Special Article
Predicting the Appropriate Use of Carotid Endarterectomy, Upper Gastrointestinal Endoscopy, and Coronary Angiography
N Engl J Med 1990; 323:1173-1177October 25, 1990
- Abstract
- Abstract
Background and Methods.
In a nationally representative population 65 years of age or older, we have demonstrated that about one quarter of coronary angiographies and upper gastrointestinal endoscopies and two thirds of carotid endarterectomies were performed for reasons that were less than medically appropriate. In this paper we examine whether specific characteristics of patients (age, sex, and race), physicians (age, board-certification status, and experience with the procedure), or hospitals (teaching status, profit-making status, and size) predict whether a procedure will be performed appropriately.
Results.
In general, we found that little of the variability in the appropriateness of care (4 percent or less) could be explained on the basis of standard, easily obtainable data about the patient, the physician, or the hospital. For all three procedures, however, performance in a teaching hospital increased the likelihood that the reasons would be medically appropriate (P = 0.09 for angiography, P = 0.30 for endoscopy, and P<0.01 for endarterectomy). In addition, angiographies were more often performed for appropriate reasons in older or more affluent patients (P<0.01 for both). Being treated by a surgeon who performed a high rather than a low number of procedures decreased the likelihood of an appropriate endarterectomy by one third, from 40 to 28 percent (P<0.01).
Conclusions.
Appropriateness of care cannot be closely predicted from many easily determined characteristics of patients, physicians, or hospitals. Thus, for the present, if appropriateness is to be improved it will have to be assessed directly at the level of each patient, hospital, and physician. (N Engl J Med 1990; 323:1173–7.)
Media in This Article
Table 1
Variables Used in the Study and Their Mean Values for the Procedures Performed.Table 2
Relative Risk of Undergoing a Medically Appropriate Procedure.*Article Activity
- Article
MAINTAINING the quality of care in an increasingly cost-conscious environment is a goal of many health policy decision makers. The ability to achieve this goal may depend on the ability to determine the medical appropriateness of care. We define a procedure or service as appropriate if its health benefit exceeds its health risk (with the explicit exclusion of cost) by a sufficiently wide margin that the service or procedure is worth performing.
Using this definition, we studied three procedures — coronary angiography, upper gastrointestinal endoscopy, and carotid endarterectomy — in a geographically diverse sample of Medicare patients.1 , 2 We examined only overuse, and we concluded that 17 percent of coronary angiographies, 17 percent of endoscopies, and 32 percent of endarterectomies represented inappropriate overuse. In addition, we considered that the use of the procedure was equivocal (i.e., the health benefit and risk were approximately equal) in 9, 11, and 32 percent of the procedures, respectively. Because we did not assess potential underuse, we do not know whether there was a large group of people for whom the procedures were medically necessary but who did not receive them.
One of the first questions raised by these data is whether one can predict that a given procedure will be performed inappropriately and by whom. In poor people who undergo coronary angiography is the procedure more likely to be medically inappropriate? Are board-certified gastroenterologists less likely to perform an inappropriate endoscopy than their non-board-certified colleagues? If we could predict accurately who will perform or undergo an inappropriate procedure, the information might be useful to patients in selecting physicians or determining whether they are in a group likely to be subjected to an inappropriate procedure. Insurance companies could use such information to help select preferred providers, and medical educators and professional societies could use it to target activities of continuing medical education and aid their efforts to improve practice.
We know very little about how the appropriateness of care varies. At the level of the individual hospital, variation in appropriateness has been shown to exist. For instance, the appropriateness of the use of coronary-artery bypass surgery ranged from 37 to 78 percent in three randomly selected hospitals.3 The appropriateness of the use of pacemakers ranged from 10 to 30 percent in hospitals in one U.S. city.4 The purpose of this paper is to provide information about whether, in a geographically diverse sample of people 65 years of age or older living in one of five states, the appropriateness of the use of angiography, endoscopy, or endarterectomy can be predicted from easily obtainable data on the characteristics of patients, physicians, or hospitals.
The analyses presented here are based on data collected in 1981. We believe, however, that the conclusions based on these analyses are relevant to current policy decisions. For the conclusions to be wrong today, both the level of appropriateness and the relation of appropriateness to the predictor variables would have to have changed — a highly unlikely possibility.
In addition, new data addressing these issues are not available, and no plans to collect additional data have been formulated.
Methods
We have previously described the method (and its validity) by which we developed ratings of appropriateness for the use of coronary angiography, carotid endarterectomy, and upper gastrointestinal endoscopy.5 6 7 We used a modified Delphi approach that combined a literature analysis with the judgment of experts. We compiled a list of indications for each procedure, and a nine-member panel representing a number of specialties rated the appropriateness of each indication twice. Appropriateness was evaluated in clinical terms.
The panel rated 300 indications for angiography, 864 for endarterectomy, and 1058 for endoscopy. For example, one of the indications was that coronary angiography may be needed in patients with chronic stable angina (without strong contraindications to coronary-artery bypass surgery) in whom angina occurs with mild exertion (Class III or IV) and who have received either less than maximal medical management or none at all and have undergone no exercise electrocardiography, no exercise thallium scanning, and no exercise multiple-gated acquisition scanning. In addition, all the clinical terms used in each indication were explicitly defined. The use of a procedure for a specific indication was considered to be appropriate if the panel's median rating was between 7 and 9 with no disagreement, inappropriate if the value was between 1 and 3 with no disagreement, or equivocal if the median rating was between 4 and 6 or if the members of the panel disagreed. Disagreement was defined as occurring when at least three panelists rated an indication from 1 to 3 and three others rated it from 7 to 9.
Data for the assessment of appropriateness were obtained from the medical records of 4564 Medicare patients 65 or older who underwent one of the three procedures in one of five states in 1981.1 , 2 Details of the sampling have been described elsewhere.1 Briefly, a total of roughly 500 instances of each procedure were randomly sampled from Part B Medicare billing claims in each state or subsection of a state (average population of each site, approximately 3 million people). Each procedure was studied in three sites. Ninety percent of the physicians who performed one of the procedures participated, and complete data were obtained for 91 percent of their patients. For each site, the sample of patients for whom a procedure was performed was representative of the patients who underwent the procedure there (i.e., they represented a systematic random sample of such patients).
We have described elsewhere the reliability and validity of the abstraction process.8 , 9 Detailed clinical data obtained from the medical record by a trained abstracter were used to determine the reason or indication for which the procedure was performed. The indication was then compared with the panel's median rating, and a score for appropriateness was assigned. In order to err on the side of labeling a procedure as appropriate rather than inappropriate, when more than one indication applied to a patient (as was the case with less than 15 percent of patients), the one that yielded the highest appropriateness score was chosen.
To account for the appropriateness with which a procedure was performed, we linked data on physicians' characteristics obtained from the Directory of Medical Specialists 10 and the American Medical Directory 11 and data on hospital characteristics from the Guide to the Health Care Field of the American Hospital Association12 to data in the medical record that indicated which physician performed the procedure or at which hospital it occurred. In addition, we matched the patient's ZIP Code of residence to data from the 1980 U.S. census to determine the median 1979 income level for unrelated adults (15 or older) in the patient's neighborhood. We could not complete this match in the case of endoscopy in one site because the claims data did not include the patients' ZIP Codes. Except for information on race and neighborhood income, data were complete for 99 percent of the 4564 procedures. Data on race were missing for 9 percent of the procedures, and data on income were missing at one site, or for 12 percent of the procedures.
Finally, we used multivariate analysis to estimate the relation of the variables in Table 1Table 1
Variables Used in the Study and Their Mean Values for the Procedures Performed. to the appropriateness with which a procedure was performed. To ensure that our definition of appropriateness did not affect our results, we studied two dependent variables: whether the procedure was performed for an appropriate reason, and whether it was performed for either an appropriate or an equivocal ("not inappropriate") reason. We also examined two samples of patients: one that included only patients for whom the data for all variables were complete and one that included all patients for whom all data except those pertaining to race or income were complete. Because the results were similar, the first definition of appropriateness and the first sample of patients are used in the results reported here. Logistic regression was used in the final models. Since each procedure was studied at three sites, we attempted to replicate our findings across sites. Because relations that cannot be replicated across sites or procedures are likely to be nonreproducible and of little policy importance, we emphasize here relations that appeared to obtain in more than one site — i.e., those that were statistically significant overall and similar in at least two of the three sites. The results are presented in terms of the relative risk of an appropriate procedure as a function of each independent variable.Results
Seventy-seven percent of the patients had a medically appropriate coronary angiography, 74 percent an appropriate endoscopy, and 36 percent an appropriate carotid endarterectomy (Table 1). The average income in 1979 dollars of a person 15 or over was about $7,900, and 16 percent of the patients undergoing endoscopy were nonwhite, as compared with 4 percent of those undergoing carotid endarterectomy and 8 percent of those receiving coronary angiography. The average age of the patients undergoing endoscopy was 75; it was 72 for endarterectomy and 70 for angiography. Most of the procedures (except the endoscopies) were performed in men. The average number of like procedures performed annually in persons 65 or over by the physicians studied was 37 per year in the case of angiography, 74 in the case of endoscopy, and 17 in the case of endarterectomy. Eighty-seven percent of the angiographies were performed by board-certified cardiologists, and 76 percent of the endoscopies were performed by board-certified gastroenterologists. Between 10 and 20 percent of all procedures were done by physicians trained outside North America and Western Europe. About two fifths of all procedures were performed in teaching hospitals, about 10 percent in public hospitals, and 20 percent in for-profit hospitals. The average hospital had about 350 beds and an occupancy rate of 80 percent.
None of the regression equations accounted for more than 4 percent of the variance in medical appropriateness (4 percent for angiography, 2 percent for endoscopy, and 3 percent for endarterectomy). The equations for angiography and endarterectomy were significant (P<0.001); for endoscopy, P = 0.13. Across the three equations, seven variables were significant (P<0.05 for three of them, and P<0.01 for four): income, sex, and age of the patient; board-certification status of the physician and number of procedures performed; and teaching status and bed size of the hospital. Changing the specification of the variables for income, age, and race did not affect these results. In particular, defining income as the percentage of people 65 or older below the poverty level, adding an income-squared variable, dividing income into a categorical variable by tertiles, squaring the age, defining years of age as a categorical variable (less than 75, 75 to 84, or 85 or older), and adding a dummy variable to account for missing data on race did not affect the results materially.13
The relative risks calculated from the coefficients of the logistic regression equations1 are shown in Table 2Table 2
Relative Risk of Undergoing a Medically Appropriate Procedure.*. Among the characteristics of patients, income and age significantly affected the likelihood that a person would undergo a medically appropriate coronary angiography. Of the patients whose incomes were in the 90th percentile of the income distribution, angiography was appropriate in 76 percent of those who underwent the procedure, as compared with 65 percent for patients in the 10th percentile, when all other factors remained constant. Similarly, the older the patient undergoing angiography, the more likely it was that the angiography was medically appropriate (80 percent likelihood for a person in the 90th percentile of age vs. 63 percent for a person in the 10th percentile). Endoscopy was appropriately indicated in 67 percent of the women and 75 percent of the men. It is interesting to note that the direction of the effect (i.e., whether the care was determined to be more or less appropriate) was not the same for any characteristic of the patients for all three procedures and that the appropriateness of receiving carotid endarterectomy was independent of all the characteristics of the patients that we studied.Whether physicians were old or young, were graduates of U.S. or foreign medical schools, or had completed their residencies in the geographic areas in which they were practicing did not predict whether they would perform any of these procedures appropriately. However, if one was treated by a surgeon who performed a large number of endarterectomies as compared with one who performed fewer, the likelihood that the procedure would be medically appropriate decreased significantly, by 12 percentage points —from 40 to 28 percent. Similarly, being treated by a board-certified gastroenterologist as compared with another type of physician decreased significantly the likelihood that an endoscopy would be appropriate, from 75 to 67 percent.
Having any of the three procedures performed at a teaching hospital increased the likelihood that the procedure would be appropriate, and significantly so in the case of carotid endarterectomy (48 vs. 37 percent). The hospital's occupancy rate had no consistent effect on appropriateness, but hospital size had two large but opposite effects; for angiography, the frequency of appropriate procedures increased from 67 to 75 percent with hospital size (P not significant), but for endarterectomy it decreased significantly, from 41 to 29 percent.
Finally, in the case of carotid endarterectomy, we tried to explain clinically why we observed an inverse relation between appropriateness and volume of procedures. In establishing indications for carotid endarterectomy, our panel of physicians lowered its ratings if the patient was at high surgical risk, had no carotid symptoms (i.e., transient ischemic attacks), had no substantial stenosis on carotid angiography, or had a 100 percent stenosis of the carotid artery on the side on which the operation was to be performed. As can be seen in Table 3Table 3
Clinical Characteristics of Patients Undergoing Carotid Endarterectomy, According to the Number of Operations Performed Each Year by Physicians.*, surgeons performing many endarterectomies tended to perform more operations on people with less stenosis of their carotid artery and with no previous carotid symptoms. The lower ratings for surgeons performing more procedures did not occur because the surgeons were taking more chances operating on patients at high surgical risk or because they were performing more difficult procedures (i.e., operating on lesions with 100 percent stenosis).Discussion
When we began this study, we hoped to demonstrate strong and consistent relations, across procedures and sites, between easily obtainable data on characteristics of patients, physicians, and hospitals and the medical appropriateness of specific procedures. We found too many significant relations to be ignored, but although these relations were consistent across sites for a given procedure, they were not consistent across procedures. This suggests that specific subgroups of the insured elderly population — the poor, the very old, nonwhites, and women — do not systematically receive more or less appropriate care. In the case of angiography, the very old received more appropriate care than somewhat younger but still elderly persons, and the poor less appropriate care than persons with higher incomes. Similarly, the characteristics of physicians, such as board-certification status, age, or place of graduation, do not explain appropriateness consistently. On the other hand, having any of the three procedures we studied performed in a teaching hospital increased the likelihood of having it done appropriately (P<0.01 in the case of endarterectomy).
Our inability to explain appropriateness on the basis of easily gathered information about patients, physicians, or hospitals was consistent with the findings of other studies that have examined the effect of such variables on process and outcome measures of care.14 , 15 In general, what has been found is that some of the variability in the measures of quality can be explained by the identity of individual physicians or hospitals, but not by easily observable characteristics of hospitals or their physicians. Other variables, on which data are less readily obtainable, should be studied, such as whether physicians are salaried or the hospital is in debt. For the present, however, if the level of appropriateness is to be improved, it must be assessed on a patient-by-patient, physician-by-physician, or hospital-by-hospital basis. This is true whether the assessment is for self-improvement or education or is part of a regulatory system in which payment for services rendered might be denied, either prospectively or retrospectively. This conclusion will not please people who hope to use structural variables to build a more efficient educational or regulatory system in order to increase appropriateness. On the other hand, it is reassuring to know that at least for the insured elderly (99 percent of those over 65), stereotypical characteristics of people and their physicians do not explain appropriateness. We are all in the same predicament, and some degree of equity in the likelihood of undergoing an appropriate or inappropriate procedure has been attained.
Finally, one disturbing finding needs emphasis. For the one surgical procedure that was studied, the number of operations performed by the surgeon per year was the most important predictor of appropriateness, and the relation was negative — i.e., the likelihood of undergoing an appropriate endarterectomy decreased by almost one third (from 40 to 28 percent) for patients treated by a surgeon who performed many such procedures as compared with one who performed few. This was not because the former group of surgeons operated on desperately ill patients, but because they operated on less sick, asymptomatic patients.
Until now, on the basis of data showing that the volume of procedures may be a reasonable predictor at both a clinical and a policy level of how well a procedure is performed, there have been suggestions to move patients to physicians or centers with a high volume of operations.16 17 18 Our study would suggest some caution in this regard. High-volume physicians may perform a procedure better, but the patient may have been less likely to need it in the first place. On the other hand, it should be noted that in the case of coronary angiography higher volume was associated with more appropriate decision making, though not significantly; generalization across procedures may be unwarranted.
Nonetheless, our findings about the relation between the volume of procedures and appropriateness further confirm the need to measure the appropriateness of care directly. How well a procedure is performed is not a proxy for whether it needs to be performed. Whether a procedure is needed cannot be known from the characteristics of physicians or patients, but requires a clinical evaluation, and volume will not serve as a proxy for both using a procedure wisely and performing it well. If we do nothing to assess appropriateness, we could end by developing policies that improve the level of quality at which a procedure is performed but that lower population-based measures of health, because the wrong people are receiving the procedure, and thus the net health risk exceeds the benefit. The challenge facing us is to determine how we can move forward to improve appropriateness and outcome simultaneously, and thereby enhance the health of the American people.
Supported by a grant from the Robert Wood Johnson Foundation. The opinions expressed in the paper do not necessarily reflect the opinions of the Rand Corporation, the University of California, Los Angeles, or the Robert Wood Johnson Foundation.
Source Information
From the Health Sciences Program, the Rand Corporation (R.H.B., R.E.P., J. Keesey), and Value Health Sciences (M.R.C., J. Kosecoff), both in Santa Monica, Calif.; and the Departments of Medicine (R.H.B., D.H.S., J. Kosecoff) and Health Services (R.H.B., J. Kosecoff), University of California, Los Angeles. Address reprint requests to Dr. Brook at the Rand Corporation, 1700 Main St., Box 2138, Santa Monica, CA 90406.
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