Deborah A. Freund

Patient outcomes after knee replacement.

A prospective, observational cohort investigation was performed to help understanding the impact of knee replacement on patients with knee osteoarthritis in community practice. Of those, 291 patients (330 knees) were eligible and willing to participate. Forty-eight orthopaedic surgeons referred 563 patients from 25 institutions within the state of Indiana. Demographics, patient completed health status, satisfaction, independent radiographic measures, surgeon reported intraoperative factors, hospital discharge factors, and independent physical examinations were recorded. A minimum 2-year followup was obtained in 92% of the patients. At followup, 88% were satisfied, 3% were neutral, and 9% were dissatisfied with the results of their knee surgery. The physical composite score improved from 27.4 ± 0.4 (range, 13.3-50.3) to 37.7 ± 0.7 (range, 12.9-61.3) at two years. Maximal improvement in physical composite score was seen in patients who had their surgery performed in institutions that performed greater than 50 knee replacements per year in patients with Medicare insurance; who had a better mental health status at baseline; who had surgery performed on Monday, Friday, or Saturday; who were older; who were treated with a posterior cruciate sparing device; and who had worse preoperative function. A lower likelihood of complications were found with surgeons who performed greater than 20 knee replacements per year; midweek surgeries; in patients with more severe preoperative knee dysfunction; patients with fewer comorbidities; patients with less preoperative stiffness; patients being treated by younger surgeons; and in patients undergoing unilateral knee replacement. Among voluntarily participating physicians, knee replacement can be a highly effective medical technology with high levels of patient satisfaction and low rates of complications.

Outcome implications for the timing of bilateral total knee arthroplasties.

Health Care Financing Administration data from 1985 to 1990 revealed 339,152 total knee arthroplasties of which 62,730 (18.6%) were bilateral procedures (simultaneous 112,922; staged 6 weeks, 4354; staged 3 months, 4524; staged 6 months, 9829; and staged 1 year 31,401). Medicare beneficiaries undergoing bilateral procedures were an average of 73 years of age; demographics revealed that among the various simultaneous and staged groups 57% to 69% were females, 90% were white, 85% to 90% had a diagnosis of osteoarthritis, and 30% to 40% were performed in rural hospitals. Between 1985 and 1990, surgical and vascular complications ranged from 2.4% to 4% and 4.1% to 6.8%, respectively, for all types of bilateral staged and simultaneous total knee arthroplasties. All differences were statistically significant. After controlling statistically for demographic variables and diagnoses, a surrogate for case mix, it was found that individuals electing simultaneous bilateral arthroplasties experienced twice the number of intensive care days than those choosing staged procedures. Days in the intensive care unit were double when done simultaneously instead of staged (0.48 versus 0.21). Nosocomial infections were similar within groups (10% versus 13%); however, wound infections were nearly half when done simultaneously (0.5% versus 1%) versus in a staged fashion. Length of stay and cost were much less for the simultaneous procedure group who were sicker as measured by the number of diagnoses. Mortality at 30 days was highest for the simultaneous procedure group (.99%) versus staged 3 or 6 months (0.30%); however, by 2 years it was close to 4% for all groups. Staging the procedure 3 to 6 months seems to offer the fewest disadvantages, is only slightly more expensive, and has the lowest mortality rate.

REVISION RATES AFTER KNEE REPLACEMENT IN THE UNITED STATES

OBJECTIVES Each year approximately 100,000 Medicare patients undergo knee replacement surgery. Patients, referring physicians, and surgeons must consider a variety of factors when deciding if knee replacement is indicated. One factor in this decision process is the likelihood of revision knee replacement after the initial surgery. This study determined the chance that a revision knee replacement will occur and which factors were associated with revision. METHODS Data on all primary and revision knee replacements that were performed on Medicare patients during the years 1985 through 1990 were obtained. The probability that a revision knee replacement occurred was modeled from data for all patients for whom 2 full years of follow-up data were available. Two strategies for linking revisions to a particular primary knee replacement for each patient were developed. Predictive models were developed for each linking strategy. ICD-9-CM codes were used to determine hospitalizations for primary knee replacement and revision knee replacement. RESULTS More than 200,000 hospitalizations for primary knee replacements were performed, with fewer than 3% of them requiring revision within 2 years. The following factors increase the chance of revision within 2 years of primary knee replacement: (1) male gender, (2) younger age, (3) longer length of hospital stay for the primary knee replacement, (4) more diagnoses at the primary knee replacement hospitalization, (5) unspecified arthritis type, (6) surgical complications during the primary knee replacement hospitalization, and (7) primary knee replacement performed at an urban hospital. CONCLUSIONS Revision knee replacement is uncommon. Demographic, clinical, and process factors were related to the probability of revision knee replacement.

Racial Disparities in Service Use among Medicaid Beneficiaries after Mandatory Enrollment in Managed Care: A Difference-in-Differences Approach

Managed care may improve access to health care to previously underserved populations when providers need plan enrollees. However, capitation and utilization management often give providers the incentive to withhold care. Managed care organizations have yet to demonstrate that racial disparities in treatment are not exacerbated. Using Medicaid eligibility, claims, and managed care encounter data, we examine racial disparities in service use among Medicaid beneficiaries after mandatory enrollment in managed care. We use count data models adjusted for nonrandom selection within difference-in-differences econometric approaches. The results show that mandatory enrollment has disproportionately reduced the relative use of physician and inpatient services among African-American beneficiaries.

Specialty differences in the treatment of asthma

This is one of a series of occasional articles reflecting the opinions of respected authors or groups in areas of considerable interest and debate. They have not been peer reviewed in the usual manner and have not been edited by the JOURNAL. This particular article describes a study commissioned b) the Joint Council of Allergy and Immunology. It is hoped that the Rostrum articles will spark interest and discussion.

A typology of Medicaid managed care.

This article presents a typology for use in classifying and interpreting the findings of the growing empirical literature on managed care initiatives in the Medicaid program. Six key program attributes are identified for use in examining similarities and differences among these programs. Several alternative arrangements for each attribute are described from among the more than 60 different programs attempted. The typology is illustrated with five specific program designs, and selected empirical results from them are used to demonstrate how the typology can be employed.

Cost effectiveness of postoperative carcinoembryonic antigen monitoring in colorectal cancer

Serial monitoring of carcinoembryonic antigen (CEA) has been thought to provide early indication of recurrent cancer in individuals who have undergone curative resection. The current study was designed to assess the costs associated with CEA monitoring. Costs included CEA determinations, other evaluative tests prompted by abnormal CEA values and hospital/surgical costs in patients undergoing “second‐look” procedures. The authors estimated that the cost per resectable tumor was

Dealing with the common econometric problems of count data with excess zeros, endogenous treatment effects, and attrition bias

24,779; but, under optimal circumstances, it might be as low as

Factors affecting physicians' choice to practice in a fee-for-service setting versus an individual practice association.

10,446. The most important factors were the percentage of recurrent tumors and the proportion of these that were resectable. It proved slightly more efficient to limit the preoperative workup rather than to decrease the frequency of CEA determinations. The true benefits of CEA initiated second‐look surgery in terms of prolonged survival remain unknown. More clinical experience is needed to better understand these benefits. Cancer 53:193‐198, 1984.

Influence of organizational components on the delivery of asthma care.

Abstract We use experimental panel data to estimate impacts of managed care on medical care use counts free of endogenous treatment effect bias. Our count regressions also allow for excess zeros and correct for possible attrition bias.