Larson, Dirk R.

Background: Many risk factors have been described for dislocation following total hip arthroplasty (THA), yet a patient-specific risk assessment tool remains elusive. The purpose of this study was to develop a high-dimensional, patient-specific risk-stratification nomogram that allows dynamic risk modification based on operative decisions. Methods: In this study, 29,349 THAs, including 21,978 primary and 7371 revision cases, performed between 1998 and 2018 were evaluated. During a mean 6-year follow-up, 1521 THAs were followed by a dislocation. Patients were characterized, through individual-chart review, according to non-modifiable factors (demographics, indication for THA, spine disease, prior spine surgery, and neurologic disease) and modifiable operative decisions (operative approach, femoral head diameter, and type of acetabular liner [standard, elevated, constrained, or dual-mobility]). Multivariable regression models and nomograms were developed with dislocation as a binary outcome at 1 year and 5 years postoperatively. Results: Dislocation risk, based on patient-specific comorbidities and operative decisions, was wide-ranging—from 0.3% to 13% at 1 year and from 0.4% to 19% at 5 years after primary THA, and from 2% to 32% at 1 year and from 3% to 42% at 5 years after revision THA. In the primary-THA group, the direct anterior approach (hazard ratio [HR] = 0.27) and lateral approach (HR = 0.58) decreased the dislocation risk compared with the posterior approach. After adjusting for the approach in that group, the combination of a ≥36-mm-diameter femoral head and an elevated liner yielded the largest decrease in dislocation risk (HR = 0.28), followed by dual-mobility constructs (HR = 0.48). In the patients who underwent revision THA, the adjusted risk of dislocation was most markedly decreased by the use of a dual-mobility construct (HR = 0.40), followed by a ≥36-mm femoral head and an elevated liner (HR = 0.88). The adjusted risk of dislocation after revision THA was decreased by acetabular revision (HR = 0.58), irrespective of whether other components were revised. Conclusions: Our patient-specific dislocation risk calculator, which was strengthened by our use of a robust multivariable model that accounted for comorbidities associated with instability, demonstrated wide-ranging patient-specific risks based on comorbidity profiles. The resultant nomograms can be used as a screening tool to identify patients at high risk for dislocation following THA and to individualize operative decisions for evidence-based risk mitigation. Level of Evidence: Prognostic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Abstract Mass-spectrometry (MS) assays detect lower levels of monoclonal proteins and result in earlier detection of monoclonal gammopathy of undetermined significance (MGUS). We examined heavy chain MGUS prevalence using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS among 3 risk groups, ages 50 or older: 327 African Americans (AA) and 1223 European Americans (EA) from a clinical biobank and 1093 unaffected first-degree relatives (FDR) of patients with hematologic disorders. Age- and sex-adjusted prevalence rates were directly standardized to 2010 United States population. Prevalence ratios were estimated for comparisons of AA and FDR to the EA group using the Poisson distribution. Results were also compared with population-based prevalence using conventional gel-based methods. Risk groups had similar sex and age distributions. MALDI-TOF MGUS prevalence was higher in the AA (16.5% [95% confidence interval (CI), 12.2%, 20.8%]) and FDR (18.3% [95% CI, 16.6%, 21.6%]) than in EA (10.8% [95% CI, 8.8%, 12.7%]), translating to prevalence ratios of 1.73 (95% CI, 1.31, 2.29) and 1.90 (95% CI, 1.55, 2.34), respectively. MALDI-TOF EA prevalence was over threefold higher than conventional estimates but showed similar age trends. Thus, the MALDI-TOF assay found greater numbers with MGUS but similar relative differences by race, family history, and age as prior studies.

SummaryPatients with asymptomatic/smouldering Waldenström macroglobulinaemia (SWM) have a variable risk of progression to active WM. Our study evaluated 143 patients with SWM consecutively seen between January 1996 and December 2013. With a median [95% confidence interval (CI)] follow‐up of 9·5 [8·1–11·5] years, the cumulative rate of progression was 11% at 1 year, 38% at 3 years and 55% at 5 years. On multivariate analysis, haemoglobin (Hb) ≤123 g/l [risk ratio (RR) 2·08; P = 0·009] and β2‐microglobulin (β2M) ≥2·7 µg/ml (RR 2·0; P = 0·01) were independent predictors of a shorter time‐to‐progression (TTP) to active WM. Patients with myeloid differentiation factor 88 wild type (MYD88WT) genotype (n = 11) demonstrated a trend toward shorter TTP [median (95% CI) 1·7 (0·7–8·7) vs. 4·7 (2·4–7·7) years for the MYD88L265P cohort, n = 42; P = 0·11]. The presence of C‐X‐C chemokine receptor type 4 (CXCR4) mutation (n = 29) did not impact the TTP (median: 3 years for CXCR4WT vs. 5·6 years for CXCR4MUT, P = 0·34). The overall survival (OS) for patients with SWM (median: 18·1 years) was comparable to an age‐, sex‐ and calendar year‐matched USA population (median: 20·3 years, P = 0·502). In conclusion, Hb and β2M at diagnosis represent independent predictors of progression to active WM. Comparable survival of SWM and a matched USA population argues against pre‐emptive intervention in this patient population.

Abstract Background. —The reported operating characteristics of the plasma fibrin D-dimer level for the diagnosis of acute pulmonary embolism vary widely. Objective. —To determine the sensitivity, specificity, predictive value, and clinical utility of the D-dimer for the diagnosis of pulmonary embolism, and to describe the effect of D-dimer assay method (enzyme-linked immunosorbent assay [ELISA], latex agglutination, membrane ELISA) and discriminate level, patient location at onset, comorbid disease, duration and intensity of concurrent heparin administration, and duration of symptoms on these operating characteristics. Design. —Prospective laboratory investigation. Setting. —Community and tertiary care teaching hospital. Patients. —Consecutive patients with suspected acute pulmonary embolism referred for pulmonary angiography from April 1993 through March 1996. Measurements. —Baseline characteristics, the duration and intensity of heparin anticoagulation, the time interval between symptom onset and plasma D-dimer testing, pulmonary angiography, and the D-dimer level on the day of pulmonary angiography. Results. —Of 105 consenting patients, 33 (31%) had a positive pulmonary angiogram. The D-dimer sensitivity/negative predictive value for the ELISA, latex agglutination (American Bioproducts Co/Diagnostica Stago and Biopool International), and membrane ELISA were 100%/100%, 94%/94%, 100%/100%, and 97%/96%, respectively, at a discriminate level of 250 μg/L or less. The clinical utility, defined as the prevalence of a negative test, ranged from 17% to 33%. D-dimer sensitivity was unaffected by patient location at onset, comorbid disease, or heparin therapy but was inversely related to the duration of symptoms. Conclusions. —The sensitivity of the plasma fibrin D-dimer for the diagnosis of pulmonary embolism depends on the assay method, the assay-specific discriminate level, and the duration of symptoms. At the appropriate discriminate level, the plasma D-dimer is a sensitive but nonspecific test for the diagnosis of pulmonary embolism.

Introduction Monoclonal gammopathy of undetermined significant (MGUS) is a premalignant plasma cell disorder that is common in individuals over age 50. MGUS prevalence estimates to date have generally been based on results of serum electrophoresis and immunofixation (for heavy chain [HC] MGUS) and additionally, free light chain (for light chain [LC] MGUS). Mass-spectrometry assays, however, can detect lower levels of monoclonal (M) proteins, identify the isotype and provide accurate quantification of the M-protein. Given the evidence that MGUS is likely present at least 10 years prior to its detection, mass spectrometry may provide more accurate estimates of underlying MGUS. We examined the prevalence of HC-MGUS using matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry among three risk groups: European Americans (EA), African Americans (AA) and first-degree relatives (FDR) of patients with multiple myeloma (MM), MGUS, chronic lymphocytic leukemia (CLL) or non-Hodgkin's lymphoma (NHL). Methods We sampled all AA and a random sample of EA participants ages 50 and older enrolled in the Mayo Clinic Biobank. We also selected unaffected first-degree relatives (limiting to ages 50 and older) from our ongoing family study of hematological malignancies. We screened serum samples by the MALDI-TOF mass spectrometry assay, which is clinically used at Mayo Clinic (known as MASS-FIX) for detection and isotypes of M-proteins. The assay uses isotype-specific nanobody enrichment coupled to MALDI-TOF mass spectrometry. For each of the risk groups, HC- MGUS prevalence was estimated by age (50-59, 60-69, 70+). Age- and sex-adjusted prevalence rates were calculated by direct standardization to the 2010 US population. Ninety-five percent confidence intervals (95% CI) for the prevalence rates and comparisons across the three groups were based on the Poisson distribution. Because free LC information was unavailable, LC-MGUS was not estimated. Results A total 327 AA, 854 EA and 792 FDR were screened for M-proteins using the MASS-FIX assay. All three groups had similar sex (42-44% male) and age distributions (mean[SD] age was 64.5[9.5] yrs., 64.4[8.8] yrs. and 64.9[10.5] yrs. for AA, EA and FDR, respectively). As previously noted using conventional detection methods, the overall prevalence of HC-MGUS was higher in the AA population (16.5% [95%CI: 12.2%, 20.8%]) and FDR (21.5% [95%CI: 18.3%, 24.7%]) than in EA (11.2% [95%CI: 8.8%, 13.5%]), both p-values <0.0001. This pattern was generally seen across age groups (Table 1), with increasing prevalence with age. FDR of MM or MGUS cases had a higher prevalence (22.2% [95%CI: 18.4%, 26.0%]) than FDR of CLL or NHL cases (18.8% [95%CI: 13.3%, 24.4%]), although the difference was not statistically significant (p-value=0.82). Overall prevalence estimates of HC-MGUS using MASS-FIX were at least three-fold higher than estimates using conventional methods alone (i.e. age- and sex-adjusted prevalence in Olmsted County, MN, was 3.1% [95% CI: 2.9%-3.4%]). Conclusion We provided some of the first data on prevalence of HC-MGUS across three risk groups, using a sensitive method for detecting monoclonal proteins. The MASS-FIX assay resulted in substantially higher absolute rates of HC-MGUS (at least 3-fold higher) relative to conventional methods. Further, the prevalence of HC-MGUS among the AA and FDR was significantly higher than the EA population. Thus, the more sensitive assay identified greater absolute numbers of individuals with MGUS, but resulted in similar relationships as seen in prior studies across these risk groups. Our results have implications for future studies of the etiology of MGUS and its progression. Disclosures Dispenzieri: Janssen: Research Funding; Pfizer: Research Funding; Alnylam: Research Funding; Intellia: Research Funding; Celgene: Research Funding; Takeda: Research Funding. Kumar:Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Karyopharm: Consultancy; Genecentrix: Consultancy; Cellectar: Other; Carsgen: Other, Research Funding; Merck: Consultancy, Research Funding; Dr. Reddy's Laboratories: Honoraria; Adaptive Biotechnologies: Consultancy; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Kite Pharma: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Tenebio: Other, Research Funding; Sanofi: Research Funding; MedImmune: Research Funding; Novartis: Research Funding. Murray:The Binding Site: Patents & Royalties: Patent Use of Mass Spec to identify monoclonal proteins licensed to The Binding Site.

Introduction Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant clonal disorder, which progresses at a rate of 1% per year to multiple myeloma (MM), or other plasma-cell or lymphoid disorders. MGUS is common and occurs in approximately 3% and 5% of persons 50 and 70 years of age or older, respectively. Clinical factors reported to be associated with MGUS progression include MGUS isotype, abnormal serum free light-chain ratio (FLCr), and high serum monoclonal protein (M protein) level (>=1.5 g per deciliter). Body mass index (BMI) has also been seen associated with MGUS progression, but has not been evaluated in context of established clinical prognostic factors. Here, we evaluate the contribution of BMI to MGUS progression beyond clinical prognostic factors in a population-based study and examine differential associations by sex. Methods We studied 594 patients residing in Olmsted County Minnesota, who were identified with MGUS in a screening study conducted between1995 through 2003. Patients with light-chain MGUS were not included. Patients were screened for M-protein [normal (<1.5 g/dl) or high (≥1.5 g/dl)], FLCr [normal (0.26-1.65) or abnormal (<0.26 and/or >1.65)], and isotype (IgG, IgM, IgA, bi-clonal). Follow-up time was calculated from date of MGUS screening to date of last follow-up, death, or progression to MM or another plasma-cell or lymphoid disorder. BMI (kg/m2) was calculated using height and weight values reported close to sample date (80% of patients within 2 years), and then categorized into BMI<25 and BMI≥25. We used Cox regression to estimate the association of BMI with risk of MGUS progression to MM or another plasma-cell or lymphoid disorder, univariately, and accounting for clinical factors. Analyses were also stratified by sex. We report hazard ratios (HR) and 95% confidence intervals (CI). Results Of the 594 patients, 51% were male, and the median age at screening date was 73 (range:50-98 years). The immunoglobulin type was IgG in 71% of patients, IgM in 17%, IgA in 10%, and bi-clonal in 2%. High M protein level was observed in 22% and abnormal FLCr in 28%. BMI≥25 was observed in 67% of patients. The median follow-up time was 10.5 years (range:0-25). Over a median of 6,846 person-years, 465 patients (78%) died and 57 patients progressed and developed MM (N=39), amyloidosis (N=8), lymphoma (N=5), or Waldenstrom macroglobulinemia (N=5). The overall rate of progression was 0.87 events (CI:0.67-1.12) per 100 person-years, and higher among males (1.01, CI:0.73-1.42) than in females (0.72, CI:0.48-1.08), however, the difference was not statistically significant (P=0.24). In univariate analyses, BMI≥25 (HR=2.14, CI:1.05-4.36, P=0.04), non-IgG isotype (HR=2.84, CI:1.68-4.80, P=0.0001), high M protein (HR=2.57, CI: 1.50-4.42, P=0.001), and abnormal FLCr (HR=3.39, CI:1.98-5.82, P<0.0001) were associated with increased risk of progression (Table 1.A). These four factors were independently associated with MGUS progression in a multivariable model, with a c-statistic=0.75 (CI:0.68-0.82). When stratifying by sex, associations of BMI with progression were stronger among females than males (Table 1.B) [c-statistic=0.81 (CI:0.72-0.90) vs 0.71 (CI:0.60-0.82) for females vs. males respectively], however, a test for interaction between BMI and sex was not statistically significant (P=0.15). Conclusions In this study we found evidence that high BMI is a prognostic factor independent of isotype, M protein, and FLC ratio in the full cohort, however, this was mainly driven by the effect in females rather than males. Future studies should further investigate sex differences in evaluating prognostic factors among MGUS patients. Disclosures Dispenzieri: Intellia: Research Funding; Pfizer: Research Funding; Alnylam: Research Funding; Takeda: Research Funding; Celgene: Research Funding; Janssen: Research Funding. Kumar:Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Cellectar: Other; Kite Pharma: Consultancy, Research Funding; Tenebio: Other, Research Funding; BMS: Consultancy, Research Funding; Karyopharm: Consultancy; MedImmune: Research Funding; Sanofi: Research Funding; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Merck: Consultancy, Research Funding; Adaptive Biotechnologies: Consultancy; Genecentrix: Consultancy; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Dr. Reddy's Laboratories: Honoraria; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Novartis: Research Funding; Carsgen: Other, Research Funding; Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member.

Background: Spinal anesthesia provides several benefits for patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA), but historically comes at the cost of slow and unpredictable return of lower-extremity motor function related to the use of long-acting local anesthetics. In this prospective, double-blinded, randomized clinical trial we sought to determine if an alternative local anesthetic, mepivacaine, would allow more consistent return of motor function compared with low-dose bupivacaine spinal anesthesia during primary THA and TKA. Methods: This trial was conducted at a single academic institution. Prior to trial initiation an internal pilot study determined that 154 patients were required to achieve 80% power. Patients were randomized in a 1:1 fashion with use of advanced computerized stratification based on procedure, age group, sex, and body mass index. Following the surgical procedure, motor function was assessed every 15 minutes in the nonoperative lower extremity according to the Bromage scale and discontinued once Bromage 0 was achieved (spontaneous movement at hip, knee, and ankle). Results: Return of lower-extremity function was more predictable in patients who received mepivacaine than in those who received low-dose bupivacaine. Among patients who received mepivacaine, 1% achieved motor function return beyond 5 hours compared with 11% of patients who received bupivacaine (p = 0.013). The mean time to return of lower-extremity motor function was 26 minutes quicker in patients who received mepivacaine (185 minutes; 95% confidence interval, 174 to 196 minutes) compared with low-dose bupivacaine (210 minutes; 95% confidence interval, 193 to 228 minutes) (p = 0.016). There were no significant differences in safety outcomes including pain scores, time to participation in physical therapy, incidence of orthostatic hypotension, urinary retention, or transient neurologic symptoms in patients receiving mepivacaine compared with low-dose bupivacaine. Conclusions: In patients undergoing primary THA and TKA, spinal anesthesia with mepivacaine allowed more consistent return of lower-extremity motor function compared with low-dose bupivacaine, without a concomitant increase in complications potentially associated with spinal anesthetics. This is particularly of value in an era of short-stay and outpatient surgical procedures. Level of Evidence: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Abstract Background: Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant plasma cell disorder that carries a 1% per year risk of progression to multiple myeloma (MM) or related malignancy. The prevalence and natural history of MGUS, in which by definition intact immunoglobulin heavy chain (IgH) is expressed, has been well described. However, up to 20% of myeloma (MM) is characterized by complete lack of IgH expression (Light-chain MM); the prevalence of a corresponding precursor entity, light chain MGUS (LC-MGUS) has not been determined. We report the first prevalence estimates of LC-MGUS in the general population from a large, well-defined geographic population using modern laboratory techniques. Methods: The cohort for this study was derived from one previously assembled by us to estimate the prevalence of MGUS (N Engl J Med2006;354:1362-9). The original cohort used to estimate the prevalence of MGUS consisted of 21,463 of the 28,038 enumerated residents aged 50 or over of Olmsted County Minnesota as of January 1, 1995. The sensitive serum free light chain (FLC) assay (The Binding Site Limited, Birmingham, U.K.) was performed on stored serum samples from these 21,463 persons. IgH expression was determined by immunofixation on all FLC results that had an abnormal kappa/lambda ratio (<0.26 or >1.65). LC-MGUS was defined as the presence of an abnormal FLC ratio and a negative immunofixation for IgH expression. Results: Adequate stored serum samples were available in 20,733 (97%) of the 21,463 persons. To date, the FLC assay has been performed and results were available for analysis on samples from 16,637 persons. An abnormal FLC ratio was observed in 572 persons. IgH expression was detected in 255 of these cases on immunofixation; these persons are considered as having MGUS, and were excluded from the estimation of LC-MGUS prevalence. This resulted in 317 persons out of 16,637 who had an abnormal FLC ratio without evidence of IgH expression, resulting in an estimated prevalence of LC- MGUS of 2%. Of the 317 cases of LC-MGUS identified in this study, 217 were kappa and 100 were lambda; in 35 cases the presence of the corresponding monoclonal light chain was apparent on immunofixation. The median age of the cohort of LC-MGUS was 62 years; males=151, females =166. The involved FLC level ranged from 0.118–270.0 mg/dL. The FLC ratio ranged from 0.014–0.253 (lambda) and 1.67–511.01 (kappa). So far, progression to multiple myeloma has occurred in 4 patients, a rate much higher than what is expected based on the prevalence of myeloma in the general population. Two additional patients have developed CLL. Conclusions: LC-MGUS is prevalent in 2% of the general population aged 50 years of age or older. The natural history of this disorder needs to be determined.

Abstract Due to the diagnostic sensitivity of serum free light chain quantitation for monoclonal light chain diseases, it has been suggested that urine assays no longer need be performed as part of the diagnostic algorithm for monoclonal proteins. We reviewed our experience to determine the relative diagnostic contribution of urine assays. Methods: Patients with a monoclonal gammopathy and monoclonal urinary protein at initial diagnosis who also had a serum immunofixation and serum free light chain quantitation within 30 days of diagnosis were identified (n = 428). The laboratory results for serum protein electrophoresis, serum immunofixation, serum free light chain, urine protein electrophoresis, and urine immunofixation were reviewed. Results: The patients in this cohort had diagnoses of multiple myeloma, primary amyloid, monoclonal gammopathy of undetermined significance, smoldering multiple myeloma, solitary plasmacytomas, and other less frequently detected monoclonal gammopathies. By definition of the cohort, all 428 had a monoclonal urine protein. 86% had an abnormal serum free light chain K/L ratio, 81% had an abnormal serum protein electrophoresis, and 94% had an abnormal serum immunofixation. In only 2 patients, however, were all 3 serum assays normal. Both of these were patients with monoclonal gammopathy of undetermined significance (idiopathic Bence Jones proteinuria). Conclusion: Discontinuation of urine studies and reliance on a diagnostic algorithm using solely serum studies (protein electrophoresis, immunofixation, and free light chain quantitation), missed 2 of the 428 monoclonal gammopathies (0.5 %) with urinary monoclonal proteins, and these 2 cases required no medical intervention.

Abstract Smoldering multiple myeloma (SMM) is characterized by a serum M protein ≥ 3g/dL and/or 10% or more of plasma cells in the bone marrow. However, the definition is not standardized, and it is not known whether both serum M protein levels and bone marrow plasma cell counts are necessary for diagnosis or if one parameter is sufficient. We reviewed the medical records and bone marrows of all patients from Mayo Clinic seen within 30 days of recognition of an IgG or IgA M protein ≥ 3g/dL or a bone marrow containing ≥ 10% plasma cells from 1970 to 1995. This allows for a minimum potential follow-up of 10 years. Patients with end-organ damage at baseline from plasma cell proliferation, including active multiple myeloma (MM) and primary amyloidosis (AL) and those who had received chemotherapy were excluded. A differential of the bone marrow aspirate coupled with the bone marrow biopsy morphology and immunohistochemistry using antibodies directed against CD138, MUM-1 and Cyclin D1 were evaluated in every case in order to estimate the plasma cell content. In all, 301 patients fulfilled either of the criteria for SMM. Their median age was 64 years and only 3% were less than 40 years of age; 60% were male. The median hemoglobin value was 12.9 g/dL; 7% were less than 10 g/dL, but the anemia was unrelated to plasma cell proliferation. IgG accounted for 75%, IgA 22%, and biclonal proteins were found in 3%. The serum light-chain was κ in 67% and λ in 33%. The median serum M spike was 2.9 g/dL; 11% were at least 4.0 g/dL. Uninvolved serum immunoglobulins were reduced in 81%; only 1 immunoglobulin was reduced in 31% and both were decreased in 50%. The urine contained a monoclonal κ protein in 36% and λ in 18% and 46% were negative. The median size of the urine M spike was 0.04 g/24h; only 5 (3%) were > 1 g/24h. The median bone marrow plasma cell content was 15 – 19%; 10% had less than 10% plasma cells, while 10% had at least 50% plasma cells in the bone marrow. Cyclin D-1 was expressed in 17%. Patients were categorized into 3 groups: Group 1, serum M protein ≥ 3g/dL and bone marrow containing ≥ 10% plasma cells (n= 113, 38%); Group 2, bone marrow plasma cells ≥ 10% but serum M protein < 3g/dL (n= 158, 52%); Group 3, serum M protein ≥ 3g/dL but bone marrow plasma cells < 10% (n= 30, 10%). During 2,204 cumulative years of follow-up 85% died (median follow-up of those still living 10.8 years), 155 (51%) developed MM, while 7 (2%) developed AL. The overall rate of progression at 10 years was 62%; median time to progression was 5.5 yrs. The median time to progression was 2.4, 9.2, and 19 years in groups 1, 2, and 3 respectively; correspondingly at 10 years, progression occurred in 76%, 59%, and 32% respectively. Significant risk factors for progression with univariate analysis were serum M spike ≥ 4g/dL (p < 0.001), presence of IgA (p = 0.003), presence of urine light chain (p = 0.006), presence of λ urinary light chain (p = 0.002), bone marrow plasma cells ≥ 20% (p < 0.001) and reduction of uninvolved immunoglobulins (p < 0.001). The hemoglobin value, gender, serum albumin, and expression of cyclin D-1 were not of prognostic importance. On multivariate analysis, the percentage of bone marrow plasma cells was the only significant factor predicting progression to MM or AL.