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Abstract:
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CD4 count is a measure of HIV disease progression after a person has been infected with HIV. The assumed relationship between CD4 count and time since infection is based on published results. Without treatment after HIV infection, CD4 count is expected to follow a linear decline in the square root. This relationship was recently used to estimate HIV incidence and the proportion of undiagnosed HIV infections. However, this incidence estimation method works well when the following conditions hold: HIV incidence is relatively stable, HIV testing hazard is constant, and the CD4 count depletion model is correct. The sensitivity of the method when these conditions are not met is unknown. Therefore, we conducted a simulation study to evaluate the performance of this method to estimate incidence and the proportion of undiagnosed infections. Using simulated data, we obtain expected biases and the coverage of 95% confidence interval estimates to evaluate the method when conditions are not met.
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