Biomedical subjects

Jeffrey N Katz

Publications and source records attributed to Jeffrey N Katz.

At least 19 recordsLinked to original sources

PubMed2025

Distinct roles of the two BRCA2 DNA-binding domains in DNA damage repair and replication fork preservation.

Homologous recombination (HR) removes DNA double-strand breaks (DSBs) and preserves stressed DNA replication forks. Successful HR execution requires the tumor suppressor BRCA2, which harbors distinct DNA-binding domains (DBDs): one that possesses three oligonucleotide/oligosaccharide-binding (OB) folds (OB-DBD) and another residing in the C-terminal recombinase binding domain (CTRB-DBD). Here, we employ multi-faceted approaches to delineate the contributions of these domains toward HR and replication fork maintenance. We show that OB-DBD and CTRB-DBD confer single-strand DNA (ssDNA)- and dsDNA-binding capabilities, respectively, and that BRCA2 variants mutated in either domain are impaired in their ability to load the recombinase RAD51 onto ssDNA pre-occupied by RPA. While the CTRB-DBD mutant is modestly affected by DNA break repair, it exhibits a strong defect in the protection of stressed replication forks. In contrast, the OB-DBD is indispensable for both BRCA2 functions. Our study thus defines the unique contributions of the two BRCA2 DBDs in genome maintenance.

BRCA2 Protein↗

PubMed2023

DNA binding and RAD51 engagement by the BRCA2 C-terminus orchestrate DNA repair and replication fork preservation.

The tumor suppressor BRCA2 participates in DNA double-strand break repair by RAD51-dependent homologous recombination and protects stressed DNA replication forks from nucleolytic attack. We demonstrate that the C-terminal Recombinase Binding (CTRB) region of BRCA2, encoded by gene exon 27, harbors a DNA binding activity. CTRB alone stimulates the DNA strand exchange activity of RAD51 and permits the utilization of RPA-coated ssDNA by RAD51 for strand exchange. Moreover, CTRB functionally synergizes with the Oligonucleotide Binding fold containing DNA binding domain and BRC4 repeat of BRCA2 in RPA-RAD51 exchange on ssDNA. Importantly, we show that the DNA binding and RAD51 interaction attributes of the CTRB are crucial for homologous recombination and protection of replication forks against MRE11-mediated attrition. Our findings shed light on the role of the CTRB region in genome repair, reveal remarkable functional plasticity of BRCA2, and help explain why deletion of Brca2 exon 27 impacts upon embryonic lethality.

DNA Replication↗

PubMed2006

Osteoporosis management in patients with rheumatoid arthritis: Evidence for improvement.

OBJECTIVE: Osteoporosis in patients with rheumatoid arthritis (RA) is increasingly recognized as a major comorbidity. We examined past management patterns for glucocorticoid-induced osteoporosis and attempted to improve care through an educational intervention. The goal was to examine the frequency of osteoporosis management in patients with RA treated at a large academic rheumatology practice. METHODS: We performed a structured chart review on randomly selected patients seen during 2004 for RA. Osteoporosis management was defined as a bone mineral density test or receipt of a medication for osteoporosis in the prior 24 months. The frequency of osteoporosis management among our study group was assessed. We also examined how glucocorticoid dosage affected osteoporosis management in adjusted models. RESULTS: We reviewed the records for 193 patients, 99 had not used glucocorticoids in the prior 24 months, and 94 had used them. Of the total study population, 48% had received a bone mineral density test or medication for osteoporosis. Some form of osteoporosis management was present for 64% of patients taking > or =5 mg prednisone for > or =3 months compared with 38% for patients taking none (P = 0.002). Predictors of osteoporosis management included older age, female sex, glucocorticoid dosage, and prior osteoporosis diagnosis or fracture. CONCLUSION: The frequency of osteoporosis management appears to have increased compared with a prior chart review.

Aged↗

PubMed2006

Primary and revision hip arthroplasty: 5-year outcomes and influence of age and comorbidity.

OBJECTIVE: Revision hip arthroplasty is associated with less favorable short and longterm results than primary total hip arthroplasty (THA). We compared quality of life and satisfaction 5 years after the 2 interventions, to determine the influence of patient characteristics on poorer outcomes after revision, and to analyze if their influence differed for primary and for revision arthroplasty. METHODS: This was a hospital-based prospective cohort study including patients who underwent primary (n = 435) or revision THA (n = 116). Quality of life was measured by Harris Hip Score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Medical Outcomes Study Short Form-12 questionnaire. Satisfaction was evaluated with a visual analog scale. RESULTS: Patients undergoing a revision were older, more often obese, and had more medical and orthopedic comorbidities. Five years after surgery, 349 patients with primary THA and 85 with revisions were available for followup. Unadjusted quality of life and satisfaction were significantly lower after revision (Harris Hip Score 76.7 vs 88.1; WOMAC pain 66.4 vs 73.3; WOMAC function 61.6 vs 70.0; satisfaction 7.7 vs 8.9). Adjustment for patient characteristics revealed that this difference was partly explained by the greater morbidity and older age of patients undergoing revision. The influence of age, comorbidities, and preoperative function on 5-year outcomes did not substantially differ for the 2 intervention groups. However, obesity was associated with a stronger negative effect on revision surgery. CONCLUSION: Patients and physicians should acknowledge additional risks and consequently lower results associated with revision THA. Better information and medical preparation before surgery may help to improve the success of revision surgery.

Age Factors↗

PubMed2006

Effect of preoperative exercise on measures of functional status in men and women undergoing total hip and knee arthroplasty.

OBJECTIVE: To evaluate the effect of a short preoperative exercise intervention on the functional status, pain, and muscle strength of patients before and after total joint arthroplasty. METHODS: A total of 108 men and women scheduled for total hip arthroplasty (THA) or total knee arthroplasty (TKA) were randomized to a 6-week exercise or education (control) intervention immediately prior to surgery. We assessed outcomes through questionnaires and performance measures. Analyses examined differences between groups over the preoperative and immediate postoperative periods and at 8 and 26 weeks postsurgery. RESULTS: Among THA patients, the exercise intervention was associated with improvements in preoperative Western Ontario and McMaster Universities Osteoarthritis Index function score (improvement of 2.2 in exercisers versus decline of 3.9 in controls; P = 0.02) and Short Form 36 physical function score (decline of 0.4 in exercisers versus decline of 14.3 in controls; P = 0.003). No significant differences were seen in TKA patients. Exercise participation increased muscle strength preoperatively (18% in THA patients and 20% in TKA patients), whereas the control patients had essentially no change in strength (P > 0.05 for exercise versus education in both THA and TKA groups). Exercise participation prior to total joint arthroplasty substantially reduced the risk of discharge to a rehabilitation facility in THA and TKA patients (adjusted odds ratio 0.27, 95% confidence interval 0.074-0.998). The intervention had no effects on outcomes 8 and 26 weeks postoperatively. CONCLUSION: A 6-week presurgical exercise program can safely improve preoperative functional status and muscle strength levels in persons undergoing THA. Additionally, exercise participation prior to total joint arthroplasty dramatically reduces the odds of inpatient rehabilitation.

Aged↗

PubMed2006

Computed tomography evaluation of superior-segment facet-joint violation after pedicle instrumentation of the lumbar spine with a midline surgical approach.

STUDY DESIGN: Retrospective study. OBJECTIVES: To determine the frequency of pedicle screw violation of superior nonfused facet joints adjacent to the most cephalad pedicle screws after a midline approach for lumbar fusion. SUMMARY OF BACKGROUND DATA: Facet-joint violations have been evaluated in patients undergoing lumbar pedicle screw instrumentation and fusion with a Wiltse muscle-splitting approach, but not via the more common midline approach. METHODS: Between 1995 and 2003, 204 patients underwent this procedure. Computed tomography scans (within 1 year postsurgery) were evaluated independently for superior facet-joint violation. chi tests were used to examine bivariate associations of superior level facet-joint violation, patient age, construct level, diagnosis, and revision status for significance (P < or = 0.05). RESULTS: Superior-level facet-joint violation occurred in 24% of patients and 15% of screws, twice as often on the left side (P = 0.0396) than on the right, more frequently in single than in multiple-level procedures (P < 0.0001), and most frequently with the most cephalad screws at L5 (48%). We found no significant associations between violation rates and other designated parameters. CONCLUSION: The left side, single-level fusion, and most cephalad pedicle screws at L5 are targets for interventions to reduce pedicle violations in this procedure.

Adult↗

PubMed2006

Trends in the epidemiology of total shoulder arthroplasty in the United States from 1990-2000.

OBJECTIVE: Longitudinal trends in epidemiology and utilization of total shoulder arthroplasty (TSA) have not been previously reported. We evaluated trends in the distribution of age, race, hospital volume and teaching status, outcomes, and indications for TSA during the last decade. METHODS: TSA cases (n = 12,758) were extracted from the 1990-2000 Nationwide Inpatient Sample databases. TSA trends were obtained for 3 time periods: 1990-1993 (period I), 1994-1997 (period II), and 1998-2000 (period III). RESULTS: Between 1990 and 2000, there were minor increases in the rate of TSA in most age groups. Ninety-three percent of the patients undergoing TSA in all 3 time periods were white. An increased proportion of patients were operated on in high volume hospitals in period III as compared with period I. Patients discharged to inpatient rehabilitation facilities after surgery had longer lengths of in-hospital stays as compared with those discharged home. Osteoarthritis was diagnosed in an increasing proportion of patients undergoing TSA (56.6% in period I versus 70.9% in period III). CONCLUSION: There was a minor increase in the rate of TSA, and almost no change in use of TSA by nonwhites from 1990 through 2000. Efforts to understand and narrow this apparent underutilization of TSA among nonwhites are required. Further research should determine whether the observed shift of TSA to high volume centers improves surgical outcomes.

Adult↗

PubMed2006

Methodological approaches to developing criteria for improvement in lumbar spinal stenosis surgery.

STUDY DESIGN: The study design was an outcomes measure validation for overall patient success. OBJECTIVE: The objective of this study was to validate an established lumbar spinal stenosis outcomes measure for individual patient success. SUMMARY OF BACKGROUND DATA: The Brigham Spinal Stenosis (BSS) Questionnaire has been used to evaluate lumbar spinal stenosis patients since the early 1990s. The three-domain questionnaire has been previously validated for patient improvement in each domain, but criteria for overall patient success have not been established. METHODS: The sample consisted of preoperative and 24-month postoperative BSS scores from 197 individuals who had undergone a lumbar decompressive procedure with or without an instrumented fusion. For each of the three BSS domains, we determined a threshold score that marked a successful outcome in that domain using receiver operator characteristic (ROC) curves. We combined these threshold scores in different ways to produce varying definitions of overall surgical success. RESULTS: The threshold for changes in the Symptom Severity and Physical Function domain scores were calculated as 0.46 and 0.42, respectively, while for Patient Satisfaction it was 2.42 based on the ROC analysis. The definition for individual patient success that requires the patient achieve threshold scores in each domain was less sensitive but more specific than alternative definitions of overall success that required the patient achieve at least two criteria or at least one criterion. CONCLUSIONS: The threshold values for each domain were similar to previously established values and the most balanced definition of overall success required that a patient achieve at least two criteria.

Aged↗

PubMed2006

The validity of a rheumatoid arthritis medical records-based index of severity compared with the DAS28.

The objective of this work was to assess the convergent validity of a previously developed rheumatoid arthritis medical records-based index of severity (RARBIS) by comparing it with the 28-joint Disease Activity Score (DAS28). This study was conducted in subjects within the Brigham and Women's Hospital Rheumatoid Arthritis Sequential Study (BRASS). We selected 100 patients with rheumatoid arthritis (RA) from the BRASS with DAS28 scores equally distributed in four quartiles. The medical records were reviewed to calculate the RARBIS, which includes indicators from the following categories: prior surgical history, radiologic and laboratory findings, clinical and functional status, and extra-articular manifestations. The Spearman correlation between the RARBIS and the DAS28 was assessed in the total study population and in relevant subgroups. We re-weighted on subscales and recalculated the RARBIS score. This was performed based on findings of correlations between the DAS28 and subscales; and also the result from a multiple linear regression with the DAS28 (as a dependent variable) and five subscales (as independent variables). The mean RARBIS was 4.36 (range 0-11). Among the total study cohort, the RARBIS was moderately correlated with the DAS28 (r = 0.41, 95% confidence interval [CI] 0.23-0.56). In subgroup analyses, including age, gender, rheumatoid factor status, and disease duration, we found no statistically significant differences in the correlations. After re-weighting, the correlation between the RARBIS and the DAS28 was somewhat improved (r = 0.48, 95% CI 0.31-0.62). In conclusion, the RARBIS correlated moderately well with the DAS28 in this population. The RARBIS has both face and convergent validity for patients with RA and relevant subgroups and may have application for medical records studies in patients with RA.

Arthritis, Rheumatoid↗

PubMed2006

A review of the 2001 Volvo Award winner in clinical studies: lumbar fusion versus nonsurgical treatment for chronic low back pain: a multicenter randomized controlled trial from the Swedish lumbar spine study group.

The current debate over the efficacy of lumbar fusion for low back pain has not been settled. Fritzell et al published a landmark paper entitled "Lumbar fusion versus nonsurgical treatment for chronic low back pain: a multicenter randomized controlled trial from the Swedish lumbar spine study group." Their goal was to provide objective evidence supporting lumbar fusion. While it was well designed and important to our knowledge base, it has limitations. We set out to review their work in an unbiased yet critical manner. Our goals are to summarize the strengths and weaknesses of the paper, place it in the context of current knowledge, and highlight its significance for present-day practice and research. From technical and study design perspectives, Fritzell et al were able to validate the use of lumbar fusion for the treatment of low back pain. However, their use of "usual nonoperative" care and nonspecific definition of low back pain precluded a truly genuine comparison of operative and nonoperative groups. We commend the Swedish lumbar spine study group and their remarkable efforts; they elevated the sophistication of spine research and spawned many more excellent works to help settle the ongoing controversy on the ideal treatment of low back pain.

Awards and Prizes↗

PubMed2006

Development of a preliminary index that predicts adverse events after total knee replacement.

OBJECTIVE: We undertook this study to assess the relationships between hospital characteristics, volume of procedures, and perioperative outcomes after total knee replacement (TKR), and to use this information to construct a simple predictive index for perioperative outcomes that incorporates hospital- and patient-level characteristics. METHODS: We studied Medicare beneficiaries who underwent TKR in 4 US states in 2000. Orthopedic surgery administrators from hospitals caring for patients in this sample were surveyed about a range of hospital characteristics. The relationships between these hospital characteristics, patient variables, and 90-day postoperative adverse events (including death, pulmonary embolus, pneumonia, deep wound infection, and acute myocardial infarction) were assessed using generalized estimating equations adjusting for hospital volume. These relationships were assessed in low- and high-risk patient groups. Variables from the final multivariate model were used to create an index that was tested against 90-day adverse event rates. RESULTS: Three hundred twenty-seven (3.6%) of the patients undergoing TKR in our sample experienced an adverse event. In the final multivariate regression models, variables that predicted adverse perioperative events included low hospital volume (fewer than 23 TKRs in the Medicare population per year), absence of a preoperative teaching program, fewer TKRs conducted in a dedicated orthopedic surgery operating room, patient age >70 years, male sex, and at least 1 comorbid condition. The effect of volume on perioperative adverse events was evident both in patients with few risk factors and in patients with several risk factors. An index including the 6 patient and hospital variables discriminated well, with adverse events occurring in 2.0% (95% confidence interval [95% CI] 1.4-2.7%) of patients in the lowest risk category and in 7.4% (95% CI 4.5-12.3%) of patients in the highest risk category (P for trend < 0.001). The index predicted adverse event rates both in hospitals with a low volume of TKRs and in those with a high volume of TKRs. CONCLUSION: Characteristics of hospital care, procedure volume, and patient-level factors are all associated with perioperative outcomes of TKR. A preliminary index combining hospital characteristics and volume is moderately predictive of adverse perioperative outcomes. The index is predictive of outcome in low- and high-volume hospitals.

Aged↗

PubMed2006

Performance of an automated computer-based scoring method to assess joint space narrowing in rheumatoid arthritis: a longitudinal study.

OBJECTIVE: To compare the diagnostic performance of a computer-based method for measuring joint space width with the Sharp joint space narrowing (JSN) scoring method in patients with rheumatoid arthritis (RA). METHODS: A random sample of patients with early RA, for whom sequential hand radiographs and Sharp scores were available, was selected from the National Data Bank for Rheumatic Diseases. Hand joint space width was measured using an automated, computer-based method in random order and with blinding for clinical information. We constructed a receiver operating characteristic curve and compared the diagnostic performance of the computer-based and Sharp methods based on the areas under the curve. RESULTS: One hundred twenty-nine patients with early RA who underwent serial radiography were included. Changes in the computer-based and Sharp methods were highly correlated (r = 0.75, P < 0.001). The computer-based method was significantly more discriminant than the Sharp JSN subscale. The area under the curve of the computer-based method was 0.96 (95% confidence interval [95% CI] 0.94, 0.99) compared with 0.93 (95% CI 0.89, 0.96) for the Sharp subscale (P = 0.024). At the most discriminant cutoff, specificity of the computer-based method was 88.4% compared with 81.4% for the Sharp subscale (P = 0.11); sensitivity was 87.6% for the computer-based method compared with 82.2% for Sharp subscale (P = 0.19). The signal-to-noise ratio for the computer-based method was 83% compared with 70% for the Sharp subscale (P = 0.013). CONCLUSION: The computer-based method for measuring joint space width is more discriminant than the semiquantitative Sharp JSN subscale.

Adult↗

PubMed2006

Tumor necrosis factor alpha antagonist use and cancer in patients with rheumatoid arthritis.

OBJECTIVE: Concerns persist about a possible association between tumor necrosis factor alpha (TNFalpha) antagonist treatment and development of cancers in patients with rheumatoid arthritis (RA). This study was undertaken to estimate the association between treatment with biologic disease-modifying antirheumatic drugs (DMARDs) and development of cancer in patients with RA. METHODS: We conducted a cohort study pooling administrative databases from 2 US states and 1 Canadian province. A cohort of patients who had received a diagnosis of RA on > or =1 occasion and had been prescribed DMARDs was identified. We categorized patients with a prescription for a biologic DMARD as biologic DMARD users, and those with a prescription for methotrexate (MTX) but no biologic DMARD as MTX users. We used time-varying propensity scores to adjust for the large number of possible confounders and stratified proportional hazards regression to estimate the effects of biologic DMARDs on cancer. The primary end points were hematologic malignancies (lymphoma, multiple myeloma, and leukemia) and common solid tumors (colorectal, lung, stomach, breast, prostate, uterine, ovarian, urinary tract/bladder, and melanoma). RESULTS: The pooled cohort included 1,152 biologic DMARD users and 7,306 MTX users. We identified 11 hematologic malignancies and 46 solid tumors during 2,940 person-years of biologic DMARD use, and 88 hematologic malignancies and 558 solid tumors during 30,300 person-years of MTX use. Comparing biologic DMARD users with MTX users, the propensity score-adjusted pooled hazard ratio was 1.37 (95% confidence interval 0.71-2.65) for hematologic malignancies and 0.91 (95% confidence interval 0.65-1.26) for solid tumors. CONCLUSION: Our results indicate that users of biologic agents are unlikely to have a substantial increase in the risk of hematologic malignancies and solid tumors as compared with MTX users. Despite the use of large combined data sets, studying the effect of an infrequent exposure (biologic DMARDs) on rare diseases (hematologic malignancies) remains a challenge.

Aged↗

PubMed2006

Immunosuppressive medications and hospitalization for cardiovascular events in patients with rheumatoid arthritis.

OBJECTIVE: The risk of cardiovascular disease (CVD) is increased in patients with rheumatoid arthritis (RA), most likely because of increased systemic inflammation. Prior research suggests that immunosuppressive medications may reduce the risk of CVD among RA patients. This study was undertaken to investigate the effects of various immunosuppressive medications on the risk of cardiovascular events among a group of older patients with RA. METHODS: In this nested case-control study, the source cohort was derived from Medicare beneficiaries receiving a drug benefit from the state of Pennsylvania. These individuals were required to have been diagnosed as having RA on at least 2 visits and to have filled a prescription for an immunosuppressive agent. Cases were defined as those patients who were hospitalized for a cardiovascular event such as myocardial infarction or stroke, and 10 control subjects were matched to each case by age, sex, and calendar year of the index date (the time of the first cardiovascular event in each case). Current use of an immunosuppressive medication was defined as having filled a prescription for these agents within the 90 days prior to the index date. Multivariate logistic regression models that included important covariates were assessed to determine the risk of cardiovascular events associated with immunosuppressive agents and their combinations. RESULTS: Among the study cohort, we identified 3,501 RA patients who fulfilled our eligibility criteria. During followup of this cohort, 946 patients were hospitalized for a cardiovascular event. Although the 95% confidence intervals (95% CIs) were wide in adjusted risk regression models with methotrexate (MTX) monotherapy as the reference group, biologic immunosuppressive agents showed neither protective nor deleterious effects (with biologics monotherapy, odds ratio [OR] 1.0, 95% CI 0.5-1.9; with biologics plus MTX combination therapy, OR 0.8, 95% CI 0.3-2.0; and with biologics plus other immunosuppressive agents, OR 1.2, 95% CI 0.7-2.2). Monotherapy with oral glucocorticoids was associated with an increased risk of cardiovascular events (OR 1.5, 95% CI 1.1-2.1), and a similar trend in the direction of risk was seen with glucocorticoid combination therapy (OR 1.3, 95% CI 0.8-2.0). Cytotoxic immunosuppressive agents other than MTX (azathioprine, cyclosporine, and leflunomide) were also associated with an increased risk of cardiovascular events (with both monotherapy and combination treatment, OR 1.8, 95% CI 1.1-3.0). CONCLUSION: When compared with RA patients receiving MTX monotherapy, those receiving biologic immunosuppressive agents had neither an increased nor decreased risk of experiencing a cardiovascular event, whereas use of oral glucocorticoids and cytotoxic immunosuppressive agents was associated with significant increases in the risk of cardiovascular events.

Aged, 80 and over↗

PubMed2006

Total joint replacement in osteoarthritis.

Surgical approaches have been developed for most of the sites of osteoarthritis, including the carpal metacarpal and first metatarsal phalangeal joint, the hips, knees, shoulders, ankles and elbows. This chapter will address surgical options for advanced osteoarthritis of the hips and knees and will focus primarily on total hip and knee replacement.

Arthroplasty, Replacement↗

PubMed2006

Geographic diversity of low-volume hospitals in total knee replacement: implications for regionalization policies.

BACKGROUND/OBJECTIVES: Centers performing low volumes of total knee replacements (TKR) have worse outcomes of TKR than higher volume centers. Regionalization policies that shift patients to higher volume centers are being considered as a means of improving TKR outcomes. We sought to describe geographic diversity in the distribution of low-volume centers and examine state level characteristics associated with states that have a higher proportion of low-volume centers and/or a higher proportion of TKRs performed in low-volume centers. METHODS: We used U.S. Census data and geocoded Medicare claims to ascertain state-level demographic factors, procedure volume, and TKR rates and to conduct our state level analysis. We defined 2 outcomes: 1) proportion of all hospitals with a low annual TKR volume (<26 per year in the Medicare population); and 2) proportion of all TKRs in the Medicare population performed in low-volume centers. We examined linear associations among the 2 outcomes and state factors, and used multivariate regression to identify factors associated independently with these outcomes. RESULTS: Half of hospitals performing TKR in the Medicare population were low-volume centers, accounting for 13% of TKRs. Multivariate analysis revealed lower TKR rates, higher proportion of rural areas and larger state area were associated with a higher proportion of low-volume hospitals in a state. Lower proportion of elderly residents, higher population density and higher proportion of rural areas predicted a higher proportion of TKRs performed in low-volume centers. CONCLUSIONS: The distribution of low-volume hospitals among U.S. states varies substantially. Regionalization of TKR may require different strategies in states with small and large numbers of low-volume centers.

Aged↗

PubMed2006

Lumbar disc disorders and low-back pain: socioeconomic factors and consequences.

Socioeconomic factors are important risk factors for lumbar pain and disability. The total costs of low-back pain in the United States exceed $100 billion per year. Two-thirds of these costs are indirect, due to lost wages and reduced productivity. Each year, the fewer than 5% of the patients who have an episode of low-back pain account for 75% of the total costs. Because indirect costs rely heavily on changes in work status, total costs are difficult to calculate for many women and students as well as elderly and disabled patients. These methodologic challenges notwithstanding, the toll of lumbar disc disorders is enormous, underscoring the critical importance of identifying strategies to prevent these disorders and their consequences.

Adolescent↗

PubMed2006

Bilateral total knee replacement: staging and pulmonary embolism.

BACKGROUND: When a bilateral total knee replacement is indicated, it is not clear whether it is preferable to operate on both knees during the same hospitalization (simultaneously) or to stage the procedures in two separate hospital stays. A greater risk of pulmonary embolism after simultaneous total knee replacement has been reported by some authors, but little national data are available. METHODS: We reviewed the records of 122,385 United States Medicare enrollees who had had a total knee replacement in 2000. We noted whether they had had a unilateral procedure or two procedures and, if they had had two procedures, whether both had been done during the same hospitalization or whether the operations had been performed during two separate hospital stays. Age, sex, race, residence, Medicaid eligibility (a proxy for low income), and the Charlson comorbidity score were documented for each patient as were the total numbers of total knee replacements performed in the year 2000 by the hospital and the surgeon. The probability of a symptomatic pulmonary embolism developing in the first three months after surgery was calculated for the simultaneous, staged, and unilateral procedures. RESULTS: Simultaneous procedures were much more likely to be performed in high-volume hospitals and by high-volume surgeons than were staged procedures. Men had proportionately more simultaneous procedures than did women. Hospitals in the northeastern United States were the most likely to perform simultaneous procedures. A pulmonary embolism developed in the first three months in 0.81% of the patients who had had a single procedure compared with 1.44% of the patients who had undergone a simultaneous procedure (adjusted hazard ratio 1.81; 95% confidence interval, 1.49, 2.20). CONCLUSIONS: The systematic differences in patient gender, hospital and surgeon volume, and geographic region between those who undergo simultaneous total knee replacements and those who undergo staged procedures should be borne in mind when outcomes are being compared. The adjusted risk of pulmonary embolism is about 80% higher in the three months after a simultaneous procedure than in the three months after a single procedure, which suggests that the sum of the risks associated with the two operations of a staged procedure may equal or exceed the risk of simultaneous total knee replacement.

Aged↗