Benefits of Adding Viral Load or CD4 Cell Count Monitoring to Clinical Monitoring Alone Are Modest

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In lower-income developing nations, the World Health Organization (WHO) recommends a population-based approach to antiretroviral treatment with standardized regimens and clinical decision making based on clinical status and -- where available -- CD4 cell count, rather than HIV viral load monitoring.

The objective of the present study, published in the April 26, 2008 issue of The Lancet, was to examine the potential consequences of such monitoring strategies, especially in terms of survival and emergence of drug resistance.

A validated computer simulation model of HIV infection and the effect of antiretroviral therapy was used to compare survival, use of second-line regimens, and development of resistance that result from different monitoring strategies -- based on viral load, CD4 cell count, or clinical observation alone -- for determining when to switch therapy in people who started antiretroviral treatment using the WHO-recommended first-line regimen of stavudine (d4T; Zerit), lamivudine (3TC; Epivir), and nevirapine (Viramune).

Results

• Over 5 years, the predicted proportion of potential life-years survived was:
• 83% with viral load monitoring (switching when HIV RNA > 500 copies/mL);

• 82% with CD4 count monitoring (switching at 50% drop from peak);

• 82% with clinical monitoring (switching when 2 new WHO stage 3 events or 1 WHO stage 4 event occurs).

• Corresponding values over 20 years were 67%, 64%, and 64%.

• Findings were robust to variations in model specifications in extensive univariate and multivariate sensitivity analyses.

• Although survival was slightly longer with viral load monitoring, this strategy was not the most cost effective.

Conclusion

Based on these findings, the study authors concluded that for patients on the first-line regimen of stavudine, lamivudine, and nevirapine, "the benefits of viral load or CD4 cell count monitoring over clinical monitoring alone are modest."

"Development of cheap and robust versions of these assays is important," they noted, "but widening access to antiretrovirals -- with or without laboratory monitoring -- is currently the highest priority."

HIV Epidemiology and Biostatistics Group, Department of Primary Care and Population Sciences, and Royal Free Centre for HIV Medicine, Royal Free and University College Medical School, University College London, London, UK.

5/16/08

Reference
AN Phillips, D Pillay, AH Miners, and others. Outcomes from monitoring of patients on antiretroviral therapy in resource-limited settings with viral load, CD4 cell count, or clinical observation alone: a computer simulation model. The Lancet 371(9622):1443-51. April 26, 2008.

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