Risk of pneumocystosis after early discontinuation of prophylaxis among HIV-infected patients receiving highly active antiretroviral therapy

BACKGROUND Risk of pneumocystosis after discontinuation of primary or secondary prophylaxis among HIV-infected patients before CD4 counts increase to >==200 cells/microL (early discontinuation) after receiving highly active antiretroviral therapy (HAART) is rarely investigated. METHODS Medical records of 660 HIV-infected patients with baseline CD4 counts <200 cells/microL who sought HIV care and received HAART at a university hospital in Taiwan between 1 April, 1997 and 30 September, 2007 were reviewed to assess the incidence rate of pneumocystosis after discontinuation of prophylaxis for pneumocystosis. RESULTS The incidence rate of pneumocystosis after HAART was 2.81 per 100 person-years among 521 patients who did not initiate prophylaxis or had early discontinuation of prophylaxis, which was significantly higher than the incidence rate of 0.45 per 100 person-years among 139 patients who continued prophylaxis until CD4 counts increased to >==200 cells/microL (adjusted risk ratio, 5.32; 95% confidence interval, 1.18, 23.94). Among the 215 patients who had early discontinuation of prophylaxis after achievement of undetectable plasma HIV RNA load, the incidence rate of pneumocystosis was reduced to 0.31 per 100 person-years, which was similar to that of the patients who continued prophylaxis until CD4 counts increased to >==200 cells/microL (adjusted risk ratio, 0.63; 95% confidence interval, 0.03, 14.89). CONCLUSIONS Compared with the risk of pneumocystosis among patients who continued prophylaxis until CD4 counts increased to >==200 cells/microL after HAART, the risk was significantly higher among patients who discontinued prophylaxis when CD4 counts remained <200 cells/microL, while the risk could be reduced among patients who achieved undetectable plasma HIV RNA load after HAART.