Optimal Frequency of Cd4 Cell Count and HIV Rna Monitoring Prior to Initiation of Antiretroviral Therapy in HIV-Infected Patients

Abstract

Context

Guidelines regarding the frequency of CD4 cell count and HIV RNA monitoring in HIV-infected patients vary, with recommended strategies ranging from every 2 to every 6 months.

Objective

To determine optimal CD4 cell count and HIV RNA monitoring frequency in HIV-infected patients prior to antiretroviral therapy initiation. Design: Cost-effectiveness (CE) analysis using an HIV simulation model incorporating CD4 cell count and HIV RNA as immunological and virological predictors of clinical outcomes.

Setting

Hypothetical clinical setting.

Patients

Simulated cohort based on initial clinical presentation of HIV-infected patients in the US.

Intervention

CD4 cell count and HIV RNA monitoring at frequencies ranging from every 2 to 24 months prior to antiretroviral initiation, as well as accelerated monitoring frequencies as CD4 cell counts approach a specified treatment threshold.

Outcome measures

Life expectancy, quality-adjusted life expectancy and costs.

Results

For patients presenting with median CD4 cell count 546/mm³ and median HIV RNA 4.8 log₁₀ copies/ml, incremental CE ratios ranged from US$37800/quality-adjusted life year (QALY) gained for a constant testing frequency of every 18 months compared with every 24 months, to US$303300/QALY gained for a constant testing frequency of every 2 months compared with every 4 months when starting treatment at a CD4 cell count of 350/mm³. Monitoring every 12 months until a warning CD4 cell count threshold of 450/mm³ followed by every 3 months until 350/mm³ had an incremental CE ratio of US$74700/QALY gained. When starting antiretroviral therapy at CD4 cell count 200/mm³, monitoring every 12 months until 300/mm³ followed by every 2 months until treatment initiation yielded an incremental CE ratio of US$52200/QALY gained compared with the next best strategy. Increasing monitoring frequency as CD4 cell counts approached a treatment threshold yielded greater incremental clinical benefit for less cost than strategies using a constant frequency.

Conclusions

Monitoring HIV-infected patients every 12 months until 100 CD4 cells/mm³ prior to a specified treatment threshold followed by more frequent monitoring every 2 or 3 months until antiretroviral therapy initiation is both more effective and cost-effective than the current standard of care.