Establishment of reference intervals for free light chains and immunoglobulins in Saudi population.

OBJECTIVES: Testing of serum-free light chains kappa (κ) and lambda (λ), along with ratio (FLCR) is essential for the diagnosis and management of monoclonal gammopathies. Accurate clinical diagnosis depends upon appropriate local population reference intervals (RIs). This study examined the Saudi population for serum-free light chains and other immunoglobulins to establish RIs and to explore variations in the test results by using the International Federation for Clinical Chemistry and Laboratory Medicine's global protocol for harmonized implementation of RI study. METHODS: A total of 180 healthy Saudi adults were recruited. All serum samples were assayed using the Freelite reagents from the Binding Site. The variation in reference values attributable to sex, age, BMI, and region was calculated by ANOVA as a standard deviation ratio (SDR). The RIs for the FLCR were derived by the parametric method and validated by using samples from patients with hypo- and hypergammaglobulinemia. RESULTS: The new RIs for free κ and FLCR were shifted to a higher side from the manufacturer-adapted RIs. Based on the SDR cutoff value (>0.4), between-sex partition RIs were not required for all analytes except IgM. Validation using patients with hypo- or hypergammaglobulinemia and without multiple myeloma, was all within the new RI. BMI, smoking, and exercise were not relevant sources of variation for any analyte. CONCLUSIONS: Locally derived RIs for free light chains and immunoglobulins analytes specific for Saudis were established after careful consideration of various factors. These RIs were more reliable than those provided as guidance by the manufacturer, or from other countries, for appropriate classification and prediction of disease progression for Saudi patients.

Derivation of sex and age-specific reference intervals for clinical chemistry analytes in healthy Ghanaian adults.

OBJECTVIES: This study is aimed at establishing reference intervals (RIs) of 40 chemistry and immunochemistry analytes for Ghanaian adults based on internationally harmonized protocol by IFCC Committee on Reference Intervals and Decision Limits (C-RIDL). METHODS: A total of 501 healthy volunteers aged ≥18 years were recruited from the northern and southern regions of Ghana. Blood samples were analyzed with Beckman-Coulter AU480 and Centaur-XP/Siemen auto-analyzers. Sources of variations of reference values (RVs) were evaluated by multiple regression analysis (MRA). The need for partitioning RVs by sex and age was guided by the SD ratio (SDR). The RI for each analyte was derived using parametric method with application of the latent abnormal values exclusion (LAVE) method. RESULTS: Using SDR≥0.4 as threshold, RVs were partitioned by sex for most enzymes, creatinine, uric acid (UA), bilirubin, immunoglobulin-M. MRA revealed age and body mass index (BMI) as major source of variations of many analytes. LAVE lowered the upper limits of RIs for alanine/aspartate aminotransferase, γ-glutamyl transaminase and lipids. Exclusion of individuals with BMI≥30 further lowered the RIs for lipids and CRP. After standardization based on value-assigned serum panel provided by C-RIDL, Ghanaian RIs were found higher for creatine kinase, amylase, and lower for albumin and urea compared to other collaborating countries. CONCLUSIONS: The LAVE effect on many clinical chemistry RIs supports the need for the secondary exclusion for reliable derivation of RIs. The differences in Ghanaian RIs compared to other countries underscore the importance of country specific-RIs for improved clinical decision making.

Exploring the seasonal and regional features of cat-scratch disease on the basis of anti-Bartonella henselae IgM/IgG positive rates in Japan.

OBJECTIVES: This study aimed to explore the seasonal and regional features of cat-scratch disease (CSD) based on 15-years of test results for anti-Bartonella henselae IgG and IgM by immunofluorescence assay (IFA) performed as a laboratory specialized in diagnostic testing of CSD in Japan. A literature search was performed to put our findings in perspective. METHODS: A total of 956 sera from patients suspected of CSD were submitted to our laboratory from nationwide. Seasonal changes in the monthly positive rates of IgG/IgM antibodies and regional distribution of the test specimens were analyzed. RESULTS: The monthly positive rates of anti-B. henselae IFA of IgG and IgM were both significantly high between September and January and low between March and July. The seasonal pattern observed in this study was similar to the ones reported from US and France, which were analyzed from a clinical database (monthly incidence of CSD diagnosis) or from monthly positive rates of either B. henselae PCR or anti-B. henselae IFA. However, fluctuations in the IFA monthly positive rates in this study were more pronounced than other reports. Regarding regionality, the test specimens submitted to us for IFA were prominently more from southwestern areas than from northern/middle-northern areas of Japan. The distribution coincided well with the regional distribution of CSD case reports and with a known regional prevalence of Bartonella-species bacteremia among pet cats in Japan. CONCLUSION: These epidemiological features in Japan are of relevance in the clinical diagnoses of CSD.

Determination of diagnostic threshold in harmonization and comparison of clinical utility for five major antiphospholipid antibody assays used in Japan.

BACKGROUND: Anticardiolipin antibodies (aCL) and anti-ß2 -glycoprotein I antibodies (aß2 GPI) are essential in diagnosing antiphospholipid syndrome (APS) according to the international APS guideline. Five commercial assays for aCL and aß2 GPI are available in Japan, but their test results are quite discordant. For harmonization of diagnosing APS, upper reference limit (URL) and diagnostic accuracy of each assay were evaluated and compared by testing common sets of specimens across all assays. METHODS: We evaluated two manual and three automated assays for aCL and aß2 GPI of IgG- and IgM classes. 99%URL (the upper limit of reference interval: as per guideline) together with 97.5%URL were determined by testing sera from 198 to 400 well-defined healthy subjects. Both URLs were compared with the cutoff values, which were determined based on ROC analysis by testing 50 each of plasma specimens from patients with/without APS. Diagnostic accuracy was evaluated as area under curve (AUC) of the ROC curve. RESULTS: A variable degree of discrepancy between URLs and the cutoff values was observed, which was partly attributable to between-year assay variability. 97.5%URLs were set lower and closer to the cutoff values than 99%URLs. For all assays, diagnostic accuracies of both aß2 GPI-IgG and aCL-IgG were generally high (AUC: 0.84-0.93); whereas those for IgM-class assays were low (AUC: 0.57-0.67), implicating its utility is limited to rare IgG negative APS cases. CONCLUSION: To ensure harmonized APS diagnosis, the diagnostic thresholds of the five assays were evaluated by common procedures. Contrary to the guideline, 97.5%URL is rather recommended for diagnosing APS, which showed a closer match to the cutoff value.

Factors characterizing gait performance of patients before and soon after knee arthroplasty.

[Purpose] For monitoring patients with knee osteoarthritis undergoing knee arthroplasty, the Timed Up and Go and maximum walking speed tests are commonly used. To provide appropriate peri-surgical rehabilitation, we evaluated the factors associated with postsurgical changes in Timed Up and Go and maximum walking speed results. [Participants and Methods] We enrolled 545 knee osteoarthritis patients undergoing either of the following knee arthroplasties: conventional total knee arthroplasty, minimally invasive total knee arthroplasty, and unicompartmental knee arthroplasty. Comfortable Timed Up and Go, maximum Timed Up and Go, and maximum walking speed were measured 2 weeks before and soon after surgery. Factors (gender, age, and surgical mode) that might influence changes in test results were evaluated by multiple regression analysis and a two-factor stratification diagram. [Results] Multiple regression analysis revealed that postsurgical changes in comfortable/maximum Timed Up and Go and maximum walking speed results were associated with age and surgical mode after adjustment for preoperative values. Two-factor diagrams showed that the older the patient, the greater was the slowdown in the Timed Up and Go test performed postoperatively. The levels of slowdown in the postoperative Timed Up and Go and maximum walking speed tests were the smallest in those who underwent conventional total knee arthroplasty, followed by those who underwent minimally invasive and unicompartmental knee arthroplasty. Among patients whose preoperative Timed Up and Go and maximum walking speed were slow, slowdown in Timed Up and Go was pronounced with age, and slowdown in maximum walking speed was higher in conventional total knee arthroplasty. [Conclusion] The changes in Timed Up and Go and maximum walking speed results 2 weeks after knee arthroplasty depended on age and surgical modes. These findings are relevant for the implementation of appropriate peri-surgical rehabilitation.

Selection of Oral Antifungals for Initial Maintenance Therapy in Chronic Pulmonary Aspergillosis: A Longitudinal Analysis.

BACKGROUND: There are limited data for direct comparisons of the efficacy of oral itraconazole (ITCZ) and oral voriconazole (VRCZ) therapy in the treatment of chronic pulmonary aspergillosis (CPA). METHODS: We conducted a retrospective, follow-up, observational study of CPA patients enrolled in 2 previous multicenter trials. RESULTS: Of the 273 CPA patients, 59 and 101 patients started maintenance therapy with oral ITCZ and oral VRCZ, respectively, just after the end of acute intravenous therapy in each trial. At the end of the observation period in this follow-up study (median observation period, 731 days), the percentage of patients who showed improvement was lower in the ITCZ group than in the VRCZ group (18.2% vs 40.0%). However, after including stable patients, the percentages were 50.9% and 52.6%, respectively, in the ITCZ and VRCZ groups, which were not significantly different (P = .652). Multivariable Cox regression analysis showed no significant influence of the choice of initial maintenance treatment (ITCZ or VRCZ) on overall mortality as well as CPA-associated mortality. Multivariable logistic regression showed that oral ITCZ selection for initial maintenance therapy was an independent risk factor for hospital readmission and switching to other antifungal agents (odds ratio [OR], 3.1; 95% confidence interval [CI], 1.3-7.5 and OR, 5.7; 95% CI, 2.0-15.7, respectively). CONCLUSIONS: Oral VRCZ for initial maintenance therapy showed better effectiveness than oral ITCZ for clinical improvement in CPA patients. There was no difference in crude mortality between initial maintenance therapy with VRCZ and ITCZ, especially in elderly CPA patients. CLINICAL TRIALS REGISTRATION: UMIN000007055.

Establishment of reference intervals for immunoassay analytes of adult population in Saudi Arabia.

Background This is a second part of report on the IFCC global multicenter study conducted in Saudi Arabia to derive reference intervals (RIs) for 20 immunoassay analytes including five tumor makers, five reproductive, seven other hormones and three vitamins. Methods A total of 826 apparently healthy individuals aged ≥18 years were recruited in three clinical laboratories located in western, central and eastern Saudi Arabia using the protocol specified for the global study. All serum specimens were measured using Abbott, Architect analyzers. Multiple regression analysis (MRA) was performed to explore sources of variation of each analyte: age, body mass index (BMI), physical exercise and smoking. The magnitude of variation of reference values (RVs) attributable to sex, age and region was calculated by ANOVA as a standard deviation ratio (SDR). RIs were derived by the parametric (P) method. Results MRA revealed that region, smoking and exercise were not relevant sources of variation for any analyte. Based on SDR and actual between-sex differences in upper limits (ULs), we chose to partition RIs by sex for all analytes except for α-fetoprotein and parathyroid hormone (PTH). Age-specific RIs were required in females for ferritin, estradiol, progesterone, testosterone, follitropin, luteotropin and prolactin (PRL). With prominent BMI-related increase, RIs for insulin and C-peptide were derived after excluding individuals with BMI > 32 kg/m2. Individuals taking vitamin D supplements were excluded in deriving RIs for vitamin D and PTH. Conclusions RIs of major immunoassay analytes specific for Saudi Arabians were established in careful consideration of various biological sources of variation.

Previous antibiotic use and the development of Kawasaki disease: a matched pair case-control study.

BACKGROUND: Kawasaki disease (KD) is an acute febrile illness with systemic vasculitides, mostly affecting infants and young children. The etiology of KD is still unclear; however, altered gut microbiota have been recently implicated as a contributing factor for the development of vasculitis. METHODS: We conducted an age- and gender-matched case-control study on 50 patients and 200 control subjects to search for potential factors leading to intestinal dysbiosis associated with KD. Data were analyzed using conditional multivariable logistic regression. RESULTS: Previous antibiotic administration was associated with the patients who developed KD (odds ratio [OR] 11.7, 95% confidence interval [CI] 4.7-29.1, P < 0.0001), but not other variables, including breastfeeding and group nursery. In subgroup analyses, cesarean birth was indicated as an associated factor in addition to previous antibiotic administration in infants under 12 months of age (OR: 8.0, 95% CI: 1.8-34.4, P = 0.005), but not in older children. CONCLUSIONS: The association between previous antibiotic administration and the onset of KD was demonstrated. Antibiotics may contribute to the development of KD by affecting the intestinal microbiota in infants and young children.

Serum soluble ST2 as a marker of renal scar in pediatric upper urinary tract infection.

BACKGROUND AND OBJECTIVES: Upper urinary tract infection is the most common serious bacterial infection in childhood. Patients with upper urinary tract infection have a risk for renal scarring with subsequent complications including hypertension, proteinuria, and progressive renal failure. However, the predictive biomarkers of renal scarring in children with upper urinary tract infection are still unknown. In this study, we evaluated whether soluble ST2 levels can be biomarkers of subsequent renal scarring in patients with upper urinary tract infection. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: We retrospectively studied pediatric patients with upper urinary tract infection at a tertiary center. Twenty-eight children had an upper urinary tract infection with (n = 14) and without (n = 14) renal scarring and underwent 99mtechnetium dimercaptosuccinic acid imaging. In addition, 13 control subjects were enrolled. The clinical data and serum cytokine levels, including soluble ST2 levels, were compared between those with and without renal scars. RESULTS: Serum soluble ST2 levels were significantly higher in the scar group than in the non-scar group, whereas there was no difference in the levels of serum interferon-γ, interleukin-6, interleukin-10, soluble tumor necrosis factor receptor 1, and transforming growth factor-ß between the scar and non-scar groups. The area under the curve for differentiating between the non-scar and scar groups on the basis of measurements of serum soluble ST2 was 0.79, with a sensitivity and specificity of 92.9% and 64.3%, respectively. CONCLUSION: These results suggest that serum soluble ST2 levels on admission could be a useful biomarker of subsequent renal scarring in pediatric patients with upper urinary tract infection.

Elucidation of stability profiles of common chemistry analytes in serum stored at six graded temperatures.

Background Many reports address the stability of biochemical analytes in serum. However, studies covering a wide range of storage temperatures are unavailable. Using equipment enabling precise temperature control, we investigated the effect of six different storage temperatures on serum analytes. Methods Serum specimens from seven healthy volunteers were obtained and divided into multiple aliquots for storage at -30, -20, -10, 0, 4, and 25 °C. On days 1, 3, 7, 14, 28 and 56, the aliquots stored at each temperature were relocated to a deep freezer maintained at -80 °C. On day 60, all aliquots were measured collectively for 13 major chemistry analytes. Results (1) At 25 °C, alanine aminotransferase (ALT), creatine kinase (CK), aspartate aminotransferase (AST) and total bilirubin (TBil) were very unstable especially on day 7 and later. (2) At ≤4 °C, alkaline phosphatase (ALP), γ-glutamyltransferase (GGT), amylase (AMY), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), triglyceride (TG), TBil and complement component-4 (C4) were generally stable and were very stable at 25 °C until day 14. (3) Between -20 and 4 °C, especially at -10 °C, test results of ALT, AST and lactate dehydrogenase (LDH) showed prominent decreases, but their stability was greatly improved at -30 °C. (4) In contrast, the value of complement component-3 (C3) increased at ≥- 20 °C. (5) At -30 °C, test results of all analytes were generally very stable except for ALT and CK, which showed noticeable reductions in activity after 14 days. Conclusions This is the first study to assess the stability of serum analytes at six graded temperatures simultaneously. Each analyte has a unique stability pattern for a range of temperatures.

Bartonella henselae DNA in Seronegative Patients with Cat-Scratch Disease.

We used real-time PCR to detect Bartonella henselae DNA in 7.9% (5/63) of blood specimens from seronegative patients in Japan suspected of having cat-scratch disease. The combined use of serologic tests and real-time PCR to analyze blood specimens is recommended for the prompt, noninvasive laboratory diagnosis of cat-scratch disease.

Utility of Bartonella henselae IgM Western Blot Bands for Serodiagnosis of Cat Scratch Disease.

We evaluated the utility of Western blot (WB) bands of Bartonella henselae in detecting anti-B. henselae immunoglobulin M (IgM) for serodiagnosis of cat scratch disease (CSD). IgM band patterns were examined using sera from 92 patients clinically suspected of having CSD and from 130 healthy individuals. Positive WB bands were observed in 49 (53.5%) of the 92 patient sera. Three bands at 8 to 10, 31 to 35, and 70 kDa were regarded as relevant for B. henselae because all of the positive sera yielded at least one of the three bands, and none of the healthy control sera showed reactivity to any of them. In contrast, the positive rate of the patient sera by conventional indirect fluorescence antibody assay (IFA) for B. henselae IgM was 28.3% (26/92) among the patients. These finding suggest that the IgM-WB assay, although cumbersome to perform, can be used for confirmatory diagnosis of CSD with no false positivity in the control sera. Purification of proteins in the specific bands may contribute to the development of an IgM enzyme-linked immunosorbent assay (IgM-ELISA) with improved specificity and sensitivity.

Reference intervals for 33 biochemical analytes in healthy Indian population: C-RIDL IFCC initiative.

Background In 2011, the IFCC Committee on Reference Intervals and Decision Limits (C-RIDL) initiated a worldwide multicenter study on references values facilitating the implementation of country-specific reference intervals (RIs). There has been no well-designed RI study in India. This study aims to derive RIs for 33 major biochemical analytes in carefully selected healthy Indians as defined in C-RIDL protocol. Methods A total of 512 healthy Indians were recruited. Sera collected from overnight fasting blood samples were measured collectively for the analytes. Multiple regression analysis (MRA) and nested analysis of variance (ANOVA) were used to identify the potential sources of variation (SV) of test results. RI were derived by both parametric and non-parametric methods for comparison. The need for secondary exclusion by latent abnormal values exclusion (LAVE) method was examined. Results MRA results indicated that both age and BMI were apparent SV for many analytes in both sexes. ANOVA revealed that partition of RIs by gender and age was required for 17 analytes (TC, HDL-C, TG, hsCRP, ALB, AST, ALT, ALP, GGT, TBil, Urea, CRE, UA, Fe, TTR, CK and IgM) and 5 (Glu, ALB, TC, ALP and Urea), respectively. RIs by parametric method were generally narrower than by non-parametric method, reflecting distorted peripheral distributions of test results. The LAVE method had no appreciable effect on RIs possibly due to inconsistency among abnormal values of related analytes. Conclusions This study has for the first time provided comprehensive RIs information in healthy Indians. The final RIs adopted were those derived by parametric method without LAVE procedure.

Establishing reference intervals for sex hormones and SHBG in apparently healthy Chinese adult men based on a multicenter study.

BACKGROUND: Measuring sex hormones is essential in diagnosing health issues such as testicular dysfunction, male infertility and feminization syndrome. However, there are no reports on reference intervals (RIs) in Chinese men. We conducted a nationwide multicenter study to establish RIs for seven sex hormones (luteinizing hormone [LH], follicle-stimulating hormone [FSH], prolactin [PRL], total testosterone [TT], free testosterone [FT], bioavailable testosterone [BAT] and estrogen [E2]), as well as sex hormone-binding globulin (SHBG). METHODS: In 2013, 1043 apparently healthy adult men from five representative cities in China (Beijing, Hangzhou, Guangzhou, Dalian and Urumqi) were recruited; hormones were measured using an automated immunoassay analyzer. Multiple regression analysis (MRA) was performed to identify sources of variation (SVs) that might influence the hormone serum levels. RIs were computed using the parametric method. RESULTS: Dalian and Hangzhou had significantly higher E2 values than other cities; age was a major source of variation for FSH, LH, PRL, SHBG, FT and BAT. FSH, LH and SHBG increased significantly with age, while PRL, FT and BAT decreased with age. TT showed no significant age-related changes. Median (RIs) derived without partition by age were as follows: FSH, 5.6 (1.9-16.3) IU/L; LH, 4.2 (1.6-10.0) IU/L; PRL, 189 (88-450) mIU/L; E2, 85 (4.7-195) pmol/L; SHBG, 29.4 (11.5-66.3) nmol/L; TT, 15.6 (7.4-24.5) nmol/L; FT, 0.31 (0.16-0.52) nmol/L; and BAT, 8.0 (3.7-13.2) nmol/L. RIs were also derived in accordance with between-city and between-age differences. CONCLUSIONS: RIs were established for sex hormones and SHBG in apparently healthy Chinese men in consideration of age.

Psychological and physiological effects of laughter yoga sessions in Japan: A pilot study.

The purpose of this pilot study was to examine and evaluate the psychological and physiological effects of multiple sessions of laughter yoga on community members. Participants took part in a 45 min laughter yoga session once per month for 6 months. Before and after all sessions, participants completed the Profile of Mood States-Brief Japanese Version (J-POMS-B) questionnaire to assess their mood, and had blood drawn for the measurement of stress indicators and immune function. Serial changes in J-POMS-B scores were tested by three way analysis of variance, and changes in laboratory results per session were evaluated with a paired t-test. The results showed that repeated sessions of laughter yoga had psychologically beneficial effects, especially on the aspects of tension-anxiety, and vigor. Adrenocorticotropic hormone and cortisol values related to the participants' stress levels were significantly decreased after the fourth laughter yoga session. These results indicated that multiple laughter yoga sessions appeared to be effective in improving the psychological and physiological status of healthy adults.

Distinctive inflammatory profile between acute focal bacterial nephritis and acute pyelonephritis in children.

BACKGROUND: Acute focal bacterial nephritis (AFBN) is a severe form of upper urinary tract infection (UTI) with neurological manifestations and focal renal mass lesions on computed tomography (CT). Prolonged antibiotic therapy may improve the renal outcome, but the early differential diagnosis of AFBN from acute pyelonephritis (APN) is challenging. We searched for effective biomarkers of AFBN based on the pathophysiology of upper UTIs. METHODS: Of 52 upper UTI cases treated at Yamaguchi University between 2009 and 2016, 38 pediatric patients with AFBN (n=17) or APN (n=21) who underwent ultrasonography and/or CT were enrolled. The clinical data and serum cytokine concentrations were analyzed to differentiate AFBN from APN. RESULTS: AFBN patients tended to be older, and have a higher body temperature, longer febrile period, more frequent neurological symptoms, higher immature neutrophil count, lower lymphocyte count, higher procalcitonin and urine ß2-microglobulin levels. AFBN patients showed higher serum levels of IFN-γ, IL-6, IL-10 and soluble TNF-receptor 1 (sTNFR1) (all p<0.05). Although the cytokine levels were variably correlated among each other, multiple logistic regression analysis revealed that combination of IFN-γ and IL-6 levels were most relevant for distinguishing AFBN from APN. The discriminant power of the logistic equation was 0.86 in terms of the area under the curve by the ROC analysis. CONCLUSIONS: Circulating 4 out of 7 cytokines in AFBN patients were at higher levels compared with those in APN patients. IFN-γ and IL-6 levels might most effectively distinguish AFBN from APN.

Metabolic syndrome and its predictors in an urban population in Kenya: A cross sectional study.

BACKGROUND: The metabolic syndrome (MetS) is a clustering of interrelated risk factors which doubles the risk of cardio-vascular disease (CVD) in 5-10 years and increases the risk of type 2 diabetes 5 fold. The identification of modifiable CVD risk factors and predictors of MetS in an otherwise healthy population is necessary in order to identify individuals who may benefit from early interventions. We sought to determine the prevalence of MetS as defined by the harmonized criteria and its predictors in subjectively healthy black Africans from various urban centres in Kenya. METHOD: We used data collected from healthy black Africans in Kenya as part of a global study on establishing reference intervals for common laboratory tests. We determined the prevalence of MetS and its components using the 2009 harmonized criterion. Receiver operator characteristic (ROC) curve analysis was used to determine the area under the curves (AUC) for various predictors of MetS. Youden index was used to determine optimum cut-offs for quantitative measurements such as waist circumference (WC). RESULTS: A total of 528 participants were included in the analysis. The prevalence of MetS was 25.6% (95% CI: 22.0%-29.5%). Among the surrogate markers of visceral adiposity, lipid accumulation product was the best predictor of MetS with an AUC of 0.880 while triglyceride was the best predictor among the lipid parameters with an AUC of 0.816 for all participants. The optimal WC cut-off for diagnosing MetS was 94 cm and 86 cm respectively for males and females. CONCLUSIONS: The prevalence of MetS was high for a healthy population highlighting the fact that one can be physically healthy but have metabolic derangements indicative of an increased CVD risk. This is likely to result in an increase in the cases of CVD and type 2 diabetes in Kenya if interventions are not put in place to reverse this trend. We have also demonstrated the inappropriateness of the WC cut-off of 80 cm for black African women in Kenya when defining MetS and recommend adoption of 86 cm.

Development of a Highly Specific IgM Enzyme-Linked Immunosorbent Assay for Bartonella henselae Using Refined N-Lauroyl-Sarcosine-Insoluble Proteins for Serodiagnosis of Cat Scratch Disease.

The conventional anti-Bartonella henselaeIgM enzyme-linked immunosorbent assay (IgM-ELISA) methods for diagnosing cat scratch disease (CSD) remain poor in both sensitivity and specificity. We sought to develop an IgM-ELISA with improved accuracy in the serodiagnosis of CSD by exploring the antigens that are most suitable for an ELISA. We prepared 5 different protein antigens: antigen I (sonicatedB. henselaewhole-cell antigen), antigen II (N-lauroyl-sarcosine-insoluble antigen), antigen III (processed sarcosine-soluble antigen), and antigen IV and antigen V (sarcosine-insoluble and sarcosine-soluble antigens refined by DEAE-Sepharose Fast Flow ion-exchange chromatography). The IgM antibodies in the sera of 47 patients with clinically suspected CSD (24 definite, 23 suspected) and of 85 healthy individuals were examined by ELISAs using the 5 antigens, and the results were compared with those of an IgM indirect fluorescent antibody assay (IgM-IFA). In a reference panel, which consisted of 5 positive and 5 negative sera, antigen I and antigen III failed to distinguish between the two statuses, whereas the other three antigens succeeded in distinguishing between them. When the cutoff value was set at the 98th percentile of the ELISA index for healthy individuals, the sensitivity of IgM-IFA for the 24 cases of definite CSD was 54%, whereas the sensitivities of the IgM-ELISAs with antigen II, IV, and V were 75%, 83%, and 75%, respectively. The sensitivities of these three IgM-ELISAs for all 47 of the clinically suspected cases were 49%, 64%, and 51%, respectively. In contrast, the sensitivity of IgM-IFA was 28%. These results indicate that the refined sarcosine-insoluble proteins (antigen IV), which possessed the highest specificity among the 5 antigens, are the most appropriate for developing an IgM-ELISA for the highly specific serodiagnosis of CSD.

Derivation of level-specific reference change values (RCV) from a health screening database and optimization of their thresholds based on clinical utility.

BACKGROUND: Reference change values (RCV) are used for judging the significance of changes between any two measurements. Based on the within-individual CV (CVI), RCV is conventionally computed as the 95% confidence limit (CL) of the changes: RCV=1.96×2CVI. $RCV = 1.96 \times \sqrt 2 C{V_I}.$ However, the appropriateness of assuming a constant CVI and using the 95% CL for RCV remains controversial. METHODS: The level-specific CVI and RCV were estimated for 20 screening tests using a database composed of results from 13,545 health-screening attendees over a 17-year period, after preliminary exclusion of individuals taking medications or having unusual changes in body mass index (BMI). A rational CL for RCV was explored in reference to a clinical score for the metabolic syndrome, sMS, which was derived based on a logistic regression model consisting of tests related to metabolic syndrome. The effect of adjusting CL for the RCV on diagnostic efficacies of detecting between-year change in sMS was evaluated. RESULTS: Test level dependency of CVI was apparent for some screening tests which have distributions with prominent skewing. The use of level-specific RCV was thus essential for them. The sensitivity for detecting a critical change in sMS based on the RCV set at 95%CL was extremely low in the majority of tests. However, by lowering CL stepwise from 95 to 75%, the sensitivity improved greatly without much change in specificity and positive predictive value. Loss-and-gain analysis showed that CL for RCV set around 80% gave the lowest loss, assuming a policy of reducing false negative judgment. CONCLUSIONS: Level specific CVI and RCV were necessary in tests with skewed distributions. RCV using 80%-90% CL is suitable in health screening for diseases that require early intervention for changes.

Establishment of reference intervals of clinical chemistry analytes for the adult population in Saudi Arabia: a study conducted as a part of the IFCC global study on reference values.

BACKGROUND: This study is a part of the IFCC-global study to derive reference intervals (RIs) for 28 chemistry analytes in Saudis. METHOD: Healthy individuals (n=826) aged ≥18 years were recruited using the global study protocol. All specimens were measured using an Architect analyzer. RIs were derived by both parametric and non-parametric methods for comparative purpose. The need for secondary exclusion of reference values based on latent abnormal values exclusion (LAVE) method was examined. The magnitude of variation attributable to gender, ages and regions was calculated by the standard deviation ratio (SDR). Sources of variations: age, BMI, physical exercise and smoking levels were investigated by using the multiple regression analysis. RESULTS: SDRs for gender, age and regional differences were significant for 14, 8 and 2 analytes, respectively. BMI-related changes in test results were noted conspicuously for CRP. For some metabolic related parameters the ranges of RIs by non-parametric method were wider than by the parametric method and RIs derived using the LAVE method were significantly different than those without it. RIs were derived with and without gender partition (BMI, drugs and supplements were considered). CONCLUSIONS: RIs applicable to Saudis were established for the majority of chemistry analytes, whereas gender, regional and age RI partitioning was required for some analytes. The elevated upper limits of metabolic analytes reflects the existence of high prevalence of metabolic syndrome in Saudi population.