In HIV positive patients, measuring immune system function, rather than just symptoms, appears to provide health benefits in low- and middle-income countries, according to a report about a computer based model released on September 22, 2008 in Archives of Internal Medicine, one of the JAMA/Archives journals.
The study of HIV management techniques in developing countries is important, because “two-thirds of the world’s HIV-infected population resides in Africa, and most of the world’s new infections occur in low- and middle-income countries,” write the authors. Only 20% of adults who are in need of highly active antiretroviral therapy (HAART) receive it, despite significant progress made in increasing access to treatment.
For adults who receive treatment at all, this is usually monitored without regular checks of CD4 count, a measure of immune system function, or viral load, an indication of the number of active viruses in the body. Without regular monitoring of these levels, HAART treatment can be rendered less effective. The authors say: “Therefore, key questions in the management of HIV infection in resource-constrained settings are whether and how to monitor persons infected with HIV and when to initiate HAART.”
To investigate various options of diagnoses surrounding HIV/AIDS status for HAART treatment, Eran Bendavid, M.D., of Stanford University, Calif., and colleagues, created a computer model comparing three major strategies for starting, switching, and stopping HAART. These included models based on symptoms, based on CD4 counts, and based on the CD4 counts and viral load together. The analysis took many directions, according to the authors: “We used clinical and cost data from southern Africa and performed a cost-effectiveness analysis,” the authors write. “All assumptions were tested in sensitivity analyses.”
Approaches based on regular monitoring of CD4 counts, in comparison to those based on symptoms, in the conditions specified in the model, was associated with additional months of life expectancy and a reduction in medical costs. When the CD4-based strategies were initiated at a higher threshold, this was associated with an increased life expectancy, but not as long as the lower threshold. This overall increased life expectancy was also associated with a significant decrease in opportunistic infections.
The authors summarize their results: “Monitoring viral load with CD4 was more expensive than monitoring CD4 counts alone, added two months of life and had an incremental cost-effectiveness ratio of $5,414 per life-year gained relative to monitoring of CD4 counts.” This was also associated with the average costs of inpatient care in the proposed country, as fewer hospitalizations for opportunistic infections were associated with regular monitoring. This cost-effectiveness was influenced by the cost of testing in that area, along with the rates of virologic failure, when the HAART treatment is not effective against the viral levels in the blood.
“Our analysis shows that, where HAART is available, CD4 count monitoring with earlier treatment initiation provides a substantial increase in life expectancy, which in some settings may be achievable while reducing total expenditures for HIV infection,” they conclude. “As the number of persons receiving HAART increases, the potential health benefit and cost savings from use of CD4 monitoring will also increase.”
Cost-effectiveness of HIV Monitoring Strategies in Resource-Limited Settings: A Southern African Analysis
Eran Bendavid, MD; Sean D. Young, MS; David A. Katzenstein, MD; Ahmed M. Bayoumi, MD, MSc; Gillian D. Sanders, PhD; Douglas K. Owens, MD, MS
Arch Intern Med. 2008;168(17):1910-1918.
Written by Anna Sophia McKenney