Achievement and maintenance of viral suppression in persons newly diagnosed with HIV, New York City, 2006-2009: using population surveillance data to measure the treatment part of "test and treat".

BACKGROUND: Viral suppression reduces HIV-related morbidity and transmission to uninfected partners. Models suggest that the transmission benefit may extend to whole communities.
METHODS: We used New York City surveillance data to analyze viral suppression among persons newly diagnosed with HIV between 2006 and 2009. The Kaplan-Meier product limit method was used to estimate the cumulative proportion achieving suppression and experiencing failure. Cox proportional hazards regression was used to identify factors associated with time to achieve suppression and duration of suppression and to calculate hazard ratios (HRs).
RESULTS: Among the 12,122 new diagnoses, 7663 (63.2%) ever achieved suppression by June 30, 2011, 26.6% within 6 months and 39.8% within 12 months of diagnosis. 89.2% of those ever achieving suppression maintained it for 6 months, and 81.9% for 12 months. The proportion achieving and maintaining suppression improved with each successive diagnostic year (P < 0.0001). Patients with initial CD4 <350 cells per cubic millimeter achieved suppression more rapidly (P < 0.0001) and maintained it longer. Those with the highest nadir CD4 before suppression (≥500 cells/mm³) were least likely to maintain it (men: HR = 0.72; 95% confidence interval, 0.61 to 0.82 and women: HR = 0.67; 95% confidence interval, 0.53 to 0.87).
CONCLUSIONS: Persons in successively later diagnostic cohorts and those with nadir CD4 at the federal antiretroviral therapy threshold had larger proportions suppressed, faster time to suppression, and longer duration. New guidelines recommending therapy independent of CD4 may result in improvements in proportion suppressed in future diagnostic cohorts.