Epidemiology of carotid endarterectomies among Medicare beneficiaries David C. Hsia, JD, MD, M P H , W. Mark Krushat, M P H , and Linda M. Moscoe, BA, Baltimore, A/id. Extensive debates exist in the literature on the indications, effectiveness, and risks of carotid endarterectomy. Hnwever~ no investigations analyze the procedure's epidemiology. Medicare paid for essentially all carotid endarterectomies on patients over 65 years old, more than two thirds of all such surgery. Accordingly, we identified all 1985 to 1989 Medicare bills for ICD-9-CM code 38.12. This report found an average annual decrease of 6.4% in the frequency of carotid endarterectomies. Higher proportions and incidence rates occurred among 65- to 79-year-old people, men, and whites. Larger, urban, and nonprofit hospitals performed the procedure more often. The number of hospitals performing this procedure has increased over time. Mortality rates within 30 days decreased from 3.0% of procedures in 1985 to 2.5% in 1989. Higher than average death rates occurred among older, male, and black patients, and in low volume hospitals. Clinical trials undertaken in large, urban, teaching, high-volume institutions reported only 1% deaths. The institutions actually performing carotid endarterectomies differ from the cfinical trials in their demography and perioperative mortality rates. This difference in community practice may limit the applicability of the clinical trials. (J VASC SURG

1992;16:201-8.)

Since its 1953 development, 1 carotid endarterectomy for arteriosclerotic occlusive disease has become one of the most common vascular surgery procedures. 2 Many debates exist in the literature on its efficacy, indications, and side effects. 36 Some studies find that carotid endarterectomy produces more favorable outcomes than medical treatment, 7,s but others find no difference between surgical and nonsurgical therapy. 9-~2 Accordingly, the National Institute of Neurological and Communicative Disorders and Strok@ 3 U.S. Department of Veterans Affairs, ~416 Mayo Clinic, 17 and Canada ~8 are each sponsoring controlled, prospective studies of carotid endarterectomy in symptomatic or asymptomatic patients. One such investigation, the North American Symptomatic Carotid Endarterectomy Trial, recently reported that for one subgroup, symptomatic patients with high-grade stenosis, surgery significantly reduces stroke over i8 months follow-up (5% versus i2%), despite a 1% perioperative mortality rate.19 Fromthe U.S. Departmentof Healthand HumanServices,Office of InspectorGeneral. The viewsexpressedin this paperdo not representthe policiesof any U.S. governmentagency. Reprint requests: DavidHsia, MD, OM l-D-16, ItHS Officeof InspectorGeneral,6340 Securi.tyBlvd.,Baltimore,MD 21207. 24/1/36523

Tiffs debate devotes little attention to who actually undergoes and performs carotid endarterectomies. Community hospitals may not attain the same outcomes as the tertiary medical centers that traditionally conduct the clinical trials. 20,21 In a similar manner, a clinical trial restricted to a homogeneous subpopulation (such as middle aged, white men) may have limited applicability to other demographic groups. 22,23The authors hypothesize that the epidemiology of carotid endarterectomy in the community may differ from the clinical trials. This report therefore seeks to identify the demographic trends for patients undergoing and institutions performing carotid endarterectomies. Nationwide estimates for the incidence of carotid endarterectomy derive exclusively from the National Center for Health Statistics' yearly National Hospital Discharge Surveys. This series annually selects approximately 250,000 discharges from approximately 500 participating hospitals and using a two-stage sample design based on hospitals and discharges, reabstracts the International Classification of Diseases (ICD-9-CM) codes,2~ and attaches appropriate sampling weights to each discharge (the inverse of the probability of selection).25 It extrapolates this sample by age and sex to approximate the procedure volume for the 33 million admissions to 7000 non-federal, short-stay hospitals. 201

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Hsia, Krmhat, and Moscoe

Table I. Estimated number and rate of CEAs in short-stay non-federal hospitals by patient demography, 1980 to 89 No. of CEAs (1000s) < 15 years 15-44 years 45-64 years 65 + years Male Female Total Rate per 10,000 pop. < 15 years 15-44 years 45-64 years 65 + years Male Female Average

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

0 0 18 37 33 22 55

0 0 22 50 39 33 73

0 0 25 55 45 36 82

0 0 25 69 56 39 95

0 0 32 70 55 48 103

0 0 32 74 60 47 107

0 0 20 62 43 40 83

0 0 23 58 48 34 81

0 0 24 45 43 27 70

0 0 19 49 37 33 70

0.0 0.0 4.0 14.1 3.0 1.9 2.4

0.0 0.0 4.9 19.0 3.5 2.8 3.2

0.0 0.0 5.6 20.5 4.0 3.0 3.5

0.0 0.0 5.6 25.2 5.0 3.3 4.1

0.0 0.0 4.4 21.3 3.7 3.2 3.4

0.0 0.0 5.1 19.4 4.0 2.7 3.3

0.0 0.0 5.2 14.8 3.6 2.1 2.8

0.0 0.0 4.1 15.8 3.1 2.6 2.8

0.0 0.0 7.2 25.0 4.9 4.0 4.4

0.0 0.0 7.1 25.9 5.2 4.2 4.5

CEA, Carotid endarterectomy; pop, population. Source: National Center for Health Statistics, Centers for Disease Control, Public Health Service, U.S. Department of Health and Human Services. Detailed diagnoses and procedures for patients discharged from short stay hospitals (1980-1989). Hyattsville, Maryland: National Center for Health Statistics, (1980-1989). (Vital and health statistics; series 13).

Table II. Number and percent distribution of Medicare CEAs by patient demography, 1985-89 No. (percent distribution) < 65 years 65-69 years 70-74 years 75-79 years 80-84 years 85 + years Male Female White Black Other Unknown Total < 95% CI of NCHS ~estimate for age 65 + >

1985

1986

1987

1988

1989

3993 (6.3) 18164 (28.8) 19213 (30.4) 13827 (21.9) 6076 (9.6) 1864 (3.0) 35O86 (55.6) 28051 (44.4) 59322 (94.0) 1617 (2.6) 399 (0.6) 1799 (2.8) 63137 (100.0) < 61-87 >

3173 (6.0) 15101 (28.5) 16185 (30.6) 11766 (22.2) 5154 (9.7) 1516 (2.9) 29653 (56.1) 23242 (43.9) 49729 (94.0) 1262 (2.4) 369 (0.7) 1535 (2.9) 52895 (100.0) < 51-74 >

2931 (5.5) 14810 (27.8) 16435 (30.9) 12164 (22.8) 5303 (10.0) 1613 (3.0) 30000 (56.3) 23256 (43.7) 49806 (93.5) 1322 (2.5) 490 (0.9) 1638 (3.1) 53256 (100.0) < 47-69 >

2617 (5.2) 14150 (28.0) 15348 (30.4) 11625 (23.0) 5176 (10.3) 1567 (3.1) 28751 (56.2) 21732 (43.8) 47260 (93.6) 1227 (2.4) 504 (1.0) 1492 (3.0) 50483 (100.0) < 36-54 >

2416 (5.1) 13076 (27.8) 14143 (30.1) 10885 (23.1) 5014 (10.7) 1497 (3.2) 26916 (57.2) 20115 (42.8) 43891 (93.3) 1140 (2.4) 581 (1.2) 1419 (3.0) 47031 (100.0) < 39-59 >

Source: Bureau of Data Management and Statistics, Health Care Financing Administration, U.S. Department of Health & Human Services. Part A bill history file, 1991. Baltimore, MD: Health Care Financing Administration, 1991. (Computer file). ~Technical notes on methods. National Center for Health Statistics, Centers for Disease Control, Public Health Service, U.S. Department of Health and Human Services. Detailed diagnoses and procedures for patients discharged from short stay hospitals (1980-1989). Hyattsville, Maryland: National Center for Health Statistics, (1980-1989). (Vital and health statistics; series 13).

According to these projections, the annual number of carotid endarterectomies rose from 15,000 in 1972 to peak at 107,000 in 1985. 26,27The procedure subsequently declined in frequency an average of 8.4% annually, possibly in reaction to the controversy about its risks and effectiveness. Essentially no one under age 45 years underwent this procedure, with patients aged 65 years and older ranging from 67.1% (in 1982) to 74.7% (in 1986) of the total volume. Men made up 51.8% (in 1986) to 61.4% (in

1988) of patients. Dividing by their respective populations, men and the elderly also had higher rates of surgery. This series did not tabulate by race, but single institutions reported performing more than 95% of their carotid endarterectomies on whites 2s (Table I). This report uses Medicare billing data to further detail the epidemiology of carotid endarterectomy. Medicare's volume of billing data permits more precise and detailed counts than the National Center

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Zcledicare carotid endarterectomies

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Table III. N u m b e r o f Medicare beneficiaries and rate o f CEAs by patient demography, !985-89 1985

No. (rate per 10,000 beneficiaries) < 65 years 2906876 (13.7) 65-69 y e a r s 8818437(20.6) 70-74 y e a r s 7292456(26.3) 75-79 y e a r s 5314757(26.0) 80-84 y e a r s 3403124(17.9) 85 + years 2853818 ( 6 . 5 ) Male 12992759 (27.0) Female 17596709 (15.9) White 26760225 (22.2) Other 2956762 ( 6 . 8 ) Unknown 872481 (20.6) Total 30589468 (20.6)

1986

2958525(10.7) 9012573(16.8) 7411255(21.8) 5430928(21.7) 3478726(14.8) 2923522( 5 . 2 ) 13258893(22.4) 17956636(12.9) 27257093(18.2) 3062511( 5 . 3 ) 895925 (17.1) 31215529(16.9)

1987

3030708( 9 . 7 ) 9200508(16.1) 7496395(21.9) 5546610(21.9) 3557802(14.9) 3013172( 5 . 4 ) 13526356(22.2) 18318839(12.7) 27739119(18.0) 3182299( 5 . 7 ) 923777 (17.7) 31845195(16.7)

1988

3101482( 8 . 4 ) 9311100(15.2) 7605080(20.2) 5650472(20.6) 3658607(14.1) 3086297( 5 , 1 ) 13773367 (20.2) 18639671(11.7) 28146680(16.8) 3312029( 5 . 2 ) 954329 (15.6) 32413038(15.6)

1989

3170917(7.6) 9510986(13.7) 7639618(18.5) 5800860(18.8) 3757517(13.3) 3160079(4.7) 14037275(19.2) 19002702(10.6) 28600386(15.3) 3465199(5.0) 974392 (14.6) 33039977 (14.2)

Source: Moaney-HowzeA. Table 7.B -Medicare: Enrollment,utilization, and reimbursement.In: MarbrayPA. SocialSecureT Bulletin, Annual Statistical Supplement, 1989: 290. Social SecurityAdministration publication no. 13-11700. And: DrexlerJ. Table AE 10-Hospital insurancefor all persons by age, race, sex, and place for residence, 1985-1989. Baltimore,MD: Health Care Financing Administration, 1991. Unpublished.

Table IV. N u m b e r o f Medicare discharges and rate o f CEAs by patient demography, 1985-89 1985

No. (rate per 10,000 discharges)

Epidemiology of carotid endarterectomies among Medicare beneficiaries.

Extensive debates exist in the literature on the indications, effectiveness, and risks of carotid endarterectomy. However, no investigations analyze t...
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