Comparison of dynamic monitoring strategies based on CD4 cell counts in virally suppressed, HIV-positive individuals on combination antiretroviral therapy in high-income countries: a prospective, observational study. Lancet HIV
Caniglia et al. on behalf of the HIV-CAUSAL Collaboration and the Centers for AIDS Research Network of Integrated Clinical Systems aimed to establish whether information about an individual’s time-varying CD4 cell count can provide any additional benefit in determining when monitoring frequency can be decreased.
The authors compared three strategies using different CD4 cell count thresholds to determine whether CD4 cell count and HIV RNA viral load was measured every 3–6 months (when below the threshold) or every 9–12 months (when above the threshold). The threshold was 200 cells per μL in the first strategy, 350 cells per μL in the second strategy, and 500 cells per μL in the third strategy.
They found that the different strategies had no effect on survival, AIDS-free survival, and mean CD4 cell count at 2 years, suggesting that decreasing monitoring to annually when CD4 count is higher than 200 cells per μL compared with higher than 500 cells per μL does not worsen the short-term clinical and immunological outcomes of HIV-positive individuals with viral suppression. However, the authors found that decreasing monitoring frequency when CD4 count is higher than 200 cells per μL compared with higher than 500 cells per μL results in an increased risk of virological failure at 2 years. Compared with threshold 500, the 24 month risk ratios of virological failure (viral load more than 200 copies per mL) were 2.01 (1.17–3.43) for threshold 200 and 1.24 (0.89–1.73) for threshold 350.
In conclusion, the study-results suggest that in virologically suppressed individuals on ART in resource-rich settings, the CD4 threshold at which monitoring frequency can be decreased to annually might be as low as 200 cells per μL with no effect on clinical and immunological outcomes after 2 years. However, more frequent virological monitoring might be necessary to reduce the risk of virological failure. Further research is warranted to obtain more precise effect estimates over longer periods of follow-up, and to determine the generalisability of these results to resource-limited settings.