Differences in hepatitis C virus prevalence and clearance by mode of acquisition among men who have sex with men.

We examined the characteristics associated with hepatitis C virus (HCV) antibody (anti-HCV) prevalence and HCV clearance between injection drug using (IDU) and non-IDU men who have sex with men (MSM). Stored serum and plasma samples were tested for anti-HCV and HCV RNA to determine the HCV status of 6925 MSM at enrolment into the Multicentre AIDS Cohort Study (MACS). Prevalence and clearance ratios were calculated to determine the characteristics associated with HCV prevalence and clearance. Multivariable analyses were performed using Poisson regression methods with robust variance estimation. Anti-HCV prevalence was significantly higher among IDU than among non-IDU MSM (42.9% vs 4.0%), while clearance was significantly lower among IDU MSM (11.5% vs 34.5% among non-IDU MSM). HIV infection, Black race, and older age were independently associated with higher prevalence in both groups, while smoking, transfusion history, and syphilis were significantly associated with prevalence only among non-IDU MSM. The rs12979860-C/C genotype was the only characteristic independently associated with HCV clearance in both groups, but the effects of both rs12979860-C/C genotype [clearance ratio (CR) = 4.16 IDUs vs 1.71 non-IDUs; P = 0.03] and HBsAg positivity (CR = 5.06 IDUs vs 1.62 non-IDUs; P = 0.03) were significantly larger among IDU MSM. HIV infection was independently associated with lower HCV clearance only among non-IDU MSM (CR = 0.59, 95% CI = 0.40-0.87). IDU MSM have higher anti-HCV prevalence and lower HCV clearance than non-IDU MSM. Differences in the factors associated with HCV clearance suggest that the mechanisms driving the response to HCV may differ according to the mode of acquisition.

Higher risk of AIDS or death in patients with lower CD4 cell counts after virally suppressive HAART.

BACKGROUND: The clinical implications of a failure to achieve high CD4 cell counts while receiving virally suppressive highly active antiretroviral therapy (HAART) are uncertain. METHODS: We analysed data from HIV-infected men participating in the Multicenter AIDS Cohort Study (MACS) to elucidate associations between CD4 cell counts achieved during virally suppressive HAART and risks of AIDS or death. Inclusion criteria were: CD4 cell count <200 cells/microL before HAART initiation; >or=2 viral load (VL) determinations after HAART initiation; and sustained viral suppression, defined as all VL <50 HIV-1 RNA copies/mL, but allowing a single VL of 50-1000 copies/mL. RESULTS: One hundred and twenty-one men were included; median age was 42 years. After first VL <50 copies/mL, six participants had a new AIDS diagnosis and seven died. The median CD4 cell count change/year (cells/microL) after first VL <50 copies/mL was zero among patients who either developed AIDS or died vs. 39 among those who did not meet either endpoint (P=0.119). After controlling for time from HAART initiation to first VL <50 copies/mL, age at first VL <50 copies/mL, history of AIDS and antiretroviral therapy (ART) experience before HAART, the hazard ratio for AIDS or death at CD4 cell count of 350 cells/microL was 10.7 (P=0.013), and at CD4 cell count of 201-350 vs. >350 cells/microL was 8.54 (P=0.014). CONCLUSION: In this cohort, lower CD4 cell count at the time of viral suppression was associated with increased risk of AIDS or death.

Antibiotic levels in pericardial fluid.

An experimental model was designed to study the ability of antibiotics to enter the pericardial compartment. Noninfected and infected pericardial fluid and serum antibiotic activities were determined in adult mongrel dogs before and at intervals after antibiotic administration. After the administration of penicillin G, methicillin, cephaloridine, streptomycin, or gentamicin, clinically adequate antibiotic levels in the noninfected pericardial fluid were obtained within 1 h, and these levels approached or exceeded the serum levels within 2-4 h. Antibiotic levels obtained from infected dog pericardial fluids were higher than those from noninfected animals. Patients' serum and pericardial fluid antibiotic levels were measured after penicillin G, penicillin V, cephalothin, and gentamicin administration. We have found, both in the canine and human studies, that pericardial antibiotic levels taken at least 2 h after antibiotic administration are almost identical to those in the blood.

Bacteremic pneumonia due to gram-negative bacilli.

Bacteremic pneumonia due to aerobic gram-negative bacilli was diagnosed in 27 patients during a 20-month period. The mortality was high (81.5%) among these elderly patients (mean age, 61.2 years) with serious underlying disease, in spite of amikacin sulfate therapy that was appropriate as determined by susceptibility testing. Bacteremic pneumonia accounted for 14.1% of patients with gram-negative bacteremia but was responsible for 39.4% of the deaths in the total group of 191 patients. The worsened prognosis of patients with pneumonia was unrelated to the species of infecting organisms or the underlying conditions or disease.

Recombinant human erythropoietin treatment: investigational new drug protocol for the anemia of the acquired immunodeficiency syndrome. Overall results.

BACKGROUND: Anemia associated with human immunodeficiency virus infection may be due to reduced erythropoiesis related to the disease itself or to concomitant medications (eg, zidovudine). Clinical studies have shown recombinant human erythropoietin (r-HuEPO) to be effective in correcting the anemia of zidovudine-treated patients infected with human immunodeficiency virus with baseline serum erythropoietin levels of 500 U/L or less. A treatment investigational new drug protocol that provided r-HuEPO to 1943 anemic patients with the acquired immunodeficiency syndrome was studied. METHODS: Enrollment criteria included a clinical diagnosis of acquired immunodeficiency syndrome, serum erythropoietin level of 500 U/L or less, hematocrit less than 0.300, and age of 12 years or more. The initial r-HuEPO dosage was 4000 U subcutaneously for 6 days each week. On the basis of response, the r-HuEPO dosage could be increased sequentially to 8000 U subcutaneously for 6 days per week. This was an open-label multicenter treatment protocol. A total of 1943 patients were treated by 510 investigators. Efficacy evaluations were based on the effect of r-HuEPO on hematocrit levels and transfusion requirements relative to baseline. Adverse experiences that were considered by the investigator to be possibly related to r-HuEPO therapy were collected to assess safety. RESULTS: Therapy with r-HuEPO resulted in an increase in mean hematocrit from a baseline of 0.280 to 0.331 at week 12 and 0.338 at week 24. This increase was sustained throughout the course of the study to week 54. Overall, 40% of patients (769/1943) required at least one transfusion in the 6-week interval immediately preceding study entry (baseline). After 12 and 24 weeks of r-HuEPO treatment, corresponding percentages were 22% (311/1387) and 18% (119/650), respectively. Response to therapy, defined as an increase of 0.060 from baseline in hematocrit, with no transfusions within 28 days before achieving that hematocrit, was observed in 44% of patients. Adverse experiences not clearly related to acquired immunodeficiency syndrome were reported by 11% of patients. CONCLUSION: In a study population of 1943 anemic patients with acquired immunodeficiency syndrome treated with r-HuEPO, the hematocrit increased and blood transfusion requirements decreased. Therapy with r-HuEPO was well tolerated.

Herpes simplex virus associated with recurrent Stevens-Johnson syndrome. A management strategy.

We describe a 36-year-old man with recurrent Stevens-Johnson syndrome, which became progressively more severe over a 13-year period. His episodes were apparently preceded by herpes simplex virus oral mucosal infections. A management protocol, including immediate therapy with acyclovir and prednisone at the onset of herpes simplex virus oropharyngitis, is outlined. This management strategy has successfully prevented four subsequent episodes of progression to Stevens-Johnson syndrome. Thus, Stevens-Johnson syndrome associated with herpes simplex virus may be prevented by early use of acyclovir and prednisone.

Acquired immunodeficiency syndrome in a patient with multiple risk factors.

To our knowledge, we report the first case of a homosexually active man with severe hemophilia A in whom acquired immunodeficiency syndrome (AIDS) developed. Alterations in cell-mediated immunoregulation and development of AIDS have been described in both healthy homosexually active men and heterosexual men with hemophilia A. Patients with multiple risks may be more likely to have AIDS develop. Physicians should be aware of the risk factors associated with AIDS; persons with multiple predisposing factors require intensive examination and close follow-up.

Infective endocarditis in a community hospital.

Recent reviews from major university centers of infective endocarditis have stressed an increase in unusual infections owing to virulent pathogens. This article compares the 40 episodes of infective endocarditis at a community hospital complex with the recent literature. It was observed that the majority of infecting microorganisms were penicillin-susceptible streptococci similar to those seen in the early antibiotic era. An older patient population was encountered, but overall mortality was low. Streptococcus bovis was a frequent cause of both natural and prosthetic valve infections. Symptoms lasting longer than two months were associated with vegetations demonstrated by echocardiography and high morbidity. Clinical features in this series that significantly correlated with a poor prognosis were height of fever at admission, the failure of fever to resolve within one week of appropriate therapy, the degree of peripheral leukocytosis, gross hematuria, and CNS signs. Conservative parenteral treatment closely monitored by serum bactericidal levels was employed. No relapses occurred among patients surviving initial therapy.

Sequential clinical and immunologic abnormalities in hemophiliacs.

We examined 35 patients with hemophilia to determine if there was an association between impaired cell-mediated immunity and the amount of factor concentrate use. There was a significant negative relationship between the logarithm of the helper-suppressor ratio and the logarithm of concentrate use determined over the previous one year, five years, and total lifetime. Similarly, the presence of splenomegaly was significantly associated with the logarithm of concentrate use for each time interval. Hypergammaglobulinemia, anergy, and lymphadenopathy were present in a high proportion of patients. Repeated study of 30 of these patients at eight to 14 months showed no significant changes in their T-cell subsets. At follow-up, 16 patients had lymphadenopathy with or without splenomegaly and four had splenomegaly alone. No significant associations between concentrate use during the study period and changes in T-cell subsets or clinical condition were found.

Absence of a clinical correlation for complement-mediated, infection-enhancing antibodies in plasma or sera from HIV-1-infected individuals. Multicenter AIDS Cohort Study Group.

Neutralizing and complement-mediated infection-enhancing antibodies to HIV-1 were measured in sera or plasma from 54 HIV-1-positive individuals at various stages of disease, and from an additional 36 HIV-1-positive individuals for whom no clinical data were available. Antibodies were measured in microtiter infection assays utilizing MT-2 cells and the IIIB strain of HIV-1. The frequency of detection of both types of antibodies was identical, being 77 out of 90 cases (86%). Neutralizing and infection-enhancing antibodies were not always found together, and in four cases both were undetectable. No correlation was found between titers of either type of antibody and stage of disease. Furthermore, titers of infection-enhancing antibodies at early stages of disease did not predict rate of disease progression.

Effectiveness of potent antiretroviral therapies on the incidence of opportunistic infections before and after AIDS diagnosis.

OBJECTIVES: To determine the effectiveness of potent antiretroviral therapy in reducing opportunistic infections (OI) as both a presenting event and subsequent to an AIDS-defining event. DESIGN AND METHODS: A total of 543 seroconverters and 1470 men with AIDS were compared for the time to development of OI as the presenting AIDS event and as a subsequent event in the 1984-1989, 1990-1992, 1993-1995, and 1996-1998 periods, when the major treatments were no therapy, monotherapy, combination therapy, and potent antiretroviral therapy, respectively. RESULTS: The seroconverters suffered 132 OI and the participants with AIDS had 717 OI. The relative hazard (RH) of OI as the presenting AIDS event declined by 81% in the calendar period when potent antiretroviral therapy was available compared with the monotherapy period. Declines were observed for Mycobacterium avium complex, cytomegalovirus disease, and esophageal candidiasis, but were statistically significant only for Pneumocystis carinii pneumonia. The RH of OI as a secondary infection dropped by 77% in the last calendar period compared with the monotherapy period. A significant decline was observed for all four OI. Prophylactic drug use did not increase in the era of potent antiretroviral therapy. CONCLUSION: The hazard of OI in the era of potent antiretroviral therapy has declined dramatically compared with the era of monotherapy, despite the concurrent decrease in the use of prophylactic drugs. Physicians should consider whether it is necessary to include prophylactic drugs as part of the complex drug regimen for patients on potent antiretroviral therapy.

Clinical manifestations of acute infection with human immunodeficiency virus in a cohort of gay men.

During a prospective study of the natural history of human immunodeficiency virus (HIV) infection in a cohort of gay/bisexual men, information on self-reported symptoms lasting for 3 or more days during the previous 6 months was collected without knowledge of the subject's HIV serological status. Twenty-two people were retrospectively found to have seroconverted to HIV during the interval. Each seroconverter was matched to two seronegative and two seropositive controls. Matched case-control analyses using the seronegative controls determined that the following symptoms lasting for 3 or more days were associated with new HIV infection: fever greater than 37.7 degrees C, swollen lymph nodes, night sweats and headaches. Matched case-control analyses using the seropositive controls determined that the following symptoms lasting for 3 or more days were associated with new HIV infection: fatigue, fever greater than 37.7 degrees C, swollen lymph nodes, night sweats and headaches. It was notable that the majority of seroconversions were not associated with any symptoms lasting for 3 or more days. Due to their non-specificity, symptoms associated with seroconversion are not likely to have a high positive predictive value. In high risk populations, however, appearance of these symptoms may facilitate identification of early infection that may be important for studies of natural history or for optimal timing for initiating antiviral therapy.

Prognostic value of plasma HIV RNA in the natural history of Pneumocystis carinii pneumonia, cytomegalovirus and Mycobacterium avium complex. Multicenter AIDS Cohort Study.

OBJECTIVES: To use follow-up on untreated HIV-positive men to assess the prognostic information provided by baseline data on plasma HIV RNA, CD4 cell count, age, and HIV-related symptom status, separately for three specific AIDS-defining illnesses: Pneumocystis carinii pneumonia (PCP), cytomegalovirus (CMV), and Mycobacterium avium complex (MAC). METHODS: The study population were 734 HIV-positive homosexual men enrolled in the Multicenter AIDS Cohort Study, with follow-up (1984-1985 through mid-1988) restricted to the antiretroviral treatment-free and prophylaxis-free era. Baseline marker values were categorized and assessed as predictor variables in separate time-to-event analyses for each of the three specific outcomes. RESULTS: A total of 138 cases of PCP, 25 cases of CMV, and 25 cases of MAC were observed. For PCP and CMV, higher categories of HIV RNA and lower categories of CD4 cell count were associated with increased risk relative to the respective reference groups. For MAC, oral candidiasis or fever and elevated HIV RNA at baseline were the primary risk factors. Further analysis highlighted the importance of monitoring HIV RNA levels in addition to CD4 cell counts when evaluating patients' risk of developing PCP. CONCLUSIONS: In the absence of treatment, plasma HIV RNA levels provide prognostic information about the risk of these three specific AIDS-defining illnesses, independently of the CD4 cell count. These data provide a useful reference as researchers investigate changing patterns in the incidence and predictors of opportunistic infections in the era of increasingly active antiretroviral therapies.

Immunologic and virologic response to highly active antiretroviral therapy in the Multicenter AIDS Cohort Study.

OBJECTIVES: To evaluate prior antiretroviral therapy experience and host characteristics as determinants of immunologic and virologic response to highly active antiretroviral therapy (HAART). METHODS: We studied 397 men from the Multicenter AIDS Cohort Study (MACS) who initiated HAART between October 1995 and March 1999. CD4 cell count and HIV-1 RNA responses to HAART were measured at the first visit following HAART (short-term) and extending from the first visit to approximately 33 months after HAART (long-term). Prior antiretroviral experience was classified into three groups based on antiretroviral therapy use during the 5 years prior to HAART. Age, race and host genetic characteristics also were assessed for their effects on treatment response. RESULTS: Better short- and long-term CD4 cell and HIV-1 RNA responses were observed in the treatment-naive users. Intermittently and consistently experienced users did not significantly differ in response. Whereas race did not independently affect response, among those initiating HAART with > 400 x 10(6) CD4 cells/l, younger age and the Delta32 CCR5 genotype were associated with a better short-term CD4 cell response. There was a suggestion that having the protective CCR5 genotype also was associated with a better long-term CD4 cell response. CONCLUSION: Immunologic and virologic response to HAART was stronger in individuals who had no prior experience with the antiretroviral therapy agents subsequently included in their initial HAART regimen. Age, level of immune competence and immunogenetics appeared to play a role in the subsequent immune reconstitution following use of highly effective HIV therapy.

The predictive value of changes in serologic and cell markers of HIV activity for subsequent clinical outcome in patients with asymptomatic HIV disease treated with zidovudine.

OBJECTIVE: To determine if serologic marker responses to zidovudine treatment during the first year of antiretroviral therapy could predict subsequent HIV disease progression independently of absolute CD4 lymphocyte responses. METHODS: We conducted a case-control study in patients with asymptomatic HIV disease, who were initiating zidovudine therapy in a randomized, prospective trial. A total of 102 patients who progressed to AIDS or advanced AIDS-related complex and 177 randomly selected controls matched by baseline CD4 cell count and duration of follow-up had serum samples (from prior to and at 8, 16, 32 and 48 weeks of zidovudine treatment) assayed for acid-disassociated HIV p24 antigen, beta 2-microglobulin (beta 2M), neopterin, soluble interleukin (IL)-2 receptor, soluble CD4 protein and soluble CD8 protein. RESULTS: Median time to event for cases was 20.2 months; median follow-up on study was 35.4 months for controls. After controlling for absolute CD4 count at baseline, increased baseline serum concentrations of HIV p24 antigen, beta 2M, neopterin, and soluble IL-2 receptor were highly predictive of increased risk of HIV disease progression. In a multiple logistic regression model, controlling for baseline marker values, change in beta 2M consistently added independent value to change in CD4 count in predicting subsequent risk of disease progression. CONCLUSIONS: Monitoring serum immunologic markers, in particular beta 2M, in addition to absolute CD4 lymphocyte counts prior to and within the first 4 months after initiating dideoxynucleoside therapy can increase the accuracy of estimations of subsequent long-term risk of clinical HIV disease progression. This information may be useful to clinicians and patients who are making decisions about initiating or changing antiretroviral therapy.

Association of HLA profiles with early plasma viral load, CD4+ cell count and rate of progression to AIDS following acute HIV-1 infection. Multicenter AIDS Cohort Study.

BACKGROUND: Host genetic factors, such as HLA alleles, play an important role in mediating the course of HIV-1 disease progression through largely undefined mechanisms. OBJECTIVES: To examine the association of HLA markers with HIV-1 RNA plasma viral load and other factors associated with course of disease progression in HIV-1 infection. DESIGN AND METHODS: A group of 139 HIV-1 seroconverters from the Multicenter AIDS Cohort Study had been typed for a variety of HLA markers. HIV-1 RNA plasma viral load was measured from frozen plasma specimens obtained approximately 9 months following seroconversion. CD4+ cell counts were available from the same study visit. Statistical analysis was performed using survival techniques and linear regression models to quantify the relative associations of an HLA score profile, HIV-1 RNA plasma viral load, CD4+ cell count and age with each other and with rate of progression to AIDS and death. RESULTS: Cox proportional hazards models showed statistically significant differences in time to AIDS by HLA score profile category per unit increase [relative hazard (RH), 0.64; P < 0.0001], HIV-1 RNA plasma viral load per 10-fold increase (RH, 2.04; P = 0.0003), and CD4+ cell count per 100 cell (x 10(6)/l) increase (RH, 0.90; P = 0.02). Multivariate linear regression showed that viral load was 39% lower (P = 0.0001) for each unit increase in HLA score profile and 13% lower (P = 0.002) for each 100 cell (x 10(6)/l) increase in CD4+ cell count. CONCLUSION: The means by which the HLA score profile influences the time to AIDS is probably through immunologic responses that affect the rate of HIV-1 replication, as manifested by the HIV-1 RNA plasma viral load during the first 6-12 months following acute infection.

Prevalence of Toxoplasma infection in a cohort of homosexual men at risk of AIDS and toxoplasmic encephalitis.

The purpose of this study was to characterize the epidemiologic, clinical, and laboratory parameters of a cohort of men at risk of AIDS-associated toxoplasmic encephalitis. One hundred seventeen (11%) of the 1,073 participants at the time of enrollment into the Chicago Multicenter AIDS Cohort Study (MACS) were seropositive for Toxoplasma antibodies. Significant differences in prevalence of antibodies between African-American, Hispanic, or white men were not observed (p = 0.49). One hundred one (86%) of the 117 antibody-positive participants had at least one follow-up serology performed and 6 (6%) of the 101 had a significant rise in IgG antibody titer on subsequent visits. Five of six participants with a significant rise in titer were also seropositive for HIV-1 at entry or seroconverted during the study. A trend toward higher IgG Toxoplasma titers and prevalence of IgM antibodies in participants seropositive for HIV-1 was observed, but the differences did not reach statistical significance. There was no evidence that the presence of Toxoplasma infection predisposed to development of CD4+ depletion or AIDS. None of the 183 individuals in the cohort who developed AIDS and who were seronegative for Toxoplasma antibodies developed toxoplasmic encephalitis. In contrast, of the 13 persons who developed AIDS and who were positive for Toxoplasma antibodies, 5 (38%) developed toxoplasmic encephalitis. Prevalence of Toxoplasma antibodies in the MACS population was independent of HIV-1 serostatus. Toxoplasma infection does not appear to predispose to progression of HIV-1 infection. The risk of development of toxoplasmic encephalitis in persons with AIDS and chronic Toxoplasma infection may have been underestimated by previous retrospective studies.

Factors influencing survival after AIDS: report from the Multicenter AIDS Cohort Study (MACS).

The objective of this study was to determine if clinical signs, symptoms, laboratory variables, and use of therapeutic or prophylactic agents have prognostic associations with survival after diagnosis of clinical AIDS. A total of 2,168 homosexual men, seropositive for human immunodeficiency virus type 1 (HIV-1) participated in a longitudinal cohort study of the greater metropolitan areas of Baltimore, Maryland, Washington, D.C., Chicago, Illinois, Pittsburgh, Pennsylvania, and Los Angeles, California, U.S.A.--the Multicenter AIDS Cohort Study (MACS). Variables within 6 months prior to AIDS diagnosis included age, CD4+ lymphocyte counts, hemoglobin, and self-reported thrush, fever, anti-retroviral therapy (ART) beginning prior to AIDS onset, and ART beginning after AIDS (as a time-dependent covariate) were analyzed as mutually exclusive categories, as was prophylaxis for Pneumocystis carinii pneumonia (PCP). Univariate and multivariate survival models of time from AIDS to death were fit. In univariate analysis, younger age, higher counts of CD4+ lymphocytes, hemoglobin, and absence of thrush or fever prior to AIDS onset were associated with longer survival after AIDS. Those who began ART within 3 months after AIDS onset had longer median survival (1.75 years), from 3 months after AIDS, when compared with those who began ART prior to AIDS (1.18 years). This comparison is not influenced by the bias that those who survive longer have a greater likelihood to subsequently receive ART. Prophylaxis for PCP beginning after AIDS onset was also associated with longer post-AIDS survival when compared with beginning prophylaxis prior to AIDS or never using prophylaxis.(ABSTRACT TRUNCATED AT 250 WORDS)

Thrush and fever as measures of immunocompetence in HIV-1-infected men.

The occurrence of Pneumocystis carinii pneumonia (PCP) in human immunodeficiency virus type 1 (HIV-1)-infected individuals with high CD4+ counts indicates poor immunologic function. Thrush and persistent fever, easily recognized clinically, are potential measures of immunocompetence. This analysis establishes the complex interactions of CD4+ count, thrush, and persistent fever to predict the occurrence of PCP. Analyses used 20,632 person visits from 2,568 HIV-1-seropositive homosexual or bisexual men participating in the Multicenter AIDS Cohort Study (MACS). Comprehensive examinations were conducted semiannually, while occurrences of PCP were assessed continuously. The occurrence of thrush and fever increase in frequency as CD4+ levels decrease. The relative hazard of PCP in the presence of thrush compared with the absence of thrush rises (p < 0.05) from 1 for the lowest CD4+ category to approximately 5 in the highest categories. The relative hazard of PCP in the presence of fever compared with the absence of fever is above one (p < 0.05) in all CD4+ categories. No cases of PCP occurred in individuals on PCP prophylaxis with CD4+ counts > 200/mm3. These results suggest that HIV-1-related symptoms provide a measure of failing immune function that is not reflected by enumeration of CD4+ lymphocytes alone and support the United States Public Health Service recommendation that symptomatic individuals with CD4+ counts > 200/mm3 should be considered for PCP prophylaxis.

CD4+ lymphocyte response to zidovudine as a predictor of AIDS-free time and survival time.

It is unknown whether the early rise in CD4+ lymphocyte count seen in zidovudine-treated patients is associated with increased AIDS-free time and survival time. To determine the association of this and other changes in immunologic and hematologic markers with prognosis for time to AIDS and survival, we followed 747 AIDS-free patients from initiation of zidovudine therapy in the Multicenter AIDS Cohort Study (MACS). Participants were seen semiannually and had data collected on medication use, immunologic and hematologic variables, and clinical outcomes. AIDS was diagnosed in 216 participants and 165 died during the median follow-up period of 2.0 years. Duration of zidovudine use was categorized into 1-6 months (after 6 months of follow-up) and 7-12 months (12 months of follow-up). During the 6-month follow-up period in which zidovudine was first used, CD4+ lymphocyte levels rose by 17 cells/microliters compared with a mean decrease of 30 cells/microliters/6 months in untreated individuals (after adjusting for baseline CD4+ lymphocyte count). Baseline levels of CD4+ lymphocytes, platelets, and hemoglobin were significant predictors of AIDS and death. After 1-6 months with patients taking zidovudine and controlling for baseline (pretreatment) variables, change in markers after 6 months of follow-up and use of Pneumocystis carinii pneumonia prophylaxis and other antivirals, change in CD4+ lymphocyte count significantly predicted progression to AIDS [relative hazard (RH) = 0.71 for each 100 cell/microliters increase, p = 0.0001] and survival (RH = 0.78 per 100 cell/microliters increase; p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)