The question about proportion of inpts with opioid addiction is complicated.
First, the number of clear opioid addicts is small. These addicts are people who use heroin for example, or inject or snort other opioids. This also includes people who clearly have use that is out of control. Remember, addiction is compulsive, destructive drug use. Examples of this latter group are people who use far in excess of what is prescribed, who go to multiple doctors, who use to get intoxicated, and whose use is clearly dysfunctional. Pain management for this group is difficult and these patients are usually grossly undertreated, out of both ignorance and moral condemnation. However, the approach to these patients in overall management is pretty clear in that ongoing prescription of regular opioids by a typical provider is contraindicated and these pts by and larger only respond to opioid agonist therapy (maintenance) with either buprenorphine or methadone. There is not a single study demonstrating efficacy of 12 step or other rehab in treating established opioid addiction and relapse is all but inevitable, usually shortly after leaving rehab. Unfortunately, that is usually what they are referred to. That's like referring a diabetic to a spa for a couple of weeks, and not offering any medication, but that's what's done.
Second are those with no prior significant opioid use, or relatively minimal use, in other words, typical pts requiring pain management. I don't think we do very well with this group based on my observations, in large part due to ignorance about individual variation in pain sensitivity, pain tolerance, opioid metabolism, etc. This is the easiest group to demonstrate improvement.
Third are the most problematic. These poor folks have chronic severe pain requiring ongoing management with opioids. Unfortunately, there is a wide variability in how these pts and this treatment are perceived. There is a group of vocal opponents who strongly believe pts should never be offered this treatment. Most experts are in the middle, realizing that long term opioid treatment for chronic pain has modest benefit on average (about 30% reduction in pain, range 0-50%) and which comes with a fair amount of risk and baggage. Nevertheless the vast majority of pain experts understand that although some pts are able to tolerate severe pain without opioids, many are not and with with all of its baggage, we're stuck with opioids until something else comes along. Note that opponents of opioid therapy have no evidence on their side and there arguments are based on studies of highly select patients and animal models and they usually exaggerate the harms, so I think their beliefs are mostly based on moral judgements or at least wishful thinking. All the published expert guidelines recommend appropriate use of long term opioid treatment if managed properly.
Whether a pt like this is "addicted," a "drug-seeker," a "somatizer," "manipulative," a "drug-coper," "malingering," or other pejorative terms is therefore mostly in the eye of the beholder, and projection of the clinician's values, beliefs and judgments rule the day. Basically, the observers are voicing an opinion that the patient is asking for and using these medications for inappropriate or invalid reasons, such as emotional relief (as if one could discern between pain and one's response to it.) Here's my rule about the value of such judgements: Can this opinion be disproved? If not, to me it's worthless. For example, I might interpret pain behavior in a certain individual as a manipulation "just to get high" rather than to "relieve legitimate pain." Now try to disprove that. You can't. So I might respond to the clinician, "You're just saying that because your father was an alcoholic and your mother was histrionic and constantly complaining about various vague physical symptoms." Now try to disprove that. You can't. So if you ask certain other clinicians in the hospital, you're more likely to get a "diagnosis" of "addiction" than if you ask me. None of us can prove we're right because the science isn't there and this is an almost impossible problem to conduct rigorous studies on. I choose to stay with ignorance and not assume I understand something that we cannot (because the science isn't there) and to approach the problem pragmatically: "How can I maximize function and relief from suffering?"
In my practice, the rule I use is this: is the patient better or worse off with the medication than without? If the answer is better, and the patient takes the medication as directed, then that person isn't addicted. By definition, their use is not compulsive or destructive, so therefore they are not addicted. (Although they will have symptoms if they suddenly stop, but that's true with Effexor too.)
So I think this last group of patients experiences wide fluctuations in attitudes, behaviors, opinions and treatments from one clinician or facility to the next. My patients complain bitterly about this, about how they feel that everyone sees them as "addicts" or "Junkies," how they are treated with contempt and judgment by some clinicians, and how often their pain is inadequately treated. They may be overtreated or undertreated, but undertreatment is much more common that overtreatment. This is a group that would require a concerted focused effort to improve pain management. Scott Tongen helped with this by developing new protocols for opioid tolerant patients, and Ben has been promoting the use of ketamine to reduce need for opioids, which I think is not well researched, but appears to be very promising.
Sorry for the lengthy reply, but there's no simple way to think/talk about this, unless you're one of the people who just says,"Man up!"
As for quality improvement, I would guess that considerable work would need to be done to actually understand who is and is not getting good pain management before developing an intervention.
And no, I do not think UTD is better/worse than other places in this regard.
All the best!