/kg was given to three cynomolgus monkeys; and doses of 1, 8, 16, 24, and 36 micrograms/kg were given to 10 patients with AIDS and 8 patients with ARC in an escalating dose design. Plasma clearance was 0.85 +/- 0.24 liter/h/kg in rats, 0.16 +/- 0.08 liter/h/kg in monkeys, and 0.13 +/- 0.07 liter/h/kg in patients with AIDS or ARC. The volume of distribution at steady state was 0.42 +/- 0.12, 0.21 +/- 0.20, and 0.18 +/- 0.50 liter/kg in rats, monkeys, and patients, respectively. The elimination half-life was 1.3 +/- 0.4, 3.7 +/- 1.5, and 3.2 +/- 1.0 h in rats, monkeys, and patients, respectively. The disposition of GLQ223 was not dose dependent within the dose range tested in patients with AIDS or ARC. Interspecies pharmacokinetic scaling resulted in a good linear correlation for plasma clearance and the volume of distribution at steady state plotted versus species body weight on a log-log scale, indicating the predictability of elimination and distribution of GLQ223 among species. Allometric equations derived may be useful for the prediction of doses and dosage regimens to be used in animal models.

Periodontal status of individuals in early stages of human immunodeficiency virus infection

The purpose of this study was to evaluate the association of periodontal health and human immunodeficiency virus infection among individuals in the early stages of disease who were participating in randomized placebo-controlled clinical trials of zidovudine. Previous reports have described a rapidly progressive periodontitis and atypical gigivitis associated with late stages of infection by the human immunodeficiency virus. A health history was completed by each subject. Baseline oral examinations were completed on 97 asymptomatic patients and nine with AIDS-related complex (ARC) during their regular clinic visit. Follow-up examinations were conducted at 3-month intervals throughout the 48 weeks of the oral study. Evaluations of plaque, calculus, gingival abnormalities, caries, and periodontal disease were conducted. Periodontal measurements included plaque index (PI), gingival index (GI), bleeding index (BI), probing depth (PD), and observation for cratering, necrosis, and tooth mobility on six teeth in each patient. More than half of the subjects had visited their dentist during the previous year and had had an oral prophylaxis; less than 25% of them had had either restorative work or extractions. The mean scores for periodontal indices averaged over the course of the study in asymptomatic and ARC respectively were: PI: 0.9 (SE 0.04) and 0.9 (SE 0.08), 0.818; GI: 1.0 (SE 0.04) and 0.9 (SE 0.07), P = 0.412; BI: 0.6 (SE 0.04) and 0.4 (SE 0.07), P = 0.278; PD: 2.9 (SE 0.05) and 2.6 (SE 0.10), P = 0.140. There was no evidence of cratering, necrosis, or tooth mobility in either group. Few had calculus or dental caries. There were no clinically significant differences detected between ARC versus asymptomatic patients. Dental histories and oral examinations showed that two groups of patients in early stages of HIV-disease were in good periodontal health.

Drug level monitoring in a double-blind multicenter trial: false-positive zidovudine measurements in AIDS clinical trials group protocol 019

Twenty-three different laboratories using four different assay methods reported zidovudine (ZDV; azidothymidine) measurements in a double-blind trial of ZDV for asymptomatic human immunodeficiency virus-infected patients (AIDS Clinical Trials Group Protocol 019). The risk of false-positive ZDV measurements was defined with coded specimens containing no ZDV in a quality control testing program. This testing identified six problem laboratories which reported ZDV levels of greater than or equal to 100 ng/ml for specimens with no ZDV; all of these laboratories used high-performance liquid chromatography. These six laboratories reported a disproportionately high fraction of positive assays for subjects randomized to the placebo group (31% for these 6 laboratories versus 4% for the other 17 laboratories; P less than 0.0001). The high number of false-positive ZDV results reported by these six laboratories suggested that many of the positive results that they reported for patient specimens were also false-positive results. This hypothesis was examined by retesting specimens from patients in the placebo group that had been reported as positive by these laboratories. Ninety percent (19 of 21) of these specimens were negative on retesting at the reference laboratory. These results confirm the hypothesis; they demonstrate the need for quality control testing to avoid the misinterpretation of multicenter trials because of incorrect laboratory data.

Clinical and virologic effects of recombinant human granulocyte-macrophage colony-stimulating factor in patients receiving chemotherapy for human immunodeficiency virus-associated non-Hodgkin's lymphoma: results of a randomized trial

Thirty patients with human immunodeficiency virus (HIV)-associated non-Hodgkin's lymphoma (NHL) receiving chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) were randomized to receive either subcutaneous recombinant human granulocyte-macrophage colony-stimulating factor (rGM-CSF) or no additional therapy. Recombinant rGM-CSF (at a dose of 10-20 micrograms/kg/d) was given on days 1 to 10 (early rGM-CSF) to the first five patients, but was changed to days 4 to 13 (delayed rGM-CSF) of each chemotherapy cycle in subsequent patients. Compared with the control group (N = 10), the delayed rGM-CSF group (N = 11) had higher mean nadirs of the absolute neutrophil count (0.36 v 0.89 x 10(9)/L; P = .009), shorter mean durations of neutropenia (4.9 v 1.3 days; P = .02), fewer chemotherapy cycles complicated by neutropenia and fever (67% v 27%; P = .001), fewer days hospitalized for fever and neutropenia (4.9 v 1.8; P = .004), fewer reductions in chemotherapy dosages, and less frequent delays in chemotherapy administration. No significant differences were observed between patients in the control group and those in the early rGM-CSF group (N = 5). Median levels of serum HIV-1 p24 antigen decreased to 18% and 17% of baseline values in control (N = 4) and rGM-CSF groups (N = 6), respectively, 1 week following administration of the first cycle of chemotherapy. In the third week after chemotherapy, median antigen levels remained below baseline in the control group, but rose to 243% of baseline values in the rGM-CSF group (P = .01), suggesting stimulation of HIV replication. The effect of this change in HIV activity on clinical outcome of treated patients could not be determined, and therefore the clinical significance of this finding remains unclear. Complete response rates of 67%, 70%, and 60% were observed in the control, delayed rGM-CSF, and early rGM-CSF groups, respectively, with corresponding survival times of 9.0, 11.4, and 8.0 months.

Treatment of AIDS-related Kaposi's sarcoma

Kaposi's sarcoma (KS) is the most common malignancy seen in association with AIDS. Important epidemiologic trends in the occurrence of AIDS-associated Kaposi's sarcoma (AIDS-KS) have been identified, and the molecular processes associated with the development of KS are being studied intensively. It is hoped that these studies will ultimately lead to an understanding of the etiology of the disease and to a rational approach to therapy. Treatment with conventional chemotherapy, radiation therapy, biologic therapy, and various local treatment modalities is effective for palliation of clinical problems associated with AIDS-KS, although the toxicities of these approaches may be problematic. Therapy for AIDS-KS must be individualized, with appropriate consideration given to the patient's overall clinical and immunologic status.

Interferon-alpha 2a in the treatment of acquired immunodeficiency syndrome-related Kaposi's sarcoma

In a series of studies, recombinant interferon-alpha 2a (rIFN alpha 2a, Roferon-A) was administered alone (273 men) or combined with vinblastine (91 men) to patients with acquired immunodeficiency syndrome (AIDS)-related Kaposi's sarcoma (KS). Patients were treated with daily doses of rIFN alpha 2a ranging from 3 to 54 million international units (I.U.) administered intramuscularly. A dose of 36 million I.U. daily for approximately 10 weeks followed by a three times weekly maintenance schedule with the same dose resulted in the best overall therapeutic benefit. An escalating-dose regimen of 3, 9, and 18 million I.U. daily, each for 3 days, followed by 36 million I.U. daily, produced equivalent therapeutic benefit with amelioration of acute toxicity in some patients. Response was more likely in patients without a history of opportunistic infection or B symptoms (fever, night sweats, or weight loss). Response rate increased with increasing baseline CD4 lymphocyte count and was 45.5% in patients with a CD4 count of greater than 400/mm3. Responding patients with a CD4 count of greater than 200/mm3 had a distinct survival advantage over patients who had similar CD4 counts but whose tumors did not regress with therapy. The addition of vinblastine increased toxicity and did not improve the response rate or prolong survival. Side effects included fatigue, fever, chills, myalgias, headaches, anorexia, nausea, diarrhea, and dizziness. Mild abnormalities in hematologic and liver function tests occurred in some patients. Most adverse effects diminished or resolved with continued therapy. We conclude that rIFN alpha 2a offers important therapeutic benefit in a select group of patients with AIDS-related KS.

Controversies in the management of HIV-related illnesses

The care of patients who have HIV infection requires technical competence, skill in clinical decision making, a commitment to continuing self-education, the ability to collaborate with medical and community-based service providers, and attention to the psychological and ethical aspects of patient care. General internists bring these attributes to their work and will be increasingly involved in meeting the challenges presented by the AIDS epidemic. Controversial issues in the management of HIV illness include: assessment and management of latent syphilis in patients with intercurrent HIV infection; risk assessment and postexposure zidovudine prophylaxis of health care workers after occupational accidents; determination of the risk of reactivation tuberculosis in HIV-infected individuals; and treatment or nontreatment of infections with the Mycobacterium avium complex in symptomatic patients. Patients illustrating these management problems are presented by progressive disclosure; the points made in discussion by a panel of general internists and AIDS specialists are presented.

Recent advances in the medical management of early HIV disease

The management of patients who have HIV disease, particularly those in early, asymptomatic disease stages, has recently improved. Clinical trials with zidovudine have demonstrated efficacy and greatly reduced toxicity when the drug is used for asymptomatic HIV-infected persons who have fewer than 500 CD4+ cells/mm3. Also, the optimum dose of zidovudine is lower than previously believed, probably in the range of 300-500 mg daily in oral divided doses. The use of antibiotics to prevent Pneumocystis carinii pneumonia (PCP) is also of clear value for HIV-infected asymptomatic or symptomatic persons with fewer than 200 CD4+ cells/mm3. While aerosolized pentamidine is the only regimen approved for PCP prophylaxis, oral drugs, such as trimethoprim/sulfamethoxazole or dapsone, also appear effective. Together, these and similar advances argue for the widespread use of voluntary HIV testing to enable optimum medical monitoring and appropriate intervention. These issues and recommendations for laboratory and clinical monitoring are provided in this review.

The safety and pharmacokinetics of GLQ223 in subjects with AIDS and AIDS-related complex: a phase I study

A phase I dose-escalation study was performed to evaluate the safety and pharmacokinetics of a single intravenous infusion of GLQ223 in subjects with AIDS and AIDS-related complex (ARC). The active ingredient in GLQ223 is trichosanthin. Trichosanthin, imported from China, is the active drug in community-initiated treatment programs for patients with HIV infection. Eighteen subjects were enrolled, 10 with AIDS and eight with ARC. All subjects were monitored for tolerance and toxicity. Immunological and virological parameters were also followed. GLQ223 administration was not associated with notable toxicity with the exception of one subject who experienced a severe neurological adverse reaction. No consistent or sustained changes in CD4+ lymphocyte populations or HIV antigen levels were observed. Serum concentrations of GLQ223 that were comparable to concentrations shown to have antiviral activity in vitro were achieved transiently but may not have been maintained for a sufficient duration to exert antiretroviral effects. Further studies are indicated to determine pharmacodynamic properties of GLQ223, its optimal dosing schedule, and whether GLQ223 or related molecules will be useful in the treatment of HIV infection.

Aerosolized pentamidine for prophylaxis against Pneumocystis carinii pneumonia. The San Francisco community prophylaxis trial

BACKGROUND AND METHODS

Pneumocystis carinii pneumonia (PCP) is the most frequent life-threatening opportunistic infection associated with human immunodeficiency virus (HIV) infection. To assess the possible value of aerosolized-pentamidine prophylaxis in different doses, a controlled clinical trial was begun in 1987 with 408 subjects at 12 treatment centers. The participants were randomly assigned to receive 30 mg of pentamidine every two weeks, 150 mg every two weeks, or 300 mg every four weeks.

RESULTS

Eighteen months after randomization, the subjects in the 300-mg arm had had 8 confirmed episodes of PCP while receiving treatment, as compared with 22 in the 30-mg arm (P = 0.0008). The 150-mg arm had intermediate results but ones not significantly different from those of the 300-mg arm. Participants with previous episodes of PCP and CD4-cell counts less than 200 per cubic millimeter were at the highest risk for PCP.

CONCLUSIONS

Aerosolized pentamidine was effective for prophylaxis against PCP in patients infected with HIV, according to the dose and schedule of administration. It and zidovudine were well tolerated together and had independent prophylactic benefits.

Zidovudine in asymptomatic human immunodeficiency virus infection. A controlled trial in persons with fewer than 500 CD4-positive cells per cubic millimeter. The AIDS Clinical Trials Group of the National Institute of Allergy and Infectious Diseases

Zidovudine (AZT) is a potent inhibitor of the replication of the human immunodeficiency virus (HIV), and it has been shown to improve survival in advanced HIV disease. We conducted a randomized, double-blind trial in adults with asymptomatic HIV infection who had CD4+ cell counts of fewer than 500 per cubic millimeter on entry into the study. The subjects (92 percent male) were randomly assigned to one of three treatment groups: placebo (428 subjects); zidovudine, 500 mg per day (453); or zidovudine, 1500 mg per day (457). After a mean follow-up of 55 weeks (range, 19 to 107), 33 of the subjects assigned to placebo had the acquired immunodeficiency syndrome (AIDS), as compared with 11 of those assigned to receive 500 mg of zidovudine (P = 0.002; relative risk, 2.8; 95 percent confidence interval, 1.4 to 5.6) and 14 of those assigned to receive 1500 mg of zidovudine (P = 0.05; relative risk, 1.9; 95 percent confidence interval, 1.0 to 3.5). In the three treatment groups, the rates of progression (per 100 person-years) to either AIDS or advanced AIDS-related complex were 7.6, 3.6, and 4.3, respectively. As compared with those assigned to placebo, the subjects in the zidovudine groups had significant increases in the number of CD4+ cells and significant declines in p24 antigen levels. In the 1500-mg zidovudine group, severe hematologic toxicity (anemia or neutropenia) was more frequent than in the other groups (P less than 0.0001). In the 500-mg zidovudine group, nausea was the only toxicity that was significantly more frequent (in 3.3 percent) than in the placebo group (P = 0.001). We conclude that zidovudine is safe and effective in persons with asymptomatic HIV infection and fewer than 500 CD4+ cells per cubic millimeter. Additional study will be required to determine whether such treatment will ultimately improve survival for persons infected with HIV.