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Results for “Reproducibility”

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PubMed1996

Reproducibility of left ventricular volume measurements at rest and during bicycle exercise in patients with congestive heart failure: a combined radionuclide and haemodynamic study.

A series of 14 patients with heart failure due to coronary artery disease and impaired left ventricular function underwent radionuclide ventriculography with simultaneous thermodilution measurement of cardiac output by pulmonary artery catheter on two occasions (m1, m2) separated by 6 weeks in order to determine the reproducibility of haemodynamic and left ventricular volume measurements at rest and during supine bicycle exercise. The patients were in NYHA grade II or III and had baseline left ventricular ejection fractions below 40%. Derived haemodynamic variables were calculated from the thermodilution cardiac output and from the radionuclide ejection fraction as follows: stroke volume = thermodilution cardiac output/heart rate; left ventricular end-diastolic volume = stroke volume/ejection fraction; left ventricular end-systolic volume = end-diastolic volume - stroke volume. The percentage difference (PD) between each pair of data (m1, m2) was calculated using the following formula: PD = 100% x (m2-m1)/m1. The data showed that reproducible measurements of left ventricular volume can be obtained at rest and during exercise. The mean (+/- S.D.) PD values for end-systolic volume and end-diastolic volume at rest were - 0.1 +/- 17% and - 0.2 +/- 13%, respectively. The mean PD values for end-systolic volume and end-diastolic volume during exercise were - 0.3 +/- 19% and - 0.7 +/- 15%, respectively. By contrast, the reproducibility of the pulmonary capillary wedge pressure measurements was poor, as reflected by a PD value of 14 +/- 51% for exercise pulmonary capillary pressure. Combining radionuclide ventriculography and the thermodilution measurement of cardiac output is useful for measuring left ventricular volume at rest and during exercise in patients with heart failure. This minimally invasive technique allows for a comprehensive assessment of left ventricular performance and appears to be particularly suited for assessing the effects of therapeutic interventions aimed at minimizing the progressive left ventricular enlargement in heart failure.

Adult↗

PubMed1998

Reproducibility of gastric emptying of a pancake and milkshake meal in normal subjects.

Comparisons of gastric emptying between different centres are difficult because of wide variations in methods. Reproducibility of a method is very important before it is used to compare different subjects or to assess the effect of treatment. The aim of this study was to measure the reproducibility of gastric emptying of a solid and liquid meal in normal subjects. Ten males were studied on two occasions. After an overnight fast, the subjects ate a radiolabelled solid and liquid meal. There were no significant differences in T50 on the 2 days (136.6 +/- 23.2 vs 121.3 +/- 26.7 min for solid and 30.7 +/- 12.6 vs 32.6 +/- 18.7 min for liquid; mean +/- SD). Intra-subject variability was between 7 and 21% for the solid component and 1.5 and 63% for the liquid component. The mean difference in T50 between the 2 days was 15.3 +/- 21.9 min for the solid component and -5.1 +/- 19.7 min for the liquid component. Only one difference between the T50 results was not in the 95% confidence interval for the liquid component. Thus despite some inter- and intra-subject variability, the method showed good reproducibility.

Adult↗

PubMed2000

Reproducibility of assessment of myocardial function using gated 99Tc(m)-MIBI SPECT and quantitative software.

PURPOSE: We investigated the reproducibility of the quantification of left ventricular volumes and ejection fraction, and grading of myocardial wall motion and systolic thickening with gated myocardial single-photon emission computed tomography (SPECT) and Cedars quantification software. PATIENTS, MATERIALS AND METHODS: We performed post-stress gated myocardial SPECT in 33 consecutive patients twice sequentially in situ. Sixteen frames per cycle were used for gating. Using Cedars quantitative gated SPECT software ventricular volumes and ejection fraction (EF) were calculated. Wall motion and thickening was graded using 5- and 4-point scores, respectively. Coefficients of variation for re-examination of volumes and EF were calculated. Kappa values for assessing reproducibility of wall motion or wall thickening were calculated. RESULTS: Root mean square of errors was 5.0 ml for end-diastolic volume, 3.9 ml for end-systolic volume and 1.9% for EF. No bias or difference was found between the first and second acquisition by Bland-Altman analysis. Kappa values for wall motion and thickening of repeated acquisition was 0.76 and 0.87, respectively. The value of 2 SD from Bland-Altman analysis was 14.4 ml for EDV, 11.2 ml for ESV and 5.3% for EF. CONCLUSION: We conclude that quantification of functional indices and assessment of wall motion or thickening using gated 99Tc(m)-sestamibi (MIBI) SPECT was reproducible and we found that their ranges of physiological fluctuation were narrow enough.

Aged↗

PubMed2001

Reproducibility of [11 C]FLB 457 binding in extrastriatal regions.

Extrastriatal D2 dopamine receptors represent an important target of research into the pathophysiology and pharmacotherapy of psychiatric disorders. The high affinity radioligand [11C]FLB 457 makes possible the measurement of low concentrations of D2 receptors in extrastriatal regions using positron emission tomography (PET). The aim of this study was to assess the test/retest variability and reliability of [11C]FLB 457 binding using a reference tissue model. Eight healthy male subjects (aged 20-33 years) underwent two [11C]FLB 457 PET examinations. Radioactivity in the cerebellum was used as the reference. The binding potentials (BPs) for five cortical regions of interest (ROIs) were calculated using the reference tissue model. The BP was also calculated for each pixel in the form of parametric images. Reproducibility was assessed both for the ROI method and for the parametric images. The test/retest reproducibility for [11C]FLB 457 binding was good, with a mean variability ranging from 4.5% for the thalamus to 15.5% for the hippocampus. The parametric images also demonstrated good reproducibility. These results support the suitability of using [11C]FLB 457 for the quantitative evaluation of extrastriatal D2 receptors and for protocols requiring repeated measurements in the same individual.

Adult↗

PubMed1994

The application of different correlation coefficients to assess the reproducibility of a food frequency questionnaire.

We computed four different correlation coefficients to investigate the degree of reproducibility of the weekly consumption of 77 food items or groups of foods and of seven summary questions from a food frequency questionnaire developed in Italy for a case-control study on cancers of the breast and digestive tract. The questionnaire had been administered twice to 452 Italian men and women. These included Pearson correlation coefficients (a) using the weekly frequencies of consumption without any transformation (P1); (b) after applying the transformation log (x + 1) (P2); (c) after applying the transformation log (x + 0.01) (P3); and (d) the Spearman correlation coefficient (SP). The mean values were 0.55 for P1, 0.59 for P2, 0.56 for P3 and 0.59 for SP. All coefficients were positively correlated, although to variable extents: the Spearman correlation coefficient between P2 and SP was 0.92, and that between P1 and P3 was 0.53. Differences between the four coefficients were more marked for food items with a lower kappa statistic and lower intraclass correlation, ie for those items with more severe reproducibility problems. Thus, a single correlation coefficient may not be enough to detect zones of the distribution of a food item where misclassification problems are more severe. The correlation coefficients used to investigate reproducibility should therefore be chosen on the basis of subsequent data analyses.

Feeding Behavior↗

PubMed2000

Reproducibility of serial intravascular ultrasound measurements in patients with angiographically silent coronary artery disease after heart transplantation.

BACKGROUND: Intracoronary ultrasound (ICUS) imaging is the most sensitive method for the early detection and serial evaluation of vasculopathy of transplants. Both lack of agreement between observers and lack of agreement between serial, independent pullback procedures (repeatability), which can result in a variable intraluminal catheter position may limit the reproducibility of ICUS measurements. OBJECTIVE: To evaluate the reproducibility of serial measurements of standard linear and area cross-sectional coronary dimensions in patients with non-obstructive transplant vasculopathy. METHODS: We performed ICUS imaging of patients without angiographic evidence of obstructive epicardial coronary artery disease after heart transplantation. A 30 MHz phased-array transducer was used. Two independent pullbacks of the left anterior descending coronary artery were performed and recorded on CD-ROM for off-line quantitative analysis of the most severely diseased site. Agreement of observers and repeatability of serial measurements were calculated by the use of linear regression analysis and Bland-Altman plots. RESULTS: Regarding agreement of observers, correlation coefficients for intra-observer agreement ranged from r = 0.98 to r = 0.99; those for interobserver agreement ranged from r = 0.87 to r = 0.98. Serial measurements of the identical coronary artery cross-section within independent catheter pullback procedures were possible for 104 of 112 target lesions (92.90/%). Correlation coefficients ranged from r = 0.91 to r = 0.97 (for lumen diameter r = 0.91, for lumen area r = 0.93, for vessel diameter r = 0.91, for vessel area r = 0.97, for thickness of plaque r = 0.96 and for area of plaque 0.94). The mean difference of measurements was around zero for all parameters with SD from 0.13 to 0.4 mm for linear parameters and from 1.53 to 1.82 mm2 for area parameters. CONCLUSION: Serial intravascular ultrasound measurements are highly reproducible without any evidence of systematic error and a SD of differences of measurements beyond the maximal spatial resolution of currently available intravascular ultrasound catheters.

Coronary Angiography↗

PubMed2005

A novel rabbit model of mild, reproducible disc degeneration by an anulus needle puncture: correlation between the degree of disc injury and radiological and histological appearances of disc degeneration.

STUDY DESIGN: An in vivo study to radiographically and histologically assess a new method of induction of disc degeneration. OBJECTIVE.: To establish a reproducible rabbit model of disc degeneration by puncturing the anulus with needles of defined gauges and to compare it to the classic stab model. SUMMARY OF BACKGROUND DATA: New treatment approaches to disc degeneration are of great interest. Although animal models for disc degenerative disease exist, the quantitative measurement of disease progression remains difficult. A reproducible, progressive disc degeneration model, which can be induced in a reasonable time frame, is essential for development of new therapeutic interventions. METHODS: The classic anular stab model and the new needle puncture model were used in the rabbit. For the needle puncture model, 3 different gauges of needle (16G, 18G, and 21G) were used to induce an injury to the disc to a depth of 5 mm. Radiographic and histologic analyses were performed; magnetic resonance images were also assessed in the needle puncture model. RESULTS: Significant disc space narrowing was observed as early as 2 weeks after stabbing in the classic stab model; there was no further narrowing of the disc space. In the needle puncture model, all needle sizes tested induced a slower and more progressive decrease in disc height than in the classic stab model. The magnetic resonance imaging supported the results of disc height data. CONCLUSIONS: The needle puncture approach, using 16G to 21G needles, resulted in a reproducible decrease of disc height and magnetic resonance imaging grade. The ease of the procedure and transfer of the methodology will benefit researchers studying disc degeneration.

Animals↗

PubMed2006

Cervical motion in patients with chronic disorders of the cervical spine: a reproducibility study.

STUDY DESIGN: Test-retest of cervical motion in patients with chronic disorders of the cervical spine. OBJECTIVES: To determine the reproducibility of cervical motion and examine the feasibility of its representation by a single parameter. SUMMARY OF BACKGROUND DATA: Reproducibility of cervical motion findings has been largely limited to normal subjects, leaving a conspicuous void regarding the measurement error in clinical groups. METHODS: There were 2 groups of 25 chronic patients with whiplash and degenerative changes of the cervical spine tested twice (4-7 days). Head movement was measured along the 6 directions, as well as during rotation out of flexion and extension (cervical degenerative changes only). RESULTS: Compared to normal subjects, both groups had a 25% to 35% reduction in cervical motion. High intraclass correlation coefficients (ICCs) (range 0.8-0.92) were derived for all directions. The ICCs for rotation out of flexion and extension were low. The relative standard error of measurement ranged from 15% to 28% for all directions, whereas the corresponding scores of the total cervical motion excursion were 10.6 (cervical degenerative changes) and 13.6% (whiplash). CONCLUSIONS: Judged by the ICCs cervical motion, findings were reproducible. However, in view of the measurement error as well as the homogenous reductions, total cervical range of motion should be considered a suitable parameter for interpretation of cervical motion limitations in these patients.

Adult↗

PubMed2003

Temporal change, reproducibility, and interobserver variability in pressure-volume curves in adults with acute lung injury and acute respiratory distress syndrome.

OBJECTIVES: To assess the reproducibility of the static pressure-volume curve of the respiratory system by using a "mini-syringe" technique; to assess the temporal change in upper (UIP) and lower inflection points (LIP) measured from pressure-volume curves of the respiratory system; to assess the inter- and intraobserver variability in detection of the UIP and LIP in patients with acute lung injury (ALI)/acute respiratory distress syndrome (ARDS); and to compare the syringe and multiple occlusion techniques for determining LIP and UIP. DESIGN: Prospective observational study. SETTING: Academic medical-surgical critical care unit. PATIENTS: Consecutive patients with ALI or ARDS. INTERVENTIONS: Static inspiratory pressure-volume curves of the respiratory system were determined twice on day 1 of diagnosis of ALI/ARDS and then once daily for up to 6 days by using the syringe technique. Pressure-volume curves were determined from zero positive end-expiratory pressure. At each time point, three separate measurements of the pressure-volume curve were made to determine reproducibility. A 100-mL graduated syringe was used to inflate patients' lungs with 50- to 100-mL increments up to an airway pressure of 45 cm H2O or a total volume of 2 L; each volume step was maintained for 2-3 secs until a plateau airway pressure was recorded. On day 1, the static pressure-volume curve also was determined by using the multiple occlusion technique. In a random and blinded sequence, the pressure-volume curves were examined visually by three critical care physicians on three different occasions, to determine the intra- and interobserver variability in visual detection of the LIP and UIP. Observers were given objective instructions to visually identify LIP and UIP. MEASUREMENTS AND MAIN RESULTS: Eleven patients were enrolled, with a total of 134 pressure-volume curves generated. LIP and UIP could be detected in 90-94% and 61-68% of curves, respectively. When the three successive pressure-volume curves were compared, both the LIP and UIP were within 3 cm H2O in >65% of curves. The index of reliability (intraclass correlation coefficient) in LIP and UIP was 0.92 and 0.89 for interobserver variability and 0.90 and 0.88 for intraobserver variability. Daily variability was as high as 7 cm H2O for LIP and 5 cm H2O for UIP. When pressure-volume curves obtained by using the multiple occlusion and syringe techniques were compared, LIP was within 2 cm H2O, and UIP was within 4 cm H2O with the two techniques. CONCLUSIONS: The static pressure-volume curve of the respiratory system is reasonably reproducible, thus avoiding the need for multiple measurements at a single time. We found excellent interobserver and intraobserver correlation in manual identification of the LIP and UIP. Both LIP and UIP show appreciable daily variability in patients with ALI/ARDS. The multiple occlusion and syringe techniques generate similar values for LIP and UIP.

APACHE↗

PubMed2005

Reproducibility of self-measured intraocular pressure with the phosphene tonometer in patients with ocular hypertension and early to advanced glaucoma.

PURPOSE: To evaluate the reproducibility of self-measured intraocular pressure with the Proview tonometer in ocular hypertensives and early to advanced glaucoma patients. PATIENTS AND METHODS: Thirty-three patients with glaucoma and three with ocular hypertension (72 eyes) were prospectively enrolled. History of cornea surgery was the only exclusion criterion. A trainer took a set of three readings first. Subsequently, the patient (after successful training) took one set of three readings and a physician took two sets of three Goldmann readings. One hour later this was repeated. RESULTS: 72% of patients could see the phosphene in both eyes, 8% could see it in one eye, and 19% could not see it in either eye. Patients who could not see the Phosphene had an average mean deviation of -10.9 compared with -3.4 for those who could see it (P = 0.01). Eyes that could not see the phosphene were excluded from further analysis. The average absolute difference between two Proview measurements one hour apart was 1.76 +/- 1.76 mm Hg (r = 0.71). The measurement error (difference between Goldmann and Proview readings) tended to remain constant between sets of measurements taken one hour apart (average error was 2.4 +/- 2.1 mm Hg, r = 0.85). No adverse event was recorded. CONCLUSIONS: Repeated self-tonometry measurements showed very good reproducibility. The systematic, reproducible error between Proview and Goldmann readings may be clinically acceptable and suggests that a baseline "calibration" should be obtained for each patient before the Proview values are used clinically. Self-administered tonometry can play a role in the clinical care of ocular hypertensive and glaucoma patients with the possible exception of very advanced cases.

Adolescent↗

PubMed2006

Optical coherence tomography of the optic nerve head: interindividual reproducibility.

PURPOSE: Optical coherence tomography may be a new technique for quantitative 3-dimensional assessment of the optic nerve head for diagnosis of optic nerve anomalies and diseases such as the glaucomas. The purpose of the present study was to examine its reproducibility. PATIENTS AND METHODS: The clinical noninterventional study included 10 randomly chosen eyes of 10 healthy individuals who underwent 24 optical coherence tomographic examinations with the high-resolution and fast scan program, interactively corrected or uncorrected. The pupils were not dilated. All examinations were performed by 3 examiners independently of one another. The coefficient of variation was calculated as the ratio of the mean of the standard deviations divided by the mean of the means. RESULTS: The coefficients of variation for redetermination of optic disc area, ranging between 0.047 and 0.119, were lowest for the manually corrected fast scan mode and highest for the uncorrected fast scan mode. For remeasurements of the neuroretinal rim area, the best mean coefficient of variation was 0.073+/-0.026 (corrected fast scan mode). CONCLUSIONS: In healthy eyes, the morphometric measurements of the optic nerve head by optical coherence tomography show a relatively high reproducibility with mean coefficients of variation lower than 10% for remeasurements of the optic disc and neuroretinal rim area. With undilated pupils, reproducibility is better with the fast scan mode with interactive correction of the outlining of the optic disc border than it is with the high-resolution mode.

Adult↗

PubMed2004

Interobserver reproducibility of percent Gleason grade 4/5 in prostate biopsies.

PURPOSE: Percent Gleason grade 4/5 (GG4/5) has been proposed as a predictor of prognosis in prostate cancer and it has been shown to add prognostic information to that given by Gleason score (GS). We recently noted that the interobserver reproducibility of percent GG4/5 in total prostatectomy specimens is at least as good as that of the GS. However, to our knowledge the reproducibility of percent GG4/5 in needle biopsies has not yet been investigated. MATERIALS AND METHODS: A consecutive series of needle biopsies from 69 men with prostate cancer was reviewed. Biopsies were taken according to a standardized octant protocol. All 279 slides containing cancer were circulated among 4 genitourinary pathologists, who assessed GS and percent GG4/5. Results were compared pairwise and weighted kappa was calculated. RESULTS: The 4 observers had a mean weighted kappa for GS and percent GG4/5 of 0.48 to 0.55 (overall mean 0.51) and 0.52 to 0.68 (overall mean 0.60), respectively. There was less disagreement in percent GG4/5 when a single biopsy was positive for cancer than when 6 or more biopsies were positive. The number of positive biopsies showed a stronger correlation with a discrepancy in percent GG4/5 than cancer length. Disagreement was worse when cribriform or fusion patterns were present. CONCLUSIONS: Interobserver reproducibility of percent GG4/5 on prostate biopsies is at least as good as that of GS. Hence, concern about interobserver variability should not deter pathologists from using percent GG4/5. Grading appears to be most difficult when cancer is present in multiple biopsies or it contains cribriform or fusion patterns.

Aged↗

PubMed2005

Reproducibility of lymphoscintigraphy for lymphatic mapping in patients with penile carcinoma.

PURPOSE: We evaluated the reproducibility of lymphoscintigraphy in the assessment of the location and number of sentinel nodes in patients with penile carcinoma. MATERIALS AND METHODS: A total of 20 patients were prospectively included in analysis. Lymphoscintigraphy was performed after intradermal injection of technetium nanocolloid around the tumor or excision scar. We performed 10-minute anterior dynamic imaging, and static anterior and lateral images were obtained at 30 minutes and 2 hours. The following day scintigraphy was repeated after a second injection of the radiolabeled colloid given in an identical fashion, preceded by acquisition of a starting image. An observer evaluated the paired images and count rates were calculated from the images. RESULTS: At least 1 sentinel node was visualized in all patients on the first lymphoscintigram. A total of 56 sentinel nodes were seen in 38 basins. Drainage to both groins was seen in 18 patients. In 1 of these patients drainage to the prepubic area was also observed. There were 2 patients with drainage to 1 groin. The second lymphoscintigram revealed the same drainage pattern in all patients- the same number of nodal basins and number of sentinel nodes were visualized at identical locations. All hotspots that were visualized during the first lymphoscintigram showed an unequivocal increase in radioactivity after repeat injection. Thus, the reproducibility of penile lymphoscintigraphy was 100% (95% CI 85%-100%). The Pearson correlation coefficient of the paired count rates was 0.69 (p <0.0001). CONCLUSIONS: Results of lymphoscintigraphy in patients with penile carcinoma are highly reproducible for assessment of the number and location of sentinel nodes.

Adult↗

PubMed2006

Reproducibility of postural changes of blood pressure in hypertensive elderly patients in primary care.

OBJECTIVE: To determine the reproducibility of postural changes of blood pressure among hypertensive elderly patients in a primary care setting. METHODS: Measurements of blood pressure were carried out in 60 community-dwelling hypertensive patients aged 65 years or more, in a sitting position and after 1-min and 3-min standing, and were repeated not more than 10 days later. RESULTS: A significant (P<0.05) fall in systolic and diastolic sitting blood pressure was observed between the first visit (151.1+/-20.8/79.7+/-10.1 mmHg) and the second visit (143.5+/-20.6/76.8+/-10.9 mmHg). The intraclass correlation coefficients of the repeated measurements were 0.46 (CI: 0.23-0.65) and 0.42 (CI: 0.17-0.61) for the changes in systolic blood pressure after 1- and 3-min standing, and 0.55 (CI: 0.34-0.71) and 0.40 (CI: 0.16-0.60) for diastolic blood pressure after 1- and 3-min standing, respectively. The repeatability coefficients were greater for the orthostatic changes of blood pressure (54-65%), which indicates lower reproducibility, than for the blood pressure levels on both visits (31-44%). CONCLUSIONS: The reproducibility of the postural changes of blood pressure found in hypertensive elderly patients in primary care is poor. This should be taken into account when making diagnoses of orthostatic hypotension in this type of patient.

Aged↗

PubMed2005

Reproducibility of cerebral oxygenation measurement in neonates and infants in the clinical setting using the NIRO 300 oximeter.

OBJECTIVE: To study reproducibility of cerebral tissue oxygenation index (cTOI) values in neonates and infants in a clinical setting using the NIRO 300 oximeter (Hamamatsu Photonics, Hamamatsu City, Japan). DESIGN: Clinical, observational study. SETTING: University hospital, pediatric intensive care unit. PATIENTS: Twenty neonatal and pediatric intensive care patients (age 0-190 days; median 4.5 days). INTERVENTIONS: Reproducibility of cTOI was measured at the lateral forehead of the patients. MEASUREMENTS AND MAIN RESULTS: Sensor exchange experiments were performed by removing the sensor and reapplying another sensor (sensor 1 vs. sensor 2) at the same position. Simultaneous measurements, comparing cTOI values from the right and left forehead, were performed using both sensors. Corresponding sensor exchange experiments were performed within 10 mins. All tests were done under stable, steady-state cardiorespiratory conditions. Data were compared using Bland-Altman bias analysis and paired, two-sided Student's t-test (p < .05). Sensor exchange experiments and simultaneous left-to-right forehead measurements revealed only small mean differences (<5%) and no significant differences between corresponding values (p = .953/.164). However, Bland-Altman bias analysis revealed poor agreement with large 95% limits of agreement in particular for sensor exchange experiments (-17.8% to 17.6%) and less for simultaneous left and right measurements (-14.4% to 10.4%). CONCLUSIONS: The present study shows that cTOI measurements using the NIRO 300 oximeter at the lateral forehead of neonates and infants are not well reproducible under clinical conditions. This raises the question whether generally valid normal values can be defined with the used approach and makes it difficult to determine a normal range of cerebral oxygenation.

Brain↗

PubMedDate not supplied

Is the objective assessment of cerebral palsy gait reproducible?

It is important to determine the reproducibility of objective measures of gait in children with motor disorders in order that the effect of interventions to improve gait can be monitored. Data for walking velocity and vertical ground reaction force expressed as a percentage of body weight were collected from 15 normal children and 11 with spastic cerebral palsy. Five recordings were obtained for each foot of each child on 3 consecutive days, and calculations of variability made for each set of five recordings. Children with cerebral palsy had slower walking velocities and greater ground reaction force values, and both these parameters had low intraindividual variation for both normal children and those with cerebral palsy (coefficients of variation < 12.5%). This good reproducibility applied to intrasubject and intraday variability; no learning effect was seen over 3 days' recordings. There was no significant difference in variability whether the first three recordings or all five were used. These techniques of gait measurement in children have good reproducibility and a potential role in the objective assessment of medical and surgical interventions.

Cerebral Palsy↗

PubMed2004

Reproducibility of patch tests: comparison of identical test allergens from different commercial sources.

The reproducibility of patch tests is an important determinant of the clinical value of this diagnostic procedure. The aim of the present study was to delineate comparatively the efficiency and reproducibility of identical test reagents from 2 different commercial sources. Purchased in duplicate from brial and Boots-Hermal, 30 allergens from the European standard and an extension series were simultaneously applied to Finn Chambers and affixed next to each other. Out of 2070 paired patch tests in 71 patients, 97.2% presented with concordant-negative results. 60 patch tests were classified as allergic with 95% concordant-positive results. From these paired positive patches, a subgroup of 13 (22.8%) corresponding allergens presented with minor differences in the visible strength of the allergic reaction. Generated by cobalt chloride, formaldehyde and 2-bromo-2-nitropropane-1,3-diol in 1 patient each, discordant results, i.e. 1 positive and 1 negative test in parallel, were found in only 5%. Taken together, we were able to demonstrate that patch test preparations from 2 different companies exhibited a high level of reproducibility. This standardized quality of test reagents from different suppliers provides useful information on several aspects of everyday practice.

Adolescent↗

PubMed2004

Reproducibility of patch test results: a concurrent right-versus-left study using TRUE Test.

Wide variations in the reproducibility rate of positive patch test responses have been reported. We hypothesized that a major source of non-reproducibility resides in the methodological pitfalls of routine patch testing. Simultaneous duplicate patch testing on opposite sides of the upper back was performed on 500 consecutive patients, using the TRUE Test system consisting of 2 panels, each one containing 12 standard allergens. A rigorous methodological design was applied and relevance was assessed for all discordant patch test reactions. A total of 435 positive patch test reactions were observed either on one or both sides in 289 patients (58.8%). Of these, 22 (5%) were discordant, i.e. interpreted as positive allergic on one side whilst negative or doubtful on the opposite side. The allergens responsible for discordant reactions were nickel sulfate (4 patients), cobalt chloride (3), lanolin alcohol (3), fragrance mix (2), carba mix (2), thiuram mix (2), colophonium (1), potassium dichromate (1), p-phenylenediamine (1), formaldehyde (1), balsam of Peru (Myroxylon pereirae resin) (1) and thimerosal (1). Of the 19 (4%) patients with discordant patch test reactions, the allergen was deemed to be of definite present or past relevance in 9 patients (1.8% of the total and 3.1% of all patients with positive patch test reactions) and of possible relevance in a further 2 patients. These data suggest that patch testing is a reasonably reproducible procedure as long as methodological error is minimized.

Adolescent↗