Remembering Dr. Bob: “The father of ICD-10-PCS”

January 25th, 2017 / By Rhonda Butler

Dr. Robert Mullin passed away on Friday, January 20. A sad day for all of us. Dr. Bob was one of the clearest, toughest, most visionary thinkers it has ever been my privilege to know.

I am too sad at heart to write more today, so I offer some excerpts from a blog I wrote four years ago in tribute to him:

If any one person deserves author credit for ICD-10-PCS, it is Dr. Robert Mullin. His career included cardiothoracic surgery in the Navy and at St. Raphael’s in New Haven, Connecticut among other places, as well as research in healthcare payment methodologies, beginning with his role in developing the original DRGs in the 1970s. Toward the end of his career, he spent five years working with Rich Averill and a team of coding specialists and physicians, developing the initial version of ICD-10-PCS. PCS was first released by CMS for public comment in 1998.

At the time, when he gave talks about ICD-10-PCS, Dr. Bob was often introduced as “the father of PCS.” As the years went by and we were no closer to ICD-10 implementation, he would change it to “grandfather,” and the audience would laugh, ruefully, because it was a little too true.

Dr. Bob retired about seven years ago [now 11 years], before the ICD-10 proposed rule was published. He was my mentor and friend in the years before he retired, and whatever bedrock understanding of PCS I have, I owe to him. He was a visionary and a “mad scientist”—a term I use for some of my favorite people on the planet.

His design for PCS was radical—a taxonomy of the physical actions (aka root operations) that can be performed on a body part. You can cut out some of a body part (Excision), you can cut out all of it (Resection), or you can obliterate it (Destruction). If the body part is a tube or opening, you can widen the diameter (Dilation), narrow the diameter (Restriction), close it off altogether (Occlusion). If the body part is a tube or reservoir you can reroute the plumbing (Bypass). And so on—31 root operations in all, easily learned by anyone who uses the system.

Dr. Bob’s architecture for PCS was equally radical—a set of tables containing the building blocks for PCS codes. Organized by body system, each body system contains the root operation tables and these tables contain the available choices of body part, approach, device and qualifier for that root operation.  This architecture is tailor-made for efficient aggregation, database queries and policies that can define a patient population with ridiculous ease.

In Dr. Bob’s vision of the future, the very act of coding would be transformed by PCS, including new hardware. Early in the 2000s, he described hospitals having an ATM-like screen for procedure coding—no keyboard, only the PCS menu of tables on a standalone screen. The coder could select the desired PCS table and choose a value from each column of a table to build the code. Dr. Bob was essentially describing the iPad—back when it was only a twinkle in Steve Jobs’ eye.

PCS is different, by design, and that after all is the point. Dr. Bob was the first to remind people, “Of course PCS is different. If it weren’t different there would be no point in switching.”

Rhonda Butler is a clinical research manager with 3M Health Information Systems.


To learn more about the life and legacy of Dr. Bob, visit his memorial webpage