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PubMedDate not supplied

Baboon basal ganglia stereotaxy using internal MRI landmarks: validation and application to PET imaging.

PURPOSE: We report the residual anatomic error after a nine parameter visually guided registration of MR images with a baboon brain atlas to validate a stereotactic method for use in PET studies. METHOD: MPRAGE images of brain in six baboons and one nemestrina monkey were placed in atlas space using internal landmarks and proportional measurements. An expert noted the location of 23 subcortical test points in the transformed images and in the atlas. RESULTS: The average absolute error at the test points was 1.62 mm. At the extremes of the brain surface, there was more variability. PET images could be combined across animals in a common atlas space. CONCLUSION: There is minimal subcortical error attributable to anatomic variability after this method of transforming MR images of baboon to stereotactic space. This method provides a useful tool for intrasubject PET baboon studies as well as "bootstrapping" for more refined methods.

Animals↗

PubMed2000

Validation of the international prognostic index in working formulation group A low-grade non-Hodgkin's lymphoma: retrospective analysis of 137 patients from the Gruppo Italiano per lo Studio dei Linfomi registry.

BACKGROUND AND OBJECTIVE: The subset of non-follicular non-Hodgkin's lymphoma (NHL) includes patients with varied prognoses, thus suitable for different therapeutic approaches. The International Prognostic Index (IPI), originally proposed for aggressive NHL, has been demonstrated to be of prognostic relevance also in follicular NHL. The main aim of the study was to validate the IPI in this histologic category; in addition, the specific prognostic classification, currently employed in the Gruppo Italiano per lo Studio dei Linfomi (GISL) prospective therapeutic trials and based on different features, more similar to those applied to chronic lymphocytic leukemia, was analyzed. DESIGN AND METHODS: The present series consists of 137 evaluable patients affected by Working Formulation group A NHL out of 256 cases referred to the GISL Registry. The retrospective prognostic study included the evaluation by both univariate and multivariate analyses of overall survival, response to therapy and response duration. The IPI was applied as originally proposed. The GISL definition of indolent and aggressive disease at diagnosis was based on the presence of B symptoms, bulky disease, anemia and thrombocytopenia. RESULTS: The distribution of patients in IPI risk groups was rather unbalanced with 18%, 47%, 28% and 7% of cases classified as low (L), intermediate-low (IL), intermediate-high (IH) and high (H) risk, respectively. The median overall survival was not reached in either L or IL risk groups, and was 84.1 and 7.4 months for IH and H risk groups, respectively (p=0. 0005). A simplified IPI model was designed merging patients in both intermediate risk groups and the statistical difference of survival retained its significance. GISL prognostic stratification was demonstrated to have a significant association with survival, with a median survival of 71.3 months in aggressive disease and a median survival not reached at 152 months in indolent disease. Both the simplified IPI model and the GISL risk definition retained their significance in multivariate analysis for overall survival, while for response to therapy only the simplified IPI model resulted to be of statistical significance. In addition, the GISL prognostic stratification identified patients with different outcomes within the IPI intermediate risk group, with a median survival of 70.2 months for patients with aggressive disease wheras the median survival for those with indolent disease was not reached. Finally, a prognostic score resulting from the integration of the simplified IPI and the GISL system was statistically validated. INTERPRETATION AND CONCLUSIONS: The retrospective analysis of this series demonstrates the validity of the IPI in non-follicular indolent NHL and the usefulness of integrating the IPI parameters with disease specific prognostic variables.

Lymphoma, Non-Hodgkin↗

PubMed2006

Validation of the International Classification of Functioning, Disability and Health (ICF) Core Set for rheumatoid arthritis from the patient perspective using focus groups.

Functioning is recognized as an important study outcome in rheumatoid arthritis (RA). The Comprehensive ICF Core Set for RA is an application of the International Classification of Functioning, Disability and Health (ICF) of the World Health Organisation with the purpose of representing the typical spectrum of functioning of patients with RA. To strengthen the patient perspective, persons with RA were explicitly involved in the validation of the Comprehensive ICF Core Set for RA using qualitative methodology. The objective of the study was twofold: to come forward with a proposal for the most appropriate methodology to validate Comprehensive ICF Core Sets from the patient perspective; and to add evidence to the validation of the Comprehensive ICF Core Set for RA from the perspective of patients. The specific aims were to explore the aspects of functioning and health important to patients with RA using two different focus group approaches (open approach and ICF-based approach) and to examine to what extent these aspects are represented by the current version of the Comprehensive ICF Core Set for RA. The sampling of patients followed the maximum variation strategy. Sample size was determined by saturation. The focus groups were digitally recorded and transcribed verbatim. The meaning condensation procedure was used for the data analysis. After qualitative data analysis, the resulting concepts were linked to ICF categories according to established linking rules. Forty-nine patients participated in ten focus groups (five in each approach). Of the 76 ICF categories contained in the Comprehensive ICF Core Set for RA, 65 were reported by the patients based on the open approach and 71 based on the ICF-based approach. Sixty-six additional categories (open approach, 41; ICF-based approach, 57) that are not covered in the Comprehensive ICF Core Set for RA were raised. The existing version of the Comprehensive ICF Core Set for RA could be confirmed almost entirely by the two different focus group approaches applied. Focus groups are a highly useful qualitative method to validate the Comprehensive ICF Core Set for RA from the patient perspective. The ICF-based approach seems to be the most appropriate technique.

Adult↗

PubMedDate not supplied

Diffuse large cell lymphomas: identification of prognostic factors and validation of the International Non-Hodgkin's Lymphoma Prognostic Index. A Hellenic Cooperative Oncology Group Study.

Several clinical prognostic factors have been identified that predict treatment outcome in patients with diffuse large cell lymphomas. An International Non-Hodgkin's Lymphoma Prognostic Index (IPI) has been recently formulated. We tried to identify the clinical prognostic factors that predict treatment outcome in Greek patients with diffuse large cell lymphomas and validated the IPI in these patients. The possible prognostic variables for tumor response, relapse-free (RFS) and overall survival (OS) were analyzed in 239 consecutive patients treated with anthracycline-based chemotherapy regimens. In univariate analysis, factors associated with poor response were stages III-IV, performance status (PS) >/=2, spleen and bone marrow involvement, more than one extranodal site involved, increased lactate dehydrogenase (LDH) value, hemoglobin (Hb) <12 g/dl, albumin <3.5 g/dl, erythrocyte sedimentation rate (ESR) >50 mm/h. Multivariate analysis identified stage, PS, more than one extranodal site involved, increased LDH level, and ESR > 50 mm/h as the factors more predictive of poor response. For RFS, multiple Cox analysis found stages III-IV and bone marrow involvement to be statistically significant. For OS, multiple Cox analysis identified stage III-IV, PS >/=2, bone marrow involvement, more than one extranodal site involved, increased LDH level and ESR > 50 mm/h as negative prognostic factors. Patients stratified in the different risk groups of the IPI had a significantly different outcome regarding complete response (CR) rate, RFS and OS. In conclusion, although age >60 years was not recognized as an adverse factor in this analysis, our patients stratified in the different groups of the IPI had significant differences in CR rate, 2-year RFS and OS verifying the prognostic significance of the index. Bone marrow involvement and ESR > 50 mm/h, parameters that are not included in the IPI, adversely affected survival.

Adult↗

PubMedDate not supplied

International coordination and validation of analytical methods.

Most experimentation dealing with analytical methodology in the physical and biological sciences has been conducted within a single laboratory. Method validation by other laboratories was considered not only unnecessary but also detrimental because, in the words of one commentator, 'the results are too variable'. Within the last two decades, however, largely as a result of the requirements of international environmental and food standards programmes, it has become increasingly apparent that a collaborative interlaboratory study is the only way to estimate the variability characteristics of methods of analysis as performed by the typical population of laboratories using the methods. To obtain a common basis for measuring the statistical characteristics of analytical methods, representatives of almost two dozen international organizations meeting in Geneva, in May 1987, approved by consensus a protocol for the design and interpretation of data from collaborative studies of chemical methods of analysis.

Bias↗

PubMed2001

Cross-cultural validation of an international questionnaire, the General Measure of the Functional Assessment of Cancer Therapy scale (FACT-G), for Japanese.

The General Measure of the Functional Assessment of Cancer Therapy scale (FACT-G) was developed in an English-speaking culture (USA). To determine if FACT-G could be used in Japan, a cross-cultural validation was performed. The Japanese version was created through an iterative forward-backward translation sequence used throughout the FACT multi-lingual translation project. In evaluating psychometric testing, its construct validity was investigated by factor analysis and multi-trait scaling analysis. Clinical validity was estimated by known-groups comparison using stage, performance score (PS) and patient location, and validated longitudinally by PS. The FACT-G (version 3) was given to 180 patients with lung cancer. Analyses showed that the scales of Physical, Functional, Emotional Well-Being, and Relationship with Doctors were constructively valid in Japan. Japanese patients felt that familial relationships were different than those with friends and neighbors, indicating that the Social/Family Well-Being scale needed cultural adaptation. Two items concerning coping with illness and acceptance of illness did not load predictably onto their respective scales and were considered to be cross-culturally problematic. However, clinical validity demonstrated its sensitivity. Japanese version 4 has been improved to address the weakness in an attempt to become an instrument that is applicable across cultures.

Adult↗

PubMed1992

Form E of the 16PF and adults with mental retardation: internal consistency and validity.

Form E of the Sixteen Personality Factors Questionnaire (16PF-E) was administered to 70 adults (45 men and 25 women) who resided in a public facility for mentally retarded persons. Alpha coefficients were computed for each of 16 primary trait scales. The Intelligence (B), Ego Strength (C), Dominance (E), Superego Strength (G), Parmia (H), Protension (L), Autia (M), Shrewdness (N), Guilt Proneness (O), and Self-Sentiment (Q3) scales exhibited low internal consistency, whereas Premsia (I) and Self-Sufficiency (Q2) evidence relatively higher levels. Personality traits of subjects were also assessed by staff ratings. Ratings were compared to 16PF-E primary and secondary trait scores via correlation coefficients. Results provided virtually no support for the validity of the 16PF-E primary scales and the Exvia, Anxiety, and Cortertia secondary factors as applied to the subject population. Limited support for the validity of the Independence secondary factor was found.

Activities of Daily Living↗

PubMed1998

[Internal consistency and validity of work disability duration].

In this study results of a survey taken of persons insured under the public health care system were presented. The main objective of the survey was to determine the health of the insured on the basis of their subjective data, as well as to assess their prevention behaviour and their wish that the health insurance should offer prevention programmes. In addition, the health insurance provided data on how often the insured persons were unable to work for health reasons during a period of seven years. The data of work absenteeism are used to divide the group of respondents according to their health. To determine internal consistency it was first investigated whether persons with periods of disablement during one year (cross-section) also had long periods of disablement in the years before or after (longitudinal section). It was found that in the cross-section, persons with serious health problems (more than six weeks of disablement) differed little from those with average disablement periods (from one to six weeks) in the long-term development of disablement. The study also examined the correlation of periods of disablement and subjective data (validity). A mean correlation was found between the respondents' subjective assessment of their health and the length of disablement periods. There was also a significant negative correlation between internal health locus of control beliefs and the length of disablement. The results are discussed, and the ways and limits of using periods of disablement for empirical studies are presented.

Absenteeism↗

PubMed1994

Quality of life in asthma. I. Internal consistency and validity of the SF-36 questionnaire.

Asthma is a chronic disease in which social life is altered. The importance of restrictions on social life may be greater in severe asthma or when symptoms are not adequately controlled. General scales of quality-of-life (QOL) may be used to detect the importance of social life impairment, but it is not yet known whether the scores of such QOL measures are reliable and valid in asthmatic patients. A study was carried out in 252 patients with asthma of variable severity (FEV1 ranging from 25 to 131% of predicted) to assess the validity of a general QOL scale, the first French version of the SF-36 health status questionnaire (SF-36). This is based on 36 items selected to represent nine health concepts (physical, social, and role functioning; mental health; health perceptions; energy or fatigue; pain; and general health). All nine SF-36 category scores were highly significantly correlated with the severity of asthma assessed by the clinical score of Aas (p < 0.0007 to p < 0.0001). Eight SF-36 category scores were highly significantly correlated with FEV1 (p < 0.003 to p < 0.0001). A high internal reliability of SF-36 was found using the alpha coefficient of Cronbach (0.91 for the whole questionnaire). The SF-36 questionnaire is valid and reliable in asthma and can therefore be used to examine QOL in asthmatic and nonasthmatic patients and to determine to what extent asthma impairs social life.

Adult↗

PubMed2004

Prospective validation of the International Society of Thrombosis and Haemostasis scoring system for disseminated intravascular coagulation.

OBJECTIVES: A diagnosis of disseminated intravascular coagulation (DIC) is hampered by the lack of an accurate diagnostic test. Based on the retrospective analysis of studies in patients with DIC, a scoring system (0-8 points) using simple and readily available routine laboratory tests has been proposed. The aim of this study was to prospectively validate this scoring system and assess its feasibility, sensitivity, and specificity in a consecutive series of intensive care patients. DESIGN: Prospective cohort of intensive care patients. SETTING: Adult intensive care unit in a tertiary academic center. PATIENTS: Consecutive patients with a clinical suspicion of disseminated intravascular coagulation. INTERVENTIONS: Patients were followed during their admission to the intensive care unit, and the DIC score was calculated every 48 hrs and compared with a "gold standard" based on expert opinion. In addition, an activated partial thromboplastin time (aPTT) waveform analysis, which has been reported to be a good predictor for the absence or presence of DIC, was performed. MEASUREMENTS AND MAIN RESULTS: We analyzed 660 samples from 217 consecutive patients. The prevalence of DIC was 34%. There was a strong correlation between an increasing DIC score and 28-day mortality (for each 1-point increment in the DIC score, the odds ratio for mortality was 1.25). The sensitivity of the DIC score was 91% and the specificity 97%. An abnormal aPTT waveform was seen in 32% of patients and correlated well with the presence of DIC (sensitivity 88%, specificity 97%). In 19% of patients, the aPTT waveform-based diagnosis of DIC preceded the diagnosis based on the scoring system. CONCLUSIONS: A diagnosis of DIC based on a simple scoring system, using widely available routine coagulation tests, is sufficiently accurate to make or reject a diagnosis of DIC in intensive care patients with a clinical suspicion of this condition. An aPTT waveform analysis is an interesting and promising tool to assist in the diagnostic management of DIC.

Aged↗

PubMed2001

The internal consistency and validity of the Self-Assessment Parkinson's Disease Disability Scale.

OBJECTIVE: To test the consistency and validity of the Self-assessment Parkinson's Disease Disability Scale in patients with Parkinson's disease living at home. DESIGN: Patients with Parkinson's disease responded to a set of questionnaires. In addition, an observation of the performance of daily activities was carried out on a subgroup. SETTING AND SUBJECTS: Patients with Parkinson's disease living at home (n = 142). MEASURES: The Self-assessment Parkinson's Disease Disability Scale (SPDDS), the Hoehn & Yahr Rating Scale (H&Y), and the Sickness Impact Profile (SIP68). The observation concerned nine activities that correspond to items of the SPDDS questionnaire. RESULTS: Internal consistency of the SPDDS was very high (Cronbach's alpha = 0.97; reliability rho = 0.97). The items of the SPDDS are hierarchical (Loevinger's H = 0.64): patients had least difficulty with 'washing' and 'brushing teeth' and most difficulty with 'turning in bed', 'travelling by public transport' and 'writing a letter'. Validity of the SPDDS was good: the relationship between the SPDDS questionnaire and the H&Y rating scale, the SIP68 and the results of the observation was strong and significant. CONCLUSION: The SPDDS is a unidimensional instrument measuring disabilities in Parkinson's disease patients living at home.

Activities of Daily Living↗

PubMed2000

Internal structure and validity of the multidimensional pain inventory, Italian language version.

OBJECTIVE: The aim of the study is an investigation of the psychometric characteristics of the Italian translation of the Multidimensional Pain Inventory and a comparison with the American, German, Swedish and Dutch versions of the MPI. METHOD: The Italian translation of the MPI was administered together with Melzack McGill Pain Inventory, Beck Depression Inventory, Spielberger State-Trait Anxiety Inventory, and Visual Analog Scales. Confirmatory factor analyses were accomplished on the MPI scores. Furthermore, reliability, intercorrelations, and convergent validity of MPI were evaluated. PATIENTS: Participants were 220 patients suffering from a variety of chronic pain syndromes (cephalalgia 45.8%; low-back pain 30.5%). RESULTS: Confirmatory factor analyses suggest changes to all 3 sections of the MPI-IV. Factor structure, after having excluded several items sorted according to the 3 sections of the questionnaire, is basically the same as in other versions of the MPI. Internal consistency analyses yielded acceptable reliability (Cronbach alpha coefficients) for 11 out of 13 scales. CONCLUSIONS: After making appropriate changes in all 3 sections of the inventory, the MPI is substantially suitable for use in cross-cultural and international research.

Journal Article↗

PubMed2004

Cross-cultural development and validation of a patient self-administered questionnaire to assess quality of life in upper gastrointestinal disorders: the PAGI-QOL.

OBJECTIVE: Summarize the Patient Assessment of Upper GastroIntestinal Disorders-Quality of Life (PAGI-QOL) development and provide results on its reliability and validity from the international psychometric validation in dyspepsia, GastroEsophageal Reflux Disease (GERD), and gastroparesis. METHODS: Subjects completed the pilot PAGI-QOL at baseline and 8 weeks; and a subsample also at 2 weeks. Other assessments were: Patient Assessment of Upper Gastrointestinal Disorders-Symptom Severity Index, SF-36, number of disability days. RESULTS: 1736 patients completed the PAGI-QOL at baseline. The questionnaire was reduced, producing a 30-item final version covering five domains: Daily Activities, Clothing, Diet and Food Habits, Relationship (REL), and Psychological Well-Being and Distress. Internal consistency was excellent (Cronbach's alpha range: 0.83-0.96). Test-retest reproducibility was good: intraclass correlations coefficients were over 0.70 except for the REL scale (0.61). Concurrent validity between the PAGI-QOL total score and all SF-36 subscale scores was good with moderate (0.52) to strong (0.72) correlations. PAGI-QOL scores showed excellent discriminant properties: patients who had spent some days in bed, had missed some days at work, and were kept from usual activities had much lower PAGI-QOL scores than those who did not (p < 0.0001). CONCLUSION: The PAGI-QOL is a valid and reliable instrument assessing quality of life in patients with dyspepsia, GERD, or gastroparesis.

Cross-Cultural Comparison↗

PubMed2002

The Impaired Control Scale: confirmation of factor structure and psychometric properties for social drinkers and drinkers in alcohol treatment.

AIMS: To examine (1). the structure of the Impaired Control Scale using confirmatory factor analytical techniques and (2). the internal consistency and validity of the ICS subscales. DESIGN: Cross-sectional data were collected on alcohol-related variables using standard self-completion scales. PARTICIPANTS: Three hundred and fifty-seven social drinkers (not in alcohol treatment) and 137 treatment drinkers (in alcohol treatment) who acknowledged experiencing impaired control over alcohol intake in the last 6 months. Impaired control was defined as drinking more than intended or more than one thinks one should. MEASUREMENTS: Self-completion questionnaire consisting of demographic questions, Severity of Alcohol Dependence Data questionnaire (SADD), Impaired Control Scale (ICS) and three questions assessing alcohol consumption from the Alcohol Use Disorders Identification Test (AUDIT). FINDINGS: This first confirmatory factor analytical study of the ICS found that all three parts of the ICS were unidimensional for both social and treatment drinkers. These results confirmed previous exploratory principal components analysis findings. The excellent validity and internal consistency of all three parts of the ICS found here also confirmed results of previous research into the scale. CONCLUSIONS: The confirmation of the structure and psychometric properties of the ICS suggest that the scale is a reliable and valid instrument, with a predictable and stable factor structure, for use with both clinical and non-clinical samples.

Adult↗

PubMed1999

Validation of the internal reference technique for microdialysis measurements of interstitial histamine in the rat.

The internal reference technique (IRT) was compared with the no net flux method (NFM) as a microdialysis calibration technique for sampling of interstitial histamine in the rat. Microdialysis catheters (polyacrylonitrile, 50 kD cut off) were inserted in liver, muscle, subcutaneous tissue and in an induced adenocarcinoma. Estimated relative recovery with IRT ranged from 23+/-2% in liver to 30+/-3% in subcutaneous tissue with and without tumor (p<0.05). By using the NFM-technique we found similar recovery as compared to the IRT in all tissues studied. Interstitial histamine was up to 3-fold higher than the mean plasma histamine concentration (54+/-2 nmol/l). Subcutaneous tissue (177+/-39 nmol/l) and subcutaneous tumor (165+/-29 nmol/l) exhibited high histamine while liver (65+/-14 nmol/l) and liver tumor (75+/-7 nmol/l) had low interstitial histamine concentrations. In conclusion, the IRT was validated against the NFM as a rapid method for histamine measurements in situ in the rat.

Adipose Tissue↗

PubMed2004

Validation of the OSCAR 2 oscillometric 24-hour ambulatory blood pressure monitor according to the International Protocol for the validation of blood pressure measuring devices.

OBJECTIVES: The accuracy of blood pressure measuring devices is of prime importance and should be validated before devices are used clinically. We carried out an independent evaluation of the OSCAR 2 oscillometric ambulatory blood pressure monitor (SunTech Medical model 222) according to the European Society of Hypertension International Protocol. METHODS: Adult subjects were recruited from patients and staff at The James Cook University Hospital, Middlesbrough, UK. Nine sequential same-arm blood pressure measurements were taken alternating between simultaneous readings by two independent, trained observers using mercury sphygmomanometers and the device operated by a third observer. In phase one, 15 subjects participated (five in each of the low, medium and high blood pressure ranges) with 18 subjects participating in phase two. Data from 33 subjects (11 in each of the three blood pressure ranges) were analysed for systolic (19 male, 14 female, mean age 56.0 years) and for diastolic (17 male, 16 female, mean age 51.1 years) blood pressure. RESULTS: The OSCAR 2 passed the first phase of the validation process. In phase 2.1, the OSCAR 2 monitor had 71 readings within 5 mmHg, 86 within 10 mmHg and 94 within 15 mmHg for systolic blood pressure (SBP) and 72 readings within 5 mmHg, 88 within 10 mmHg and 96 within 15 mmHg for diastolic blood pressure (DBP). Mean (+/-SD) differences between observers and device were 0.9+/-2.3 mmHg for SBP and -0.5+/-2.3 mmHg for DBP. In phase 2, 24 subjects had at least two of the differences within 5 mmHg and three subjects had no differences within 5 mmHg for SBP while for DBP 25 subjects had at least two of the differences within 5 mmHg and two subjects had no differences within 5 mmHg. CONCLUSIONS: The OSCAR 2 passes all requirements for validation by the International Protocol and can be recommended for clinical use in an adult population.

Adult↗

PubMedDate not supplied

[The validity of the International Headache Society criteria and the modifications put forward in 2002 in the diagnosis of migraine and tension type headaches].

INTRODUCTION: The diagnosis of migraine (M) and tension type headaches (TH) is clinical; it is therefore important to refine the diagnostic criteria. The International Headache Society (IHS) set out the currently used criteria in 1988; 14 years later it has just put forward a number of modifications. AIMS: Our aim was to test the comprehensiveness, sensitivity and specificity of both the current and the newly proposed diagnostic criteria in Primary Health Care (PHC), where patients must be screened properly before referral to Neurology services. PATIENTS AND METHODS: 74 cases of M and 44 of TH attended in two PHC centres in Seville, in the course of a study about the psychological aspects of headaches. The doctors used a semi structured clinical interview based on the IHS criteria to carry out diagnoses. RESULTS: The comprehensiveness of the system was 100%; sensitivity and specificity of the diagnostic criteria were, generally speaking, appropriate and one point highlighted was the intensity of the pain and the fact that it was aggravated by physical activity. Discriminating analysis correctly classified 94.1% of the cases according to the 1988 IHS criteria and 90.7% according to the IHS proposals from 2002, although in the latter case an extra criterion was included in the discrimination. DISCUSSION: As shown by different studies, diagnosis carried out by professionals who are well trained in the use of the current IHS criteria is perfectly valid. The present proposals for modification seem to reorganise the classification more efficiently, since they include chronic migraine and also divide episodic TH into infrequent and frequent bouts. These new proposals are now beginning their test period in different fields of application.

Adult↗

PubMed2005

Prognostic validation of the international classification of immunoglobulin M gammopathies: a survival advantage for patients with immunoglobulin M monoclonal gammopathy of undetermined significance?

PURPOSE: To verify the reliability of the new criteria for the diagnosis of IgM gammopathies recently proposed by an international panel of experts (Athens, 2002). EXPERIMENTAL DESIGN: A retrospective series of 698 patients with IgM gammopathy was reviewed paying attention to symptoms, serum IgM concentration, bone marrow infiltration, blood cell count and clinical course. Four clinical entities can be identified: IgM monoclonal gammopathy of undetermined significance (IgM-MGUS), asymptomatic and symptomatic Wandenstrom's macroglobulinemia (A-WM and S-WM, respectively), and IgM-related disorders, although this last was excluded from the study because of the scarcity of patients due to probable selection biases. The observed mortality was studied related to that expected in the general population of comparable age and sex and over an equivalent period of follow-up (standardized mortality ratio, SMR). RESULTS: IgM-MGUS, A-WM, and S-WM shared many clinical aspects but, with respect to the general population, patients with IgM-MGUS had a slight but definite survival advantage, those with A-WM had a mortality rate equivalent to that of the general population, whereas the SMR of patients with S-WM was 5.4. Within A-WM and S-WM the SMR values did not vary significantly in relation to marrow lymphocyte counts or serum IgM concentrations. CONCLUSIONS: Our findings represent a prognostic validation of the applied diagnostic criteria for three of the four identifiable clinical entities and highlight the importance of symptoms over serum IgM concentration and marrow infiltration.

Adult↗