PDMP dates and must-access PDMP dates are highly contested.
PDMP start dates for PDMPs that do not have a usage mandate
Start dates of early PDMPs are terribly hard to pin down, with many differences in dates reported by PDAPS and NAMSDL. For dates on PDMPs that do not require doctors to check them, I believe that the recent Horwitz et al. paper is destined to become the new "gold standard" for these dates. Check it out at https://www.nber.org/papers/w24947.pdf
Must-Access PDMP dates that require prescribers to query PDMP under various circumstances
"Mandated" PDMPs, also known as "must access" PDMPs, legally require prescribers to query them under certain circumstances. I use Mandate dates that differ in some ways from Carey and Buchmueller (2018). These mandated PDMP dates vary across sources, and researchers should specify whether they are concerned with mandates of registration (which require practitioners to register within the state's PDMP by a certain date) and mandates of use (which require practitioners to query the PDMP under various circumstances).
For my own work, I only care about mandates of use. Since I am being contacted about these dates, I will provide my dates and sources below:
I'm currently updating the Mandate dates. Please email me if you'd like the set of start dates.
Papers to reference:
Buchmueller, Thomas C., and Colleen Carey. "The effect of prescription drug monitoring programs on opioid utilization in medicare." (2017). 2017 version of the paper available at https://www.nber.org/papers/w23148.pdf
Horwitz, Jill, Corey S. Davis, Lynn S. McClelland, Rebecca S. Fordon, and Ellen Meara. "The problem of data quality in analyses of opioid regulation: The case of prescription drug monitoring programs." (2018). Draft available at https://www.nber.org/papers/w24947.pdf