Towards common reference intervals in clinical chemistry. An attempt at harmonization between three hospital laboratories in Skåne, Sweden

Establishing a Pediatric Acute-Onset Neuropsychiatric Syndrome Clinic: Baseline Clinical Features of the Pediatric Acute-Onset Neuropsychiatric Syndrome Cohort at Karolinska Institutet

Objectives: Pediatric acute-onset neuropsychiatric syndrome (PANS) is a descriptive clinical entity defined by the abrupt onset of psychiatric and somatic symptoms leading to significant loss of function. Data on well-characterized PANS patients are limited, biomarkers have yet to be identified, and a solid evidence base to guide treatment is lacking. In this study, we present our experience of a systematic evaluation of the first 45 patients included in a Swedish cohort. Methods: During the period 2014-2018, our clinic received 100 referrals regarding suspected PANS. All patients underwent a standardized psychiatric/medical evaluation by a child/adolescent psychiatrist and a clinical psychologist or a nurse. Those with severe symptoms were also assessed by a pediatric neurologist and a pediatric rheumatologist. Laboratory tests were obtained at different time points in an attempt to capture an active disease state. Results: Of the 100 referrals, 45 met strict PANS criteria and consented to participate in a long-term follow-up study. The median age at intake was 7.2 years (range 3.0-13.1) and 56% were male. Ninety-three percent fulfilled both criteria for acute/atypical onset of PANS symptoms and having had an infection in relation to onset. Sixteen percent had an onset of an autoimmune or inflammatory disorder in temporal relation to the onset of PANS-related symptoms. The most common onset symptoms were obsessive-compulsive disorder (89%), anxiety (78%), and emotional lability (71%). Twenty-four percent had a preexisting autoimmune disease (AD) and 18% a preexisting psychiatric/neuropsychiatric diagnosis. Sixty-four percent of biological relatives had at least one psychiatric disorder and 76% at least one AD or inflammatory disorder. Complement activation (37%), leukopenia (20%), positive antinuclear antibodies (17%), and elevated thyroid antibodies (11%) were the most common laboratory findings. Conclusions: In our PANS cohort, there was a strong indication of an association with AD. Further work is needed to establish whether any of the potential biomarkers identified will be clinically useful. Long-term follow-up of these patients using the Swedish national registers will enable a deeper understanding of the course of this patient group.

Secondary prevention and lifestyle indices after stroke in a long-term perspective

OBJECTIVES

To describe the long-term perspective regarding prevalence of risk factors, secondary stroke prevention, and lifestyle indices after stroke.

METHODS

From a population-based one-year cohort (n = 416), we performed an observational study of 145 survivors at 16 months and 10 years after stroke (age 27-97 years) regarding secondary prevention including reaching acceptable treatment goals; nutritional status with focus on underweight; and the lifestyle indices: living situation, level of dependence, and self-assessed health condition.

RESULTS

Ten years after stroke, 50% of the subjects with hypertension diagnosis and 55% of those without hypertension diagnosis were within the blood pressure goal <140/90 compared with 32% (P = .008) and 37% (N.S.) at 16 months. Acceptable HbA1c levels among subjects with diabetes mellitus diagnosis increased from 35% to 45% (N.S.). Among those without diabetes diagnosis, satisfactory HbA1c levels decreased from 98% to 79% (P < .001). Underweight increased from 9% to 17% (P = .019). Among patients with cerebral infarction, the prevalence of atrial fibrillation increased from 22% to 29% (P = .004), and treatment with oral anticoagulants from 75% to 78% (N.S.). Acceptable LDL cholesterol levels increased from 59% to 80% (P = .033) among subjects on lipid lowering treatment, and from 18% to 40% among untreated (P = .010). At 10 years, 90% still lived in their own home. Health condition was reported as good/very good/excellent by 65%. Age, female sex, and living situation were associated with intensity of secondary prevention measures and underweight.

CONCLUSIONS

The proportion of individuals within treatment goals improved over time, but secondary prevention still needed additional consideration 10 years after stroke.

Improved diabetes management in Swedish schools: results from two national surveys

BACKGROUND

Support in diabetes self-care in school is essential to achieve optimal school performance and metabolic control. Swedish legislation regulating support to children with chronic diseases was strengthened 2009.

OBJECTIVE

To compare the results of a national survey conducted 2008 and 2015 measuring parents' and diabetes specialist teams' perceptions of support in school.

METHOD

All pediatric diabetes centers in Sweden were invited to participate in the 2015 study. In each center, families with a child being treated for T1DM and attending preschool class or compulsory school were eligible. The parents' and the diabetes teams' opinions were collected in two separate questionnaires.

RESULTS

Forty-one out of 42 eligible diabetes centers participated and 568 parents answered the parental questionnaire in 2015. Metabolic control had improved since the 2008 survey (55.2 ± 10.6 mmol/mol, 7.2% ± 1.0%, in 2015 compared with 61.8 ± 12.4 mmol/mol, 7.8% ± 1.1% in 2008). The proportion of children with a designated staff member responsible for supporting the child's self-care increased from 43% to 59%, (P < .01). An action plan to treat hypoglycemia was present for 65% of the children in 2015 compared with 55% in 2008 (P < .01). More parents were satisfied with the support in 2015 (65% compared with 55%, P < .01).

CONCLUSIONS

This study shows that staff support has increased and that more parents were satisfied with the support for self-care in school in 2015 compared with 2008. More efforts are needed to implement the national legislation to achieve equal support in all Swedish schools.

Systemic inflammatory impact of periodontitis on acute coronary syndrome

AIM

A causative relationship between acute coronary syndrome (ACS) and periodontitis has yet to be defined. The aim of this study was to assess differences in levels of serum cytokines between individuals with or without ACS or periodontal comorbidity.

MATERIAL AND METHODS

In a case-control study, individuals with ACS (78 individuals, 10.3% females) and matching healthy controls (78 individuals, 28.2% females) were included. Medical and dental examinations were performed to diagnose ACS and periodontitis. Serum levels of cytokines were assessed, using Luminex technology.

RESULTS

A diagnosis of periodontitis in the ACS and control group was diagnosed in 52.6% and 12.8% of the individuals, respectively. The unadjusted odds-ratio that individuals with ACS also had periodontitis was 7.5 (95% CI: 3.4, 16.8, p < 0.001). Independent of periodontal conditions, individuals with ACS had significantly higher serum levels of IL8 (mean: 44.3 and 40.0 pg/ml) and vascular endothelial growth factor (VEGF) (mean: 82.3 and 55.3 pg/ml) than control individuals. A diagnosis of periodontitis made no difference in serum cytokine expressions.

CONCLUSION

Elevated serum levels of VEGF were associated with ACS. Serum cytokine expression in individuals with ACS is unrelated to periodontal conditions.

Commutability and interchangeability of commercial quality control materials with feline plasma for common biochemical analytes

BACKGROUND

Species-specific plasma or serum pools are considered the ideal standard material for quality control materials (QCM) instead of commercially available human QCM. However, using plasma or serum pools is limited by volume restrictions, degradation over time, and a narrow range of analyte concentrations. Concentrations of QCM analytes should be consistent or commutable with those from species-specific plasma/serum samples, and the precision from plasma pools should be comparable or interchangeable with commercial human QCM.

OBJECTIVES

The aims of this study were to determine the commutability and interchangeability of 2 levels of commercial QCM (MAS chemTRAK-H [CT]) with feline plasma pools (PP) from normal and renal disease cats measured using a commercial laboratory analyzer and a veterinary in-house analyzer.

METHODS

Agreement between the 2 analyzers was assessed for 16 analytes by correlation and Passing-Bablok regression analyses of feline plasma samples. The difference between each CT data point and the regression line (residuals) was determined and standardized, and CT were considered 'commutable' with PP if the standardized residual was within a range of -3 to 3. Coefficients of variation (CVs) for CT and PP for 16 analytes on 2 analyzers were compared by bootstrap analysis to determine interchangeability.

RESULTS

Most CT analytes were within the range of patient plasma sample analytes, thus commutable. Only 2 analytes had equivalent precision for both levels of CT and both levels of PP, and 5 additional analytes had similar precision for at least one level of CT compared to at least one level of PP.

CONCLUSIONS

The QCM assessed is commutable to feline PP within the tested ranges for 2 particular analyzers. Commutability does not grant interchangeability.

Clinical use of conventional reference intervals in the frail elderly

RATIONALE, AIMS AND OBJECTIVES

Reference intervals provided by the laboratory are commonly established by measuring samples from apparently healthy subjects in the ages 18-65 years, excluding elderly individuals with chronic diseases and medication. The aim of our study was to establish whether current reference intervals for immune parameters and chemical biomarkers are valid for older individuals including those with chronic diseases, so-called frail elderly.

METHODS

Data from our cohort of 138 non-infected nursing home residents (NHR), mean age 86.8 years, range 80-98, were compared with raw data, as basis for the development of reference intervals, obtained from reference populations, like blood donors (IgA, IgG, IgM, C3 and C4) and from the Nordic Reference Interval Project (NORIP) (alanine aminotransferase, albumin, aspartate aminotransferase, creatinine, gamma-glutamyl transferase, lactate dehydrogenase, phosphate, sodium and urea). Immune parameters were measured by nephelometry and in NORIP the measurements were performed by means of different routine methods, in more than 100 laboratories.

RESULTS

Only nine individuals (7%) of NHR were found to be free from chronic disease. C3, C4 (P < 0.001) and IgG levels (P < 0.05) were higher, while IgM levels (P < 0.001) were lower in NHR compared with reference blood donors. Levels of alanine aminotransferase, phosphate (P < 0.001), albumin (P < 0.05) and sodium (P < 0.01) were lower while creatinine and urea levels were higher (P < 0.001) in NHR compared with NORIP subjects.

CONCLUSION

Comparing laboratory results from elderly people with conventional reference intervals can be misleading or even dangerous, as normal conditions may appear pathological, or vice versa and thus lead to unnecessary or even harmful treatment.

Immune responses following meningococcal serogroups A, C, Y and W polysaccharide vaccination in C2-deficient persons: evidence for increased levels of serum bactericidal antibodies

Complement C2 deficiency (C2D) is associated with immunological diseases and increased susceptibility to invasive infections caused by encapsulated bacteria such as Neisseria menigitidis. In this study we evaluate the immunogenicity of vaccination against N. menigitidis in C2D. C2D patients (n=22) and controls (n=52) were given a tetravalent meningococcal polysaccharide vaccine. Serum bactericidal antibody (SBA) titres (serogroups A, C, Y and W) were analysed using a rabbit complement source. Levels of IgG, IgM, and IgA, factor B, and factor H, polymorphisms of MBL and Fc-gamma receptors were determined. The C2D patients responded with an increased SBA titre to all four serogroups (p<0.001). The response rates define as SBA titres ≥8 were found to be between 85.7% and 92.5%. The post-vaccination titres for serogroups C, Y and W were equal to healthy controls. C2D patients with a history of invasive infection had a lower post-vaccination SBA titres both compared to healthy C2D persons (p=0.03) and compared to controls (p<0.0001). We found that the G2M*n/G2M*n genotype were associated with a higher SBA titres after immunization (p=0.03). None of the other investigated immunological factors appear to be important in influencing the vaccine responses. Autoimmune diseases in C2D did not affect the vaccine response. In general, vaccination against meningococci gave rise to antibody responses in the C2D patients that equal healthy controls. The response rate was lower to serogroup A and among C2D patients with history of invasive infections. The presence of G2M*n/G2M*n genotype was associated with higher SBA titres after immunization.

Diabetes management in Swedish schools: a national survey of attitudes of parents, children, and diabetes teams

BACKGROUND

Parents of children with type 1 diabetes often raise complaints about self-care support during school time. The aim of this study was to investigate attitudes to diabetes care in school reported by children with type 1 diabetes, their parents, and their diabetes teams.

METHODS

Children who had completed preschool class or at least one grade in the 9-yr compulsory school system were invited to participate. Data were collected using separate questionnaires for the children and their parents. In addition, the members of the diabetes team answered a separate questionnaire. All pediatric diabetes centers in Sweden were invited to participate in the study.

RESULTS

All Swedish children and adolescents with diabetes are treated at pediatric diabetes centers. Out of 44 eligible centers, 41 were able to participate. The questionnaires were completed by 317 children and adolescents and 323 parents. The mean age was 11.4 ± 2.7 yr and hemoglobin A1c (HbA1c) was 61.8 ± 12.4 mmol/mol (7.8 ± 1.1%). For 57% of the children, there was no member of staff at the school with principal responsibility to support diabetes self-care. A written action plan for hypoglycemia existed for 60% of the children. Twenty-one percent of the parents regularly gave less insulin than they calculated would be needed at breakfast because of fear of hypoglycemia during school time.

CONCLUSIONS

Although Sweden has legislation underlining the specific need for diabetes care in school, this nationwide study demonstrates deficiencies in the support of self-care management.

Inflammatory activity increases with haemoglobin A1c in patients with acute coronary syndrome

OBJECTIVE

To study the relationship between inflammation, diabetes and HbA(1)c levels in patients with acute coronary syndrome (ACS).

DESIGN

Single-centre cross-sectional study comprising 688 consecutive patients with ACS (108 with diabetes) and 341 with stable coronary artery disease (SCAD) (51 with diabetes). High-sensitive C-reactive protein (hsCRP), albumin and fibrinogen concentrations, erythrocyte sedimentation rates (ESR) and leukocyte counts were measured.

RESULTS

hsCRP, fibrinogen and ESR levels were higher and albumin lower in ACS patients. ESR was higher, albumin lower and hsCRP borderline significantly higher (p=0.053) in ACS patient with diabetes compared to those without. All inflammatory markers were associated with HbA(1)c in all 688 ACS patients as well as in 540 non-diabetic ACS patients with normal HbA(1)c. In multivariate analyses, all inflammatory markers were independently associated with HbA(1)c in the entire ACS group, regardless of diabetes being present or not. When non-diabetic ACS patients were analyzed separately, only ESR and leukocyte counts were independently correlated with HbA(1)c.

CONCLUSIONS

Patients with ACS had increased inflammatory activity, which increased with HbA(1)c levels in patients who neither had a history of diabetes nor HbA(1)c above normal, and was further exaggerated in the presence of diabetes.

Reference intervals: the way forward

New facts have recently enhanced interest in the topic of reference intervals. In particular, the International Organization for Standardization standard 15189, requesting that 'biological reference intervals shall be periodically reviewed', and the directive of the European Union on in vitro diagnostic medical devices asking manufacturers to provide detailed information on reference intervals, have renewed interest in the subject. This review presents an update on the topic, discussing the theoretical aspects and the most critical issues. The basic approach to the definition of reference intervals proposed in the original International Federation of Clinical Chemistry documents still remain valid. The use of data mining to obtain reference data from existing databases has severe limitations. New statistical approaches to discard outliers and to compute reference limits have been recommended. On the other hand, perspectives opened by the improvement in standardization through the implementation of the concept of traceability suggest new models to define 'common' reference intervals that can be transferred and adopted by different clinical laboratories in order to decrease the proliferation of different reference intervals not always justified by differences in population characteristics or in analytical methodology.

Ethnic variation in certain hematological and biochemical reference intervals in a south Indian healthy adult population

BACKGROUND

We established the biochemical and hematological reference intervals among a south Indian healthy adult population attending an HIV referral centre in Chennai, southern India.

METHODS

In a cross sectional study, 213 study subjects (129 male and 84 female) were studied between March and August 2005. All of the parameters were analyzed using standard hematological and biochemical techniques.

RESULTS

Certain biochemical (viz. total bilirubin, alanine transaminase, albumin, creatinine, total protein, lipid profile, creatine phosphokinase, uric acid and lactate) and hematological (mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration and lymphocyte levels) parameters presented higher upper limits. In addition, the upper limits of white blood cell count, platelet count, hematocrit, red blood cell count and hemoglobin level were low in comparison to the currently reported ranges.

CONCLUSION

Ethnic variation in reference intervals was observed in certain biochemical and hematological analytes in a south Indian adult population.

Multicentre physiological reference values for the concentration of creatininium in plasma and diagnostic specificity of glomerular filtration rate estimated with the MDRD equation

BACKGROUND

The National Kidney Disease Education Program recommends that clinical laboratories, when asked for an estimation of glomerular filtration rate in a patient by means of the "four-variable" Modification of Diet in Renal Disease (MDRD) Study equation, also provide the measurement result for creatininium concentration in plasma and the appropriate reference interval. On the other hand, clinical laboratories seeking accreditation for compliance with ISO 15189:2003 need to demonstrate that the physiological reference intervals communicated to all users of laboratory services are appropriate for the patient population served, and for their measurement systems.

METHODS

Ten clinical laboratories in different regions of Spain collaborated in identifying reference individuals and producing reference values for the concentration of creatininium in plasma using RD/Hitachi Modular Analytics analysers, and for the volume rate of glomerular filtrate in kidneys (glomerular filtration rate), estimated with the "four-variable" MDRD Study equation. All the logistic work was carried out in co-operation with the supplier of the reagents and analysers (Roche Diagnostics España, S.L., Sant Cugat del Vallès, Catalonia, Spain). Using all the reference values obtained by each laboratory, multicentre reference limits were estimated non-parametrically.

RESULTS AND CONCLUSIONS

Reference intervals estimated in this study for concentrations of plasma creatininium are 52-85 micromol/L for women and 64-106 micromol/L for men. The diagnostic specificity of the estimated glomerular filtration rate is 99.2% when applied to healthy persons to screen for chronic kidney disease.

Multicentre physiological reference intervals for serum concentrations of immunoglobulins A, G and M, complement C3c and C4 measured with Tina-Quant® reagents systems

BACKGROUND

Clinical laboratories seeking accreditation for compliance with ISO 15189:2003 need to demonstrate that the physiological reference intervals communicated to all users of the laboratory service are appropriate for the patient population served and for the measurement systems used. In the case of immunological quantities, few articles have been published in peer-reviewed journals.

METHODS

A total of 21 clinical laboratories in different regions of Spain collaborated in identifying reference individuals and determining adult reference intervals for some immunological quantities measured using RD/Hitachi Modular Analytics analysers and Tina-Quant reagent systems. These immunological quantities are the mass concentrations of immunoglobulin A, immunoglobulin G, immunoglobulin M, complement C3c and complement C4 in serum. All the logistic work was carried out in co-operation with the supplier of the reagents and analysers (Roche Diagnostics España, S.L., Sant Cugat del Vallès, Catalonia, Spain). From the set of reference values obtained by each laboratory, multicentre reference limits were estimated non-parametrically.

RESULTS AND CONCLUSIONS

The reference intervals estimated in this study for concentrations of serum components under consideration are: complement C3c, 0.62-1.64 g/L for women and men; complement C4, 0.14-0.72 g/L for women and men; immunoglobulin A, 0.89-4.80 g/L for women and men; immunoglobulin G, 6.5-14.3 g/L for women and men; and immunoglobulin M, 0.48-3.38 g/L for women and 0.41-2.46 g/L for men.

Use of total patient data for indirect estimation of reference intervals for 40 clinical chemical analytes in Turkey

In the present study we used patient data to calculate laboratory-specific indirect reference intervals. These values were compared with reference intervals obtained for a healthy group according to recommendations of the International Federation of Clinical Chemistry and Laboratory Medicine and manufacturer suggestions. Laboratory results (422,919 records) from all subjects of 18–45years of age over a 1-year period were retrieved from our laboratory information system and indirect reference intervals for 40 common analytes were estimated using a modified Bhattacharya procedure. Indirect reference intervals for most of the biochemical analytes were comparable, with small differences in lower [alkaline phosphatase (ALP) (male), alanine aminotransferase (ALT), creatine kinase, iron (male), total iron-binding capacity, folic acid, calcium (female), lactate dehydrogenase (LDH), lipoprotein (a) [Lp(a)], thyroid-stimulating hormone (TSH), total triiodothyronine (T

Clin Chem Lab Med 2006;44:867–76.

The REALAB project: a new method for the formulation of reference intervals based on current data

BACKGROUND

In a primary healthcare center concerned more with maintaining wellness than with diagnosing and monitoring illness, it is particularly important to compare patients' results with reference intervals derived from a matched population by use of defined statistical methods.

METHODS

Laboratory results over a 3-year period (approximately 15,000,000 records; 197,350 individuals) were retrieved from our laboratory information system. An inclusion/exclusion procedure for individual patients was applied based on (a) presence of at least 1 of 23 previously defined "basic tests"; (b) only 1 measurement per test by the laboratory over the 3-year period; (c) for each test, absence of any abnormality in the correlated tests. Before the third step, correlations among quantities were assessed by a Spearman correlation matrix, comparing each of the 23 basic tests with all remaining tests by use of a novel multivariate algorithm.

RESULTS

The initial sample group (n = 197,350) was reduced stepwise by the selection criteria outlined above to 166,027, then to 93,649, and finally to 61 246 individuals constituting our reference sample group. Results from the last 2 groups were used to calculate sex-specific, and in some cases age-related, reference limits for the 23 basic tests and for 13 additional quantities. Reference limits were calculated throughout this study by nonparametric estimation of percentiles.

CONCLUSION

Reference values derived by retrospective analysis of large samples of data obtained at a given institution are particularly suitable for the evaluation of results for the presenting patient population at that institution.

Hereditary C2 deficiency in Sweden: frequent occurrence of invasive infection, atherosclerosis, and rheumatic disease

Although frequently asymptomatic, homozygous C2 deficiency (C2D) is known to be associated with severe infections and rheumatic disease. We describe the clinical findings in 40 persons with C2D from 33 families identified in Sweden over 25 years. Medical records covering 96% of the accumulated person-years were reviewed, giving a mean observation time of 39 years (range, 1-77 yr). Severe infection was the predominant clinical manifestation in the cohort: 23 patients had a past history of invasive infections, mainly septicemia or meningitis caused by Streptococcus pneumoniae, and 12 patients had repeated infections of this kind. Nineteen patients had at least 1 episode of pneumonia, and recurrent pneumonia was documented in 10 patients. Repeated infections occurred mainly during infancy and childhood. Systemic lupus erythematosus was found in 10 patients. Another 7 patients had undifferentiated connective tissue disease (n = 4) or vasculitis (n = 3). We found no correlation between susceptibility to invasive infection and rheumatologic disease. Cardiovascular disease occurred at a high rate, with a total of 10 acute myocardial infarctions and 5 cerebrovascular episodes in 6 patients. Causes of death among the C2D patients were infection (n = 5), acute myocardial infarction (n = 3), and cancer (n = 1). We suggest that severe infection may be the principal clinical manifestation of C2D. We also provide novel evidence for a possible role of C2D in the development of atherosclerosis consistent with findings in mannan-binding deficiency and experimental C3 deficiency. In addition, we confirm the well-known association between C2D and systemic lupus erythematosus.

Multicentre physiological reference values for some urinary component-to-creatinine (creatininium) concentration ratios

Nine clinical laboratories in different regions of Spain have shared the search for reference individuals and the production of reference values for urinary component-to-creatininium concentration ratios measured in first morning urine samples using RD/Hitachi<MODULAR ANALYTICS> analysers. These urinary quantities include albumin, calcium(II), chloride, magnesium(II), phosphate, potassium ion, protein, sodium ion, urate and urea. All the logistic work was done in co-operation with the reagents' and analysers' supplier (Roche Diagnostics España, S.L., Sant Cugat del Vallès, Catalonia, Spain). From the blend of reference values obtained by each laboratory, the multicentre reference limits were estimated parametrically after mathematical transformation of original data.

External quality assessment for biochemical markers of myocardial damage: an Italian experience

In 1999 the Centre of Biomedical Research (CRB) in co-operation with the Italian interdisciplinary and intersociety Working Group on Markers of Myocardial Damage proposed a national external quality assurance scheme that was granted in accordance with the UK Clinical Pathology Accreditation Standards in 2001. The scheme, which stresses the importance of educational aspects in quality assurance, was scientifically designed to ensure that it would provide an objective assessment of participants' performance and promote quality improvements to meet the needs of participants. The present paper reports on the data collected in EQA cycles conducted to evaluate improvements in the performance of participants and in related methods. The findings obtained demonstrate that during the 4-year experience the scheme provided opportunities to improve the performance of laboratories and promoted an efficient, more satisfactory approach to analytical aspects. The number of unacceptable performances decreased from 11.6% to 5.6% for troponin I, from 19.5% to 9.0% for myoglobin and from 13.2% to 4.3% for creatine kinase myocardial isoenzyme (CK-MB). During cycles in 2001 and 2002, inter-variability (coefficient of variation, CV%) data for all markers appeared satisfactory and showed a significant improvement (lower than 10%), in particular for procedures automated on Dade Behring Dimension and Beckman Access systems. However, reference values/decisional limits declared by laboratories and those suggested by the manufacturers are not comparable, even within the same diagnostic system. The findings demonstrate that participation in EQA schemes provided an opportunity for participating laboratories to continuously improve the quality of their services.

Proposal for guidelines to establish common biological reference intervals in large geographical areas for biochemical quantities measured frequently in serum and plasma

A suggestion for a standard procedure to establish biological reference intervals for biochemical quantities by a multicenter approach is presented. This procedure was developed for and used in the Nordic Reference Interval Project 2000 (NORIP). This project established biological reference intervals for 25 frequently requested biochemical quantities through cooperation of 102 Nordic laboratories. Each laboratory performed collection of reference samples and measurement using their routine methods. The bias of each routine method was eliminated by use of common reference materials measured in each of the participating laboratories.

Interpretative comments and reference ranges in EQA programs as a tool for improving laboratory appropriateness and effectiveness

INTRODUCTION

Laboratory information is generated when a meaning is given to certain data. This is usually achieved by comparing a laboratory test result with the reference range/decisional limit (RL), and by providing consultation for the interpretation of data, advice, and follow-up testing.

AIM

In this paper, we investigate factors affecting the conversion of data into useful information with regard to biochemical markers of myocardial damage (CK-MB mass, myoglobin, and troponins), in view of their importance in detecting myocardial necrosis. Our aim was to report results obtained in order to verify the consensus between laboratories with reference to interpretative comments and the reference ranges/decisional limits added to clinical reports.

METHODS

A questionnaire and simulated medical reports on three different patients were distributed to participants (94 laboratories) in the 2001 cycle of the External Quality Assessment (EQA). Moreover, we analysed 113 medical reports sent by laboratories during the most recent EQA cycle 2002, and checked the number of different RLs used, both independent and within the diagnostic system used. We also compared each laboratory result of a control sample, obtained in the 2002 cycle, with declared RL in order to verify the clinical significance of results ("normal" or "pathological") for troponin I and CK-MB.

RESULTS

Our findings show that few laboratories regularly add interpretative comments to medical reports. On the contrary, they cooperate with clinicians who require consultation, advice, and information for the appropriate use of biochemical markers. There is a general consensus among participants regarding probable syndromes suggested by the interpretation of the same result and most laboratories also agree on further investigations to be carried out for several diseases. Concerning RL, the data demonstrate that numerous different RLs are used to report the results of the biochemical markers evaluated, both when considered independent of the diagnostic system used and within the diagnostic system used.

DISCUSSION AND CONCLUSIONS

The biochemist does not have the opportunity to verify the efficacy of the interpretation that he/she provided. An audit of this activity is therefore required to allow the laboratory to monitor its own performance and to assure good practice. The evaluation of interpretative comments, through specific surveys, should be a prime objective of EQA organisers. Well-designed EQA programs can, moreover, support laboratories in establishing appropriate RL and in verifying the clinical significance of their results with respect to that of other laboratories. Our survey on interpretative comments and the analysis of the RLs further demonstrate how laboratory medicine can contribute to the objective evaluation of the patients' health status.

Using multiples of the median to normalize serum protein measurements

Quantification of serum proteins is useful in the diagnosis and clinical management of many disorders. With the introduction of automated analyzers and standardized reference materials, one of the last barriers to more widespread utilization of these measurements is the lack of availability of reliable and transferable age- and gender-specific reference ranges. One normalization method that deserves consideration is converting values to multiples of the median (MoM) for age and gender. When two analytic methods agree, or differ only by a proportional amount, conversion to MoM can be used to simplify the clinical interpretation of serum protein results. As a test of this method, assay results for IgG, transferrin, and albumin from three Swedish hospitals were normalized using published reference ranges from the United States. All assays were standardized to CRM 470. IgG results were in agreement in mass units, and transferrin measurements were proportionally different. However, there were important, non-proportional differences in albumin measurements. After converting IgG and transferrin measurements to MoM, published reference ranges were appropriate for the Swedish Hospitals.