Virological conditions indicating that a change to second-line therapy is warranted include:
Persistently elevated viral load in the absence of poor adherence to medication
Progressive increase in viral load after the beginning of treatment (changes greater than 5-fold (0.7 log) in children less than 2 years of age, and of at least 3-fold (0.5 log) in children 2 years of age or older
< 1.0 log reduction in relation to the initial level after 24 weeks
Repeated viral load detection in children with earlier undetectable levels.
Before an ARV regimen is thought be failing based on clinical criteria, the child should have had a reasonable trial on the ARV therapy (e.g., have received the regimen for at least 6 months).
Because of age-related declines in CD4 absolute cell count through age 6 years, when near-adult levels are reached, it is difficult to use absolute CD4 cell count to assess failure of therapy in younger children. However, for children aged 6 years or more, similar CD4 cell count criteria as used in adults is appropriate. Because CD4 cell percentage varies less with age, it can be used to gauge treatment response regardless of age. Data on use of total lymphocyte count to evaluate response to ARV therapy are not available.