Correspondence

The Prospective Payment System and Discharge Diagnoses for Coronary Heart Disease

N Engl J Med 1994; 330:578-579February 24, 1994

Article

To the Editor:

The article by Assaf et al. (Sept. 23 issue)1 discusses many possible theories about the effect of prospective payment systems and diagnosis-related groups (DRGs) in leading to more expensive coding of discharge diagnoses, so that payments to hospitals are increased. The article does not clarify whether hospitals are making more precise diagnoses or whether there is a behavioral bias favoring acute conditions.

What requires serious consideration, however, is the improvement in the knowledge base available to physicians from 1980 through 1988, the time of this study. During these years the diagnosis of unstable angina was extensively evaluated, both in the angiographic laboratory and at the autopsy table. From these studies emerged the understanding that unstable angina is caused by an acute coronary arterial lesion consisting of atheromatous-plaque disruption with superimposed thrombus.

Better comprehension of the underlying pathological characteristics may have led to the use of the more frequent diagnosis of unstable angina pectoris as the DRG, rather than the diagnosis of unqualified angina pectoris in itself. The latter diagnosis had often been modified -- as “crescendo,” “intensified,” or the like -- in a way that may have led to lower DRG-based reimbursement than the diagnosis of unstable angina, which could often be shown to overlap with what is euphemistically called non-Q-wave infarction when the same clinical syndrome is associated with elevated cardiac enzymes.

I wonder whether the authors would agree that a clarification of the pathological and pathophysiologic features at the very time of the emergence of prospective payment was a factor in the results they reported? An interesting comparison might be made with data from another country, such as Canada, to see whether there was a similar shift in diagnoses during the same period, even though the health care system offered no change in economic incentives through the mechanism of coding.

Richard Gorlin, M.D.
Mount Sinai Medical Center, New York, NY 10029-6574

1 References

1. 1

   Assaf AR, Lapane KL, McKenney JL, Carleton RA. Possible influence of the prospective payment system on the assignment of discharge diagnoses for coronary heart disease. N Engl J Med 1993;329:931-935
   Full Text | Web of Science | Medline

To the Editor:

The recent article by Assaf et al. about “overcoding” struck a familiar chord with those of us who work with medical records. Over the years, “optimizing” DRG-based reimbursement has become an art form similar to the identification of tax loopholes.

Consider the case of a 67-year-old woman in whom congestive heart failure with new-onset atrial fibrillation develops. She is treated with furosemide and digoxin, and her condition improves. On the sixth day of her hospital stay, she has an embolus in the left kidney. She receives anticoagulants and undergoes cardioversion. The hospital course is complicated by gastrointestinal bleeding, but ultimately she recovers and is discharged on the 31st hospital day.

As the rules of coding dictate, the principal diagnosis can be any condition present at admission that requires a hospital stay and further treatment. Thus, to maximize reimbursement, in this case an effective coder would probably assign the principal diagnosis of congestive heart failure (rather than atrial fibrillation).

The follies of DRG coding result directly from the use of a coding system as a billing system. Financial need dictates that medical-records departments play by an unusual set of coding guidelines. Of greater concern is the increasing use of DRGs in outcome studies and the judgment (or misjudgment) of hospitals on that basis.

Medical reform must encompass the medical coding system if data analysis is to have any validity.

Howard Edelstein, M.D.
99 Montecillo Rd., San Rafael, CA 94903

Author/Editor Response

The authors reply:

To the Editor: As Dr. Gorlin points out, the 1980s were a decade of very substantial, steady advances in our knowledge of coronary heart disease, its pathological aspects, and its pathophysiologic features. We do not believe, however, that the data we reported reflect this change. Our reasoning is straightforward. One would anticipate that a continuing accretion of new knowledge would produce a slow, steady change in outcome.

In this instance, one would have anticipated a steady and slow change in DRG assignments over the years in question. This was not what we observed. Indeed, in Rhode Island, there was a rather abrupt change in 1983. In the data derived from a community in Massachusetts, a similar abrupt change occurred in 1985. These were the years in which the prospective payment system was instituted in these states. Accordingly, whereas we agree with Dr. Gorlin that substantial changes in knowledge have occurred, the events in question most clearly relate to the implementation of the prospective payment system. The suggestion of a comparison with Canada, though interesting and challenging, seems unlikely to yield data that would further clarify the contribution of the prospective payment system.

Dr. Edelstein writes to describe the complexities of DRG assignment. More important, he points out the difficulties inherent in mixing coding of diagnoses and the reimbursement system. We share his concern, as we indicated in our paper, that local and even national statistics about disease trends may inadvertently be obscured by such a system.

Annlouise R. Assaf, Ph.D.
Richard A. Carleton, M.D.
Memorial Hospital of Rhode Island, Pawtucket, RI 02860