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 100 PY (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 of multiple methods would provide better information for public health purposes.