Dirk R. Larson

Bio: Dirk R. Larson is an academic researcher from Mayo Clinic. The author has contributed to research in topics: Monoclonal gammopathy of undetermined significance & Population. The author has an hindex of 79, co-authored 271 publications receiving 24067 citations. Previous affiliations of Dirk R. Larson include University of California, San Francisco & Dartmouth–Hitchcock Medical Center.

Review of 1027 Patients With Newly Diagnosed Multiple Myeloma

Abstract: Objective To determine the clinical and laboratory features of newly diagnosed multiple myeloma. Patients and Methods Records of all patients in whom multiple myeloma was initially diagnosed at the Mayo Clinic in Rochester, Minn, from January 1, 1985, to December 31, 1998, were reviewed. Results Of the 1027 study patients, 2% were younger than 40 years, and 38% were 70 years or older. The median age was 66 years. Anemia was present initially in 73% of patients, hypercalcemia (calcium level ≥11 mg/dL) in 13%, and a serum creatinine level of 2 mg/dL or more in 19%. The β2-microglobulin level was increased in 75%. Serum protein electrophoresis revealed a localized band in 82% of patients, and immunoelectrophoresis or immunofixation showed a monoclonal protein in 93%. A monoclonal light chain was found in the urine in 78%. Nonsecretory myeloma was recognized in 3% of patients, whereas light-chain myeloma was present in 20%. Conventional radiographs showed an abnormality in 79%. The plasma cell labeling index was 1% or more in 34% of patients. Multivariate analysis revealed that age, plasma cell labeling index, low platelet count, serum albumin value, and the log of the creatinine value were the most important prognostic factors. Conclusion The median duration of survival was 33 months and did not improve from 1985 through 1998.

A long-term study of prognosis in monoclonal gammopathy of undetermined significance.

Abstract: Background A monoclonal gammopathy of undetermined significance (MGUS) occurs in up to 2 percent of persons 50 years of age or older. Reliable predictors of progression have not been identified, and information on prognosis is limited. Methods We identified 1384 patients residing in southeastern Minnesota in whom MGUS was diagnosed at the Mayo Clinic from 1960 through 1994. The primary end point was progression to multiple myeloma or another plasma-cell cancer. Results During 11,009 person-years of follow-up, MGUS progressed in 115 of the 1384 patients to multiple myeloma, IgM lymphoma, primary amyloidosis, macroglobulinemia, chronic lymphocytic leukemia, or plasmacytoma (relative risk of progression, 25.0, 2.4, 8.4, 46.0, 0.9, and 8.5, respectively). The overall relative risk of progression was 7.3 in these patients as compared with the white population of the Iowa Surveillance, Epidemiology, and End Results program. In 32 additional patients, the monoclonal protein concentration increased to more than 3...

Prevalence of Total Hip and Knee Replacement in the United States.

Abstract: Background Descriptive epidemiology of total joint replacement procedures is limited to annual procedure volumes (incidence). The prevalence of the growing number of individuals living with a total hip or total knee replacement is currently unknown. Our objective was to estimate the prevalence of total hip and total knee replacement in the United States. Methods Prevalence was estimated using the counting method by combining historical incidence data from the National Hospital Discharge Survey and the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases from 1969 to 2010 with general population census and mortality counts. We accounted for relative differences in mortality rates between those who have had total hip or knee replacement and the general population. Results The 2010 prevalence of total hip and total knee replacement in the total U.S. population was 0.83% and 1.52%, respectively. Prevalence was higher among women than among men and increased with age, reaching 5.26% for total hip replacement and 10.38% for total knee replacement at eighty years. These estimates corresponded to 2.5 million individuals (1.4 million women and 1.1 million men) with total hip replacement and 4.7 million individuals (3.0 million women and 1.7 million men) with total knee replacement in 2010. Secular trends indicated a substantial rise in prevalence over time and a shift to younger ages. Conclusions Around 7 million Americans are living with a hip or knee replacement, and consequently, in most cases, are mobile, despite advanced arthritis. These numbers underscore the substantial public health impact of total hip and knee arthroplasties.

Prevalence of Monoclonal Gammopathy of Undetermined Significance

Abstract: BACKGROUND The prevalence of monoclonal gammopathy of undetermined significance (MGUS), a premalignant plasma-cell disorder, among persons 50 years of age or older has not been accurately determined. We used sensitive laboratory techniques to ascertain the prevalence of MGUS in a large population in a well-defined geographic area. METHODS We identified all living residents of Olmsted County, Minnesota, as of January 1, 1995. We obtained serum that remained after the performance of routine clinical tests at Mayo Clinic or asked subjects for whom such serum was unavailable to provide a sample. Agarose-gel electrophoresis was performed on all serum samples, and any serum sample with a discrete band of monoclonal protein or thought to have a localized band was subjected to immunofixation. RESULTS Serum samples were obtained from 21,463 of the 28,038 enumerated residents 50 years of age or older (76.6 percent). MGUS was identified in 694 (3.2 percent) of these persons. Age-adjusted rates were higher in men than in women (4.0 percent vs. 2.7 percent, P<0.001). The prevalence of MGUS was 5.3 percent among persons 70 years of age or older and 7.5 percent among those 85 years of age or older. The concentration of monoclonal immunoglobulin was less than 1.0 g per deciliter in 63.5 percent and at least 2.0 g per deciliter in only 4.5 percent of 694 persons. The concentration of uninvolved immunoglobulins was reduced in 27.7 percent of 447 persons tested, and 21.5 percent of 79 tested had a monoclonal urinary light chain. CONCLUSIONS Among residents of Olmsted County, Minnesota, MGUS was found in 3.2 percent of persons 50 years of age or older and 5.3 percent of persons 70 years of age or older.

Clinical course and prognosis of smoldering (asymptomatic) multiple myeloma.

Abstract: BACKGROUND Smoldering (asymptomatic) multiple myeloma is an asymptomatic plasma-cell proliferative disorder associated with a high risk of progression to symptomatic multiple myeloma or amyloidosis. Prognostic factors for the progression and outcome of this disease are unclear. METHODS We searched a computerized database and reviewed the medical records of all patients at Mayo Clinic who fulfilled the criteria of the International Myeloma Working Group for the diagnosis of smoldering multiple myeloma between 1970 and 1995. Bone marrow aspirate and biopsy specimens were studied, and patients were followed throughout the course of disease. RESULTS During the 26-year period, 276 patients fulfilled the criteria for smoldering multiple myeloma. During 2131 cumulative person-years of follow-up, symptomatic multiple myeloma or amyloidosis developed in 163 persons (59%). The overall risk of progression was 10% per year for the first 5 years, approximately 3% per year for the next 5 years, and 1% per year for the last 10 years; the cumulative probability of progression was 73% at 15 years. At diagnosis, significant risk factors for progression included the serum level and type of monoclonal protein, the presence of urinary light chain, the extent and pattern of bone marrow involvement, and the reduction in uninvolved immunoglobulins. The proportion of plasma cells in the bone marrow and the serum monoclonal protein level were combined to create a risk-stratification model with three distinct prognostic groups. CONCLUSIONS The risk of progression from smoldering multiple myeloma to symptomatic disease is related to the proportion of bone marrow plasma cells and the serum monoclonal protein level at diagnosis.

ACC/AHA 2006 Guidelines for the Management of Patients With Valvular Heart Disease

Abstract: PREAMBLE......e4 APPENDIX 1......e121 APPENDIX 2......e122 APPENDIX 3......e124 REFERENCES......e124 It is important that the medical profession play a significant role in critically evaluating the use of diagnostic procedures and therapies as they are introduced in the detection, management,

Harrison's Principles of Internal Medicine

Abstract: The 11th edition of Harrison's Principles of Internal Medicine welcomes Anthony Fauci to its editorial staff, in addition to more than 85 new contributors. While the organization of the book is similar to previous editions, major emphasis has been placed on disorders that affect multiple organ systems. Important advances in genetics, immunology, and oncology are emphasized. Many chapters of the book have been rewritten and describe major advances in internal medicine. Subjects that received only a paragraph or two of attention in previous editions are now covered in entire chapters. Among the chapters that have been extensively revised are the chapters on infections in the compromised host, on skin rashes in infections, on many of the viral infections, including cytomegalovirus and Epstein-Barr virus, on sexually transmitted diseases, on diabetes mellitus, on disorders of bone and mineral metabolism, and on lymphadenopathy and splenomegaly. The major revisions in these chapters and many