Withdrawal of prophylaxis against Pneumocystis carinii pneumonia

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

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

The cost effectiveness of combination antiretroviral therapy for HIV disease

BACKGROUND

Combination antiretroviral therapy with a combination of three or more drugs has become the standard of care for patients with human immunodeficiency virus (HIV) infection in the United States. We estimated the clinical benefits and cost effectiveness of three-drug antiretroviral regimens.

METHODS

We developed a mathematical simulation model of HIV disease, using the CD4 cell count and HIV RNA level as predictors of the progression of disease. Outcome measures included life expectancy, life expectancy adjusted for the quality of life, lifetime direct medical costs, and cost effectiveness in dollars per quality-adjusted year of life gained. Clinical data were derived from major clinical trials, including the AIDS Clinical Trials Group 320 Study. Data on costs were based on the national AIDS Cost and Services Utilization Survey, with drug costs obtained from the Red Book.

RESULTS

For patients similar to those in the AIDS Clinical Trials Group 320 Study (mean CD4 cell count, 87 per cubic millimeter), life expectancy adjusted for the quality of life increased from 1.53 to 2.91 years, and per-person lifetime costs increased from $45,460 to $77,300 with three-drug therapy as compared with no therapy. The incremental cost per quality-adjusted year of life gained, as compared with no therapy, was $23,000. On the basis of additional data from other major studies, the cost-effectiveness ratio for three-drug therapy ranged from $13,000 to $23,000 per quality-adjusted year of life gained. The initial CD4 cell count and drug costs were the most important determinants of costs, clinical benefits, and cost effectiveness.

CONCLUSIONS

Treatment of HIV infection with a combination of three antiretroviral drugs is a cost-effective use of resources.

Discontinuation of primary prophylaxis in HIV-infected patients at high risk of Pneumocystis carinii pneumonia: prospective multicentre study

OBJECTIVES

To assess the safety of discontinuation of primary prophylaxis in HIV-infected patients on antiretroviral combination therapy at high risk of developing Pneumocystis carinii pneumonia.

DESIGN

Prospective multicentre study.

PATIENTS AND METHODS

The incidence of P. carinii pneumonia after discontinuation of primary prophylaxis was studied in 396 HIV-infected patients on antiretroviral combination therapy who experienced an increase in their CD4 cell count to at least 200 x 10(6)/l and 14% of total lymphocytes; the study population included 191 patients with a history of CD4 cell counts below 100 x 10(6)/l (245 person-years) and 144 patients with plasma HIV RNA above 200 copies/ml (215 person-years).

RESULTS

There was one case of Pneumocystis pneumonia, an incidence of 0.18 per 100 person-years [95% confidence interval (CI), 0.005--1.0 per 100 person-years]. No case was diagnosed in groups with low nadir CD4 cell counts (95% CI, 0--1.2 per 100 person-years) or detectable plasma HIV RNA (95% CI, 0--1.4 per 100 person-years).

CONCLUSIONS

Discontinuation of primary prophylaxis against Pneumocystis pneumonia is safe in patients who have responded with a sustained increase in their CD4 cell count to antiretroviral combination therapy, irrespective of the CD4 cell count nadir and the viral load at the time of stopping prophylaxis.