Correspondence

Use of Angiography in the Veterans Affairs Health Care System and Medicare

N Engl J Med 2003; 349:1093September 11, 2003

Article

To the Editor:

The study by Petersen and coworkers (May 29 issue)1 showed that patients who were treated in the Veterans Affairs (VA) health care system after having a myocardial infarction were less likely to undergo coronary angiography, in spite of meeting the criteria for class I indications according to the classification of the American Heart Association and the American College of Cardiography, than were Medicare patients who were treated in the private sector. The authors concluded that this difference might be due to the regionalization of angiography services within the VA system. Although such a conclusion may be justified, other factors should be considered. The VA patients had significantly higher rates of hypertension and diabetes, but data regarding renal function were not reported. Since impaired renal function may lead to a decision not to recommend angiography in stable patients with mild symptoms, information about the serum creatinine concentration in the two groups would be of interest. Perhaps of more importance, although not the focus of this study, was the observation that in spite of less utilization of angiography, the VA patients had lower mortality (although not significantly lower) both at 30 days and at 1 year. The explanation for this unexpected finding deserves serious consideration and reinforces the need for studies of the ways in which processes influence outcomes.

Henry S. Loeb, M.D.
Edward Hines Jr. Veterans Affairs Hospital, Hines, IL 60141
hsl4134@yahoo.com

1 References

1. 1

   Petersen LA, Normand S-LT, Leape LL, McNeil BJ. Regionalization and the underuse of angiography in the Veterans Affairs health care system as compared with a fee-for-service system. N Engl J Med 2003;348:2209-2217
   Full Text | Web of Science | Medline

Author/Editor Response

Dr. Loeb correctly emphasizes the importance of the serum creatinine concentration as a potential confounder in our process-of-care comparison of the use of clinically needed angiography. However, there was no significant difference in the proportions of the two groups with an elevated serum creatinine concentration (27.2 percent of VA patients and 29.3 percent of Medicare patients, P=0.14). Nevertheless, because of the clinical importance of the serum creatinine concentration, my colleagues and I did adjust for elevated serum creatinine concentrations in our multivariate model. Thus, elevated serum creatinine concentrations did not account for the difference between VA patients and Medicare patients in the use of clinically needed angiography.

As Dr. Loeb notes, the differences in mortality between the two groups did not reach statistical significance. He questions the apparent trend in the unadjusted findings toward lower mortality among the VA patients despite the lower rate of use of needed angiography. One of many possible explanations for this finding is the higher or equivalent rates of use of beneficial medications after acute myocardial infarction in VA patients as compared with Medicare patients.1 Use of such guideline-recommended medications may translate into a nonsignificant survival advantage despite the significantly lower rate of use of guideline-recommended angiography documented in our study.

Laura A. Petersen, M.D., M.P.H.
Houston Veterans Affairs Medical Center, Houston, TX 77030

1 References

1. 1

   Petersen LA, Normand S-LT, Leape LL, McNeil BJ. Comparison of use of medications after acute myocardial infarction in the Veterans Health Administration and Medicare. Circulation 2001;104:2898-2904
   CrossRef | Web of Science | Medline