For HIV-infected persons, CD4+ lymphocyte percentages or counts should be monitored at least every 6 months. Some experts prefer to obtain a second count within a few months of the first count to assess the rate of decline. Subsequent CD4+ enumerations may be desirable at intervals of less than 6 months in certain situations such as: a) the presence of fever or thrush, b) a recent rapid decline in CD4+ cell count, c) a CD4+ percentage in the 20-30 range, or d) a CD4+ absolute number in the 200-300/mm3 range. If a decision to start prophylaxis is to be made on the basis of a low CD4+ cell count or percentage, the CD4+ enumeration should probably be repeated, unless previous determinations indicate the low count or percentage is consistent with an established trend.
Thirteen trials performed between the years 1974 and 2008 were included, involving 1412 patients. Four trials included 520 children with acute lymphoblastic leukemia and the remaining trials included adults with acute leukemia, solid organ transplantation or autologous bone marrow transplantation. Compared to no treatment or treatment with fluoroquinolones (inactive against Pneumocystis), there was an 85% reduction in the occurrence of PCP in patients receiving prophylaxis with trimethoprim/sulfamethoxazole, RR of (95% CI to ; 10 trials, 1000 patients). The evidence was graded as moderate due to possible risk of bias. PCP-related mortality was also significantly reduced, RR of (95% CI to ; nine trials, 886 patients) (low quality of evidence due to possible risk of bias and imprecision), but in trials comparing PCP prophylaxis against placebo or no treatment there was no significant effect on all-cause mortality (low quality of evidence due to imprecision). Occurrence of leukopenia or neutropenia and their duration were not reported consistently. No significant differences in overall adverse events or events requiring discontinuation were seen comparing trimethoprim/sulfamethoxazole to no treatment or placebo (four trials, 470 patients, moderate quality evidence). No differences between once daily versus thrice weekly trimethoprim/sulfamethoxazole were seen (two trials, 207 patients).