Comparison of high-sensitivity C-reactive protein serum assay results obtained using Dade-Behring BNII nephelometer and Ortho Vitros FS 5.1 clinical analyzer in respect of CRP-related risk assessment of chronic metabolic diseases.

BACKGROUND: Serum concentration of high sensitive C-reactive protein (hsCRP) can predict the risk of chronic metabolic and cardiovascular diseases but it is unclear whether turbidimetric high sensitive assays of CRP are adequate. METHODS: Concentrations of serum CRP in 126 samples of serum were measured with high-sensitivity methods using nephelometry (BN II Nephelometer) and turbidimetry (Ortho Vitros FS 5.1). RESULTS: For CRP concentrations measured by nephelometry and turbidimetry intra-assay CVs were 3.2 and 0.9% at mean CRP concentrations of 1.4 and 2.1 mg/l, inter-assay CVs for commercial controls were 3.1% and 3.6% at mean concentrations of 1.3 and 1.7 mg/l, and mean biases were 7.62% and 2.26%, respectively. Measurements were strongly, linearly correlated (r = 0.99; CRP vitros = 0.03 +1.03 CRP (BN II)). When disease risk was assessed by nephelometry and turbidimetry, results were similar. If the risk of disease was classified as moderate (1.0 < CRP < or = 3.0 mg/l) or high (CRP > 3.0 mg/l), the frequency of misclassified cases was only 2.3 and 2.1%, respectively. The classification agreement weighted kappa coefficient was 0.94 (95% C.I.: 0.89-0.98). CONCLUSIONS: turbidimetric high sensitive CRP assays can properly classify CRP-related prediction of chronic metabolic diseases with special consideration on cardiovascular risk.

Analytical evaluation of the Optium Xido blood glucose meter.

BACKGROUND: The main prevention of chronic diabetic complications is maintaining near normoglycemia. In this study, evaluation of analytical performance of the Optium Xido blood glucose meter designed for patients' self-monitoring of glycemia was carried out. METHODS: Glucose concentrations were measured in 118 EDTA blood samples using the Xido glucose meter and the GOD/PAP method on a Modular P clinical analyzer. The results obtained were used for the assessment of accuracy, precision and linearity. Performance of the Xido glucose meter was also assessed using four different reagent strip lots, and the between-lot variation was calculated. RESULTS: The within-run imprecision coefficient of variation (CV) amounted to 4.2%. Good response linearity was found in glucose concentrations of 31-444 mg/dL (1.7-24.7 mmol/L). In the concentration range studied, the glucose meter error was 5.14% and the linear regression equation was y=0.91x+6.2, (r=0.984). The Passing-Bablok agreement test indicated good concordance of results. However, for glucose concentrations<100 mg/dL (5.6 mmol/L) (n=69) the error was 6.82% with regression equation y=0.86x+5.9 (r=0.757). Between-lot differences amounted to 0.7%-18.2%. CONCLUSIONS: The Xido glucose meter has good precision and accuracy when compared to the laboratory method and meets the quality recommendations of the National Committee of Clinical Laboratory Standards (NCCLS, currently the Clinical Laboratory Standards Institute), the National Academy of Clinical Biochemistry (NACB) and the International Organization for Standardization (ISO). However, between-lot variability may result in differences between day-to-day results when the device is continuously used. Therefore, the validation of new lots of reagent strips with a laboratory method is recommended.

Effect of moderate hypercholesterolemia on recognition of hypernatremia using indirect measurements of serum sodium and potassium concentrations.

BACKGROUND: Na+ and K+ concentration measurements by ion-selective electrodes and flame photometry are affected by lipids influencing plasma water content. METHODS: In 166 sera with total cholesterol ranging from 1.19 to 23.3 mmol/L, and triglycerides ranging from 0.34 to 56.3 mmol/L, Na+ and K+ concentrations were assayed using flame photometry and direct ion-selective electrodes of the Vitros 950 analyzer. Linear regression analysis was used to examine inter-method difference as lipid content variable. RESULTS: In hypercholesterolemia and hypertriglyceridemia flame photometry yielded Na+ concentrations lower by 1.85% and 2.15% than ion-selective electrode measurements (p < 0.05). Na+ concentration inter-method difference correlated with total cholesterol and triglycerides. In bivariate analysis, inter-method difference significantly depended on total cholesterol (r2 = 0.09), whereas the impact of triglycerides was weak. In trivariate analysis, total cholesterol had the highest impact (r2 = 0.12), followed by Na+ concentration (r2 = 0.04), while the impact of triglycerides was insignificant. Recognition of hypernatremia significantly depended on total cholesterol (chi2 p = 0.0017); 27% of samples with hyperlipidemia (total cholesterol > 5.2 mmol/L, triglycerides > 2.5 mmol/L) classified as normonatremia by flame photometry presented hypernatremia by direct ion-selective electrode. CONCLUSIONS: The lipid status of patients influences recognition of hypernatremia if assays are based on total plasma volume. No effect of lipids was observed on the recognition of hyperkalemia.

Lower confidence limits for critical systematic errors.

OBJECTIVES: The critical systematic error (DeltaSE(C)) can be used to select a quality control scheme. It is just an estimate of the true DeltaSE(C), however, and its precision depends on the sample size. Thus, the lower confidence limit (LCL) of DeltaSE(C) should be adopted instead to guard against false optimism. DESIGN AND METHODS: LCLs are calculated as a function of DeltaSE(C) and sample size using a modified version of Bissell's formula. RESULTS: The uncertainty in DeltaSE(C) may be significant. The largest relative difference between DeltaSE(C) and its LCL is 52.2%, for DeltaSE(C)=2 and n=20. This difference decreases with increasing DeltaSE(C) and sample size. CONCLUSIONS: It is shown that taking into account the uncertainty in DeltaSE(C) can greatly influence quality control planning decisions. Caution should thus be exercised when interpreting control data and choosing an appropriate quality control strategy. The derived equation for LCL is simple, and can be immediately applied to practical solutions.

An example of a bootstrap technique application for judging a variability of method performance estimates and its consequences for quality control planning.

BACKGROUND: Flexible fitting of quality control procedures to method performance is an inseparable element of a cost-effective quality management strategy. However, opinions on method performance, based on a restricted number of quality control results used to calculate bias and imprecision, can vary due to the random nature of the data-gathering process. METHODS: We present an example of the bootstrap technique application in evaluating method performance estimates. RESULTS: Our analysis reveals substantial variability in method performance assessment results that should not be omitted. We suggest that the best way of using information concerning method performance is to consider the information in a probabilistic manner. Method performance is a feature presented with an element of probability. The effectiveness of a quality control procedure should be assessed with regard to this probability. CONCLUSIONS: Presented example of a bootstrap technique application increases our awareness of the uncertainty that accompanies method performance judgment and quality control planning.

[Analysis of early surgical complications after strumectomy]. / Analiza przyczyn wczesnych powiklan po strumektomii.

UNLABELLED: The aim of the study was the analysis of early surgical complications after strumectomy. MATERIAL AND METHODS: The study involved 578 patients operated on in I Clinic of General Surgery and Transplant at the Medical Academy in Lublin in the years 1999-2002. The largest group of the operated patients was the one with a non-toxic (neutral) goitre (60.1%). Most of the patients in this group had multinodular neutral goitre. The amount of the surgically treated patients because of the hyperactive goitre prevailed in this group. RESULTS: Early postoperative complications were observe d in 35 cases, which comprise 6.05% of the operated patients. On the basis of the obtained results, we stated that there are evident differences in the frequency of occurrence of early complications depending on the type of the goitre. We concluded that statistically they were more frequent in patients operated on because of Graves-Basedov disease as well as in patients with Hashimoto goitre (chi2 test p < 0.001). The amount of the strumectomy operations conducted annually by a surgeon did not have direct influence on the occurrence of the early complications. CONCLUSIONS: Early postoperative complications after strumectomy are more frequent in patients operated on because of diseases of autoimmunological basis. Operations of the thyroid gland and trainings in the surgery of the thyroid gland should take place in centers where large amount of such operations are conducted.

Estimation of CA 125 concentration in patients with congestive heart failure.

Tumour marker CA 125 is used in the monitoring results of treatment woman with ovarian cancer. Its diagnostic effectiveness in selected groups of patients is defined by sensitivity estimated at approximately 75% and specifity at 95%. In practice diagnostic specificity of CA 125 concentration is lower as it is limited by the increase of concentration different tumour diseases (bladder cancer) and non-tumour diseases (pericardial inflammation). The aim of the paper was to estimate CA 125 concentration in patients with congestive heart failure as well as to define the range of changes taking place according to the advancement of the disease. The research included 39 patients: 20 women and 19 men aged 45-75 with diagnosed congestive heart failure graded II-IV in the NYHA classification. It has been found that CA 125 concentration in blood serum of the patiens with congestive heart failure was on average approximately 35.4 +/- 24.8 U/ml and was included in the range from 5.6 to 874 U/ml (limit value 21 U/ml). The concentration increase above the limit value was observed in 34% of patients. Significant statistic differences in CA 125 concentration rates were dependent on the disease advancement. The highest concentration rates were observed in patients classified in group IV NYHA. The results that have been obtained allow us to draw a conclusion that right interpretation of CA 125 concentration in clinical practice (screening examinations, establishment of the level of advancement, prognostication as well as monitoring the ovarian cancer treatment) brings the necessity of taking into consideration the degree of congestive heart failure.

Perception of emotions from faces and voices following unilateral brain damage.

The importance of the right hemisphere in emotion perception in general has been well documented but its precise role is disputed. We compared the performance of 30 right hemisphere damaged (RHD) patients, 30 left hemisphere damaged (LHD) patients, and 50 healthy controls on both facial and vocal affect perception tasks of specific emotions. Brain damaged subjects had a single episode cerebrovascular accident localised to one hemisphere. The results showed that right hemisphere patients were markedly impaired relative to left hemisphere and healthy controls on test performance: labelling and recognition of facial expressions and recognition of emotions conveyed by prosody. This pertained at the level of individual basic emotions, positive versus negative, and emotional expressions in general. The impairment remained highly significant despite covarying for the group's poorer accuracy on a neutral facial perception test and identification of neutral vocal expressions. The LHD group were only impaired relative to controls on facial emotion tasks when their performance was summed over all the emotion categories and before age and other cognitive factors were taken into account. However, on the prosody test the LHD patients showed significant impairment, performing mid-way between the right hemisphere patients and healthy comparison group. Recognition of positive emotional expressions was better than negative in all subjects, and was not relatively poorer in the LHD patients. Recognition of individual emotions in one modality correlated weakly with recognition in another, in all three groups. These data confirm the primacy of the right hemisphere in processing all emotional expressions across modalities--both positive and negative--but suggest that left hemisphere emotion processing is modality specific. It is possible that the left hemisphere has a particular role in the perception of emotion conveyed through meaningful speech.