Estimating the probability of diagnosis within one year of HIV acquisition.

Background: Early diagnosis of HIV is important for the prevention of ongoing transmission and development of HIV-related illness. The purpose of this study is to develop an outcome indicator to monitor the progress in early HIV diagnosis. Methods: Persons diagnosed with HIV in New York City and their first CD4(+)test results were used to estimate the distribution of HIV diagnosis delay, based on a CD4(+)count depletion model. The distribution was then used to estimate the probability of diagnosis within 1 year of HIV acquisition, which is the number of cases diagnosed in a given calendar year for which diagnosis occurred within 1 year of acquisition divided by the number of incident cases in that calendar year. Results: In 2012-2016, the estimated annual probability of diagnosis within 1 year of HIV acquisition in New York City was 43.0% [95% confidence interval (CI): 37.9-48.2%), 42.5% (95% CI: 36.8--48.3%), 42.8% (95% CI: 36.3--49.2%), 42.9% (95% CI: 35.4--50.3%), and 42.2% (95% CI: 33.1--51.2%), respectively. Conclusion: National and local health jurisdictions should consider using this new outcome indicator, the probability of diagnosis within 1 year of HIV acquisition, to monitor their progress in early HIV diagnosis.