Validation of Relative Value Scale for Congenital Heart Operations

Transcription

1 Validation of Relative Value Scale for Congenital Heart Operations Kathy J. Jenkins, MD, Kimberlee Gauvreau, ScD, Jane W. Newburger, MD, Ludmila B. Kyn, MA, Lisa I. Iezzoni, MD, and John E. Mayer, MD Departments of Cardiology and Cardiovascular Surgery, Children s Hospital, and Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts Background. To determine the validity of the newly assigned work relative value unit (RVU) scale for surgical procedures for congenital heart disease, we measured its relationship to length of hospital stay, total hospital charges, and mortality. Methods. We identified cases by the presence of ICD- 9-CM codes in nine statewide, administrative hospital discharge abstract databases for Computer algorithms were generated to assign RVUs to individual cases. Spearman correlation coefficients between work and practice expense RVUs and median length of hospital stay, total hospital charges, and in-hospital mortality were determined, as well as parameter estimates from linear and logistic regression. Results. Using data from 5,192 cases involving 34 surgical procedures for congenital heart disease, higher work RVUs were associated with longer lengths of hospital stay (r s 0.72, p < ), higher total hospital charges (r s 0.81, p < ), and higher in-hospital mortality (r s 0.45, p 0.01). A 5-point increase in the relative value scale was associated with an increase in the length of stay by a multiplicative factor of 1.3 (p < ); total hospital charges by 1.5 (p < ); and the odds of in-hospital death by 1.9 (p < ). Findings were similar for practice expense RVUs, as work and practice expense RVUs were highly correlated (r s 0.93, p < ). Conclusions. The group of work RVUs for surgical procedures for congenital heart defects are reasonable relative measures, on average, of physician work for these procedures, thus supporting the use of this scale to determine physician reimbursement. Practice expense RVUs may not be an independent measure for these procedures. (Ann Thorac Surg 1998;66:860 9) 1998 by The Society of Thoracic Surgeons On January 1, 1992, the Health Care Financing Administration (HCFA) adopted a fee schedule based, in part, on a Resource-Based Relative Value Scale (RBRVS) to reform physician reimbursement for Medicare patients [1 5]. Since its adoption, use of the scale or its components has become accepted as a standard methodology for determining professional payment [6, 7]. The intention of the RBRVS is to base compensation primarily on the work involved in performing various procedures in an equitable fashion across subspecialties. Physician work is incorporated as a work-based relative value scale, where linear weights (RVUs) are assigned to various procedures. In addition, to account for other required expenses, the Medicare fee schedule also includes scales to account for practice and malpractice expense. Fees are computed by adjusting each scale component by a factor reflecting geographic cost differences and then multiplying by a conversion factor [5]. The dimensions of work included in the work-based scale are (1) time, (2) mental effort and judgment, (3) technical skill and physical effort, and (4) psychological stress [1, 2, 8]. Work RVUs are assigned to physicians Accepted for publication April 2, Address reprint requests to Dr Jenkins, Department of Cardiology, Children s Hospital, 300 Longwood Ave, Boston, MA services in relation to standard reference procedures designed to link the scale across subspecialties, and are assigned according to the American Medical Association s (AMA s) Current Procedural Terminology (CPT) codes. Because the work-based scale was originally designed for reimbursement for Medicare patients, initial versions did not include values for many pediatric procedures. As use of these scales has become increasingly adopted by other insurers, efforts have been made by the American Academy of Pediatrics and multiple subspecialty groups to develop RVUs for pediatric procedures and to develop CPT codes for pediatric care [9]. The assignment of new RVUs for pediatric and other procedures has occurred under the auspices of the AMA Relative Value Update Committee with subsequent approval by HCFA. For pediatrics, an early effort in resulted in the assignment and adoption of new work RVUs to a group of 81 congenital heart operations. The assignment was based on newly revised CPT, version 4 codes [10], and was made using standard methodology based on the results of a national survey of pediatric cardiac surgeons. As a part of the survey, surgeons were given case scenarios of average patients undergoing congenital heart operations, as well as a previously assigned RVU for standard reference procedures. The respondents were asked to rate the preoperative, intraoperative, and 1998 by The Society of Thoracic Surgeons /98/$19.00 Published by Elsevier Science Inc PII S (98)

2 Ann Thorac Surg JENKINS ET AL 1998;66:860 9 RVUs FOR CONGENITAL HEART OPERATIONS 861 postoperative work entailed to perform each cardiac procedure. For example, if a surgeon thought that a congenital heart operation required 25% more work than the reference procedure, he or she would assign that procedure an RVU that was 25% higher than the reference RVU. In general, the median RVU value for all respondents was then assigned to the new procedure. Historically, practice expense (PE) RVUs were derived from the differences between expenses attributable to work and usual and customary charges based on Medicare historic charge data. For almost all pediatric cardiac surgical procedures, no historic charge data existed. Practice expense RVUs for these procedures were derived by comparison with analogous procedures for which values had been assigned, according to agreements between representatives of The Society of Thoracic Surgeons and HCFA. The validity of the original RBRVS as a measure of work was based primarily on excellent internal consistency among physicians regarding the ordering of procedures with respect to work [1]. Even before its implementation, the validity of the scale and the methodology by which it was created was questioned for adult cardiac surgery [11]. Since its implementation, the need for additional validation has been suggested, but little work has been performed [8, 12 14]. To begin this process, we suggest that valid work RVUs for congenital heart procedures should show reasonable correlation with other measures that reflect physician time and effort, such as resource consumption. Given the nature of congenital heart disease, RVUs for these procedures should also be correlated to some degree with clinical outcomes such as mortality, because more complicated operations are likely to represent higher risk to the patient. Relative value units that show consistently poor correlation with these measures may suggest invalid RVU assignments. We have thus measured the correlation between this portion of the work RVU scale and length of hospital stay, total hospital charges, and in-hospital mortality using administrative data from nine states. Although the theoretical basis for the practice expense scale is less well defined, making a priori hypotheses regarding the expected correlation between PE RVUs and resource consumption or clinical outcomes difficult, we have also measured these correlations. Material and Methods Databases Hospital discharge data from 1992 for patients 18 years of age and younger were obtained from nine states: California, Colorado, Florida, Illinois, Massachusetts, Maryland, Pennsylvania, Washington, and Wisconsin. These states were chosen in part based on the availability of the data in the public domain, but also to provide a wide geographic sample of states known to have centers of various sizes performing surgical procedures for congenital heart disease in children. These administrative databases included information in standard formats for acute care hospital discharges from all institutions with few exceptions (eg, federal facilities such as Veterans Affairs facilities). Data included routine demographic and administrative information such as age, sex, race, admission type and source, discharge status, length of hospitalization, and total hospital charges (excluding professional fees), as well as all discharge diagnoses and procedure codes assigned to the patient, using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. Case Selection All cases with ICD-9-CM codes indicating surgical repair of a congenital heart defect (procedure codes 35.xx, 39.0, or 39.21, excluding 35.41, 35.52, and 35.96) or codes 38.35, 38.45, 38.85, or and any diagnostic code for a congenital heart defect (745.xx, 746.xx, 747.0x 4x, , excluding ) were selected. Premature infants (diagnostic codes 765.0x 1x) and cardiac transplants (procedure code 37.5) were eliminated. Infants with patent ductus arteriosus (PDA) as an isolated cardiac defect presumably complicating newborn respiratory disease (identified by diagnostic code and procedure code and age less than 0.3 years) were also eliminated. To exclude transcatheter interventions, we also eliminated patients whose sole cardiac procedure was atrial septal defect closure (diagnosis code 745.5, procedure codes 35.51, 35.71), ventricular septal defect closure (diagnosis code 745.4, procedure codes 35.53, 35.72), PDA closure (diagnosis code 747.0, procedure code 38.85), atrial septectomy (procedure code 35.42), or vessel repair or occlusion (procedure codes or 39.59) with concomitant catheterization codes ( , , ) and no code for cardiopulmonary bypass (39.61). Assignment of CPTs to Cases Because the administrative data contained ICD-9-CM diagnostic and procedure codes, but not CPT codes, computer algorithms were generated to assign CPTs to individual cases. The ICD-9-CM and CPT coding schemes were similar for most common procedures. However, because of coding differences (eg, specification of surgical detail within the CPT scheme, which was not encoded in the ICD-9-CM codes) some cases could not be assigned to CPTs. Only unambiguous assignments were made; cases that could be assigned to more than one CPT were not assigned to any, except that complex procedures with concomitant PDA ligation, atrial septal defect closure, or atrial septectomy were assigned the CPT of the more complex procedure. The appropriate work and PE RVUs were then used for the analysis. In several instances, for similar procedures, mean values for RVUs were assigned. The ICD-9-CM codes used for CPT, work RVU, and PE RVU assignment are shown in Table 1. Data Analyses Data from all nine states were combined for analysis. Cases for which an unambiguous work RVU and PE RVU could not be assigned were eliminated. Of the remaining

3 862 JENKINS ET AL Ann Thorac Surg RVUs FOR CONGENITAL HEART OPERATIONS 1998;66:860 9 Table 1. ICD-9-CM Assignment Information for CPT Codes a Procedure CPT Code ICD-9-CM Diagnostic Codes Procedure Codes Aortic valvuloplasty LV aorta conduit AVR prosthetic AVR homograft 33406, not AVR/pulmonary autograft and Subaortic stenosis resection Mitral valve replacement or Tricuspid valve replacement or Pulmonary valvotomy or Pulmonary valve replacement 33475, not or Infundibular PS resection RV pulmonary artery conduit 33608, not not {(745.2 and ) or ( or and )} Fontan or Stage I procedure for HLHS and no other cardiac diagnoses except (745.5, 746.3, 746.5, 747.0, 747.1, or ) not (39.21, 35.94, or 35.95) and not (35.11, 35.42, or 39.0) alone ASD secundum repair 33641, not , 35.61, or ASD primum repair (35.54, 35.63, or 35.73) or (35.51, 35.61, or 35.71); allowed CCAVC repair , 35.63, or 35.73; allowed VSD closure , 35.62, or Tetralogy of Fallot repair 33692, 33694, or 33696; not and not and not 35.92, VSD closure allowed Tetralogy of Fallot with PA repair or (745.2 or 745.4) and , allowed Total anomalous pulmonary venous return repair Atrial septectomy 33735, 33736, or Systemic to pulmonary shunt 33750, 33755, not , or Cavopulmonary shunt or Atrial switch operation 33774, not Atrial switch operation/vsd closure and (35.53, 35.62, or 35.72) Arterial switch operation 33778, not Arterial switch operation/vsd closure and (35.53, 35.62, or 35.72) Truncus arteriosus repair PDA ligation or , no other cardiac diagnoses Coarctation repair 33840, 33845, or or Interrupted aortic arch/repair off bypass (38.35 or 38.45) and not Interrupted aortic arch/repair on (38.35 or 38.45) and bypass Pulmonary atresia/vsd repair and and (35.53, 35.62, or 35.72) a No additional cardiac procedures were allowed except as noted, or concomitant ASD closure, PDA ligation, or atrial septectomy. ASD atrial septal defect; AVR aortic valve replacement; CCAVC complete common atrioventricular canal; CPT current procedural terminology; HLHS hypoplastic left heart syndrome; LV left ventricle; PA pulmonary atresia; PDA patent ductus arteriosus; PS pulmonary stenosis; RV right ventricle; VSD ventricular septal defect.

4 Ann Thorac Surg JENKINS ET AL 1998;66:860 9 RVUs FOR CONGENITAL HEART OPERATIONS 863 Table 2. Summary of Cases Assigned a CPT and RVUs State Number of Cases Length of Stay, median days (range) Total Hospital Charges, median dollars (range) In-Hospital Mortality Rate (%) CA 1, , (0 352) (4,713 1,720,216) CO , (2 69) (3, ,161) FL , (1 155) (5, ,924) IL , (1 130) (2, ,730) MA , (1 101) (8, ,035) MD , (0 112) (1, ,580) PA , (1 295) ( ,063) WA , (1 125) (5, ,847) WI , (1 129) (4, ,032) TOTAL 5, , (0 352) (961 1,720,216) CPT current procedural terminology; RVU relative value unit. cases, a subset of 155 cases that did not report charges were eliminated from analyses of total hospital charges. The measures of interest were two continuous variables representing resource consumption length of hospital stay and total hospital charges and a binary indicator of clinical outcome, in-hospital mortality. Analyses were performed for both work and PE RVUs. Patient-level associations between resource consumption and RVUs were quantified using the Spearman rank correlation coefficient, because the distributions of length of stay and total hospital charges were highly skewed. Correlations for all three measures were also calculated at the procedure, or CPT, level using median values of length of stay and total charges and the overall mortality rate for each CPT. Medians were used rather than means because the median was less influenced by outlying values in the skewed distributions and thus provided a better measure of a typical value of length of stay or total charges. Three procedures for which only a single case was identified were not included in this analysis. Mean differences in RVU for patients who died in hospital and those who did not were investigated using an unpaired Student s t test. Predicted changes in resource consumption corresponding to a fixed increase in RVU were assessed by means of linear regression. Natural logarithm transformations of length of stay and charges, and trimmed datasets eliminating the highest values, were used to normalize their distributions before analysis. The change in the relative odds of in-hospital mortality for a fixed increase in RVU was evaluated using logistic regression. Results Descriptive Statistics Within the nine states, a total of 7,301 cases of surgical procedures for congenital heart defects in children were identified. Current procedural terminology codes, and thus work and PE RVUs, were successfully assigned to 5,192 (71.1%) cases involving 34 different surgical procedures, including most common congenital heart operations. Within the entire surgical series, the median length of stay was 7 days (range, 0 to 352 days); the median total hospital charges were $38,970 (range, $961 to $1,720,216); and the overall mortality rate was 6.1%. Summary data for cases that could be successfully matched to work and PE RVUs are shown in Table 2 according to state and in Table 3 by procedure. Correlation Between RVUs and Length of Stay and Total Hospital Charges Correlations were measured for 31 procedures, each of which had more than one case identified. Work and PE RVUs were highly correlated (Spearman r s 0.93; p ). Both of these were significantly correlated with median length of stay and median total hospital charges, although correlations were higher for work RVUs. These data are shown descriptively in Figures 1 and 2. Abbreviations used for these figures are shown in Table 3. Correlations were less when analyses were performed on the entire dataset, rather than on median values for each procedure (length of stay and work RVU r s 0.50, and PE RVU r s 0.40, both p ; total charges and work RVU r s 0.59, and PE RVU r s 0.49, both p ). Correlation Between RVUs and In-Hospital Mortality Mean work RVU and PE RVU were lower for patients who survived than for those who died (mean standard deviation work RVU, versus ; PE RVU, versus ; both p ). Correlations between each of the scales and in-hospital mortality rates were lower than with resource consumption (Fig 3). Similar to length of stay and total charges, the correlation was higher for work RVUs. Results From Linear and Logistic Regression By linear regression, both length of stay and total hospital charges were significantly related to both work and PE RVUs (p ). Once again, the effects were strongest (ie, r 2 was largest) for work RVUs. Using log-transformed data, an increase of 5 units in work RVU was associated with an increase in length of stay by a multiplicative factor of 1.3 (p ), and an increase of 5 units in PE RVU by 1.2 (p ). An increase of 5 units in work RVU was associated with an increase in total hospital charges by a multiplicative factor of 1.5 (p ), and an increase in 5 units of PE RVU by 1.3 (p ). Similarly, using logistic regression, an increase of 5 units in work RVU increased the odds of a patient dying in hospital by 1.88 (95% confidence interval 1.67, 2.11); an increase in 5 units of PE RVU increased the odds by Results from models trimming the highest values of

5 864 JENKINS ET AL Ann Thorac Surg RVUs FOR CONGENITAL HEART OPERATIONS 1998;66:860 9 Table 3. Resource Consumption and In-Hospital Mortality According to Procedure Procedure Abbreviation in Figures Number of Cases Work RVU PE RVU Length of Stay, median days (range) Total Hospital Charges, median dollars (range) In-Hospital Mortality Rate (%) Aortic valvuloplasty Aov , (1 112) (12, ,301) LV aorta conduit LV-Ao , (5 49) (18,628 73,986) AVR prosthetic AVR/Pr , (2 54) (1, ,820) AVR homograft AVR/Hm , (5 69) (16, ,161) AVR/pulmonary autograft AVR/PA , (6 10) (38,534 75,232) Subaortic stenosis resection SubAS , (4 20) (15,834 70,675) Mitral valve replacement MVR , (1 50) (15, ,174) Tricuspid valve replacement TVR , (5 19) (26,953 64,799) Pulmonary valvotomy PVv , (1 129) (5, ,587) Pulmonary valve replacement PVR , (4 42) (25, ,312) Infundibular PS resection InfundPS , (2 64) (22, ,814) RV pulmonary artery conduit RV-PA , (1 101) (9, ,908) Fontan Fontan a , (1 294) (7,639 1,497,020) Stage I procedure for HLHS Stage I , (0 167) (22, ,866) ASD secundum repair ASD , (1 88) ( ,295) ASD primum repair ASD , (3 26) (17,101 77,271) CCAVC repair CAVC , (1 100) (12, ,063) VSD closure VSD , (1 188) (4, ,227) Tetralogy of Fallot repair TOF a , (1 165) (4, ,464) Tetralogy of Fallot with PA repair TOF/PA a , (6 155) (31, ,622) Total anomalous pulmonary venous return repair TAPVR , (1 100) (17, ,924) Atrial septectomy AtrSep a , (1 53) (12, ,753) Systemic to pulmonary shunt Sys-PA a , (0 295) (4, ,537) Cavopulmonary shunt CavoPulm a a 9 44, (1 76) (2, ,239) Atrial switch operation AtrS , (2 53) (10, ,839) Atrial switch operation/vsd closure AtrS/VSD , (8 17) (35, ,935) Arterial switch operation ASO , (2 130) (20, ,786)

6 Ann Thorac Surg JENKINS ET AL 1998;66:860 9 RVUs FOR CONGENITAL HEART OPERATIONS 865 Table 3. Continued Procedure Abbreviation in Figures Number of Cases Work RVU PE RVU Length of Stay, median days (range) Total Hospital Charges, median dollars (range) In-Hospital Mortality Rate (%) Arterial switch operation/vsd ASO/VSD , closure (1 130) (24, ,140) Truncus arteriosus repair Trunc , (1 99) (19, ,293) PDA ligation PDA a , (1 352) (961 1,720,216) Coarctation repair CoA a , (3 134) (3, ,944) Interrupted aortic arch/repair off IAA , bypass Interrupted aortic arch/repair on IAA/BP , bypass Pulmonary atresia/vsd repair PA/VSD , a Work RVU or PE RVU was assigned as mean value for multiple CPT codes for these procedures. ASD atrial septal defect; AVR aortic valve replacement; CCAVC complete common atrioventricular canal; CPT current procedural terminology; HLHS hypoplastic left heart syndrome; LV left ventricle; PA pulmonary atresia; PDA patent ductus arteriosus; PE practice expense; PS pulmonary stenosis; RV right ventricle; RVU relative value unit; VSD ventricular septal defect. length of stay and charges gave comparable results to log-transform models. Comment Mechanisms for determining physician reimbursement have received considerable scrutiny during the current health care reform debate. Even health care reform systems based on capitation require methods to divide capitation fees among various health care providers. The decision by HCFA to adopt a resource-based relative value scale including a multidimensional measure of physician work as a primary determinant of physician fees for Medicare patients, and the subsequent adoption of the scale by other payors, suggests the appropriateness of basing reimbursement on the time, effort, training, and skill required to perform various procedures. However, development of valid measures of relatively subjective constructs such as physician work, particularly with the potential for self-interest given the intended use of the scale to set individual income, requires considerable effort. Our findings suggest that the work RVU scale for pediatric cardiac surgical procedures has reasonable internal consistency as a measure of physician work. In a large, population-based analysis using 1992 data from nine states, a substantial portion of the scale showed high correlation with other measures that are likely to reflect physician time and effort, eg, length of hospital stay and total hospital charges, and moderate correlation with an outcome that is likely to reflect complexity, eg, in-hospital mortality. Surgical procedures that were assigned higher RVUs resulted in longer lengths of hospital stay, higher total hospital charges, and higher in-hospital death rates than cases with lower RVUs. This study does not address the important question as to whether the magnitude of pediatric cardiac surgical work RVUs are consistent with the magnitude of RVUs for other types of procedures, and thus does not affirm the entire process by which RVUs are currently assigned. Nevertheless, our work does suggest that the survey technique used to assign this group of RVUs, which was among the first to begin the important task of assigning values for pediatrics, resulted in a scale with reasonable, independent validity, despite the considerable differences between procedures performed in adults and children. Several additional observations are warranted. First, techniques similar to the ones we used might be useful to continue the important task of validation of the many additional RVUs that have been assigned. Clearly, correlation with the measures that we used, length of hospital stay, total hospital charges, and in-hospital mortality, will not be appropriate for many RVUs. Other independent measures that are likely to similarly reflect specific types of physician effort, training, and skill will need to be used for this purpose. Second, for this group of codes, based on our results, some refinements in work RVU assignment may need to be considered. For example, the three procedures for aortic valve replacement replacement with a prosthetic valve (RVU 29.17), replacement with a homograft valve (RVU 32.00), or replacement with a pulmonary autograft (RVU 35.00) had moderately disparate RVUs, but very similar median length of stay (range, 7 to 9 days) and median charges (range, $41,308 to $50,290). Also, three procedures that are technically fairly simple systemic to

7 866 JENKINS ET AL Ann Thorac Surg RVUs FOR CONGENITAL HEART OPERATIONS 1998;66:860 9 Fig 1. Relationships between the work relative value weight (RVU) (A) or the practice expense relative value weight (RVU) (B) for each procedure and the median length of stay for that procedure. A listing of the procedure represented by abbreviations is given in Table 3. The symbol r s represents the Spearman correlation coefficient for the association, with its associated p value. pulmonary artery shunt (RVU 20.94), atrial septectomy (RVU 21.49), and Glenn shunt or cavopulmonary anastomosis (RVU 23.00) but that are usually performed in infants or young children with complex disease, were all assigned very low RVUs. Yet all three had median lengths of stay, median charges, and in-hospital mortality rates that were quite high in comparison. In both of these examples, the discrepancies noted may reflect ways that resource consumption and patient outcomes fail to accurately reflect physician work (in particular, technical difficulty or other intraservice aspects of a surgical procedure), and thus reflect the incompleteness of our measures. For example, total operative time, cardiopulmonary bypass time, and aortic cross-clamp time were not incorporated in these measures, but may be different among the three aortic valve operations. However, it is also possible that the surveyed surgeons had a tendency to overemphasize technical considerations, in compari-

8 Ann Thorac Surg JENKINS ET AL 1998;66:860 9 RVUs FOR CONGENITAL HEART OPERATIONS 867 Fig 2. Relationships between the work relative value weight (RVU) (A) or the practice expense relative value weight (RVU) (B) for each procedure and the median total hospital charges for that procedure. A listing of the procedure represented by abbreviations is given in Table 3. The symbol r s represents the Spearman correlation coefficient for the association, with its associated p value. son with other dimensions of work. If this is the case, then the discrepancies may suggest procedures for which the scale is less valid, which could result in overreimbursement or underreimbursement for actual work performed. Finally, we have provided data showing the correlation between PE RVUs and resource consumption and mortality. Not surprisingly, given the very high correlation between PE and work RVUs for these procedures, correlations were similar to those for the work scale. In general, however, the correlations were lower for all measures. Given the relatively poor definition of the construct that PE RVUs are designed to reflect and the requirement that codes be assigned according to analogous codes, it is difficult to draw firm conclusions based on these findings as to whether the PE RVUs are behaving as intended in this dataset. Nevertheless, the similarities with work RVUs are striking. It is not clear from our

9 868 JENKINS ET AL Ann Thorac Surg RVUs FOR CONGENITAL HEART OPERATIONS 1998;66:860 9 Fig 3. Relationships between the work relative value weight (RVU) (A) or the practice expense relative value weight (RVU) (B) for each procedure and the percentage of patients who died during the hospitalization for that procedure. A listing of the procedure represented by abbreviations is given in Table 3. The symbol r s represents the Spearman correlation coefficient for the association, with its associated p value. data whether PE and work RVUs are independent measures for these procedures. Despite these observations, we believe that our findings suggest that the group of work RVUs for surgical procedures for congenital heart disease are reasonable relative measures, on average, of physician work for these procedures and thus support the appropriateness of use of this scale for physician reimbursement. Continued efforts will be necessary across many subspecialties to determine the general validity of the work RVU scale in its entirety and the methodology with which it was created, including cross-specialty linkages, but our results are quite encouraging. This research was supported in part by a Clinical Investigator Development Award (#HL ), NHLBI (K.J.J.) and by the Kobren Fund (K.G.).

10 Ann Thorac Surg JENKINS ET AL 1998;66:860 9 RVUs FOR CONGENITAL HEART OPERATIONS 869 References 1. Hsiao WC, Braun P, Yntema D, Becker ER. Estimating physicians work for a resource-based relative value scale. N Engl J Med 1988;319: Hsiao WC, Braun P, Becker ER, et al. A national study of resource-based relative value scales for physician services: final report to the Health Care Financing Administration. Harvard School of Public Health, 1988 (Publication no. 18-C-98795/1-03). 3. Medicare program: model fee schedule for physician services; notice. 55 Federal Register Medicare program: fee schedule for physician services. 56 Federal Register Medicare program: revisions to payment policies and adjustments to the relative value units under the physician fee schedule for calendar year Federal Register Blue Cross and Blue Shield of Massachusetts I: changes in reimbursement policy and reporting structure Medicaid RBRVS payment system begins April 1. Tex Med 1992;88: Becker ER, Dunn D, Braun P, Hsiao WC. Refinement and expansion of the Harvard resource-based relative value scale: the second phase. Am J Public Health 1990;80: AAP Division of Physician Payment Systems. AAP pushes pediatric involvement in RBRVS. Am Acad Pediatr News 1996;12: Kirschner CG, Davis SJ, Duffy C, et al. Physician s current procedural terminology. Chicago: American Medical Association, Noether M. Results from the Cardiothoracic and Vascular Surgery Work Survey by Abt Associates Inc. Ann Thorac Surg 1991;52: Morton SC, Kominski GF, Kahan JP. An examination of the resource-based relative value scale cross-specialty linkage method. Med Care 1994;32: Kahan JP, Morton SC, Farris HH, Kominski GF, Donovan AJ. Panel processes for revising relative values of physician work. A pilot study. Med Care 1994;32: Feldman R, Hillson SD, Wingert TD. Measuring the dimensions of physician work. Med Care 1994;32: The Annals of Thoracic Surgery Cumulative Index The Annals of Thoracic Surgery 31-year cumulative index, volume 1 through volume 60, January 1965 through December 1995, is available in two versions: in print (ISBN ) and on CD-ROM (ISBN ). Both print and CD-ROM versions contain subject and author indexes for the 31 years of the journal to date. The CD-ROM also contains all of the journal s published scientific abstracts; hypertext links between article titles, subject headings, authors, and abstracts; a search function that allows full-text, Boolean, and keyword searches; and functions to select and format references for future use. The CD-ROM is both DOS/ Windows and Macintosh compatible. The price is $95.00 for the CD-ROM version, $95.00 for the print version, or only $ for both the CD-ROM and print versions. Contact Elsevier Science Inc to place your order. Telephone (212) ; Fax (212) by The Society of Thoracic Surgeons Ann Thorac Surg 1998:66: /98/$19.00 Published by Elsevier Science Inc