Rolla Edward Park

Variations in the Use of Medical and Surgical Services By the Medicare Population

We measured geographic differences in the use of medical and surgical services during 1981 by Medicare beneficiaries (age greater than or equal to 65) in 13 large areas of the United States. The average number of Medicare beneficiaries per site was 340,000. We found large and significant differences in the use of services provided by all medical and surgical specialties. Of 123 procedures studied, 67 showed at least threefold differences between sites with the highest and lowest rates of use. Use rates were not consistently high in one site, but rates for procedures used to diagnose and treat a specific disease varied together, as did alternative treatments for the same condition. These results cannot be explained by the actions of a small number of physicians. We do not know whether physicians in high-use areas performed too many procedures, whether physicians in low-use areas performed too few, or whether neither or both of these explanations are accurate. However, we do know that the differences are too large to ignore and that unless they are understood at a clinical level, uninformed policy decisions that have adverse effects on the health of the elderly may be made.

Physician Ratings of Appropriate Indications for Six Medical and Surgical Procedures

We convened three panels of physicians to rate the appropriateness of a large number of indications for performing a total of six medical and surgical procedures. The panels followed a modified Delphi process. Panelists separately assigned initial ratings, then met in Santa Monica, California where they received reports showing their initial ratings and the distribution of the other panelists ratings. They discussed the indications and revised the indications lists, then individually assigned final ratings. There was generally better agreement on the final ratings than on the initial ratings. Based on reasonable criteria for agreement and disagreement, and excluding one outlying procedure, the panelists agreed on ratings for 42 to 56 per cent of the indications, and disagreed on 11 to 29 per cent.

Estimating the autocorrelated error model with trended data

Abstract : A Monte Carlo study is made of the small sample properties of various estimators of the linear regression model with first-order autocorrelated errors. When independent variables are trended, estimators using T transformed observations (Prais-Winsten) are much more efficient than those using T-1 (Cochrane-Orcutt). The best of the feasible estimators is iterated Prais-Winsten using a sum-of-squared-error minimizing estimate of the autocorrelation coefficient rho. None of the feasible estimators performs well in hypothesis testing; all seriously underestimate standard errors, making estimated coefficients appear to be much more significant than they actually are. (Author)

Predicting the Appropriate Use of Carotid Endarterectomy, Upper Gastrointestinal Endoscopy, and Coronary Angiography

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 less than 0.01 for endarterectomy). In addition, angiographies were more often performed for appropriate reasons in older or more affluent patients (P less than 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 less than 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.

Assessing the Predictive Validity of the RAND/UCLA Appropriateness Method Criteria for Performing Carotid Endarterectomy

We assessed the predictive validity of an expert panels ratings of the appropriateness of carotid endarterectomy by comparing ratings to the results of subsequent randomized clinical trials. We found the trials confirmed the ratings for 44 indications (covering almost 30% of operations performed in 1981) and refuted the ratings for none.

MEASURING THE NECESSITY OF MEDICAL PROCEDURES

This is a report on the extension of the concept of the appropriateness of a procedure to the necessity, or crucial importance, of that procedure. To state that a procedure is crucial means that withholding the procedure would be deleterious to the patients health. Appropriateness and necessity ratings for six procedures were obtained using a modified Delphi panel process developed in earlier work. Panels were composed of practicing clinicians who were recognized leaders in their fields. The panels included both performers and nonperformers of the procedure under discussion. For most procedures and panelists, necessity was related to appropriateness, but was distinct from it. The proportion of indications for which the procedure was crucial varied in clinically consistent ways both among and within procedures. However, panelists did not achieve a consensus on necessity. Further research is suggested to refine the method to promote consensus and to validate further the ratings of necessity. In conclusion, necessity ratings can be used together with appropriateness ratings to address not only the overuse of procedures, but also to indicate limited access to care through underuse of procedures.

Relation Between Surgeons' Practice Volumes and Geographic Variation in the Rate of Carotid Endarterectomy

We examined the relation between the number of operative procedures carried out by individual surgeons and the variation in the rate of carotid endarterectomy among Medicare beneficiaries in areas of high, average, and low use of the procedure in 1981. Rates ranged from 48 per 100,000 in the low-use area to 178 per 100,000 in the high-use area. Two variables accounted for most of the differences in the rates: the number of surgeons performing the procedure and the number of endarterectomies performed by surgeons with high practice volumes. Twice as many surgeons in the high-use area and 25 percent more in the average-use area performed carotid endarterectomy as compared with those in the low-use area. If the average number of cases per surgeon had been the same, the differences in the number of surgeons would have accounted for 36 percent and 15 percent, respectively, of the differences in use. Surgeons who performed 15 or more carotid endarterectomies during the year accounted for most of the variation in the rates. These high-volume surgeons represented 15 percent and 17 percent of the surgeons in the areas of high and average use, respectively, as compared with 4 percent of those in the low-use area. They accounted for 60 and 77 percent, respectively, of the additional endarterectomies. Three fourths of the surgeons performing carotid endarterectomies carried out fewer than 10, and 24 percent did only 1. We conclude that most of the geographic variation in the rate of carotid endarterectomy is caused by a few surgeons in high-use areas who perform large numbers of operations.

Physician ratings of appropriate indications for three procedures: theoretical indications vs indications used in practice.

We previously reported substantial disagreement among expert physician panelists about the appropriateness of performing six medical and surgical procedures for a large number of theoretical indications. A recently completed community-based medical records study of about 4,500 patients who had one of three procedures--coronary angiography, upper gastrointestinal endoscopy, and carotid endarterectomy--shows that many of the theoretical indications are seldom or never used in practice. However, we find that there is also substantial disagreement (5, 25, or 32 per cent for angiography, endoscopy, or endarterectomy, respectively) about the appropriateness of indications used in actual cases if disagreement is defined by first discarding the two extreme of nine ratings, then looking for at least one rating near the bottom (1 to 3) and one near the top (7 to 9) of the 9-point scale. Patients should know that a substantial percentage of procedures are performed for indications about which expert physicians disagree.

Effect of variability in the interpretation of coronary angiograms on the appropriateness of use of coronary revascularization procedures.

Abstract Background Evidence from numerous studies of coronary angiography show differences between observers’ assessments of 15% to 45%. The implication of this variation is serious: If readings are erroneous, some patients will undergo revascularization procedures unnecessarily and others will be denied an essential treatment. We evaluated the variation in interpretation of angiograms and its potential effect on appropriateness of use of revascularization procedures. Methods and Results Angiograms of 308 randomly selected patients previously studied for appropriateness of angiography, coronary artery bypass grafting (CABG), and percutaneous transluminal coronary angioplasty (PTCA) were interpreted by a blinded panel of 3 experienced angiographers and compared with the original interpretations. The potential effect on differences on the appropriateness of revascularization was assessed by use of the RAND criteria. Technical deficiencies were found in 52% of cases. Panel readings tended to show less significant disease (none in 16% of vessels previously read as showing significant disease), less severity of stenosis (43% lower, 6% higher), and lower extent of disease (23% less, 6% more). The classification of CABG changed from necessary/appropriate to uncertain/inappropriate for 17% to 33% of cases when individual ratings were replaced by panel readings. Conclusions The general level of technical quality of coronary angiography is unsatisfactory. Variation in the interpretation of angiograms was substantial in all measures and tended to be higher in individual than in panel readings. The effect was to lead to a potential overestimation of appropriateness of use of CABG by 17% and of PTCA by 10%. These findings indicate the need for increased attention to the technical quality of studies and an independent second reading for angiograms before recommending revascularization. (Am Heart J 2000;139:106-13.)

Sensitivity and specificity of the RAND/UCLA Appropriateness Method to identify the overuse and underuse of coronary revascularization and hysterectomy

There is no empirical evidence on the sensitivity and specificity of methods to identify the possible overuse and underuse of medical procedures. To estimate the sensitivity and specificity of the RAND/UCLA Appropriateness Method. Parallel three-way replication of the RAND/UCLA Appropriateness Method for each of two procedures, coronary revascularization and hysterectomy. Maximum likelihood estimates of the sensitivity and specificity of the method for each procedure. These values were then used to re-calculate past estimates of overuse and underuse, correcting for the error rate in the appropriateness method. The sensitivity of detecting overuse of coronary revascularization was 68% (95% confidence interval 60-76%) and the specificity was 99% (98-100%). The corresponding values for hysterectomy were 89% (85-94%) and 86% (83-89%). The sensitivity and specificity of detecting the underuse of coronary revascularization were 94% (92-95%) and 97% (96-98%), respectively. Past applications of the appropriateness method have overestimated the prevalence of the overuse of hysterectomy, underestimated the prevalence of the overuse of the coronary revascularization, and provided true estimates of the underuse of revascularization. The sensitivity and specificity of the RAND/UCLA Appropriateness Method vary according to the procedure assessed and appear to estimate the underuse of procedures more accurately than their overuse.