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Pediatric Cardiology

Progress in Pediatric Cardiology 7 (1997) 63-65

Foreword

Outcomes research in pediatric cardiology: an overview

Darryl T. Gray*

Assistant Professor of Epidemiology, Mayo Medical School, Mayo Clinic and Mayo Foundation, 200 First Street SW Rochester, MN 55905, USA

As a non-cardiologist, I was both flattered and intimidated by the opportunity to serve as Guest Editor for a Progress in Pediatric Cardiology issue which is devoted to outcomes research in pediatric cardiology. In point of fact, I am a physician epidemi- ologist with an interest in examining the frequencies, clinical outcomes and cost-effectiveness of interven- tional procedures in pediatric cardiology and other fields. The dissertation project for my doctorate in epidemiology provided the opportunity for me to per- form a multicenter retrospective comparison of clini- cal and cost-effectiveness and other aspects of the use of conventional surgery versus implantation of the Rashkind double umbrella occluder for closure of patent ductus arteriosus [1,2]. I am eternally grateful to those members of the pediatric cardiology and pediatric cardiac surgery communities who graciously provided access to the data which made this project possible. I hope that serving as Guest Editor of this issue will partially repay my debt of gratitude.

Outcomes research may be considered to be the systematic prospective or retrospective collection and analysis of information on the results of specific ther- apeutic interventions, with the goal of drawing con- clusions which may be generalizable to other patient populations, To the degree that the term ‘outcomes research’ is restricted to results attainable in routine practise, it might exclude findings observed in the controlled environment of randomized trials. How- ever, a broader definition would include results ob- tained from this methodologically rigorous study de- sign. In any case, outcomes research differs in scope and purpose from assessments of outcome performed

*Tel.: + 1 SO7 2847087; fax: + 1 SO7 2841516.

for internal uses, including provider profiling, quality assurance, continuous quality improvement, or finan- cial auditing.

As Bernard Bloom notes in a review of the history of measurements of quality of care [31, formalized interest in the results of medical interventions dates back at least to the time of King Hammurabi. The code of Hammurabi, noted for provisions exacting ‘An eye for an eye, a tooth for a tooth’, also mandated that payment of physicians be tied to good health care outcomes, while punishment or withholding payment were the consequences for adverse results of treat- ment. Nearly 4,000 years later in 1747, James Lind performed a well known randomized trial of the use of citrus fruits to prevent scurvy 141; this is one of the first recorded studies which might be considered out- comes research. Early evaluations of clinical proce- dures included assessments of various surgical ap- proaches to the management of gunshot wounds [5] and evaluations of the use of bloodletting to treat infection [6], carried out in the 18th and 19th cen- turies, respectively. Early in this century, Ernest Cod- man, a surgeon, advanced the parallel notions of assessing the outcomes of the interventions of individ- ual physicians and hospitals, and widely publicizing the results [7].

Bloom attributes much of the incentive for more recent interest in assessing outcomes of care to a desire to limit the growth of health care costs. How- ever, one would hope that additional impetus has come from a desire to make optimal use of the potentially bewildering array of treatment approaches which now exists within our clinical armamentarium. In the area of treating congenital heart disease, this includes increasing numbers of interventional cardi- ology procedures which represent potentially less in-

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64 D. T. Gray /Progress in Pediattic Cardiology 7 (1997) 63-65

vasive alternatives to conventional surgery [8]. The types of results of these and other interventions which may be considered ‘outcomes research’ can be viewed as a continuum. Attainment of focused, short-term clinical objectives represents one end of the spectrum. For example, research on outcomes of treating aortic valvular stenosis could include comparisons of the frequencies with which balloon dilation versus surgi- cal valvotomy eliminates the signs and symptoms of outlet obstruction, combined with assessments of the. degrees to which these procedures avoid peri-oper- ative or 30-day mortality.

The admirable short-term clinical successes now achievable through interventions in pediatric cardi- ology and other fields have provided the luxury of a greater focus on long-term clinical and non-clinical outcomes. For example, we can now expand the focus of our attention to comparing the degree to which valvuloplasty versus valvotomy avoids, or at least post- pones, the subsequent need for aortic valve replace- ment. We can also assess secondary clinical outcomes, such as avoidance of neurological sequelae following surgical treatment of congenital heart disease using circulatory arrest versus low-flow cardiopulmonary by- pass [91.

Furthermore, the increasing interest in patient- centered outcomes has led to explicit consideration of the quality of life patients experience after various interventions [lo-1.51. Thus, a discussion of ‘outcomes studies’ in gastroenterology included evaluations of ‘patient satisfaction, functional states (‘health-related quality of life’), appropriateness of care, conformance to recommended standards of performance, or change in practice patterns...’ [16] among the issues which could potentially be addressed. Finally, there is in- creasing realization of the limits of economic re- sources available for health care. This has heightened interest in incorporating benefit-cost, cost-effective- ness and cost-utility analyses into comparisons of out- comes of competing treatment strategies in various areas of medicine [17-261 including pediatric cardi- ology [27,28]. As ‘outcomes research’ may therefore encompass assessment of results in multiple dimen- sions, the field represents a broadening of the per- spective historically taken in clinical research.

The purpose of this issue of Progress in Pediatric Cardiology is to consider various aspects of outcomes research as they relate to the treatment of congenital heart disease. As the potential impacts on pediatric cardiology of various aspects of cost-effectiveness analysis, health care reform and related topics were addressed in an earlier special issue of this journal [29], the current issue focuses on more clinically-ori- ented aspects of outcomes research; considerations of quality of life issues has been deferred for possible inclusion in a subsequent issue.

In the first substantive article, David Danford uses

examples from Pediatric Cardiology to outline the techniques of clinical decision analysis [30-331. This approach combines data from prior randomized and non-randomized evaluations, while incorporating patient and/or physician preferences into studies of clinical outcome, cost, and/or quality of life associ- ated with competing diagnostic or therapeutic strate- gies. Aside from generating new insights using exist- ing data, decision analysis helps highlight key knowledge gaps which can be addressed in future investigations. In the next article. I describe the prin- ciple advantages and disadvantages of the various non-randomized study designs often used to fill these gaps, and illustrate these concepts with studies from pediatric cardiology and related fields.

Clinical registries are another increasingly impor- tant source of prospective data on outcomes of inter- ventions for treating congenital heart disease and other conditions. In the third article, Christine Powell and James Moller describe the Pediatric Cardiac Care Consortium [34], an unique voluntary registry which has amassed data on outcomes of various diagnostic and therapeutic procedures performed on congenital heart disease patients since the late 1970s. Thomas Lloyd then describes the more focused Gianturco Coil Registry 1351, which collects and analyzes data reflecting the experience which various centers are accumulating in the use of this device to treat patent ductus arteriosus.

Despite the attractiveness of using non-randomized studies and registry data for outcomes research, the randomized clinical trial is generally acknowledged to provide the most rigorous data on outcomes attain- able using competing treatment strategies. The me- chanics of performing such investigations, including pediatric applications of special randomization schemes such as the ‘play the winner’ rule [36,37] have been described in detail elsewhere [38-421. In the final article, Richard Jonas considers randomized trials from the invaluable perspective of an academic pediatric cardiac surgeon. Aside from describing the importance of randomized trials of surgical interven- tions in general, he also discusses issues which sur- round the design and execution of a recently com- pleted major randomized trial in pediatric cardiac surgery [91.

Despite the cogency of arguments made by Jonas and others to encourage performance of randomized trials, an informal MEDLINE search of the literature from 1986-1996 (unpublished data) indicates that such studies are relatively uncommon among comparisons of outcomes of treatment for congenital heart disease. While this journal issue does describe alternative study designs, it is hoped that the readers will seriously consider the more rigorous randomized trial approach when developing their own investigations or reviewing the work of others.

D. T. Gray /Progress in Pediattic Cardiology 7 (1997) 63-65 65

I am grateful to David Driscoll for having passed along to me the opportunityto serve as Guest Editor, and I am thankful for William Miller’s willingness to leave this important issue in the hands of a non- cardiologist. I thank the other contributors for their willingness to provide their unique perspectives, and I hope that readers of this issue profit from it as much as I have from working to assemble it.

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