Three years ago, and without notice, data about patients with substance use disorders began to disappear from Medicare and Medicaid files widely used in health services research. Because researchers had been afforded access to those data for decades, the change was mystifying. Austin Frakt raised an alarm, and he and I began to look into it.

The culprit was a 1976 regulation governing the privacy of information pertaining to substance use disorders. On its face, the regulation—which was drafted well before electronic records came into common use—seemed to prohibit the Centers for Medicare and Medicaid Services (CMS) from sharing such information with researchers. No one apparently noticed until 2013, at which point CMS started scrubbing its data.

This was a calamity for health services research. The data scrubbing made it impossible to use Medicare and Medicaid records to study efforts to combat addiction and the consequences of substance use. Beyond that, the non-random withholding of data would predictably skew research into any condition that was more common among people with substance use disorders—a point elegantly confirmed by a research team from Brigham & Women’s Hospital in Boston.

In the pages of the New England Journal of Medicine and the New York Times, Austin and I exhorted the Substance Abuse and Mental Health Services Agency (SAMHSA) to revisit the 1976 rule. Last February, SAMHSA agreed to do so, issuing a proposed rule to end the data-scrubbing. We crossed our fingers and waited.

The wait was rewarded on Friday with the release of a final rule that closely tracks the original proposal. Under the rule, CMS is free to share addiction-related records with researchers who secure Institutional Review Board approval and agree to appropriate safeguards—standard procedure for receipt and use of all identifiable CMS research data. In considering the comments that it received, the agency took real pains to enable research into addiction and correlated conditions, pointedly rejecting input that would have imposed needless burdens.

In short, the rule is excellent. SAMHSA should be commended.

There’s still a shadow here, however. Because the rule doesn’t take immediate effect, the incoming administration can still withdraw it. And President Trump will almost certainly impose a moratorium on any Obama-era regulations to allow his administration to review them. That doesn’t mean the rule is dead: given the President’s expressed interest in curtailing the opioid epidemic, I’m cautiously optimistic that the rule will eventually go through.

But nothing is certain. The fight isn’t quite over yet.

@nicholas_bagley