Proportion of deaths co-involving methamphetamine and heroin or fentanyl peaked at 61.2 percent in 2021 Methamphetamine-related mortality increased 50-fold from 1999 to 2021, and the proportion of deaths co-involving heroin or fentanyl also increased, according to a study published online Feb. 2 in the American Journal of Public Health. Rachel A. Hoopsick, Ph.D., M.P.H., from the...