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1.
The comparison of methods experiment is important part in process of analytical methods and instruments validation. Passing and Bablok regression analysis is a statistical procedure that allows valuable estimation of analytical methods agreement and possible systematic bias between them. It is robust, non-parametric, non sensitive to distribution of errors and data outliers. Assumptions for proper application of Passing and Bablok regression are continuously distributed data and linear relationship between data measured by two analytical methods. Results are presented with scatter diagram and regression line, and regression equation where intercept represents constant and slope proportional measurement error. Confidence intervals of 95% of intercept and slope explain if their value differ from value zero (intercept) and value one (slope) only by chance, allowing conclusion of method agreement and correction action if necessary. Residual plot revealed outliers and identify possible non-linearity. Furthermore, cumulative sum linearity test is performed to investigate possible significant deviation from linearity between two sets of data. Non linear samples are not suitable for concluding on method agreement.  相似文献   

2.
In a contemporary clinical laboratory it is very common to have to assess the agreement between two quantitative methods of measurement. The correct statistical approach to assess this degree of agreement is not obvious. Correlation and regression studies are frequently proposed. However, correlation studies the relationship between one variable and another, not the differences, and it is not recommended as a method for assessing the comparability between methods.
In 1983 Altman and Bland (B&A) proposed an alternative analysis, based on the quantification of the agreement between two quantitative measurements by studying the mean difference and constructing limits of agreement.
The B&A plot analysis is a simple way to evaluate a bias between the mean differences, and to estimate an agreement interval, within which 95% of the differences of the second method, compared to the first one, fall. Data can be analyzed both as unit differences plot and as percentage differences plot.
The B&A plot method only defines the intervals of agreements, it does not say whether those limits are acceptable or not. Acceptable limits must be defined a priori, based on clinical necessity, biological considerations or other goals.
The aim of this article is to provide guidance on the use and interpretation of Bland Altman analysis in method comparison studies.Key words: Bland-Altman, agreement analysis, laboratory research, method comparison, correlation of data  相似文献   

3.

Introduction:

Sample type recommended by the manufacturer for the digoxin Abbott assay is either serum collected in glass tubes or plasma (sodium heparin, lithium heparin, citrate, EDTA or oxalate as anticoagulant) collected in plastic tubes. In our hospital samples are collected in plastic tubes. Our hypothesis was that the serum sample collected in plastic serum tube can be used interchangeably with plasma sample for measurement of digoxin concentration. Our aim was verification of plastic serum tubes for determination of digoxin concentration.

Materials and methods:

Concentration of digoxin was determined simultaneously in 26 venous blood plasma (plastic Vacuette, LH Lithium heparin) and serum (plastic Vacuette, Z Serum Clot activator; both Greiner Bio-One GmbH, Kremsmünster, Austria) samples, on Abbott AxSYM analyzer using the original Abbott Digoxin III assay (Abbott, Wiesbaden, Germany). Tube comparability was assessed using the Passing Bablok regression and Bland-Altman plot.

Results:

Serum and plasma digoxin concentrations are comparable. Passing Bablok intercept (0.08 [95% CI = −0.10 to 0.20]) and slope (0.99 [95% CI = 0.92 to 1.11]) showed there is no constant or proportional error.

Conclusion:

Blood samples drawn in plastic serum tubes and plastic plasma tubes can be interchangeably used for determination of digoxin concentration.  相似文献   

4.
Recent studies have shown that there are systematic differences among total and free prostate-specificantigen (PSA) immunoassays. In this study we analyzedintermethod differences in total PSA (tPSA) and free PSA(fPSA) measurement using ARCHITECT i2000SR (Abbott Diagnostics) and COBAS E601 (Roche Diagnostics). A number of 160 blood samples were tested for tPSA and 50 samples for fPSA (selecting only sampleswith tPSA: 4.1–10.0 μg/L). Passing–Bablok regression analysis was used to compare the two analytical methods fortPSA, fPSA and percentage of fPSA (%fPSA). A strong correlation was noticed between ARCHITECT i2000SR and COBAS E601 for tPSA, fPSA and %fPSA (r between 0.94 and 0.99). Concentrations of tPSA and fPSA measured by COBAS E601 were higher thanthose measured by ARCHITECT i2000SR with a bias of 0.8 μg/L for tPSA and 0.14 μg/L for fPSA. Analyzing therelative difference between methods for fPSA and %fPSA, COBAS E601 exceed a 10% relative difference limit. Our study confirms that there are differences in measured concentrations of tPSA and fPSA byvarious commercial methods. Because clinical judgment on subsequent diagnostic procedures, such as prostatebiopsy, is based on tPSA and fPSA results, tests harmonization should be a priority.  相似文献   

5.
Genitourinary tuberculosis is a disease of the genitourinary system which includes the entire urinary tract and reproductive system. Genital tuberculosis is an important cause of female infertility, especially in developing nations like India. In the present study, a total of 257 clinical specimens comprising of endometrial biopsy (109), endometrial curetting (42), menstrual blood (8), semen (17), placenta (11) and urine (70) were collected from patients and subjected for PCR, Culture and AFB detection. The endometrial biopsy, endometrial curetting, menstrual blood, semen, placenta, urine showed 30.2, 45.2,12.5, 5.8, 27.2, 31.4 %, positivity rate for tuberculosis by PCR, 7.3, 9.5, 25.0, 0, 9, 8.5 % by culture and 1.8, 2.3, 0, 0, 0, 2.8 % respectively by AFB smear. Being a novel, rapid technique, PCR is the method of choice for rapid diagnosis and management of genitourinary tuberculosis shared with the other concerned tests. This study reveals that genital tuberculosis can occur in any age group, however, the majority of patients were from reproductive age (nearly 75 % of them were from 20–45 years of age) group.  相似文献   

6.
This study evaluated the types and frequencies of pre-examination errors recorded in the chemical pathology laboratory at the University Hospital of the West Indies, Jamaica. This was a retrospective analysis of errors recorded over a three year period. Data analysis was done on an average of 519,084 samples collected and tested per year. Samples included blood, urine, stool and other fluids. Pre-examination errors were identified and recorded following visual inspection of the samples and corresponding request forms by laboratory staff, then subsequently by the Senior Medical Technologist. Errors were generally classified as inappropriate sample (58 %), inappropriate form (23.4 %), inappropriate sample volume (9.3 %) and inappropriate sample tube (9.3 %). Over 90 % of recorded pre-examination errors were related to blood samples while urine samples accounted for 6.8 % error. Pre-examination errors were lower at this study location than elsewhere. Measures aimed at reducing instances of these errors are recommended for improved laboratory quality output.  相似文献   

7.
Cerebrospinal fluid protein estimation is a routine diagnostic tool for various diseases. The proposed modified bromocresol green (BCG) method is applicable to automated as well as manual measurements. Protein concentrations and absorbance at 600 nm are linearly related throughout a wide range of concentrations from 10 mg % to 2000 mg %. Ninety C.S.F. samples were analyzed and results obtained by both the modified BCG method and routine pyrogallol red method were compared. An excellent co-relation was observed (n=90, g=0.996, P<0.001).  相似文献   

8.
Abstract A variety of methods, including the Ion Selective Electrode (ISE), have been used for estimation of fluoride levels in drinking water. But as these methods suffer many drawbacks, the newer method of IC has replaced many of these methods. The study aimed at (1) validating IC for estimation of fluoride levels in drinking water and (2) to assess drinking water fluoride levels of villages in and around Vellore district using IC. Forty nine paired drinking water samples were measured using ISE and IC method (Metrohm). Water samples from 165 randomly selected villages in and around Vellore district were collected for fluoride estimation over 1 year. Standardization of IC method showed good within run precision, linearity and coefficient of variance with correlation coefficient R2 = 0.998. The limit of detection was 0.027 ppm and limit of quantification was 0.083 ppm. Among 165 villages, 46.1% of the villages recorded water fluoride levels >1.00 ppm from which 19.4% had levels ranging from 1 to 1.5 ppm, 10.9% had recorded levels 1.5–2 ppm and about 12.7% had levels of 2.0–3.0 ppm. Three percent of villages had more than 3.0 ppm fluoride in the water tested. Most (44.42%) of these villages belonged to Jolarpet taluk with moderate to high (0.86–3.56 ppm) water fluoride levels. Ion Chromatography method has been validated and is therefore a reliable method in assessment of fluoride levels in the drinking water. While the residents of Jolarpet taluk (Vellore distict) are found to be at a high risk of developing dental and skeletal fluorosis.  相似文献   

9.
A 1 year old male child with increased frequency of urine associated with increased thirst was found to have some developmental delays. Laboratory investigations showed increased serum sodium level and serum osmolality with decreased urine osmolality. An empty sella turcica was seen in contrast brain MRI; however focal demyelinating lesion was not present. He was managed with intranasal desmopressin therapy. Developmental delays in such cases can be prevented by early referral to a tertiary health care center where laboratory and imaging facilities are available.  相似文献   

10.
Cisplatinum (Cispt) is an anti-cancer drug with a low level of solubility. One of Cispt’s solvents is dimethyl sulfoxide (DMSO) which can be substituted with chlorine of drug as Cispt’s solvent. Applying such a solvent in biological studies is impossible due to intense reduction in activity. On the other hand, it is specified that Cispt’s stability is increased in aqueous media by increasing sodium chloride (NaCl) concentration up to 0.9 %. Consequently, we intended to study the effect of DMSO on cytotoxicity of Cispt in presence of sodium. MTT assay was employed to study cytotoxicity effect of Cispt + NaCl + DMSO and Cispt + DMSO on G-292 cell line. Cytotoxicity in dilutions of 300 and 9 (p < 0.01) of Cispt in Cispt + NaCl + DMSO formulation was equal to 78 and 7 %. These values were estimated 79 and 18 % for Cispt + DMSO formulation and 79 and 24 % for free drug. IC50 values demonstrated reduction of 45 % in cytotoxicity of Cispt in Cispt + DMSO formulation. Studying chemical structure of Cispt and Cispt dissolved in DMSO showed that NaCl cannot inhibit inactivating effect of DMSO on Cispt and effect of this solvent on Cispt is independent from presence of NaCl. Results represented that using NaCl does not result in stability and keeping cytotoxicity properties of Cispt in DMSO. Findings suggest more studies for using DMSO as a solvent of Cispt.  相似文献   

11.
Given the paucity of studies conducted to know the effect of suddenness and earlier onset of endocrinological changes associated with hysterectomy, on the serum and urinary levels of calcium, magnesium and phosphate the present study was conducted to compare the levels of calcium, magnesium and phosphate in serum and urine of hysterectomised and natural menopausal south Indian women. This is a cross-sectional observational study. The study included three groups of 30 healthy premenopausal, 30 early surgical menopausal and 30 natural post menopausal women. Women suffering from any endocrine disease were excluded. Analysis was performed in serum and urine sample. The levels of calcium, magnesium and phosphate in serum and calcium/creatinine, magnesium/creatinine and phosphate/creatinine ratio were estimated in urine by spectrophotometric method. Hysterectomised women (serum calcium: 8.7 ± 0.09 mg/dl; urine calcium/creatinine: 0.16 ± 0.02) have significantly low serum calcium (p < 0.001) and high urinary calcium/creatinine (p = 0.002) ratio and post menopausal women (serum magnesium: 2.1 ± 0.03; serum phosphate: 4.4 ± 0.16; urinary calcium/creatinine: 0.17 ± 0.02; urinary magnesium/creatinine: 0.09 ± 0.01) have significantly high serum magnesium (p = 0.016), serum phosphate (p = 0.043) and high urinary calcium/creatinine (p = 0.002), magnesium/creatinine ratio (p = 0.025) compared to healthy pre menopausal women. Post menopausal women (serum calcium: 9.1 ± 0.08) have significantly high serum calcium and phosphate compared to hysterectomised women (serum phosphate: 3.93 ± 0.11). Hysterectomised women have significantly low serum calcium, oestrogen and high urinary calcium/creatinine ratio compared to healthy premenopausal women and low serum calcium and low serum phosphate compared to natural postmenopausal women. Natural postmenopausal women had low serum oestrogen and high serum magnesium, serum phosphate, urinary calcium creatinine ratio and urinary magnesium creatinine ratio compared to healthy premenopausal women.  相似文献   

12.
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13.
Voriconazole, an antifungal drug exhibiting wide inter-individual variability, is an ideal candidate for therapeutic drug monitoring (TDM). The aim of the present study was to standardize a simple, sensitive and rapid high performance liquid chromatography (HPLC) method with ultraviolet detection to determine plasma voriconazole concentration. The HPLC method consisted of a combination of acetonitrile and water (7:3) as mobile phase with 1 ml/min flow rate and detection at 255 nm. Plasma protein precipitation was carried out using perchloric acid and the filtered supernatant was passed through C18 column (250 × 4.6 mm, 5 μm) for the separation of voriconazole. The limit of quantification of voriconazole was 0.2 mg/L. The assay was validated with a linearity of 0.2–15 mg/L and used clinically for TDM in patient samples. The inter-assay precision was below 15 % for routine quality control samples. Weight based voriconazole doses were prescribed to 26 patients for empirical treatment of invasive fungal infections. Voriconazole therapy was managed from the baseline drug levels and follow up analysis reflected achievement in clinical efficacy. Routine TDM of voriconazole may reduce adverse events and improve the treatment response in invasive fungal infections.  相似文献   

14.
The extract of Jatropha Gossypifolia stem was obtained by cutting the stem with a sharp knife and the fluid expressed out. The suitability of the stem latex extract as a precipitant for biochemical analysis was determined. The precipitating efficacy of the extract for creatinine and protein estimation was found to be optimum at 1/4 and 1/5 dilutions respectively aqueous solution. Plasma protein was precipitated with stem extract of J. Gossypifolia at the stated dilution. The mean plasma creatinine values obtained from 0.5 % sodium tungstate as a protein precipitant were compared with the values of plasma creatinine obtained when ¼ dilution of stem extract of J. Gossypifolia was used as protein precipitant. Similarly mean cerebrospinal fluid (CSF) and urinary protein values obtained from 3 % Tricholoro-acetic acid as protein precipitant were compared with values obtained from 1/5 dilution of stem extract of J. Gossypifolia as protein precipitant. The values obtained from the stem latex extract at the stated dilutions were comparable with values obtained from the conventional protein precipitants (p < 0.05). The stem latex extract of J. Gossypifolia is suitable as a protein precipitant for creatinine, CSF and urinary protein estimations. However further work need to be done to purify the extract and determine the exact concentration at the stated dilutions as well as the active ingredient in stem latex.  相似文献   

15.
Currently employed markers for the detection of acute coronary syndrome are Troponin T, CK (Creatine Kinase) and CKMB activity. CKMB activity measured by immunoinhibition method can give falsely elevated results due to the presence of atypical CK and CKBB and at times lead to the mis-diagnosis of acute coronary syndrome. Hence, CKMB mass (CKMB) measured by electrochemiluminence sandwich principle was employed. In this cross-sectional study 183 samples of 61 patients were analyzed within 6 h of diagnosis of acute coronary syndrome and followed up to 72 h. The correlation coefficient between CKMB activity and CKMBM at 4–6 h was 0.744, while at 12–24 h it was 0.909 and at 48–72 h it was 0.337. Thus there was good association between the two methods at 12–24 h but, statistically for method comparison studies and for replacing one method by another, the two methods need to be in agreement with one another. In this study the two methods are not in agreement with one another and thus analytically not replaceable. Another finding was obtained that CKMBM reached cut off levels prior to CKMB enzyme activity and hence, CKMBM is clinically better than CKMB activity to detect reinfarction.  相似文献   

16.
Hepcidin is a 25-amino acid peptide hormone produced by hepatocytes and plays a key role in body iron metabolism. Hepcidin deficiency is the cause of iron overload in hereditary hemochromatosis, iron-loading anemia, and its excess is associated with anemia of inflammation, chronic disease and iron deficiency anemia (IDA). The aims of this study was to evaluate HAMP gene mutation, namely IVS2 + 1(–G) (c.148–150 + 1del) and Gly71 Asp (c.212G > A (rs104894696) association with iron status in IDA conditions. Our study participants were 500 IDA patients and 550 age and sex-matched healthy controls. Hepcidin, ferritin and CRP analysis was done by ELISA method while ESR analysis was done according to Wintrobe method. CBC analysis was done by auto-analyzer. Two mutations in the HAMP genes were analysed by PCR RFLP method. Among the IDA patients, 7 were heterozygous for Met50del IVS2 + 1(–G) mutation. Nine IDA patients were heterozygous for G71D G–A mutation and homozygous were not identified in both mutations.Controls were showing heterozygous frequency 1.8 and 2.1% of Met50del IVS2 + 1(–G) and G71D G–A mutations respectively. Mutation of HAMP (Met50del IVS2 + 1(–G) and G71D G–A) were clinically associated with IDA and act as modulator of disease.  相似文献   

17.
It is well known that chronic exposure of lead leads to adverse health effects. Workers for plastic industry are generally exposed to high concentration of lead as fume, dust, and additive that protect PVC. This study was done on them to find out the detrimental effects of chronic lead exposure on hepatic and hematological toxicity. Blood and 24 h urine sample was collected from 47 plastic industry workers and matched against 42 controls for various parameters. The study group shows significant increase in blood (p < 0.0001) and urinary level of lead (p < 0.0001). Hemoglobin levels were significantly decreased (p < 0.0001), and the liver enzymes like ALP, ALT, AST and y-GT were significantly increased (p < 0.0001) in all cases exposed for >10 years. Serum lipid peroxide by quantitative assay of thiobarbituric acid reactive substances was also found increased in the study group (p < 0.0001). The observations point towards the acute health risk faced by plastic industry workers, in whom chronic exposure to lead increases the absorption and accumulation, over a period of time, of this highly toxic element in their body. This increases oxidative stress, causes metabolic damage to RBC and cell membranes, and also suggests necrosis of liver cell, hepatocellular injury and presence of space occupying lesions. Considering the data immediate health and hygiene monitoring and proper rehabilitation for the suffering population seem to be of paramount need in plastic industry to minimize occupational hazards.  相似文献   

18.
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19.
Early, accurate diagnosis of lysosomal storage disorders is a major challenge, even for trained specialists. Finding innovative, accurate diagnostic methods, and high throughput, cost-effective tools are crucial to medical progress and will contribute to improved quality of life. The goal of this work was to improve currently used protocols to determine activity of acid β-galactosidase, and discuss the possibility analysing lysosomal enzymes with microfluidic systems. A principle of the determination of β-galactosidase activity was fluorometric measurement of a deprotonated form of 4-methylumbelliferone released in the enzymatic reaction. Measurements were performed using Jurkat T cells as a source of the enzyme. We observed the temperature-dependent substrate inhibition effect and determined the substrate (4-MU-β-d-galactopyranoside) concentration which should be used to determine acid β-galactosidase activity at 37 °C (0.8 mM) and at room temperature (0.6 mM). We proved that the sample incubation time may be significantly reduced to only a few minutes. We also showed that the amount of alkaline buffer used to stop the enzymatic reaction may be minimized and even, in some cases, eliminated. The presented results show how the sensitivity of the available methods to diagnose patients suffer from gangliosidosis GM1 or Morquio B disease can be improved. The proposed method may be easily implemented with microfluidic systems, which currently are promising tools for point-of-care applications.  相似文献   

20.
Uric acid in urine was analyzed using porcine liver uricase and horseradish peroxidase immobilized on alkylamine and arylamine glass beads (pore diameter 55nm) respectively. The minimum detection limit was 5.0mg/0.1 ml urine. The recovery of added uric acid was 92%. Within and between assay CVS were <1.3% and <5.3% respectively. A good correlation (r=0.93) was found between urinary urate values obtained by a commercial kit method and the present method. The uric acid in 24hr urine of apparently healthy adults and person sufering from various diseases was found to be 450 to 900mg/24hr, 659mg/24hr (range, mean) and 910–1400mg/24hr, 1145 mg/24hr (range, mean) respectively with the present method.  相似文献   

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