Showing papers by "Dirk R. Larson published in 2009"

Screening panels for detection of monoclonal gammopathies.

Abstract: Background: The repertoire of serologic tests for identifying a monoclonal gammopathy includes serum and urine protein electrophoresis (PEL), serum and urine immunofixation electrophoresis (IFE), and quantitative serum free light chain (FLC). Although there are several reports on the relative diagnostic contribution of these assays, none has looked at the tests singly and in combination for the various plasma cell proliferative disorders (PCPDs). Methods: Patients with a PCPD and all 5 assays performed within 30 days of diagnosis were included (n = 1877). The diagnoses were multiple myeloma (MM) (n = 467), smoldering multiple myeloma (SMM) (n = 191), monoclonal gammopathy of undetermined significance (MGUS) (n = 524), plasmacytoma (n = 29), extramedullary plasmacytoma (n = 10), Waldenstrom macroglobulinemia (WM) (n = 26), primary amyloidosis (AL) (n = 581), light chain deposition disease (LCDD) (n = 18), and POEMS syndrome (n = 31). Results: Of the 1877 patients, 26 were negative in all assays. Omitting urine from the panel lost an additional 23 patients (15 MGUS, 6 AL, 1 plasmacytoma, 1 LCDD), whereas the omission of FLC lost 30 patients (6 MM, 23 AL, and 1 LCDD). The omission of serum IFE as well as urine lost an additional 58 patients (44 MGUS, 7 POEMS, 5 AL, 1 SMM, and 1 plasmacytoma). Conclusions: The major impact of using a simplified screening panel of serum PEL plus FLC rather than PEL, IFE, and FLC is an 8% reduction in sensitivity for MGUS, 23% for POEMS (7 patients), 4% for plasmacytoma (1 patient), 1% for AL, and 0.5% for SMM. There is no diminution in sensitivity for detecting MM, macroglobulinemia, and LCDD.

Surgical treatment of early wound complications following primary total knee arthroplasty.

Abstract: Background: Wound-healing problems are a known complication after primary total knee arthroplasty. However, little is known about the clinical outcomes for patients who require surgical treatment of these early wound-healing problems. The purpose of the present study was to determine the incidence, risk factors, and long-term sequelae of early wound complications requiring surgical treatment. Methods: The total joint registry at our institution was reviewed for the period from 1981 to 2004. All knees with early wound complications necessitating surgical treatment within thirty days after the index total knee arthroplasty were identified. The cumulative probabilities for the later development of deep infection and major subsequent surgery were determined. A case-control study in which these patients were matched with an equal number of controls was performed to attempt to identify risk factors for the development of early superficial wound complications requiring surgical intervention. Results: From 1981 to 2004, 17,784 primary total knee arthroplasties were performed at our institution. Fifty-nine knees were identified as having early wound complications necessitating surgical treatment within thirty days after the index arthroplasty, for a rate of return to surgery of 0.33%. For knees with early surgical treatment of wound complications, the two-year cumulative probabilities of major subsequent surgery (component resection, muscle flap coverage, or amputation) and deep infection were 5.3% and 6.0%, respectively. In contrast, for knees without early surgical intervention for the treatment of wound complications, the two-year cumulative probabilities were 0.6% and 0.8%, respectively (p < 0.001 for both comparisons). A history of diabetes mellitus was identified as being significantly associated with the development of early wound complications requiring surgical intervention. Conclusions: Patients requiring early surgical treatment for wound-healing problems after primary total knee arthroplasty are at significantly increased risk for further complications, including deep infection and/or major subsequent surgery, specifically, resection arthroplasty, amputation, or muscle flap coverage. These results emphasize the importance of obtaining primary wound-healing after total knee arthroplasty. Level of Evidence: Prognostic Level III. See Instructions to Authors for a complete description of levels of evidence.

Changes in incidence and indications of tonsillectomy and adenotonsillectomy, 1970-2005.

Abstract: Objective: To investigate 35-year epidemiological trends in tonsillectomy and adenotonsillectomy.Study Design/Subjects: Cross-sectional survey. Subjects included all patients from birth to age 29 years who had tonsillectomy or adenotonsillectomy from 1970 to 2005.Results: Study included 8106 patients (median age 8.0 years; range, 6 months to 29 years; male 3646 patients [45%]). Overall tonsillectomy incidence increased from 126 (95% confidence interval [CI], 111-140) per 100,000 person-years in 1970 through 1974 to 153 (95% CI, 139-166) in 2000 through 2005. A dominant factor, adenotonsillectomy incidence rose sharply from 243 (95% CI, 223-261) per 100,000 person-years in 1970 through 1974 to 485 (95% CI, 462-509) in 2000 through 2005. The indication of upper airway obstruction increased from 12 percent of patients in 1970 to 77 percent in 2005.Conclusions: Epidemiological trends in tonsillectomy and adenotonsillectomy have shifted substantially. Overall numbers have increased, and surgical indications ha...

Disease associations with monoclonal gammopathy of undetermined significance: a population-based study of 17,398 patients.

Abstract: OBJECTIVE To systematically study the association of monoclonal gammopathy of undetermined significance (MGUS) with all diseases in a population-based cohort of 17,398 patients, all of whom were uniformly tested for the presence or absence of MGUS. PATIENTS AND METHODS Serum samples were obtained from 77% (21,463) of the 28,038 enumerated residents in Olmsted County, Minnesota. Informed consent was obtained from patients to study 17,398 samples. Among 17,398 samples tested, 605 cases of MGUS and 16,793 negative controls were identified. The computerized Mayo Medical Index was used to obtain information on all diagnoses entered between January 1, 1975, and May 31, 2006, for a total of 422,663 person-years of observations. To identify and confirm previously reported associations, these diagnostic codes were analyzed using stratified Poisson regression, adjusting for age, sex, and total person-years of observation. RESULTS We confirmed a significant association in 14 (19%) of 75 previously reported disease associations with MGUS, including vertebral and hip fractures and osteoporosis. Systematic analysis of all 16,062 diagnostic disease codes found additional previously unreported associations, including mycobacterium infection and superficial thrombophlebitis. CONCLUSION These results have major implications both for confirmed associations and for 61 diseases in which the association with MGUS is likely coincidental.

Osteosarcoma of the Pelvis: Outcome Analysis of Surgical Treatment

Abstract: Risk factors to explain the poor survival of patients with osteosarcoma of the pelvis are poorly understood. Therefore, we attempted to identify factors affecting survival and development of local recurrence and metastasis. We retrospectively reviewed 43 patients who had high-grade pelvic tumors and were treated surgically. Twenty lesions were chondroblastic, 10 fibroblastic, 11 osteoblastic, and one each was giant cell-rich and small cell osteosarcomas. At a median of 3.5 years (range, 0.3–21 years) postoperatively, 13 patients were alive with no evidence of disease. The overall and disease-free 5-year survival rates were 38% and 29%, respectively, at 5 years. Anatomic location, tumor size, and margin predicted survival. Fifteen patients (35%) had local recurrence. The 5-year cumulative incidence of recurrence with death as a competing risk factor was 34%. Location in the ilium and size of the tumor predicted local recurrence. Twenty-one (49%) of 43 patients had metastases develop. The cumulative incidence of metastasis with death as a competing risk factor was 48% at 5 years. Six patients who presented with metastasis had a worse survival than patients who had no evidence of metastasis at presentation (2-year survival, 33% versus 76%). If distant metastasis is diagnosed subsequent to primary treatment, aggressive therapy may be justified. Level of Evidence: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

IgM monoclonal gammopathy of undetermined significance and smoldering Waldenström's macroglobulinemia.

Abstract: Immunoglobulin M monoclonal gammopathy of undetermined significance (IgM-MUS) was diagnosed in 213 Mayo Clinic patients who were residents of 11 counties in southeastern Minnesota from 1960 to 1994 During long-term follow-up, 29 (14%) developed non-Hodgkin lymphoma (n = 17), Waldenstrom's macroglobulinemia (WM; n = 6), chronic lymphocytic leukemia (n = 3), and AL amyloidosis (n = 3) with relative risks of 15-, 262-, 6-, and 16-fold, respectively The cumulative probability of progression to one of these disorders was 10% at 5 years, 18% at 10 years, and 24% at 15 years, approximately 15% per year Smoldering WM was identified in 48 patients at Mayo Clinic from 1974 to 1995 During follow-up, 33 of the 48 patients progressed to symptomatic WM The median time to progression was 46 years The risk of progression to WM was 6% at 1 year, 39% at 3 years, and 55% at 5 years

Body Mass Index and Risk of Adverse Cardiac Events in Elderly Patients with Hip Fracture: A Population-Based Study

Abstract: OBJECTIVES: To determine whether obesity affects cardiac complications after hip fracture repair. DESIGN: A population-based historical study using data from the Rochester Epidemiology Project. SETTING: Olmsted County, Minnesota. PARTICIPANTS: All urgent hip fracture repairs between 1988 and 2002. MEASUREMENTS: Body mass index (BMI) was categorized as underweight (<18.5 kg/m2), normal-weight (18.5–24.9 kg/m2), overweight (25.0–29.9 kg/m2), and obese (≥30 kg/m2). Postoperative cardiac complications were defined as myocardial infarction, angina pectoris, congestive heart failure, or new-onset arrhythmias within 1-year of surgery. Incidence rates were estimated for each outcome, and overall cardiac complications were assessed using Cox proportional hazards models adjusted for age, sex, year of surgery, use of beta-blockers, and the Revised Cardiac Risk Index. RESULTS: Hip fracture repairs were performed in 184 (15.6%) underweight, 640 (54.2%) normal-weight, 251 (21.3%) overweight, and 105 (8.9%) obese subjects (mean age 84.2 ± 7.5; 80% female). Baseline American Society of Anesthesiologists (ASA) status was similar in all groups (ASA I/II vs III–V, P=.14). Underweight patients had a significantly higher risk of developing myocardial infarction (odds ratio (OR) 1.44, 95% confidence interval (CI)=1.0–2.1; P=.05) and arrhythmias (OR=1.59, 95% CI=1.0–2.4; P=.04) than normal-weight patients. Multivariate analysis demonstrated that underweight patients had a higher risk of developing an adverse cardiac event of any type (OR=1.56, 95% CI=1.22–1.98; P<.001). Overweight and obese patients with hip fracture had no excess risk of any cardiac complication. CONCLUSION: The obesity paradox and low functional reserve in underweight patients may influence the development of postoperative cardiac events in elderly people with hip fracture.

Inflammatory laboratory markers in periprosthetic hip fractures.

Abstract: The purpose of this study was to determine the prevalence of increased inflammatory laboratory markers in patients with periprosthetic fractures. We also studied the likelihood of the elevation of these values in predicting deep prosthetic joint infection. From 2000 to 2006, 204 patients with periprosthetic hip fractures were treated at our institution. Patients had white blood cell, erythrocyte sedimentation rate, and C-reactive protein obtained on initial evaluation; these were then compared with subsequent hip aspiration, surgical pathology, and deep cultures obtained at the time of revision surgery. A true infection was diagnosed in 11.6%. White blood cell count was increased in 16.2%, erythrocyte sedimentation rate increased in 33.3%, and C-reactive protein increased in 50.5%. The positive elaborate predictive value for these markers for infection was poor (18%, 21%, and 29%, respectively). These findings suggest that increased inflammatory laboratory values in patients with periprosthetic fracture are not good indicators for deep periprosthetic infection and do not necessarily warrant additional evaluations before definitive surgical treatment.

Predictors of ischemic stroke after hip operation: A population‐based study

Abstract: BACKGROUND: Hip operation (total hip arthroplasty [THA] or fracture repair) is the most common noncardiac surgical procedure performed in patients age 65 years and older. OBJECTIVE: To determine the predictors of ischemic stroke in patients who have undergone hip operation. DESIGN: Population-based historical cohort study, in which postoperative ischemic strokes were identified from medical record review for stroke diagnostic codes and brain imaging results and were confirmed by physician review. SETTING: Tertiary care center in Olmsted County, Minnesota. PATIENTS: Residents of Olmsted County who underwent hip surgical procedure. MEASUREMENTS: Incidence of ischemic stroke within 1 year of hip operation. RESULTS: In total, 1606 patients underwent 1886 hip procedures from 1988 through 2002 and were observed for ischemic stroke for 1 year after their procedure. Sixty-seven ischemic strokes were identified. The rate of stroke at 1 year after hip operation was 3.9%. In univariate analysis, history of atrial fibrillation (hazard ratio [HR], 2.16; P = 0.005), hip fracture repair vs. total hip arthroplasty (HR, 3.80; P < 0.001), age 75 years or older (HR, 2.20; P = 0.02), aspirin use (HR, 1.8; P = 0.01), and history of previous stroke (HR, 4.18; P < 0.001) were significantly associated with increased risk of stroke. In multivariable analysis, history of stroke (HR, 3.27; P < 0.001) and hip fracture repair (HR, 2.74; P = 0.004) were strong predictors of postoperative stroke. CONCLUSIONS: This population-based historical cohort of patients with hip operation had a 3.9% cumulative probability of ischemic stroke over the first postoperative year. Hip fracture repair and history of stroke were the strongest predictors of this complication. Journal of Hospital Medicine 2009;4:298–303. © 2009 Society of Hospital Medicine.

Neurogenic tumors of the pelvis: clinicopathologic features and surgical outcomes using a multidisciplinary team.

Abstract: Few data exist regarding the outcomes in patients undergoing surgery for pelvic tumors of neurogenic origin. Our aim was to characterize the clinical and pathologic features of pelvic neurogenic tumors and assess surgical outcomes. All patients who underwent operations for pelvic neurogenic tumors at our institution between 1956 and 2004 were identified. Data analyzed included demographics, clinical features, histopathology, local recurrence, and survival. Eighty-nine patients were identified, of whom 44 were male. Median age was 38 years. The most common presenting symptom was low back or pelvic pain (56%). Malignant lesions were found in 43 patients (48%). Schwannomas were the most common benign tumor (61%) and malignant peripheral nerve sheath tumors the most common malignant lesion (81%). Median tumor size was 9.5 cm (range 0.8–32 cm). Malignant tumors had histopathologic evidence of infiltration of surrounding structures in 49% of cases. Intralesional resection was the most common surgical technique for both benign and malignant tumors. Thirty-day mortality was nil; major morbidity was seen in 13%. Adjuvant therapy was given to 91% of the patients with malignant disease. Five-year local recurrence rates for benign and malignant lesions were 35.9% and 35.0%, respectively. Distant recurrence for malignant lesions was 65.1% at 5 years. Five-year disease-free survival for malignant tumors was 25.9%. Pelvic neurogenic tumors occurring in young patients may be large when detected and present with nonspecific symptoms. Benign and malignant tumors had a high local recurrence rate and survival for malignant tumors was poor. Early detection and aggressive surgical intervention should improve outcome.

Body mass index (BMI) and risk of noncardiac postoperative medical complications in elderly hip fracture patients: A population‐based study

Abstract: Background Obese patients are thought to be at higher risk of post-operative medical complications. We sought to determine whether body mass index (BMI) is associated with post-operative in-hospital non-cardiac complications following urgent hip fracture repair.

Skate blade neck lacerations: a survey and case follow-up.

Abstract: Objective:To learn about neck lacerations caused by skate blades in hockey.Design:A retrospective Web-based survey and follow-up of registered USA Hockey players.Setting:Three hundred twenty-eight thousand eight hundred twenty-one of 457 038 registered USA Hockey players with a current e-mail addres