Sloppy Risk Adjustment and Attribution Guarantee MACRA Won’t Work

Sloppy Risk Adjustment and Attribution Guarantee MACRA Won’t Work


flying cadeuciiI just finished reading the 962-page MACRA rule CMS released late in April. I was prepared for the mind-numbing complexity of the document. What I was not prepared for was CMS’s glib treatment of two fundamental issues: The woeful inaccuracy of the scores CMS will use to punish and reward doctors, and the cost to doctors of participating in ACOs, “medical homes” and other “alternative payment models” (APMs)

These are not peripheral issues. If CMS dishes out financial rewards and punishments based on inaccurate data, MACRA will, at best, have no impact on cost and quality and may well have a negative effect. The second problem – the high cost of setting up and running APMs – may not be as lethal as the inaccurate-data problem, but at minimum it will reduce physician participation in APMs and, therefore, the already slim probability that APMs will reduce Medicare costs and improve quality.

In this comment and two more to come, I will review both of these problems and CMS’s what-me-worry attitude toward them. I begin with a jaw-dropping example of CMS’s reckless indifference to its inability to measure physician “merit” accurately.

Apres moi le deluge

Outside the bubble where Congress and CMS live, there is a widespread recognition that CMS cannot measure physician “performance” accurately. Here are three statements by experts to that effect:

  • “[T]he practical reality is that … CMS, despite heroic efforts, cannot accurately measure any physician’s overall value, now or in the foreseeable future.” (Berenson and Kaye, “Measuring a physician’s value….” New Eng J Med, 2013 )
  • “We can’t estimate what the MIPs performance results will be, but the experience with other individual or group-level assessment of clinician performance generally finds that most clinicians cannot be easily differentiated from average. For example, the value modifier results for 2015, which in Medicare applies to large groups of 100 clinicians or more, found that 80 percent could not be differentiated from average, and they received no adjustment.” (Kate Bloniarz, MedPAC staff, transcript of January 16, 2016 MedPAC meetiing, p. 74)
  • “The [MIPS] resource use measures are scheduled to become more important, but measures to date have a poor track record in identifying efficient physicians and practices. For example, 96 percent of physician practices were scored as ‘average cost’ using similar measures in the 2016 Value-Based Payment Modifier program.” (Clough and McClellan, “Implementing MACRA….” JAMA, 2016)

What these statements tell us is that CMS cannot accurately measure the value or merit of the vast majority of physicians. In a world where evidence guides policy-making rather than groupthink, CMS would acknowledge this fact. But CMS refuses to do that. CMS simply couldn’t find the space in its ponderous MACRA rule to make even a single comment like the three I quoted above.

To the contrary, CMS made it clear they are hell-bent on inflicting rewards and punishments on all doctors who treat Medicare patients regardless of the accuracy of their data. The proposed rule contains two tables showing how CMS’s pay-for-“merit” scheme would affect doctors in the “Merit-based Incentive Payment System” (MIPS) program (which is where most doctors will be in the early years of the MACRA regime). The tables show that 46 percent of doctors will be deemed to have unacceptable “merit” and therefore worthy of punishment while 54 percent will be “meritorious” and therefore deserving of rewards. Worse, one of the tables shows that doctors in small clinics will suffer far more than those in large systems. Table 64 shows that 87 percent of solo doctors and 70 percent of 2-to-9-doctor clinics will be punished while only 18 percent of doctors in clinic chains with over 100 doctors will be punished.

CMS’s failure to say a word elsewhere in the rule about the disproportionate punishment meted out to smaller clinics, and CMS’s refusal to admit it will be dishing out this punishment on the basis of crude measurement, is appalling!

Too much noise, not enough signal

The crudeness of CMS’s cost and quality measurement, and the high noise-to-signal ratio of the feedback to physicians such measurement guarantees, is due primarily to two intractable problems: CMS’s inability to determine accurately which patients “belong” to which physicians (the attribution problem), and CMS’s inability to adjust cost and quality scores for factors outside physician control (the risk adjustment problem). Either problem by itself makes accurate measurement very difficult and, at the individual doctor and clinic level, impossible for all but a few simple process measures. Together the two problems are a lethal one-two punch to the fantasy that CMS or anyone else will ever measure the “value” of the vast majority of physicians accurately. [1]

CMS and managed care advocates generally have very little to say about the risk-adjustment problem and almost nothing to say about the attribution problem. If they say anything at all about the crude risk adjusters in use today, it is that scientists are rapidly improving the accuracy of risk adjustment and it’s only a matter of time before the risk-adjustment problem is fixed. That is nonsense (see my next comment). As for the attribution problem, all we hear from managed care buffs is silence. I have been unable to find a single paper, peer-reviewed or otherwise, that demonstrates that any of the attribution methods used by CMS or other insurers are accurate enough to measure physician “value.”

Of the two sources of noise in CMS’s feedback I am discussing here – sloppy attribution and crude risk adjustment – the attribution problem is logically the first one we should address. I do so in the remainder of this comment. I’ll discuss the risk-adjustment problem and CMS’s indifference to the cost of participating in APMs in subsequent comments.

Phantom patients and medical hotels

The “attribution” fad is a relative newcomer as managed care fads go. It arose around 2005, which is approximately when the ACO and “medical home” concepts began their overnight journey from obscurity to conventional wisdom. CMS inaugurated its first test of the ACO concept, the Physician Group Practice (PGP) Demonstration, in 2005. In November 2006, the amorphous phrase “accountable care organization” was invented at a MedPAC meeting, and in March 2007 the amorphous phrase “medical home” was endorsed by four physician groups.

The ACO and “home” fads triggered the attribution craze because proponents of ACOs and “homes” didn’t want to force patients to enroll with ACOs and “homes” and to have to use only the providers in those entities. Apparently ACO and “home” proponents feared that an enrollment requirement would trigger the sort of patient rebellion that HMOs triggered in the 1990s.

In any event, having decided that enrollment was to be avoided and attribution required, CMS and the rest of the health policy cognoscenti then decided that attribution to ACOs and “homes” would be done with a two-step process: (1) Patients would be assigned to primary care doctors from whom they received the plurality of their primary care services (as determined by claims data); (2) patients would, unbeknownst to them, be assigned to the ACO or “home” the doctor they were attributed to was in. That two-step method was the one CMS used to assign patients to the ten “group practices” that participated in the PGP demo. CMS continued to use this method in its ACO and “home” demos.

There are two administrative advantages to CMS’s two-step method. First, the plurality-of-primary-care method allows CMS to assign a lot more patients than a majority method would. Second, the use of claims data only (as opposed to claims data plus medical records data) makes attribution financially feasible. But the two-step method has a serious disadvantage: A substantial portion of the patients the method attributes to doctors have no relationship or only a tenuous relationship with the doctor and, therefore, with the ACO or “home” the doctor is part of.

The seriousness of this defect became obvious during the PGP demo. The final evaluation of that demo reported that the PGPs lost 60 percent of their assigned patients over the five-year period the demo ran. [2] The loss rate appears to be even higher for Pioneer ACOs. The 23 ACOs that were still in the Pioneer demo at the end of 2013 lost 38 percent of “their” patients between 2012 and 2013. [3] Valerie Lewis et al. reported an annual loss rate of 31 percent for simulated Medicare Shared Savings Program ACOs (see p. 590). Friedberg et al. reported a 43 percent loss rate over three years among medical home clinics participating in the Pennsylvania Chronic Care Initiative.

For those of us not steeped in the peculiar traditions of the managed care culture, it is very difficult to understand why doctors should be “held accountable” for phantom patients. Or even for patients doctors see only infrequently. Similarly, it is very difficult for ordinary people to grasp why a clinic should be called a “medical home” when 43 percent of “its” patients disappear from the attribution list over a three-year period. If we must use cute labels, I suggest we call the medical home a “medical hotel” until such time as “homes” are no longer populated with sloppy attribution methods.

CMS’s silence about sloppy attribution is not acceptable

Since CMS began tinkering with attribution schemes a decade ago, it has acted as if it has no obligation to justify its use of any method of attribution. It can pick any scheme it likes and critics can go hang themselves. That see-no-evil attitude is conceivably justifiable for demonstrations affecting small slices of the physician and patient populations. But MACRA is no demonstration.

Yet in its proposed MACRA rule, CMS continues its see-no-evil attitude about its attribution methods. Here is the most informative statement in the MACRA rule that CMS makes about its attribution method: “Commenters [responding to CMS’s 2015 request for information on MACRA] also expressed concern that current attribution methods are holding many clinicians accountable for costs they have no control over, while other clinicians have no patients attributed and no way of calculating accurate scores.” (p. 137) Does CMS care what these commenters think? Apparently not. CMS has no comment. CMS simply tells us they will use the plurality-of-primary-care-visit method under MACRA. [4]

CMS should have said a lot more than that. CMS should have made at least these three statements about its attribution method:

  1. Its attribution method, while cheap, has substantially dulled the accuracy of its measurement of physician “performance” in the value-modifier program and the ACO and “home” demos;
  2. CMS’s two-step method has created high churn rates among patients assigned to ACOs and “homes”; and
  3. CMS has gotten into the habit of using the two-step approach without bothering to justify it, and CMS would now like the public to comment on whether its attribution method can be justified by any moral or logical principle.

It is obvious why CMS made no statements like these in its rule. The attribution problem isn’t fixable. CMS can cling to the plurality-of-primary-care-visit method and pay a high price in the form of grossly inaccurate assignment of patients. Or they can shift to a large-majority method, which would increase the accuracy of attribution but would worsen measurement accuracy by reducing the size of the pools of patients subject to measurement. The reduction in the size of patient pools would also reduce the size of the financial rewards and punishments relative to total Part B spending, which would in turn reduce the strength of the signal compared with the noise.

CMS should at minimum tell us which form of poison it prefers. Ideally CMS will concede neither poison should be picked and that attributing patients hither and yon was never a good idea to begin with.

[1] Note that I am discussing the measurement of the “value” of all physicians who treat Medicare patients using claims data, which is what CMS proposes to do under MACRA. I am not saying it is impossible to measure accurately the cost or quality of specific medical services using claims data, medical records data, and data from other sources such as information about income. I’ll have more to say about accurate measurement of specific services in my next comment.

[2] Here is a quote from the final evaluation of the PGP demo: “PGPs generally retained approximately 70 percent of their assigned beneficiaries from one year to the next; and … PGPs generally retained approximately 40 percent of their assigned beneficiaries after five years.” (p. 221)

[3] ] Unlike the final evaluation of the PGP demo, the evaluation of the Pioneer ACO demo by L&M Policy reported retention rates for both patients and doctors. The retention rate among Pioneer ACO doctors between 2012 and 2013 was 73 percent (see p. 96), which means the loss rate was 27 percent. I derived the 38 percent loss rate for patients in the Pioneer ACO demo from data presented in Table 23 (p. 95) using the same unweighted averaging method L&M used to derive the retention rate for doctors.

[4] CMS states in the MACRA rule that it will continue to use the plurality-of-primary-care-visit method in measuring doctors in both the MIPS and APM programs. CMS makes this statement explicitly with respect to MIPS. CMS says this implicitly with respect to APMs. They do so by listing the CPC+ “homes” and the MSSP and Next Gen ACOs as examples of entities that will qualify as APMs (see Table 32 pp. 501-502). These programs attribute patients using the plurality-of-primary-care-visit method.

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6 Comments on "Sloppy Risk Adjustment and Attribution Guarantee MACRA Won’t Work"

Steven Findlay
Jun 7, 2016

Attribution and patient migration are indeed challenging, as is the entire field of physician performance measurement I concur with Jim and Jonathan’s comments, and support their plea to start spinning the whole MACRA dialogue towards constructive solutions and recommendations….to CMS and the field. Kip, you clearly have deep knowledge in this area and raise critical issues. But I think you are much more likely to get CMS’ ear, and influence policy making and regulations, by offering options for fixes rather than bashing CMS (and government regulations in general and overall) in a way that sounds sort of Trumpish some of the time—–though your hostility seems more focused than The Donald’s. I’ll look forward to your future posts and hope they’ll be be a bit more modulated.

Jun 6, 2016

As you mention in this excellent piece, CMS has no interest in addressing either the attribution or risk adjustment problem. They are unfixable, fatal flaws that have to be ignored, otherwise it quickly becomes clear MACRA is built on a foundation of sand.

CMS has too many people working on this, too much invested to admit to this. So external forces will need to keep pressing.

Jun 6, 2016

Private practice is already dying. This will be the coup de grace.

William Palmer MD
Jun 6, 2016

Kip, thanks for plodding through MACRA. A true sacrifice.

I think that some of the new science coming along is going to be so important and politically needed that it is going to rip away much of this disgusting and infinitely proliferating regulatory bureaucracy.

Eg it appears that maybe stem cell therapy for strokes really does work. Think of these new costs! AI is coming along and may be so useful that all providers may need access. Precision therapy for most malignancies may be unavoidable politically and medically. Niacin-like derivatives may prolong survival of cells and reduce rate of aging phenomena. Topoisomerase may be used to enhance transcription and phenotypic expression of much genetic information–as it can open up tightly packed DNA strands, allowing access to RNA polymerase.

My point is that when expensive advances become highly alluring and defined as necessary, the old financing and may be ripped up and forgotten. This is just an optimistic hope.

Jun 6, 2016

Hi Kip and Jonathan….all good comments. From my non-MD perspective:

1. We have to start measuring something–anything! We won’t be close to good much less perfect at the start and have to get over that.
2. Let’s learn from our mistakes. We seem to be good at identifying the mistakes, but I don’t see any learning from them. What are your suggestions?
3. Attribution is a big problem. We may have to bite the bullett and REQUIRE substantially all treatment be from the ACO or Home and not allow patients to go wherever they wish. I know that’s a tough row, but at least there will be some integrity to measurement. Patients can switch every anniversary, but like getting Medicare, open enrollment/disenrollment.
4. Yes, the cost of an APM home is staggering. Payors need to help big time, and that means a combination of the government and commercial payors. We did just that in RI with PCMHs with some success, and developed at least a degree of trust and loyalty with primary care.

We need more solutions.


The problems Kip raises around attribution are serious. I would go so far as to say that eventually attribution models should be replaced with something else (something more real, like a patient selection with network and coverage implications on the patient side, and not just passive assignment with payment implications on the provider side). The big question is: are attribution models painfully imperfect but useful kluges to get the American health care system off its keister and moving in the direction of coordinated care and population health, or, is the gain not worth the pain? In my view, we don’t have the luxury of waiting for the perfect system any more and, unless someone has a better idea that is politically feasible now, we need to go through this pain to get somewhere better.

One cautionary point to consider: the fact that people leave any given care organization to which they’ve been assigned is unlikely to go away soon. 40% retention over 5 years is in the same ballpark as health insurer retention rates over 5 years. 20% loss in a given year is common, and 10% is exceptional. Even if we move from passive attribution to a model in which the patient/member selects a population health network tied to health benefits, there is still going to be turnover (people move, die, have bad experiences, have employers change insurers, etc.), and the ability of organizations to reap the rewards of their improved quality of care and prevention will have this as a limiting factor.

So, the next wave of thinking about population health needs to consider how to improve retention. This is something health insurers have been thinking about for years, without too much success at moving the needle. But for plans that are partnerships with providers or sponsored by providers, there are new incentives and more options available to keep people “home.” It’s a great opportunity for creative thinkers and first movers.