Consistent estimates of very low HIV incidence among people who inject drugs: New York City, 2005-2014

Objectives. To compare methods for estimating low HIV incidence among persons who inject drugs. Methods. We examined 4 methods in New York City, 2005 to 2014: (1) HIV seroconversions among repeat participants, (2) increase of HIV prevalence by additional years of injection among new injectors, (3) the New York State and Centers for Disease Control and Prevention stratified extrapolation algorithm, and (4) newly diagnosed HIV cases reported to the New York City Department of Health and Mental Hygiene. Results. The 4 estimates were consistent: (1) repeat participants: 0.37 per 100 person-years (PY; 95% confidence interval [CI] = 0.05/100 PY, 1.33/100 PY); (2) regression of prevalence by years injecting: 0.61 per 100 PY (95% CI = 0.36/100 PY, 0.87/100 PY); (3) stratified extrapolation algorithm: 0.32 per 100 PY (95% CI = 0.18/100 PY, 0.46/100 PY); and (4)newly diagnosed cases of HIV: 0.14 per 100PY (95%CI = 0.11/100 PY, 0.16/100 PY). Conclusions. All methods appear to capture the same phenomenon of very low and decreasing HIV transmission among persons who inject drugs. Public Health Implications. If resources are available, the use ofmultiple methodswould provide better information for public health purposes.