A controlled trial of aerosolized pentamidine or trimethoprim-sulfamethoxazole as primary prophylaxis against Pneumocystis carinii pneumonia in patients with human immunodeficiency virus infection. The Dutch AIDS Treatment Group

Management of Pneumocystis jiroveci pneumonia in children receiving chemotherapy

Pneumocystis jiroveci (formerly carinii) pneumonia (PCP) is a serious opportunistic infection in children and adolescents with cancer. It was the most common cause of death among children receiving chemotherapy prior to the inclusion of PCP prophylaxis as part of standard care for children with leukemia. The incidence of PCP has decreased significantly since initiation of prophylaxis; however, breakthrough cases continue to occur. Hematologic malignancies, brain tumors necessitating prolonged corticosteroid therapy, hematopoietic stem cell transplantation, prolonged neutropenia, and lymphopenia are the most important risk factors for PCP in children not infected with HIV. Of children with leukemia, 15-20% may develop PCP in the absence of prophylaxis. Infection with P. jiroveci occurs early in life in most individuals. However, clinically apparent disease occurs almost exclusively in immunocompromised persons. Dyspnea, cough, hypoxia, and fever are the most common presenting symptoms of PCP. Chest radiography and high-resolution CT scans of the chest demonstrate a characteristic ground-glass pattern. Induced sputum analysis and bronchoalveolar lavage are the diagnostic procedures of choice. Gomori's methenamine-silver stain, Geimsa or Wright's stain, and monoclonal immunofluorescent antibody stains are most commonly used to make a diagnosis. However, identification of P. jiroveci DNA using polymerase chain reaction assays in bronchoalveolar lavage fluid is more sensitive. Trimethoprim-sulfamethoxazole (TMP-SMZ; cotrimoxazole) is the recommended drug for the treatment of PCP. Patients who are intolerant of TMP-SMZ or who have not responded to treatment after 5-7 days of therapy with TMP-SMZ should be treated with pentamidine. A short course of corticosteroids is recommended for moderate to severe cases of PCP within the first 72 hours after diagnosis. Mutations in the dihydropteroate synthetase gene may confer resistance to TMP-SMZ; however, the clinical relevance of these mutations is not well established. TMP-SMZ is the most commonly used agent for prophylaxis. Myelosuppression is the most important adverse effect of TMP-SMZ and the most frequent cause for choosing alternative prophylactic agents in children undergoing chemotherapy. Alternative agents for chemoprophylaxis include dapsone, aerosolized pentamidine, and atovaquone. Alternative prophylactic agents must be used in patients developing myelosuppression secondary to TMP-SMZ or dapsone.

[Administration of anti-infective agents through the inhaled route]

OBJECTIVE

To report the doses of inhaled anti-infective agents described in the literature for both the adult and paediatric population. In the case of anti-infective agents which were not approved for inhaled administration, to propose the optimum manner in which these should be prepared in order to achieve osmolality and pH values as similar as possible to physiological values.

METHOD

A search was carried out of Pubmed (between 1960 and 2005) for each of the anti-infective agents using the words "inhalation OR inhaled OR aerosol OR aerosolized OR nebulized". We also consulted text books, Micromedex and the technical specifications of the pharmaceutical products. Nebulised solutions were prepared using the drugs for which information was found. The drugs approved for inhaled administration were prepared according to the manufacturers recommendations. For anti-infective agents which were not approved for inhaled administration, the raw materials and the branded drug products for intravenous administration available at our hospital were diluted using physiological saline solution and/or water for injection up to a final volume of 4-5 ml. The osmolality and pH values of all the solutions were measured. The optimum form of preparation was considered to be one with values as close as possible to between 150 and 550 mOsm/kg for osmolatity osmolality and 7 +/- 0.5 for pH.

RESULTS

Information about doses of 18 inhaled anti-infective agents was found (12 antibiotics, 5 antifungals and 1 antiviral); paediatric doses were described in 9 of these. Three of the anti-infective agents reviewed were approved for inhaled use in adult patients and four in paediatric patients. Of the 48 recommendations for dilution suggested for administration, two had an osmolality > 1,100 mOsm/kg and 5 an osmolality of < 100 mOsm/kg. Two dilutions had a pH > 8 and 14 a pH < 5.

CONCLUSIONS

There is limited literature regarding the doses of anti-infective agents for inhaled administration. The majority of anti-infective agents are not approved for inhaled administration. The dilution of the raw material or proprietary drugs with water or physiological saline solution for intravenous administration achieved solutions with appropriate osmolality in the majority of cases. Some of the solutions have extreme osmolality and/or pH levels, implying that it is reasonable to expect a greater risk of bronchospasm.

Late Presentation of HIV-Infected Individuals

Late presentation remains a major concern despite the dramatically improved prognosis realized by ART. We define a first presentation for HIV care during the course of HIV infection as ‘late’ if an AIDS-defining opportunistic disease is apparent, or if CD4+ T-cells are <200/μl. In the Western world, approximately 10 and 30% of HIV-infected individuals still present with CD4+ T-cells <50 and <200/μl, respectively; estimates are substantially higher for developing countries. Diagnosis and treatment of opportunistic diseases and intense supportive in-hospital care take precedence over ART. Benefits of starting ART without delay, that is, when opportunistic diseases are still active, include faster resolution of opportunistic diseases and a decreased risk of recurrence. The downside of starting ART without delay could include toxicity, drug interactions and immune reconstitution inflammatory syndrome (IRIS). Among asymptomatic or oligosymptomatic individuals presenting late, where ART and primary prophylaxis are initiated, ∼10–20% will become symptomatic from drug toxicity or undiagnosed opportunistic complications, including IRIS, which require appropriate therapies. In this review we describe late presentation to HIV care, the scale of the problem, the evaluation of a late-presenting patient and challenges associated with initiation of potent anti-retroviral therapy (ART) in the setting of acute opportunistic infections and other comorbidities.

Cotrimoxazole for prophylaxis or treatment of opportunistic infections of HIV/AIDS in patients with previous history of hypersensitivity to cotrimoxazole

BACKGROUND

Opportunistic infections continue to cause a significant amount of morbidity and mortality worldwide in patients infected with HIV. Trimethoprim-sulfamethoxazole (cotrimoxazole) is used in the treatment and prophylaxis of several opportunistic infections. In patients with HIV/AIDS, cotrimoxazole use can cause a higher rate of adverse drug reactions than in the general population. Given the cost-effectiveness of cotrimoxazole, the management of these adverse reactions has included continuing the drug (treating-through) and reintroducing the drug at a later date, either using dose-escalation (desensitization), or rechallenge at full dose. This systematic review is the first to examine the differences in patient outcomes between these strategies.

OBJECTIVES

To compare the rate of discontinuation of cotrimoxazole and adverse reactions among the three strategies of treating-through, desensitization, and rechallenge in patients living with HIV who previously had an adverse reaction to cotrimoxazole.

SEARCH STRATEGY

We searched MEDLINE, EMBASE, LILACS, The Cochrane Library, Meeting Abstracts, AIDSTRIALS, ACTIS, Current Controlled Trials, The National Institutes of Health Clinical Trials Registry, and CenterWatch (search date May 2006).

SELECTION CRITERIA

Randomised trials comparing treating-through, rechallenge, or desensitization of cotrimoxazole treatment or prophylaxis in adults (age 18 years or over) and/or children (age 17 years or under).

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial eligibility and quality, and extracted data. Where data were incomplete or unclear, a third reviewer resolved conflicts and/or trial authors were contacted for further details.

MAIN RESULTS

Three trials that examined cotrimoxazole prophylaxis and involving 268 adults were included. Meta-analysis of these studies found a beneficial effect of using a desensitization protocol over a rechallenge protocol at six months of follow-up for preventing discontinuation of cotrimoxazole (number needed to treat (NNT) 7.14, 95% confidence interval (CI) 4.0-33.0), and for lower incidence of overall hypersensitivity (NNT 4.55, 95% CI 3.03-9.09). No severe hypersensitivity reactions occurred for either protocol in the three studies.

AUTHORS' CONCLUSIONS

In the small trials included in this review, when compared to cotrimoxazole rechallenge for prophylaxis of opportunistic infections, cotrimoxazole desensitization resulted in fewer treatment discontinuations and overall adverse reactions in HIV-infected patients with a previous history of mild or moderate hypersensitivity to cotrimoxazole. Paediatric data and trials in resource-poor settings are urgently required. Further randomised controlled trials are also needed for the treatment of opportunistic infections, treating-through, adjunctive medications, and different desensitization-dosing schedules.

Aerosolised antibiotics: a critical appraisal of their use

Aerosolised antimicrobial agents have been used in clinical practice since the 1950s. The main advantage of this route of administration is the targeted drug delivery to the site of infection in the lung. Exploitation of this targeted delivery can yield high concentrations at the site of infection/colonisation while minimising systemic toxicities. It is important to note that the ability of a drug to reach the target area in the lung effectively is dependent on a number of variables, including the nebuliser, patient technique, host anatomy and disease-specific factors. The most convincing data to support the use of aerosolised antimicrobials has been generated with tobramycin solution for inhalation (TOBI, Chiron Corp.) for maintenance treatment in patients with cystic fibrosis. In addition to cystic fibrosis, the use of aerosolised antimicrobials has also been studied for the treatment or prevention of a number of additional disease states including non-cystic fibrosis bronchiectasis, ventilator-associated pneumonia and prophylaxis against pulmonary fungal infections. Key studies evaluating the benefits and shortcomings of aerosolised antimicrobial agents in these areas are reviewed. Although the theory behind aerosolised administration of antibiotics seems to be sound, there are limited data available to support the routine use of this modality. Owing to the gaps still existing in our knowledge base regarding the routine use of aerosolised antibiotics, caution should be exercised when attempting to administer antimicrobials via this route in situations falling outside clearly established indications such as the treatment of patients with cystic fibrosis or Pneumocystis pneumonia.

Toxicity and Efficacy of Daily Dapsone as Pneumocystis jiroveci Prophylaxis after Hematopoietic Stem Cell Transplantation: A Case-Control Study

The toxicity and efficacy of dapsone given daily as Pneumocystis jiroveci (PCP) prophylaxis in hematopoietic stem cell transplant (HSCT) recipients who cannot take trimethoprim-sulfamethoxazole (TMP-SMX) have not been fully evaluated. We compared 155 HSCT recipients who received daily dapsone as second-line PCP prophylaxis with 310 matched control patients who received TMP-SMX throughout the posttransplantation course. Among patients who started dapsone before transplantation because of TMP-SMX allergy, there was no difference in the transfusion requirement after HSCT when compared with controls. Among patients who started dapsone after transplantation, increased red blood cell ( P<.0001) and platelet transfusion ( P=.003) requirements were noted compared with controls. This effect was, however, limited to patients who were receiving dapsone for reasons (mostly neutropenia) other than TMP-SMX allergy. Two of 155 patients developed PCP, compared with 0 of 310 controls ( P=.11); both patients survived. In conclusion, the efficacy of daily dapsone in preventing PCP was similar to that observed in patients able to remain on TMP-SMX prophylaxis. Dapsone did not seem to cause hematologic toxicity among TMP-SMX--allergic patients. The observed higher transfusion need in patients who received dapsone for reasons other than TMP-SMX allergy seems mostly due to an underlying condition of poor marrow reserve. Further studies are required to establish whether the drug has an etiologic role in these situations.

Bronchoscopy in the diagnosis and surveillance of respiratory infections in lung and heart-lung transplant recipients

Fiberoptic bronchoscopy (FOB) with bronchoalveolar lavage (BAL) and transbronchial biopsies (TBB) is a widely used method to detect respiratory infections and to differentiate them from other postoperative complications in lung transplant (LTX) recipients, but the usefulness of surveillance FOBs is not yet established. The aim of this study was to evaluate the usefulness of FOB in the diagnosis and surveillance of infections in LTX recipients. We reviewed all the consecutive 609 FOBs performed on 40 lung or heart-LTX recipients between February 1994 and November 2002. The overall diagnostic yield was 115/190 (61%) and 43/282 (15%) for clinically indicated and surveillance FOBs respectively (P < 0.001). Infection was established by bronchoscopic samples in 96/190 (50.5.%) of the clinically indicated FOBs and 34/282 (12.1%) of the surveillance FOBs (P < 0.001). The diagnostic yield of the clinically indicated FOBs was highest (72%) from 1 to 6 months post-transplant (P = 0.04). Pneumocystis carinii was detected in 23 (4.9%) of the bronchoscopic specimens and 15 (65%) of the P. carinii infections were detected during adequate chemoprophylaxis. To conclude, in LTX recipients clinically indicated FOB has a good diagnostic yield in detecting infections and other postoperative complications, whereas the information received from surveillance FOB has remained less significant. With current prophylaxis and screening strategies FOB is still required to detect P. carinii infections.

Prevention of infection due to Pneumocystis spp. in human immunodeficiency virus-negative immunocompromised patients

Pneumocystis infection in humans was originally described in 1942. The organism was initially thought to be a protozoan, but more recent data suggest that it is more closely related to the fungi. Patients with cellular immune deficiencies are at risk for the development of symptomatic Pneumocystis infection. Populations at risk also include patients with hematologic and nonhematologic malignancies, hematopoietic stem cell transplant recipients, solid-organ recipients, and patients receiving immunosuppressive therapies for connective tissue disorders and vasculitides. Trimethoprim-sulfamethoxazole is the agent of choice for prophylaxis against Pneumocystis unless a clear contraindication is identified. Other options include pentamidine, dapsone, dapsone-pyrimethamine, and atovaquone. The risk for PCP varies based on individual immune defects, regional differences, and immunosuppressive regimens. Prophylactic strategies must be linked to an ongoing assessment of the patient's risk for disease.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pneumocystis jiroveci Pneumonia in Adult Patients with AIDS

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

The effect of lamivudine on the replication of hepatitis B virus in HIV-infected patients depends on the host immune status (CD4 cell count)

We retrospectively analysed the effect of lamivudine on hepatitis B virus (HBV) in HIV-co-infected patients. In this small study we document a CD4 cell-dependent response on HBV replication with lamivudine therapy. In this respect, hepatitis B may be considered an opportunistic infection. Our finding may have important clinical consequences, and large prospective studies are necessary to investigate this further.

Aerosolized pentamidine prophylaxis against AIDS-related Pneumocystis carinii pneumonia and its short- and long-term effects on pulmonary function in the Japanese

We evaluated the incidence of prophylaxis failure with aerosolized pentamidine (AP) for Pneumocystis carinii pneumonia (PCP) in Japanese patients with human immunodeficiency virus (HIV) infection, and we examined the short- and long-term effects of AP on pulmonary function. The patients inhaled 300 mg of pentamidine by ultrasonic nebulizer, after the inhalation of procaterol (80 micrograms), every 4 weeks. PCP developed in 2 of 16 patients receiving primary prophylaxis with AP, and in 4 of 13 patients with secondary prophylaxis. The CD4(+) T-lymphocyte count was very low in the patients with prophylaxis failure. The chest radiographic presentations were atypical in 4 of the 6 patients with prophylaxis failure. There were no significant changes in the vital capacity (VC), VC/predictive VC (%VC), forced expiratory volume in 1 s (FEV(1.0)), FEV(1.0)/forced vital capacity (FEV(1.0)%), and maximum expiratory flow rate at 25% of vital capacity (MEF(25))/height comparing values before and after initial AP treatment. However, a reduction of oxygen saturation (SpO(2)) of over 3% was noted in 4 patients during the initial AP administration. In 9 patients receiving AP prophylaxis for more than 36 months, we compared the pulmonary function parameters between the baseline and final observations (mean, 52.7 months). There were no changes in VC, %VC, FEV(1.0,) FEV(1.0)%, and SpO(2), but there was a statistically significant decline in MEF(25)/height after long-term AP treatment. We concluded that the incidence of prophylaxis failure with AP for PCP in Japanese patients was similar to that in Western patients, and that long-term AP treatment affected MEF(25)/height in spite of the safe pulmonary effects in short-term AP inhalation.

Incidence and risk factors for toxoplasmic encephalitis in human immunodeficiency virus-infected patients before and during the highly active antiretroviral therapy era

The occurrence of toxoplasmic encephalitis (TE) was studied among 19,598 and 17,016 patients enrolled in the French Hospital Database on human immunodeficiency virus whose CD4 cell counts decreased to < or =200x10(6) cells/L before (1992-1995) or after (1996-1998) the availability of highly active antiretroviral therapy, respectively. The incidence of TE decreased from 3.9 cases per 100 person-years in the first period (95% confidence interval [CI], 3.7-4.1) to 1.0 cases per 100 person-years in the second period (95% CI, 0.9-1.1). After adjustment for known risk factors for TE, patients who received cotrimoxazole prophylaxis had a lower risk of TE (adjusted relative hazard, 0.6 and 0.5, respectively, for the first and second periods; P < .001). For patients treated with cotrimoxazole at inclusion, discontinuation of cotrimoxazole increased the risk of TE in both periods (adjusted relative hazard, 4.8 and 4.2, respectively; P < .001). Among patients whose CD4 cell counts increased to > 200 x 10(6) cells/L while undergoing highly active antiretroviral therapy, the incidence of TE was 0.1 cases per 100 person-years (95% CI, 0.0-0.2) and was not increased by discontinuation of cotrimoxazole.

Cotrimoxazole prophylaxis in adults infected with HIV in low-income countries

Two recent placebo-controlled trials of cotrimoxazole in HIV-infected adults, conducted by independent groups but in the same city (Abidjan, Côte d'Ivoire), have both shown important positive impacts. One study where cotrimoxazole or placebo was given to tuberculosis-HIV co-infected patients showed a significant reduction in mortality; the second study with a similar protocol, in HIV-infected patients without major co-morbidity at trial entry, showed a significant reduction in morbidity but no effect on mortality. These data have been interpreted by some as conclusive enough to recommend cotrimoxazole for all people with HIV/AIDS in Africa. Others have been more cautious, noting that Abidjan has an atypically low rate of cotrimoxazole resistance among bacterial pathogens, and consider more data are needed before such a sweeping policy decision can be made. Recent data from Senegal showed no benefit but this trial, like several others, was terminated prematurely because the investigators felt it unethical to continue after the Abidjan results were released. The situation is somewhat confused and confusing. This review attempts to put the current debate into context and to review the current position of cotrimoxazole in relation to other primary prophylaxis strategies in Africa.

Incidence of primary opportunistic infections in two human immunodeficiency virus-infected French clinical cohorts

BACKGROUND

Clinical guidelines for the prevention of opportunistic infections in human immunodeficiency virus (HIV)-infected individuals have been developed on the basis of natural history data collected in the USA. The objective of this study was to estimate the incidence of primary opportunistic infections in HIV-infected individuals in geographically distinct cohorts in France.

METHODS

We conducted our study on 2664 HIV-infected patients from the Tourcoing AIDS Reference Centre and the hospital-based information system of the Groupe d'Epidémiologie Clinique du SIDA en Aquitaine enrolled from January 1987 to September 1995 and followed through December 1995. We estimated: (1) CD4-adjusted incidence rates of seven primary opportunistic infections in the absence of prophylaxis for that specific infection or any antiretroviral drugs other than zidovudine; and (2) CD4 lymphocyte count decline.

RESULTS

The highest incidence rates for all opportunistic infections studied occurred in patients with CD4 counts < 200/microl. With CD4 counts < 50/microl, the most common opportunistic infections were toxoplasmic encephalitis (12.6 per 100 person-years) and Pneumocystis carinii pneumonia (11.4 per 100 person-years). Mycobacterium tuberculosis was the least common opportunistic infection (< 5.0/100 person-years). Even with CD4 counts > 300/microl, cases of Pneumocystis carinii pneumonia and toxoplasmic encephalitis were reported. The mean CD4 lymphocyte decline per month was 4.6 cells/microl. There was a significant association between HIV risk behaviour and the incidence of cytomegalovirus infection, between calendar year and the incidence of Pneumocystis carinii pneumonia, toxoplasmic encephalitis and Candida esophagitis, and between geographical area and the incidence of Pneumocystis carinii pneumonia and cytomegalovirus infection.

CONCLUSIONS

Geographical differences exist in the incidence of HIV-related opportunistic infections. These results can be used to define local priorities for prophylaxis of opportunistic infections.

Initiating co-trimoxazole prophylaxis in HIV-infected patients in Africa: an evaluation of the provisional WHO/UNAIDS recommendations

OBJECTIVE

To evaluate the proposed WHO/UNAIDS criteria for initiating co-trimoxazole prophylaxis in adult HIV-infected patients in Africa [WHO clinical stages 2--4 or CD4 count < 500 x 10(6) /l or total lymphocyte count (TLC) equivalent].

DESIGN

Observational cohort study of 5-year follow-up.

SETTING

Adult HIV clinics, University of Cape Town, South Africa.

METHODS

Effect of prophylactic low dose co-trimoxazole (480 mg per day or 960 mg three times per week) on survival and morbidity was assessed in patients stratified by WHO clinical stage, CD4 T-lymphocyte count or TLC. Patients receiving antiretroviral therapy were excluded.

RESULTS

Co-trimoxazole reduced mortality [adjusted hazard ratio (AHR), 0.56; 95% confidence interval (CI), 0.33--0.85; P > 0.001] and the incidence of severe HIV-related illnesses (AHR, 0.52; 95% CI, 0.38--0.68; P < 0.001) in patients with evidence of advanced immune suppression on clinical (WHO stages 3 and 4) or laboratory assessment (TLC < 1250 x 10(6)/l or CD4 count < 200 x 10(6)/l). No significant evidence of efficacy was found in patients with WHO stage 2 or CD4 count 200--500 x 10(6)/l/TLC 1250--2000 x 10(6)/l. If we had applied the WHO/UNAIDS recommendations 88.3% of our patients would have received co-trimoxazole prophylaxis at their initial clinic visit.

CONCLUSION

Co-trimoxazole in HIV-infected adults from an area in which Pneumocystis carinii pneumonia is uncommon demonstrated a survival benefit consistent with previous randomized trials. Further studies are needed to assess the optimal time of commencement of prophylaxis, as widespread co-trimoxazole use will lead to increasing antimicrobial resistance to other major pathogens in Africa.

Opportunistic infections in HIV disease: down but not out

Despite the marked improvement in patient survival and reduction in the incidence of HIV-related opportunistic infections with the introduction of potent, combination antiretroviral therapy, these infections remain a significant challenge in the management of HIV-infected patients. Ongoing issues that will require further study include a better characterization of immune reconstitution illnesses, other potential alterations in the natural history of opportunistic infections with antiretroviral therapy, and to what degree patients who experience failure of antiviral treatment become susceptible to various opportunistic processes.

Risk Factors for Prophylaxis Failure in Patients Receiving Aerosol Pentamidine for Pneumocystis carinii Pneumonia Prophylaxis

OBJECTIVE

The purposes of this study were (1) to determine the incidence of prophylaxis failure in HIV-infected patients receiving aerosol pentamidine (AP) for Pneumocystis carinii pneumonia (PCP) prophylaxis, and (2) to identify risk factors for PCP prophylaxis failure.

SETTING AND DESIGN

In Ontario, Canada, AP has been made available for outpatient PCP prophylaxis through a centralized government program, the Ontario Drug Distribution and Monitoring Program. Data from this administrative observational database were extracted for 2,227 patients who received AP between May 1989 and December 1998.

OUTCOME MEASUREMENTS

The incidence of breakthrough PCP (BPCP) was calculated from the database. A Cox regression model with time-varying covariates was created to examine factors associated with BPCP. The follow-up time was divided into three eras: 1989 to 1991, 1992 to 1994, and 1995 to 1998. These eras were meant to reflect major changes in antiretroviral medication regimens.

RESULTS

The overall risk of BPCP was 16.2% over a mean follow-up of 1.67 years. The overall BPCP rate was 9.7/100 patient-years, with rates of 8.8/100, 13.1/100, and 6.3/100 patient-years in each of the three treatment eras. In the multivariate analysis, significant risk factors for prophylaxis failure were low CD4 count, previous diagnosis of PCP, history of AIDS-defining conditions other than PCP, and antiretroviral treatment era defined above.

CONCLUSION

The overall rate of PCP prophylaxis failure has decreased significantly after 1995, coincident with the era of highly active antiretroviral therapies. Initiation of PCP prophylaxis remains necessary in patients with risk factors.

Prognostic markers of short-term mortality in AIDS-associated Pneumocystis carinii pneumonia

BACKGROUND

Since 1990, corticosteroids have been recommended as adjunctive therapy for patients with AIDS-associated Pneumocystis carinii pneumonia (PCP) and respiratory failure. We hypothesized that the natural course of AIDS-associated PCP has changed in the era of adjunctive corticosteroid therapy.

OBJECTIVE

To study variables obtained on hospital admission for possible prognostic value of short-term (3-month) outcome of PCP.

DESIGN AND PATIENTS

Prospective observational study of 176 consecutive HIV-1-infected individuals with PCP between 1990 and 1999.

METHOD

Cox proportional-hazards regression models.

RESULTS

Univariate analysis showed that age, one or more prior episodes of PCP, use of antimicrobial therapy other than trimethoprim-sulfamethoxazole (TMP-SMZ), use of PCP prophylaxis at diagnosis, and culture of cytomegalovirus (CMV) in BAL predicted progression to death within 3 months. After adjustment, age (relative risk [RR], 4.1; 95% confidence interval [CI], 1.8 to 9.3), initial antimicrobial therapy other than TMP-SMZ (RR, 3.1; 95% CI, 1.2 to 8.5), use of PCP prophylaxis (RR, 5.6; 95% CI, 2.2 to 14.4), and culture of CMV in BAL fluid (RR, 2.7; 95% CI, 1.3 to 5.6) remained independent predictors of a poor outcome. In contrast, neither PO(2) nor serum lactate dehydrogenase, which in earlier studies were identified as prognostic markers, were predictors of mortality.

CONCLUSION

Age, initial anti-PCP therapy, use of PCP prophylaxis, and BAL CMV status may be useful predictors of outcome of PCP in patients treated in the era of adjunctive corticosteroid therapy.

Primary prevention with cotrimoxazole for HIV-1-infected adults: results of the pilot study in Dakar, Senegal

OBJECTIVES

To assess the efficacy and tolerance of chemoprophylaxis with cotrimoxazole compared with placebo among HIV-1-infected adults.

DESIGN

Randomized, double-blind, placebo-controlled clinical trial in the urban community of Dakar, Senegal.

METHODS

Eligibility criteria were age greater than 15 years, HIV-1 or HIV-1 and HIV-2 dual seropositivity, CD4 cell count lower than 400 copies/mm3, no progressive infection, no previous history of intolerance to sulphonamide, lack of severe anemia or neutropenia, and renal or hepatic failure. Written informed consent was obtained. Recruited patients received 80 mg of trimethoprim and 400 mg of sulphamethoxazole daily or a matching placebo. The main outcomes were survival and the occurrence of clinical events defined as Pneumocystis carinii pneumonia, cerebral toxoplasmosis, bacterial pneumonia, infectious enteritis, bacterial meningitis, urinary tract infection, bacterial otitis and sinusitis, and pyomyositis.

RESULTS

Between September 1996 and March 1998, 297 patients were screened, and 100 were randomized in the study. Demographic, clinical, and biological characteristics of the two groups were similar as was the mean length of follow-up (7.7 months for the cotrimoxazole group vs. 8.0 months for the placebo group). There was no significant difference between the two groups in survival (hazard ratio = 0.84; 95% confidence interval [CI]: 0.36-1.94) in the probability of severe event occurrence, defined as death or hospital admission (hazard ratio = 1.10; 95% CI: 0.57-2.13), or in the probability of clinical event occurrence (hazard ratio = 1.19; 95% CI: 0.55-2.59). Adjustment for initial CD4 cell count did not change these results. A low dose of cotrimoxazole was tolerated well clinically as well as biologically; only one treatment interruption occurred as the result of a moderate cutaneous eruption (grade 2).

CONCLUSION

Our study does not show a beneficial effect of chemoprophylaxis with low-dose cotrimoxazole on survival or occurrence of opportunistic or nonopportunistic infections for HIV-1-infected patients in Dakar, Senegal.

A randomized trial of the discontinuation of primary and secondary prophylaxis against Pneumocystis carinii pneumonia after highly active antiretroviral therapy in patients with HIV infection. Grupo de Estudio del SIDA 04/98

BACKGROUND

Prophylaxis against Pneumocystis carinii pneumonia is indicated in patients with human immunodeficiency virus (HIV) infection who have less than 200 CD4 cells per cubic millimeter and in those with a history of P. carinii pneumonia. However, it is not clear whether prophylaxis can be safely discontinued after CD4 cell counts increase in response to highly active antiretroviral therapy.

METHODS

We conducted a randomized trial of the discontinuation of primary or secondary prophylaxis against P. carinii pneumonia in HIV-infected patients with a sustained response to antiviral therapy, defined by a CD4 cell count of 200 or more per cubic millimeter and plasma HIV type 1 (HIV-1) RNA level of less than 5000 copies per milliliter for at least three months. Prophylactic treatment was restarted if the CD4 cell count declined to less than 200 per cubic millimeter.

RESULTS

The 474 patients receiving primary prophylaxis had a median CD4 cell count at entry of 342 per cubic millimeter, and 38 percent had detectable HIV-1 RNA. After a median follow-up period of 20 months (758 person-years), there had been no episodes of P. carinii pneumonia in the 240 patients who discontinued prophylaxis (95 percent confidence interval, 0 to 0.85 episode per 100 person-years). For the 113 patients receiving secondary prophylaxis, the median CD4 cell count at entry was 355 per cubic millimeter, and 24 percent had detectable HIV-1 RNA. After a median follow-up period of 12 months (123 person-years), there had been no episodes of P. carinii pneumonia in the 60 patients who discontinued prophylaxis (95 percent confidence interval, 0 to 4.5 episodes per 100 person-years).

CONCLUSIONS

In HIV-infected patients receiving highly active antiretroviral therapy, primary and secondary prophylaxis against P. carinii pneumonia can be safely discontinued after the CD4 cell count has increased to 200 or more per cubic millimeter for more than three months.

Prophylaxis of opportunistic infections

Potent antiretroviral therapy has improved the outcome of HIV-associated OIs, which have declined dramatically. The clinical manifestations of some OIs (e.g., CMV retinitis, MAC infection, and TB) have changed. These effects likely are related to the immune reconstitution observed with the suppression of HIV replication. These changes have affected approaches to the prophylaxis of OIs. Withdrawal of some prophylaxis in patients who show evidence of immune reconstitution is possible, although clinical studies are needed to address further specific questions about the timing of withdrawal. The best way to prevent OIs is to give effective antiretroviral therapy--the future epidemiology of OIs is linked inextricably with the effectiveness of future antiretroviral treatments.

A 5-day course of oral desensitization to trimethoprim/sulfamethoxazole (T/S) in patients with human immunodeficiency virus type-1 infection who were previously intolerant to T/S

BACKGROUND

Trimethoprim/sulfamethoxazole (T/S) is an essential drug in patients with human immunodeficiency virus type-1 (HIV-1) infection to prevent opportunistic infections. About 40% to 60% of them develop skin rash which leads to discontinue the medication. A precise mechanism of the reaction is not known.

OBJECTIVE

To make the patients more tolerable to the medication and to make clear whether or not the reaction is caused by serum sulfamethoxazole-specific IgE.

METHODS

We established a 5-day protocol, in which T/S was administered orally as a granular form in increasing doses beginning with 0.005 g (it contains trimethoprim 0.4 mg and sulfamethoxazole 2 mg) and doubled every 12 hours until the therapeutic dose was achieved. We tried to desensitize T/S in 17 patients with HIV-1 infection who were previously intolerant to T/S and measured the specific IgE in sera.

RESULTS

Desensitization was successfully completed in 15 (88.2%) of the patients. In two patients who failed the desensitization, one was due to fever and the other was gastric irritation. During followup in a mean period of 16.6 months (range, 8 to 23 months) as of May, 1999, none has had Pneumocystis carinii pneumonia (PCP) while receiving T/S after desensitization. Sulfamethoxazole-specific IgE did not increase, indicating that it was not the major cause of skin rash due to T/S in our cases.

CONCLUSION

These preliminary results show that most patients who were thought to be intolerant to T/S and had no sulfamethoxazole-specific IgE can be safely desensitized and received the drug subsequently as an effective prophylaxis for PCP.

Reduced toxicity with gradual initiation of trimethoprim-sulfamethoxazole as primary prophylaxis for Pneumocystis carinii pneumonia: AIDS Clinical Trials Group 268

Trimethoprim-sulfamethoxazole (TMP/SMX) is recognized as the superior agent for Pneumocystis carinii pneumonia (PCP) prophylaxis but a high incidence of adverse drug reactions, which may be due to toxic drug metabolites, limits its use. AIDS Clinical Trials Group protocol 268 was a randomized, double-blind, controlled two-arm trial designed to determine whether gradual initiation of TMP/SMX suspension reduced the incidence of treatment-limiting adverse drug reactions compared with routine initiation of double-strength (DS; 160 mg/800 mg) tablets. In all, 372 HIV-1-infected study subjects with a CD4+ cell count <250 x 10 cells/mm3 who had not previously received TMP/SMX for PCP prophylaxis were randomized to receive either daily TMP/SMX DS tablets or a gradually increasing dose of TMP/SMX suspension. The suspension dose was increased to reach the equivalent of a DS tablet by study day 13. During the first 2 weeks, study subjects also received a matching placebo tablet/suspension. After week 2, all study subjects received TMP/SMX tablets for the next 10 weeks. There were significantly fewer study subjects who discontinued prophylaxis during the first 12 weeks when TMP/SMX therapy was initiated gradually (17%) than when initiated in DS tablet formulation (33%) (p =.0002). Gradual initiation was also associated with significantly fewer adverse drug reactions. Gradual initiation of TMP/SMX for primary PCP prophylaxis reduces the incidence of its treatment-limiting adverse effects.

Comparison of high and low doses of trimethoprim-sulfamethoxazole for primary prevention of toxoplasmic encephalitis in human immunodeficiency virus-infected patients

To evaluate the influence of the dose of co-trimoxazole prophylaxis on the risk of toxoplasmosis in human immunodeficiency virus (HIV)-infected patients, we performed a nested case-control study of 32 patients with toxoplasmosis (case patients) and 64 patients without toxoplasmosis (control patients) who were matched by CD4 cell count and Toxoplasma gondii serostatus; these patients were from a cohort of 521 HIV-infected patients who underwent a diagnostic neuroimaging study between March 1993 and January 1997. Twenty-seven (84.4%) of 32 case patients and 33 (51.6%) of 64 control patients received low doses of co-trimoxazole, a finding associated with an adjusted odds ratio (OR) of 9.36 (95% confidence interval [CI], 2.05-42.75) and indicating 89% protective efficacy for high doses. Fifteen (46.9%) of 32 case patients and 16 (25%) of 64 control patients were exposed to rifampin (adjusted OR, 3.38; 95% CI, 1.08-10.61). These results indicate that high doses of co-trimoxazole appear to be more effective than low doses for lowering the risk of toxoplasmosis in HIV-infected patients and that rifampin therapy may reduce the efficacy of co-trimoxazole.

The role of fibre-optic bronchoscopy in solid organ, transplant patients with pulmonary infections

Organ transplantation is currently the standard therapy for patients with end-stage organ dysfunction. The immunosuppression caused by this therapy increases the rate of infection, particularly in the lungs. Early diagnosis is extremely important and fibre-optic bronchoscopy is a helpful tool in reaching diagnosis. Knowing the timing of various pathogens following transplantation, and the radiological picture as well as the prophylactic regimen, is helpful when specific pathogens are suspected. Bronchoscopy with bronchoalveolar lavage and transbronchial biopsies are particularly helpful in diagnosis of bacterial cytomegalovirus (CMV) and pneumocytosis carinii pneumocytosis, and is considered a safe procedure. Open lung biopsy is reserved for those who have negative bronchoscopy with a reasonable prognosis.

Lack of legal income is strongly associated with an increased risk of AIDS and death in HIV-infected injecting drug users

The aim of the study was to analyze the impact of soci-economic status in addition to other risk factors in the progression of HIV disease in a cohort of injecting drug users (IDUs) with a mean follow-up of two years. Between 1989 and 1992, 124 HIV-infected IDUs were recruited in a primary care outpatient clinic providing free consultations and free access to therapy. The main outcome measures were death and AIDs-defining events. The proportion of current daily injectors at entry in the study and at the end of follow-up was 67.7% and 57.2%, respectively. The proportion of individuals on maintenance opioid therapy at entry in the study and at the end of follow-up was 0 and 12.1%, respectively. CD4 cell counts below 200 x 10(6)/L at baseline, positive p24 antigenemia at baseline, the lack of legal income and occasional drug use at entry were risk factors for clinical progression and death. When adjusted in a multivariate analysis, the absence of legal income remained associated with death and occurrence of an AIDS-defining event with a relative risk of 5.2 (1.5-18.1) (p = 0.004). Lack of legal income is a strong risk factor for progression of HIV disease in IDUs, that is independent of CD4 cell count and p24 antigenemia.

Joint effects of HIV-1 RNA levels and CD4 lymphocyte cells on the risk of specific opportunistic infections

OBJECTIVES

To evaluate the predictive value of baseline plasma HIV-1 RNA levels and CD4 lymphocyte counts and early changes in these markers after initiating antiretroviral therapy on the risk of development of specific opportunistic infections (OIs).

DESIGN

Patient data from four antiretroviral therapy studies were combined for a retrospective analysis. The analysis included 842 participants from the virology substudies of these trials who had baseline measurements for both HIV-1 RNA levels and CD4 cell counts.

METHODS

Cox proportional hazards models were used to assess the joint effects of baseline CD4 cell count and HIV-1 RNA level and early treatment-associated changes in these values on the risk of development of Pneumocystis carinii pneumonia (PCP), cytomegalovirus (CMV), or Mycobacterium avium complex (MAC). The effects of potential confounders such as prior prophylaxis and previous OIs were also addressed.

RESULTS

Baseline CD4 cell counts and HIV-1 RNA measurements showed significant associations with the risk of PCP, CMV, and MAC. Patients with higher levels of HIV-1 RNA were estimated to have three to six times the risk of these OIs than those with lower levels. Reductions in viral load were linked to significantly reduced risks of PCP, CMV, and MAC. Early decreases in RNA were generally more predictive of risk than were early increases in CD4 cell counts.

CONCLUSIONS

Baseline viral load and reductions in viral load during therapy appeared to influence the risk of these OIs independently of the CD4 cell count. Future guidelines for the initiation of prophylaxis for these OIs may be improved by incorporating information on viral load.

HIV and the returning expatriate

Worldwide seroprevalence of the Human Immunodeficiency Virus (HIV) was estimated at 29.4 million at the end of 1996 with 75-85% of infections in adults transmitted through sexual intercourse, and by heterosexual intercourse in more then 70%. SubSaharan Africa is currently the area most heavily affected but over the past 5 years rapid spread of the virus has occurred in Asia. No developing country is free of HIV infection and HIV infection acquired abroad now accounts for most of heterosexually acquired HIV infection presenting in the (United Kingdom) UK, accounting for 25% of new HIV cases in the UK in the year to end March 1995 and 18% in the year to end March 1996, and at least 38% of new cases in Scotland in 1996.

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

BACKGROUND

It is unclear whether primary prophylaxis against Pneumocystis carinii pneumonia can be discontinued in patients infected with the human immunodeficiency virus (HIV) who are successfully treated with combination antiretroviral therapy. We prospectively studied the safety of stopping prophylaxis among patients in the Swiss HIV Cohort Study.

METHODS

Patients were eligible for our study if their CD4 counts had increased to at least 200 cells per cubic millimeter and 14 percent of total lymphocytes while they were receiving combination antiretroviral therapy, with these levels sustained for at least 12 weeks. Prophylaxis was stopped at study entry, and patients were examined every three months thereafter. The development of P. carinii pneumonia was the primary end point, and the development of toxoplasmic encephalitis the secondary end point.

RESULTS

Of the 262 patients included in our analysis, 121 (46.2 percent) were positive for IgG antibodies to Toxoplasma gondii at base line. The median CD4 count at study entry was 325 per cubic millimeter (range, 210 to 806); the median nadir CD4 count was 110 per cubic millimeter (range, 0 to 240). During a median follow-up of 11.3 months (range, 3.0 to 18.8), prophylaxis was resumed in nine patients, and two patients died. There were no cases of P. carinii pneumonia or toxoplasmic encephalitis. The one-sided upper 99 percent confidence limit for the incidence of P. carinii pneumonia was 1.9 cases per 100 patient-years (based on 238 patient-years of follow-up). The corresponding figure for toxoplasmic encephalitis was 4.2 per 100 patient-years (based on 110 patient-years of follow-up).

CONCLUSIONS

Stopping primary prophylaxis against P. carinii pneumonia appears to be safe in HIV-infected patients who are receiving combination antiretroviral treatment and who have had a sustained increase in their CD4 counts to at least 200 cells per cubic millimeter and to at least 14 percent of total lymphocytes.

Discontinuation of prophylaxis for Pneumocystis carinii pneumonia in HIV-1-infected patients treated with highly active antiretroviral therapy

BACKGROUND

Prophylactic drugs for Pneumocystis carinii pneumonia (PCP) are strongly recommended for HIV-1-infected patients with CD4 cell counts of less than 200 cells/microL. Because of the highly active antiretroviral therapy (HAART) currently available, we speculated that prophylaxis can be discontinued in patients with CD4 cell counts of more than 200 cells/microL.

METHODS

In this prospective observational study, PCP prophylaxis (primary or secondary) was discontinued in HIV-1-infected patients whose CD4 cell count had increased above 200 cells/microL (documented twice with an interval of at least 1 month) as a result of HAART. Patients and their CD4 cell counts were monitored every 3 months. The primary endpoint of the study was the occurrence or reoccurrence of PCP.

FINDINGS

78 patients were enrolled: 62 patients were receiving prophylaxis for primary prevention of PCP and 16 patients for secondary prevention of PCP. At the time of discontinuation of prophylaxis, the mean CD4 cell count was 347 cells/microL, and HIV-1-RNA was not detectable in 61 patients. The lowest mean CD4 cell count during prophylaxis was 79 cells/microL. Patients stopped prophylaxis 9.8 (SD 6.4) months after they started HAART. The mean follow-up after discontinuation of prophylaxis was 12.7 (SD 7.6) months, and none of the patients developed PCP (97.5% one-sided CI 0-4.4%).

INTERPRETATION

The preliminary results of this study indicate that PCP prophylaxis can be stopped safely in HIV-1-infected patients whose CD4 cell counts have increased above 200 cells/microL after treatment with HAART.

A controlled trial of dapsone versus pyrimethamine-sulfadoxine for primary prophylaxis of Pneumocystis carinii pneumonia and toxoplasmosis in patients with AIDS

Pneumocystis carinii pneumonia (PCP) is the most common opportunistic human immunodeficiency virus (HIV)-related infection, occurring in 85% of HIV infected patients without prophylaxis. Preventive treatment is required when CD4 cell count falls below 200 cells per cubic millimeter. Cotrimoxazole has been shown to be highly effective but alternative drug regimens are often necessary because of the frequent drug hypersensitivity exhibited by HIV infected patients. The aim of this prospective, open, randomized, one-site study, involving HIV-infected patients with a CD4 cell count below 200/mm3, or a percentage under 20%, randomly assigned to receive either dapsone 50 mg daily or Fansidar one tablet weekly, was to compare the efficacy and safety of these drugs in the primary prophylaxis of PCP. Both dapsone and Fansidar appear to be safe and effective alternative agents for the prevention of PCP. Their role in Toxoplasma gondii prophylaxis requires further evaluation.

A randomized trial of N-acetylcysteine for prevention of trimethoprim-sulfamethoxazole hypersensitivity reactions in Pneumocystis carinii pneumonia prophylaxis (CTN 057). Canadian HIV Trials Network 057 Study Group

Hydroxylamine derivatives of sulfamethoxazole may be the reactive metabolites that cause adverse reactions to trimethoprim-sulfamethoxazole (TMP-SMX). The increased frequency of reactions observed in HIV-positive individuals is hypothesized to be due to systemic glutathione deficiency and a decreased ability to scavenge these metabolites. Two hundred and thirty-eight patients were randomized to receive or not receive N-acetylcysteine (3 g of the 20% liquid solution) 1 hour before each dose of TMP-SMX (trimethoprim 80 mg, sulfamethoxazole 400 mg) twice daily, which was initiated as primary Pneumocystis carinii pneumonia prophylaxis. Forty-five patients had to discontinue TMP-SMX within 2 months because of fever, rash, or pruritus including 25 of 102 patients (25%) who were receiving TMP-SMX alone and 20 of 96 patients (21%) who were randomized to TMP-SMX and N-acetylcysteine. The difference between treatment groups is 4% (95% confidence interval [CI]: -16%, +9%). No independent association was found with the hypersensitivity reaction and age, gender, race, HIV risk factor, prior AIDS, concurrent use of fluconazole, or baseline CD4. N-acetylcysteine at a dose of 3 g twice daily could not be shown to prevent TMP-SMX hypersensitivity reactions in patients with HIV infection.

Pneumocystis carinii pneumonia incidence and chemoprophylaxis failure in ambulatory HIV-infected patients. HIV Outpatient Study (HOPS) Investigators

BACKGROUND

Pneumocystis carinii pneumonia (PCP) remains the most frequently reported serious opportunistic infection in AIDS patients and the second highest cause of mortality among persons with AIDS in the United States, despite the availability of effective chemoprophylaxis.

METHODS

To evaluate incidence of PCP and determinants of PCP chemoprophylaxis failure, we analyzed data from 2842 patients visits to infectious diseases physicians at 10 HIV clinics (eight private and two public) in eight U.S. cities from January 1992 through June 1996 as part of the HIV Outpatient Study (HOPS). We performed a time-dependent regression analysis to examine potential determinants of PCP chemoprophylaxis failure.

RESULTS

The incidence of chemoprophylaxis failure was 4.6 PCP cases/100 person-years on chemoprophylaxis; these cases represent 67% of all incident episodes of PCP. In a multivariate analysis, the only significant predictors of chemoprophylaxis failure were the use of agents other than trimethoprim-sulfamethoxazole (TMP-SMX), history of prior PCP, and a CD4+ T-lymphocyte cell count of <50 cells/microl. Dosing or frequency of TMP-SMX did not seem to influence risk of chemoprophylaxis failure.

DISCUSSION

Chemoprophylaxis failure, especially among those with the most advanced immunosuppression or history of prior PCP, was the most significant source of new PCP cases in the HOPS cohort and thus represents one of the largest contributors to morbidity and mortality in this cohort.

Evaluation of the Eiken latex agglutination test for anti-Toxoplasma antibodies and seroprevalence of Toxoplasma infection among factory workers in Addis Ababa, Ethiopia

Sera from 170 factory workers aged 18-45 years enrolled in a pilot study of human immunodeficiency virus 1 (HIV-1) infection in Addis Ababa, Ethiopia, were screened for anti-Toxoplasma immunoglobulin G antibodies by the Sabin-Feldman test (reference standard) and the Eiken latex agglutination test (under evaluation for use in developing countries). Based on the Sabin-Feldman test, the prevalence of anti-Toxoplasma antibodies was 80.0% (95% confidence interval 73.9-86.1%). The sensitivity and specificity of the Eiken latex agglutination test were 96.3% and 97.1%, respectively, showing its validity for the detection of anti-Toxoplasma antibodies. The prevalence of antibodies did not differ between individuals infected and uninfected with HIV-1 (74.2% versus 83.3%, P > 0.05). However, antibody titres were higher in HIV-infected persons than in those who were uninfected (P < 0.001). Based on these findings, we expect that toxoplasmic encephalitis will be a common opportunistic infection among HIV-infected Ethiopians, and chemoprophylaxis with co-trimoxazole may be beneficial to those with low CD4+ T cell counts. The prognostic significance of high titres of anti-Toxoplasma antibodies remains to be established among Ethiopian HIV-infected individuals.

Intention-to-treat vs. on-treatment analyses of clinical trial data: experience from a study of pyrimethamine in the primary prophylaxis of toxoplasmosis in HIV-infected patients. ANRS 005/ACTG 154 Trial Group

Randomized clinical trials analyzed by the intent-to-treat approach provide unbiased comparisons among treatment groups. To avoid dilution of treatment effect, many people also perform an analysis by treatment actually received, although this method may introduce bias into the results. This paper presents several approaches used for analyzing data of a recent trial and the difficulties encountered in interpreting the results of each approach. The ANRS 005/ACTG 154 Study was a double-blind, placebo-controlled, randomized, international (French, U.S., and Spanish) multicenter trial designed to assess the effectiveness of pyrimethamine for the primary prophylaxis of cerebral toxoplasmosis (CT) in HIV-infected patients with advanced immunodeficiency. In the intention-to-treat analysis, the cumulative probability of CT at 1 year did not differ significantly between the pyrimethamine arm (11.9%) and the placebo arm (13.1%), Hazard Ratio (HR) = 0.94 (95% Confidence Interval (CI) = 0.62-1.42), whereas an on-treatment analysis resulted in a significant difference: 4.2% in the pyrimethamine arm and 12.4% in the placebo arm, HR = 0.44 (95% CI = 0.24-0.80). The data showed a significant interaction between compliance and treatment outcome; and side effects were more frequently cited as reasons for compliance violations in the pyrimethamine group. Several different analytic approaches (censoring data at the time patients discontinued the study medication only for selected reasons) failed to explain the disparity between the estimation of effect of pyrimethamine by the intention-to-treat and on-treatment analyses. This experience led us to believe that comparing the results of both analyses was the best method to convince clinicians that intention-to-treat was the only interpretable analysis. We were concerned that even if pyrimethamine had a beneficial effect, it was very difficult (1) to quantify and (2) to apply to clinical practice unless one could predict the occurrence of study drug discontinuation for each patient at the time of treatment assignment. Although exploratory analyses may yield clinically relevant information and useful clarifications in the evaluation of treatments, intention-to-treat remains the only interpretable analysis of clinical trials.

The effect of cimetidine on the formation of sulfamethoxazole hydroxylamine in patients with human immunodeficiency virus

Hypersensitivity reactions from trimethoprim/sulfamethoxazole are likely caused by a reactive nitroso intermediate formed from sulfamethoxazole hydroxylamine. This pilot study tested whether cimetidine inhibits the urinary excretion of sulfamethoxazole hydroxylamine. Ten outpatients infected with human immunodeficiency virus (HIV) and currently receiving trimethoprim/sulfamethoxazole prophylaxis were randomly selected from 59 eligible patients. Five received cimetidine 800 mg twice daily for 1 week and five served as controls. Two spot urine samples one week apart were obtained after a trimethoprim/sulfamethoxazole dose for all patients. Patients taking cimetidine had a significant decrease in excretion of sulfamethoxazole hydroxylamine relative to total excreted drug in the two urine samples compared with control patients. Cimetidine likely caused this decrease in sulfamethoxazole hydroxylamine excretion through inhibition of CYP3A4. Because of potential differences between HIV-infected patients and healthy subjects in oxidative metabolism, future studies of inhibitors of sulfamethoxazole hydroxylamine formation should be conducted in the HIV population.