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Validity of the 1–4 mg/L efavirenz mid-dose target concentration window in children

Determine the validity of the 1–4 mg/L mid-dose efavirenz target concentration window in children living with HIV, assessing whether this therapeutic window appropriately reflects virological failure risk and adverse events in pediatric populations.

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Background

In the CHAPAS-3 trial application, the authors examine causal effects of efavirenz mid-dose concentration on virological failure. Clinical practice often targets a 1–4 mg/L window, yet the appropriateness of this range in children is not firmly established.

The paper explicitly notes uncertainty about this window’s validity in pediatric settings, motivating causal analyses focused on the lower bound and highlighting a broader clinical open question.

References

In both adults and children the mid-dose target concentration window is typically given as between 1 mg/L and 4 mg/L, but especially in children the validity of this window is partially unclear.

— A Diagnostic to Find and Help Combat Positivity Issues -- with a Focus on Continuous Treatments (2502.11820 - Ring et al., 17 Feb 2025) in Practical Application (Section 5.1: Data and Research Question)