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Results for “Repeatability and Reproducibility”

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PubMed1993

Serum levels of insulin-like growth factor I (IGF-I) and IGF binding protein 3 reflect spontaneous growth hormone secretion.

The relationship between 24-h GH secretion, insulin-like growth factor (IGF) I serum levels, IGF-binding protein 3 (IGFBP-3) levels and height was studied in 114 healthy children and adolescents (147 tests). A significant correlation was found between the spontaneous GH secretion expressed as the area under the curve above baseline (AUCb) or the calculated 24-h GH secretion rate (GHb) and IGF-I (n = 147, r = 0.65, or 0.78, respectively, P < 0.001) or IGFBP-3 levels (r = 0.48 or 0.62, P < 0.001). Correlations were also significant within the various subgroups [females (n = 51), males (n = 96), prepubertal children (n = 75), pubertal children (n = 72)]. The slopes of the regression lines of IGF-I levels vs. AUCb or GHb were clearly steeper in pubertal children than in prepubertal ones; this was not as evident with IGFBP-3. In prepubertal children, a significant correlation was found between height (compared to Swedish reference values) standard deviation scores (SDS) and IGF-I SDS (n = 75, r = 0.66, P < 0.001) or IGFBP-3 SDS (r = 0.61, P < 0.001). The reproducibility during repeated testing (19 individuals, 6 prepubertal) was best with IGFBP-3 as compared to AUCb, GHb, or IGF-I which showed considerable variability. The data suggest: 1) that IGF-I and IGFBP-3 serum levels reflect spontaneous GH secretion in healthy individuals; 2) IGF-I levels are more sensitive to GH regulation than IGFBP-3; 3) in puberty, there may be increased sensitivity of IGF-I regulation by GH as compared to the prepubertal stage; 4) short children have low IGF-I and IGFBP-3 levels, whereas tall children have high levels, a fact which is likely to contribute to the understanding of height variability in a healthy population; 5) the good reproducibility of IGFBP-3 on repeated testing makes it an interesting parameter for the evaluation of the GH-IGF-axis. IGFBP-3 measurements may substitute for GH profiles in many cases, when the goal is an estimation of the GH secretion rate.

Adolescent↗

PubMed2005

Assessment of two thoracolumbar fracture classification systems as used by multiple surgeons.

BACKGROUND: The reproducibility and repeatability of modern systems for classification of thoracolumbar injuries have not been sufficiently studied. We assessed the interobserver and intraobserver reproducibility of the AO (Arbeitsgemeinschaft für Osteosynthesefragen) classification and compared it with that of the Denis classification. Our purpose was to determine whether the newer, AO system had better reproducibility than the older, Denis classification. METHODS: Anteroposterior and lateral radiographs and computerized tomography scans (axial images and sagittal reconstructions) of thirty-one acute traumatic fractures of the thoracolumbar spine were presented to nineteen observers, all trained spine surgeons, who classified the fractures according to both the AO and the Denis classification systems. Three months later, the images of the thirty-one fractures were scrambled into a different order, and the observers repeated the classification. The Cohen kappa (kappa) test was used to determine interobserver and intraobserver agreement, which was measured with regard to the three basic classifications in the AO system (types A, B, and C) as well as the nine subtypes of that system. We also measured the agreement with regard to the four basic types in the Denis classification (compression, burst, seat-belt, and fracture-dislocation) and with regard to the sixteen subtypes of that system. RESULTS: The AO classification was fairly reproducible, with an average kappa of 0.475 (range, 0.389 to 0.598) for the agreement regarding the assignment of the three types and an average kappa of 0.537 for the agreement regarding the nine subtypes. The average kappa for the agreement regarding the assignment of the four Denis fracture types was 0.606 (range, 0.395 to 0.702), and it was 0.173 for agreement regarding the sixteen subtypes. The intraobserver agreement (repeatability) was 82% and 79% for the AO and Denis types, respectively, and 67% and 56%, for the AO and Denis subtypes, respectively. CONCLUSIONS: Both the Denis and the AO system for the classification of spine fractures had only moderate reliability and repeatability. The tendency for well-trained spine surgeons to classify the same fracture differently on repeat testing is a matter of some concern.

Adult↗

PubMedDate not supplied

Comparative tests to improve the gas chromatographic analysis of chlorobornanes in fish samples.

A comparison was made between electron capture negative ionization quadrupole mass spectrometry (ECNI-MS) and electron capture detection (ECD) with regard to repeatability and reproducibility for the gas chromatographic (GC) analysis of toxaphene congeners [chlorobornanes (CHBs)]. The tests, including standard solutions and several cleaned fish extracts, showed larger relative standard deviations (RSDs) for the repeatability of ECNI-MS but no differences in the reproducibility of the 2 techniques. The sensitivity of the GC-ECNI-MS was considerably better than that of GC/ECD. Four stepwise-designed comparative tests were also conducted on GC analysis, cleanup, and the complete method. The results showed that, according to the current state-of-the-art, coefficients of variation for the between-laboratory performance were not < 20% and were usually between 20 and 30%. In spite of separation problems, e.g., for CHB 26, which cannot be separated into a single-component peak, a 95% methyl 5% phenyl polysiloxane (CP Sil 8) column was preferred to more polar columns for the analysis of CHBs 26, 40, 41, 44, 50, and 62. CHB 62 was more difficult to determine than CHB 26 and 50. Addition of the CHBs 40, 41, and 44 to the standard set of 3 chlorobornanes (26, 50, and 62) resulted in more separation problems. A 3-step cleanup method was recommended.

Animals↗

PubMed1997

Vagal efferent fibre responses to gastric and oesophageal mechanical and chemical stimuli in the ferret.

Gastric and oesophageal afferent inputs to vagal efferent fibres were investigated in Urethane anaesthetized ferrets. Mechanical, chemical, and pharmacological stimuli were tested and efferent activity recorded from single cervical vagal fibres. Fibres showed either no basal discharge or low frequency, irregular patterns of resting discharge; only those which showed > 50% excitation or inhibition of basal activity with both gastric distension and oesophageal balloon distension were studied further. These responses were rapid and maintained only for the duration of the stimuli. 18/32 efferent fibres tested also showed changes in discharge in response to acid infused slowly into the distal oesophagus. These responses were larger after repeated acid infusions. Subsequent intra-oesophageal capsaicin elicited a similar response in 7/8 fibres. These responses were reproducible with repeated capsaicin infusions in 2/4 fibres and desensitized in 2/4 fibres. 2 capsaicin-responsive fibres were unresponsive to oesophageal acidification. 4/12 fibres tested responded to close intraarterial injections of capsaicin and 9/12 to close intraarterial bradykinin. These responses were brief and of short latency. Vagal efferent responses to mechanical and chemical stimuli above were unchanged after the NK-1 receptor antagonist CP96,345 (4 mg/kg i.v.). Subsequently, bilateral vagotomy caudal to the recording site abolished the basal activity in 4/7 fibres. In the 3 fibres where spontaneous activity remained, none of these responded to oesophageal distension or intra-oesophageal acid (2/2 fibres tested) after vagotomy, whereas 2/2 fibres tested still responded to gastric distension. The response of 1 fibre to intraarterial bradykinin and capsaicin was unchanged by vagotomy. We conclude that vagal efferent neurones respond to gastro-oesophageal mechanical inputs and also receive convergent input from oesophageal acid-sensitive and gastrointestinal bradykinin- and capsaicin-sensitive afferents. These afferent inputs are not mediated via NK-1 receptors. There also exists a nonvagal afferent input onto vagal efferent neurones which is probably spinal and likewise non NK-1 receptor mediated.

Animals↗

PubMed1992

The influence of ambulatory blood pressure monitoring on the design and interpretation of trials in hypertension.

OBJECTIVE: To describe the reproducibility of diastolic blood pressure (DBP) measurement by clinic and ambulatory monitoring and to evaluate the effects of this reproducibility on the design and interpretation of clinical trials in hypertension research. DESIGN: Prospective single-blind study of repeat measurement reproducibility of blood pressure recording. SETTING: Tertiary referral hospital hypertension clinic. PATIENTS: One hundred untreated mild-to-moderate hypertensive subjects taking 1 month of single-blind placebo. MAIN OUTCOME MEASURES: A single clinic measurement of DBP was poorly reproducible and the results for single DBP estimates taken out of a daytime ambulatory recording were similar. Average ambulatory DBP was much more reproducible, although this improvement depended upon the averaging of many measurements taken throughout the day. CONCLUSIONS: Ambulatory monitoring would decrease antihypertensive trial size by a factor of four or halve the size of detectable DBP difference between treatments. The use of poorly reproducible DBP measurements such as single clinic readings may have led to an underestimation of the risks of minor degrees of blood pressure elevation because of a 'regression dilution' bias. For single clinic DBP readings, we calculate this underestimation to be as much as 69%, and for average ambulatory DBP approximately 20%.

Adult↗

PubMed1995

Role of the completion phenomenon in the evaluation of Amsler grid results.

PURPOSE: To evaluate the limitations, particularly those related to the perceptual completion phenomenon, of Amsler grid tests in patients with central scotomas caused by macular disorders. METHODS: We tested 15 affected eyes of 15 patients with macular lesions. In each subject, the central visual field was assessed by using four different types of Amsler grid testing and a tangent screen. Tests were conducted in a random order, and the sequence of tests was repeated once. The distance between the fixation point and the closet border of the plotted scotoma was assessed. For each patient, reproducibility in repeated examinations was evaluated by assessing changes in location of the computed center of the defects and by measuring changes in the position of the center of the scotoma. RESULTS: The tangent screen was more sensitive than Amsler grids in delineating the borders of the scotoma, and the results were more reproducible. Furthermore, by using a tangent screen, the fixation point was found adjacent to the scotoma. CONCLUSION: Poor sensitivity and intraindividual variations found with Amsler grid testing are at least partly a result of the perceptual completion phenomenon. This phenomenon proved to be a dynamic and fluctuating process, as the results of two successive Amsler grid tests were not comparable, even when the technique was identical and the time between tests was no more than two to 15 minutes.

Aged↗

PubMed1998

Methodological aspects of the evaluation of endothelium-dependent vasodilatation in the human forearm.

The present study, involving 56 healthy subjects from a health screening, was undertaken to address some methodological questions regarding the measurement of endothelial function using local intra-arterial infusions of metacholine (2 and 5 micrograms min-1) to evaluate endothelium-dependent vasodilatation, and sodium nitroprusside (SNP, 5 and 10 micrograms min-1) to evaluate endothelium-independent vasodilatation. Forearm blood flow (FBF) was measured by venous occlusion plethysmography. The ratio of FBF during the highest dose of metacholine to FBF during the highest dose of SNP was used as an index of endothelial function. In 10 young volunteers the procedure was repeated after 2 h and again after 3 weeks in order to study short-term and long-term reproducibility of the method. Neither the vasodilatatory response to metacholine (r = 0.006) nor that to SNP (r = 0.08) was related to resting FBF. Neither the circumference nor the length of the arm was related to endothelial function (r = 0.01-0.11), as evaluated by the FBF on metacholine to nitroprusside ratio (mean 1.3 +/- 0.3 SD). The use of a wrist cuff to exclude hand circulation, or not, did not influence the evaluation of endothelial function significantly. Maximal FBF after 3 min of arterial occlusion of the forearm was significantly related to blood flow during both metacholine (r = 0.53, P < 0.01) and nitroprusside infusion (r = 0.36, P < 0.05), but not to the FBF on metacholine to nitroprusside ratio (r = 0.01). The short-term and long-term reproducibility of FBF during vasodilatation with metacholine and SNP was good (r = 0.89-0.97, P < 0.001), while the individual measurements for resting FBF were less reproducible when repeated after 3 weeks (r = 0.34). In conclusion, endothelial function was not related to resting FBF, nor to the arm circumference or length. No major difference was seen whether endothelial function was evaluated with or without exclusion of the hand circulation. Maximal FBF during reactive hyperaemia was not related to endothelial function.

Adult↗

PubMed2005

Evaluation of sieving polymers for fast, reproducible electrophoretic analysis of short tandem repeats (STR) in capillaries.

Efficient capillary electrophoretic STR analysis requires rapid, reproducible and robust separation of DNA fragments with reasonable capillary longevity--this is currently accomplished using proprietary commercial polymeric sieving matrices specifically developed for this separation. These matrices, while effective, are costly and do not provide adequate resolution of STR DNA fragments in capillaries with shorter effective separation lengths, increasing the time required to accomplish the separation and minimizing the potential extrapolation to other miniaturized platforms. As the forensic community looks toward next generation microchip technology as a means of processing casework more rapidly, new sieving polymers need to be evaluated for utilization in this platform. The research presented here describes the assessment of commercially-available polymeric sieving matrices for STR analysis, with consideration given to feasibility of incorporation into a microdevice. Polymer composition, molecular weight, and concentration were evaluated, along with an assessment of the effects of buffer composition, separation temperature, and capillary length. These variables were evaluated individually or collectively on the ability to resolve STR DNA fragments and the reproducibility of the separations and the results compared to a proprietary commercial product. A 600,000 Da MW poly(ethylene oxide) (PEO) solution at a 3% (w/v) concentration was determined to be the most suitable matrix for these separations. This polymer, in coated capillaries, provided highly robust and reproducible separations, with near baseline resolution of fragments having single base differences. Reductions in the temperature of the separation, from 60 degrees C to 40 degrees C, and the urea concentration of the buffer, from 7 M to 3.5 M, provided increased longevity of the PEO polymer for repeated separations. Comparison of this polymer with currently specified commercial products used for STR analysis showed that the optimized PEO matrix provided superior separations under all conditions tested. In addition, PEO could be utilized in shorter capillary systems, with a concurrent decrease in analysis time, highlighting its potential for use in shortened capillary or microdevice systems.

Buffers↗

PubMedDate not supplied

Comparison of repeatability of the multifocal electroretinogram and Humphrey perimeter.

Functional mapping of the retina by multifocal electroretinographic recordings is now possible. We compared the normal range, repeatability and response topography of this new technique with conventional static Humphrey perimetry to assess its suitability in clinical practice. The multifocal technique was performed on 60 age-matched controls. Measures of repeatability and reproducibility were obtained. Results were then compared with those obtained from a customized perimetry test. In both tests the coefficients of repeatability were found to decrease with eccentricity. The inherent measurement variation between techniques was comparable. Overall system variation indicates that the technique could be a useful tool at the clinical level.

Computer Graphics↗

PubMedDate not supplied

Analysis of DDT residues in soil by ELISA: an international interlaboratory study.

An international interlaboratory study was conducted to determine the performance of a group of laboratories from developing and developed countries. The study used a commercial microwell ELISA on unknown samples spiked with different levels of DDT. The study design was based on Youden pairs and balanced replicates. Two soils, differing in particle size distributions, organic matter content, and cation-exchange capacities and thought to be DDT-free, were spiked at 5 DDT levels between 0.025 and 2 mg/kg. Nineteen laboratories in 17 countries took part in the collaborative trial; of these, the majority were modestly equipped laboratories in developing countries. Samples were analyzed without filtration or cleanup and using standards of pure DDT in methanol. Data were analyzed for repeatability and reproducibility, and average recoveries at the spike levels were calculated. Mean real recoveries for both soils were similar (103% for soil A and 100% for soil B), with values between 0.1 and 2 mg/kg DDT. Precision estimates were best in the linear working range of the assay (0.1-0.5 mg/kg DDT), with reproducibility relative standard deviations (RSDR) typically averaging about 38 and 46% near the upper and lower detection limits, respectively. Corresponding repeatability relative standard deviation (RSDr) values were 20-36% and 36-57%. Thus, even though much of the trial was performed under developing country conditions, performance statistics were similar to other reported results obtained with ELISAs on small molecules of agricultural importance, such as mycotoxins and pesticide and antibiotic residues.

DDT↗

PubMed1991

Time-dependent variation in the cardiac conduction system assessed in young healthy individuals at weeks' interval: implications for clinical trials.

The time-dependent physiologic variations of the cardiac conduction system were evaluated at repeated invasive studies in 10 healthy individuals. Their mean age was 28 years (range 22 to 34) and they volunteered to undergo two electrophysiologic studies at intervals of 14 to 63 days (mean 25). The coefficients of variation, repeatability and reproducibility, which should be the preferred statistics when assessing the reproducibility of continuous variables, were calculated. The mean sinus cycle length had a high reproducibility, with coefficients of variation between 2% and 6%. The mean and maximal sinus node recovery times, however, varied considerably. The reproducibility was very high for ventricular depolarization and repolarization (QRS, JT, QT), with coefficients of variation between 2% and 6%. The coefficients of variation were below the acceptable 10% value for intraatrial conduction, atrioventricular (AV) node conduction, His-Purkinje conduction as well as the Wenckebach point; for the effective refractory period of the AV node, it was 12%. Repeat invasive electrophysiologic testing is a safe and reproducible method for evaluating and comparing cardioactive drug effects in healthy subjects. The same statistical analyses were applied to previously published studies on continuous electrophysiologic variables, which allowed comparisons among different groups of healthy and sick persons, as well as among different electrophysiologic variables and procedures. Furthermore, the minimal actual treatment differences that can be detected with a reasonable (80%) probability at a predetermined (5%) significance level using a crossover design were estimated for different electrophysiologic variables. These data will assist in the calculation of the necessary sample size for clinical trials and related purposes.

Adult↗

PubMed2002

Reproducibility of coronary calcium quantification in repeat examinations with retrospectively ECG-gated multisection spiral CT.

High reproducibility is a key requirement for coronary calcium scoring in follow-up examinations. We investigated the inter-examination reproducibility of calcium scoring with retrospectively ECG-gated multisection spiral CT (MSCT). Fifty patients were examined twice with MSCT. Slices were reconstructed with retrospective ECG gating in the diastolic phase with 3-mm slice width and up to 125-ms temporal resolution. We calculated the Agatston score, calcium volume with and without isotropic interpolation, and calcium mass, and derived the mean and median variability. We investigated the change of variability with use of 3-mm non-overlapping and overlapping increments (2, 1.5, 1 mm). Use of overlapping increment results in considerably reduced interscan variability. We observed a minimum mean variability of 12% and a minimum median variability of 9% for the Agatston score. For volume and mass quantification we obtained a minimum mean variability of 7.5% and a minimum median variability of 5%. Multisection spiral CT enables coronary calcium quantification with high reproducibility in follow-up examinations mainly founded on image data with reduced partial-volume errors due to overlapping increment.

Adult↗

PubMed2002

Field test of the reproducibility of the semiflexed metatarsophalangeal view in repeated radiographic examinations of subjects with osteoarthritis of the knee.

OBJECTIVE: To estimate the reproducibility of the semiflexed metatarsophalangeal (MTP) view in repeat radiographic examinations of the knee of subjects with osteoarthritis (OA) with respect to radioanatomic alignment of the medial tibial plateau and the central x-ray beam and the precision of measurements of minimum medial tibiofemoral joint space width (JSW). METHODS: Thirty-eight subjects with definite knee OA underwent 2 semiflexed MTP examinations on the same day. Radioanatomic alignment of the medial tibial plateau and the x-ray beam (distance between anterior and posterior margins of the plateau) was measured manually (Lequesne method). Manual measurements of the JSW in repeat radiographs also were obtained. The reproducibility of JSW measurements was estimated by the method of Bland and Altman. RESULTS: Only 29% of the initial semiflexed MTP radiographs exhibited satisfactory radioanatomic alignment (intermargin distance < or =1 mm). However, intermargin distances in initial and repeat radiographs were highly correlated (r = 0.86, P < 0.01). In 89% of knees, the intermargin distance in the first examination was reproduced (+/- 1 mm) in the second examination. The standard error of measurement (mean of within-knee standard deviations of repeat JSW values) was 0.30 mm. The magnitude of discrepancy between repeat measurements of JSW was related positively to overall radiographic severity of knee OA (P < 0.05). CONCLUSION: The semiflexed MTP protocol affords highly reproducible radioanatomic positioning of the knee, although misalignment of the medial tibial plateau and the x-ray beam occurs in >70% of cases. Precision of measurement of JSW in the semiflexed MTP view approaches that associated with fluoroscopically assisted positioning protocols. However, the consequences of poor, albeit reproducible, alignment of the knee in serial semiflexed MTP radiographs in longitudinal studies of OA progression are currently unknown.

Aged↗

PubMed2002

Reproducibility of mammary gland structure during repeat setups in a supine position.

PURPOSE: In breast conserving therapy, complete excision of the tumor with an acceptable cosmetic outcome depends on accurate localization in terms of both the position of the lesion and its extent. We hypothesize that preoperative contrast-enhanced magnetic resonance (MR) imaging of the patient in a supine position may be used for accurate tumor localization and marking of its extent immediately prior to surgery. Our aims in this study are to assess the reproducibility of mammary gland structure during repeat setups in a supine position, to evaluate the effect of a breast immobilization device, and to derive reproducibility margins that take internal tissue shifts into account occurring between repeat setups. MATERIALS & METHODS: The reproducibility of mammary gland structure during repeat setups in a supine position is estimated by quantification of tissue shifts in the breasts of healthy volunteers between repeat MR setups. For each volunteer fiducials are identified and registered with their counter locations in corresponding MR volumes. The difference in position denotes the shift of breast tissue. The dependence on breast volume and the part of the breast, as well as the effect of a breast immobilization cast are studied. RESULTS: The tissue shifts are small with a mean standard deviation on the order of 1.5 mm, being slightly larger in large breasts (V> 1000 cm3), and in the posterior part (toward the pectoral muscle) of both small and large breasts. The application of a breast immobilization cast reduces the tissue shifts in large breasts. A reproducibility margin on the order of 5 mm will take the internal tissue shifts into account that occur between repeat setups. CONCLUSION: The results demonstrate a high reproducibility of mammary gland structure during repeat setups in a supine position.

Adult↗

PubMed2002

Induction of Darier's disease by repeated irradiation by ultraviolet B; protection by sunscreen and topical ascorbic acid.

Darier's disease, keratosis follicularis, is frequently aggravated by sun exposure. Although there have been reports of Darier's disease reproduced by repeated exposure to ultraviolet B, little is known about its photo-protection. We artificially induced Darier's disease in a 47-year-old Korean man, and tested the protection afforded by sunscreen and topical ascorbic acid. Complete lesions of Darier's disease arose with repeated exposure of ultraviolet B (2,600 mJ/cm2 for 10 days), and sunscreen and topical ascorbic acid protected against its appearance. This result strongly suggests that sunscreen and ascorbic acid would be very helpful in preventing the aggravation of Darier's disease caused by sun exposure.

Administration, Topical↗

PubMed1995

Estimates of variability for somatic cell count measurements in the Iowa dairy industry.

The SCC collected from 15 instruments in 12 laboratories were used to quantify accuracy, repeatability, and reproducibility in the Iowa dairy industry. For each of three trials, milk was sampled at the morning milking from 30 different Holsteins in the Iowa State University herd. Identified samples and unidentified duplicates were provided for each participating instrument. Mean SCC was 418,000 cells/ml, and mean SCC for duplicates ranged from 9000 to 3,966,000. Accuracy for a set of 30 duplicates was lowest for trial 1 (CV = 16.4%) and highest for trial 2 (CV = 7.6%). Intraclass correlations estimated repeatability and were .99 for all but one instrument. Coefficients of variation for repeatability (weighted mean = 11.4%) were similar to estimates for accuracy (weighted mean = 11.0%), but reproducibility was considerably lower (30.0%). Samples were classified by SCC as very low, < 125,000; low, 125,000 to 249,000; medium, 250,000 to 500,000; and high, > 500,000. Repeatability for high samples was higher than repeatability for very low SCC samples; coefficient of variation for high SCC samples was 6.8% but was > 25.0% for samples with < 500,000 cells. Repeatability was within standards set by the industry, but current procedures for quality control may not adequately address reproducibility.

Animals↗

PubMed1992

Evaluation of human diaphragm contractility using mouth pressure twitches.

Mouth (PmT), esophageal (PesT), and transdiaphragmatic pressure twitches (PdiT) in response to single supramaximal bilateral phrenic nerve shocks were recorded during relaxation between total lung capacity (TLC) and functional residual capacity (FRC) in five normal volunteers. The PmT versus PesT or PmT versus PdiT relationships, which were linearly correlated (all r greater than 0.76), were not affected by diaphragm fatigue and were reproducible on repeated determinations over a period exceeding 1 yr. The PmT versus lung volume relationship was also linear (all r greater than 0.72) and reproducible, and its changes following diaphragm fatigue reliably reflected the changes in diaphragm contractility. We conclude that PmT is a reliable measure of diaphragm pressure-generating capacity in normal individuals and has the potential of providing similar information in patients.

Adult↗

PubMed1997

Redefining end of test (EOT) criteria for pulmonary function testing in children.

In order for an individual FVC maneuver to be considered acceptable according to the 1994 American Thoracic Society (ATS) standards it must meet end of test (EOT) criteria of a minimum expiration time of 6 s with minimal volume change (0.03 L) over 1 s. We have found that while these criteria are often not met in children, most of the tests do meet the ATS criteria for reproducibility with repeated efforts. We, therefore, sought to develop new EOT criteria that would be more appropriate for children and in keeping with the findings for reproducibility. Using an exponential curve fitting of the volume time tracing, we determined a theoretical curve that closely approximated the actual curve (mean difference between actual and derived FEV1 0.01 +/- 0.04 L). The theoretical FVC (FVCFULL) at the point where the curve reached its asymptote was then determined using the fitted curve. Since this point could be difficult to reach for some patients, 95% of FVCFULL (FVC95) was proposed as the new EOT in children. Data from 382 patients were reviewed. Their ages ranged from 5 to 18 yr and their FEV1s from 21 to 120% of predicted. Only 19% of the patients met current ATS EOT requirements despite the fact that 91% met the reproducibility criteria for both FEV1 and FVC. However, 90% of them reached their FVC95. When this was broken down by age, 37% of those < or = 7 yr failed to reach FVC95 whereas only 4% of the older children failed to do so. It is proposed that patients be coached to obtain maximal effort and that the curves be individually fitted to an exponential equation to determine whether the patient has achieved EOT as defined by FVC95.

Adolescent↗