New method for estimating HIV incidence and time from infection to diagnosis using HIV surveillance data: results for France.

OBJECTIVE: To estimate HIV incidence and time between HIV infection and diagnosis of infection.
DESIGN: We devised a new model for estimating the incidence of HIV infection and the time between infection and diagnosis from HIV surveillance data. Our approach takes into account temporal changes in HIV test-seeking behaviors and requires few data on individuals newly diagnosed with HIV (i.e. date of diagnosis and clinical status at diagnosis). Using our new approach, we analyzed data for patients newly diagnosed with HIV in France between April 2003 and December 2008.
RESULTS: The estimated mean time between infection and diagnosis ranged from 37.0 months among men who have sex with men to approximately 53.0 months among heterosexual men. Intermediate values were obtained for injecting drug users and heterosexual women. We estimated that mean times changed very slightly (≤1.2 months) during the period 2004-2007: it shortened among MSM, remained stable among non-French-national heterosexual men, and lengthened in all the other exposure categories. We estimated that the total number of new infections increased, but not significantly, between 2004 and 2007, reaching 7851 [95% confidence interval 5400-9919] in 2007. MSM accounted for the largest number of new infections (38%).
CONCLUSION: HIV continues to spread in France, and the average time between infection and HIV diagnosis remains excessively long. New policies to expand the offer and acceptance of voluntary HIV testing are thus urgently needed. Our method will also be very useful to monitor and evaluate the impact of future HIV testing policies.