Epidemiology of carotid endarterectomy among Medicare beneficiaries: 1985-1996 update.

BACKGROUND AND PURPOSE: This article describes changes in the rate and outcome of carotid endarterectomies among Medicare beneficiaries. METHODS: We analyzed International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes as shown on Medicare bills to calculate carotid endarterectomy frequency, rate, and perioperative mortality by patient demography and hospital characteristics. RESULTS: After initially peaking at 61273 procedures (20.6 per 10000 beneficiaries) in 1985, the frequency of carotid endarterectomy among Medicare beneficiaries declined to 46571 (14.3 per 10000) in 1989 and then rose to 108275 (28.6 per 10000) in 1996. Patients were predominantly aged 65 to 74 years, male, and white; surgery occurred mainly in large, urban, nonprofit, and teaching hospitals. Perioperative mortality declined from 3.0% in 1985 to 1.6% in 1996. CONCLUSIONS: The frequency and rate of carotid endarterectomy showed prompt response to reports from clinical trials. Perioperative mortality both improved and converged over time but did not attain the rates reported by the trials. Patients aged 85+ years suffered twice the average perioperative mortality.

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 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 clinical trials in their demography and perioperative mortality rates. This difference in community practice may limit the applicability of the clinical trials.

Medicare reimbursement accuracy under the prospective payment system, 1985 to 1988.

BACKGROUND: Hospital reimbursement by Medicare's prospective payment system depends on accurate identification and coding of inpatients' diagnoses and procedures using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). A previous study showed that 20.8% +/- 0.5% (mean +/- SE) of hospital bills for 1985 contained errors that changed their diagnosis related group (DRG) and that a significant 61.6% +/- 1.3% of errors overreimbursed the hospitals. This DRG "creep" improperly increased net reimbursement by 1.9%, +308 million when projected nationally. The present study updated our previous study with 1988 data. METHODS: The Office of Inspector General, US Department of Health and Human Services, obtained a simple random sample of 2451 hospital charts for Medicare discharges from 1988. The American Medical Record Association reabstracted the ICD-9-CM codes on a blinded basis, grouped them to DRGs, and determined the reasons for discrepancies. RESULTS: Coding errors declined to 14.7% +/- 0.7% in 1988, and a nonsignificant 50.7% +/- 2.6% of DRG errors overreimbursed the hospitals. Projected nationally, hospitals did not receive a significant overreimbursement. Physician misspecification of the narrative diagnoses underreimbursed the hospitals, while billing department resequencing overreimbursed them. CONCLUSIONS: The attestation requirement may have deterred DRG creep due to attending physician upcoding, but the peer review organizations' sentinel effect and educational activities have not eliminated hospital resequencing.