Skip to main content

Advertisement

ADVERTISEMENT

Commentary

The Apophenia of Interventional Cardiology

March 2018

Operator quality assessment in percutaneous coronary intervention (PCI) continues to be disposed to the view that the more cases the interventionist performs, the more proficient the operator. Yet the quest to identify a precise annual or lifetime volume threshold that defines competence has not been rewarded; no powerful multivariate association between case volume and competence exists, and the relationship between volume and clinical outcomes is weak and inconsistent.1-3 The evidence does not support any particular volume level as a quality indicator. This observation, proven in every modern study over many years, confirms the maxim that not everything that counts can be counted, and not everything that can be counted counts.

Yet societal clinical competence statements continue to impose arbitrary “minimum” case volumes based primarily on political necessity.4,5 The perseverance on setting a minimum case volume, despite the results of numerous studies that cannot confirm this approach, is extraordinary in a field that prides itself on evidence-based practice. Moreover, since many studies show that a large number, if not a majority, of interventionists fail to achieve these volumes,2,6 the insistence on promulgating them places many board-certified practitioners in a Prohibition-style scofflaw state: we know that many in our profession do not meet our own competency criteria, which our own studies cannot show to be predictors of quality.

This unwillingness to acknowledge the implications of the data is irrational, and reflects a form of cognitive bias. Apophenia is a form of patternicity, defined as “the tendency to find meaningful patterns in meaningless noise” or “the experience of seeing patterns or connections in random or meaningless data.” Poulson7 describes it as “a ubiquitous feature of human nature; when our pattern-recognition systems misfire, they tend to err on the side of caution and self-deception.” That means that when we believe something is real even when it isn’t, we subconsciously over-interpret a perceived pattern in the data to fit our belief, because instinctively we expect to find it.

Liang and colleagues8 demonstrate the operator volume trends in Taiwan over a 13-year period, and show that three-fifths of the operators in that country do not meet the current arbitrary threshold that “defines” quality. Although they do not report outcomes, clearly, 60% of their country’s interventionists are not incompetent. Moreover, their data show that over time, while some of the lower-volume operators develop large practices, new operators join the workforce with low volumes until they and their practices mature. This life-cycle description seems highly relevant to American practice, and may well connect PCI volume to the cycle of maturation of one’s practice, rather than competence. Liang8 provides information that challenges preconceptions. Their data wonderfully illustrate that the economic and clinical realities of the practice environment establish operational metrics of quality better than arbitrary criteria. 

Moreover, the quality metrics employed in contemporary practice probably do not reflect technical or cognitive skill. Cardiology remains focused on collecting 30-day mortality as its primary measure, despite mathematical reasons for why its discrimination of quality is limited.3,9 Precisely on this basis, Fanaroff10 recently emphasized a somewhat increased odds ratio – just 1.16 – for low-volume operators vs high-volume operators, based on an absolute difference of only 0.4% mortality. Although they conclude that this suggests lesser quality, they note that low-volume operators (44% of the entire United States cohort) treated more cardiogenic shock, ST-elevation myocardial infarction (STEMI), emergent, and recent cardiac arrest cases (all P<.001), and that there was no difference compared with intermediate-volume operators (odds ratio, 1.05). Although the authors were careful to state that future studies should identify better correlates of competency, their analysis exaggerates the clinical significance of a weak correlation, and encourages a misleading and deceptive precept; the fact is that complications in PCI-treated patients are not usually a consequence of poor operator quality, but most often reflect case selection. Their occurrence is uncommon in elective cases, and to some extent occurs randomly in cases of higher acuity, so that statistically, it is difficult to discern quality on this basis.3,9 Basically, we need to build a better mousetrap if we intend to catch anything. But this misperception is propagated despite the recognition2,3 “…that the unadjusted incidence of adverse events is a potentially misleading indicator of PCI quality…” and that unless case selection is adequately accounted for, it “…may lead to incorrect conclusions regarding relative quality.”

These data will trouble some unconvinced colleagues for several reasons: operator quality cannot be simplified to an easily measured variable, it eliminates a potential marketing tool, and it is inconsistent with our competitive nature. Although interventions in particularly complex patient subsets (eg, STEMI, chronic total occlusions),11 which require a specialized expertise, do sometimes show an advantage to the most experienced, even then it is a rather small absolute effect. The reasons behind this result are clear: the advent of high-quality training programs, the astounding innovations in equipment and pharmacologic adjuncts, widespread comfort and experience in the toughest cases, outstanding continuing education in conferences throughout our careers, and ongoing local quality-assurance programs. By our own design, the foresight of pioneers in our field, and our insistence on self-preparedness, there is not a steep learning curve for new operators. We have succeeded in developing a system that truly works for our patients, which is a major reason behind the fact that interventional cardiology is the great medical success story of our lifetime. Part of the reason that the volume-quality myth has not been laid to rest is economic; practices must keep PCI volumes high, motivated by income incentives, as well as control by practice administrators to measure/assess performance. Despite the recent proposal to adopt a set of quality metrics,3 there has been no movement toward its adoption, primarily because to do so would lead to more strict case selection, decreasing volume.

The reality is that PCI outcome, volume, and quality are related, but not in the simplistic relationship offered by competence statements; rather, they are related in an extremely complex manner that may be threatening to some. In a controversial matter like this one, everyone is entitled to their own opinion, but not to their own facts. Those who want to hold on to their cognitive bias ought to “walk the walk” and limit the number of new trainees and practitioners to guarantee that the volume they believe defines competence can actually be achieved. With declining utilization and diminishing reimbursement, it behooves us to take a hard look at our workforce requirements for the next decade. However, given the likely deleterious impact of closing PCI programs in critical locations and the reality of our expanding clinical roles,12 it would be impossible to defend the consequences of decreasing the number of interventionists on health-care provision. Inevitably, like Sesame Street’s Count von Count, some interventionists become sad when there is nothing for them to count.

References

1.    Maroney J, Khan S, Powell W, Klein LW. Current operator volumes of invasive coronary procedures in Medicare patients: implications for future manpower needs in the catheterization laboratory. Catheter Cardiovasc Interv. 2013;81:34-39.

2.    Klein LW, Ho KKL, Singh M, et al. Quality assessment and improvement in interventional cardiology. A position statement of the Society of Cardiovascular Angiography and Interventions. Part II. Public reporting and risk-adjustment. Catheter Cardiovasc Interv. 2011;78:493-502.

3.    Klein LW, Harjaj KJ, Resnic F, et al. 2016 Revision of the SCAI position statement on public reporting. Catheter Cardiovasc Interv. 2017;89:269-279.

4.    Levine GN, Bates ER, Blankenship JC, et al. 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Society for Cardiovascular Angiography and Interventions. J Am Coll Cardiol. 2011;58:e44-e122.

5.    Harold JG, Bass TA, Bashore TM, et al. ACCF/AHA/SCAI 2013 update of the clinical competence statement on coronary artery interventional procedures: a report of the American College of Cardiology Foundation/American Heart Association/American College of Physicians Task Force on Clinical Competence and Training (Writing Committee to Revise the 2007 Clinical Competence Statement on Cardiac Interventional Procedures). J Am Coll Cardiol. 2013;62:357-396.

6.    Badheka AO, Patel NJ, Grover P, et al. Impact of annual operator and institutional volume on percutaneous coronary intervention outcomes: a 5-year United States experience (2005-2009). Circulation. 2014;130:1392-1406.

7.    Poulsen B. Being amused by apophenia. Psychology Today. July 31, 2012. Available at https://www.psychologytoday.com/blog/reality-play/201207/being-amused-apophenia.

8.    Liang FW, Lee JC, Lu TH, Yin WH. Trends in proportions of hospitals and operators not meeting minimum percutaneous coronary intervention volume standards in Taiwan, 2001-2013. Catheter Cardiovasc Interv. 2017 Sep 30 (Epub ahead of print).

9.    Gupta A, Yeh RW, Tamis-Holland JE, et al. Implications of public reporting of risk-adjusted mortality following PCI: misperceptions and potential consequences for high-risk patients including the non-surgical patient. JACC Cardiovasc Interv. 2016;9:2077-2085.

10.    Fanaroff AC, Zakroysky P, Dai D, et al. Outcomes of PCI in relation to procedural characteristics and operator volumes in the United States. J Am Coll Cardiol. 2017;69:2913-2924.

11.    Kumbhani DJ, Cannon CP, Fonarow GC, et al. Association of hospital primary angioplasty volume in ST-segment elevation myocardial infarction with quality and outcomes. JAMA. 2009;302:2207-2213.

12.    Lotfi A, Klein LW. The metamorphosis of ST segment elevation myocardial infarction programs: the changing role of the interventional cardiologist and its manpower implications. JACC Cardiovasc Interv. 2017;10:2574-2576.


From Rush Medical College, Chicago, Illinois.

Disclosure: The author has completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The author reports no conflicts of interest regarding the content herein.

Manuscript submitted September 14, 2017 and accepted September 22, 2017.

Address for correspondence: Lloyd W. Klein, MD, Rush Medical College, 3000 North Halsted Ave, Suite 625, Chicago, IL 60614. Email: lloydklein@comcast.net


Advertisement

Advertisement

Advertisement