In King County, WA, men who have sex with men (MSM) who inject methamphetamines (meth) are among the populations at highest risk for HIV infection, while HIV prevalence among other people who inject drugs (PWID) is low. Local drug problem indicators suggest recent increased meth use. It is not known if this increase is among MSM or non-MSM men and women, and if these networks are connected through injection equipment sharing. We investigated temporal trends in meth use among PWID in King County and estimated frequency and characteristics of injection equipment sharing.
We used data from two serial cross-sectional surveys of PWID in King County. From 2005-2015, four National HIV Behavioral Surveillance (NHBS) IDU surveys used respondent-driven sampling to survey PWID about their drug use behaviors (N=2,103). From 2004-2015, the Public Health–Seattle and King County Needle Exchange (NX) conducted 5 behavioral surveys of all NX clients over a two week period (N=1,964). These analyses were restricted to PWID who reported any sex in the past year and stratified by MSM, men who have sex with women (MSW), and women. We calculated frequencies and evaluated temporal trends using multivariable Poisson regression with a log link adjusting for age, gender, race, and NHBS field site locations.
Any meth injection in the past year increased significantly among PWID – including MSM, MSW, and women – in King County between 2005-2015 (see Figure). NX survey data were nearly identical. In NHBS-IDU, the magnitude of change was greatest among women with reported meth use increasing from 27% in 2005 to 61% in 2015. Among MSW, meth use increased from 40% to 63%, and among MSM from 55% to 88%. These trends remained statistically significant after adjusting for potential confounders. Among NHBS-IDU meth injectors, sharing any drug injection equipment in the last year was reported by 54% of MSM, 73% of MSW, and 78% of women. Among meth injectors who were not MSM, 6% of men and 12% of women reported sharing injection equipment with someone who was likely to be a MSM in the previous 12 months. Likewise, 25% of MSM meth injectors reported sharing injection equipment with a MSW or woman.
Meth use has increased dramatically among PWID in King County over the past decade. Given non-trivial rates of sharing injection equipment with meth-using MSM – a population with an HIV prevalence of 35-40% – non-MSM men and women who inject meth could be an emerging population at risk for HIV.