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PubMed1993

The quality of survey data obtained from elderly adults.

The quality of survey data obtained from elderly adults has important implications for nutrition status assessment, policy decisions and program development. Self-reported information by adults of all ages is subject to inaccuracies. Accuracy of data obtained from older respondents may be lower than that of younger respondents. Errors made by older adults are largely due to misinterpretation of the questions asked, motivations related to participation and reporting of information, and changes in memory associated with aging and other factors which may impact respondent accuracy. Cooperative efforts by cognitive psychologists, survey researchers and nutritionists are necessary for improving both questionnaire design and the accuracy of information obtained.

Age Factors↗
PubMed2001

Source apportionment of fine particulate matter by clustering single-particle data: tests of receptor model accuracy.

The source apportionment accuracy of a neural network algorithm (ART-2a) is tested on the basis of its application to synthetic single-particle data generated by a source-oriented aerosol processes trajectory model that simulates particle emission, transport, and chemical reactions in the atmosphere. ART-2a successfully groups particles from the majority of sources actually present, when given complete data on ambient particle composition at monitoring sites located near the emission sources. As particles age in the atmosphere, accumulation of gas-to-particle conversion products can act to disguise the source of the primary core of the particles. When ART-2a is applied to synthetic single-particle data that are modified to simulate the biases in aerosol time-of-flight mass spectrometry (ATOFMS) measurements, best results are obtained using the ATOFMS dual ion operating mode that simultaneously yields both positive and negative ion mass spectra. The results of this study suggest that the use of continuous single-particle measurements coupled with neural network algorithms can significantly improve the time resolution of particulate matter source apportionment.

Aerosols↗
PubMed1992

Database use in neonatal intensive care units: success or failure.

The purpose of this national survey was to define the extent and features of database use by 445 tertiary level neonatal intensive care nurseries in the United States. Of the 305 centers responding to our survey, 78% had a database in use in 1989 and 15% planned to develop one in the future. Nurseries varied remarkably in the volume of data collected, the amount of time devoted to completing data collection forms, and the personnel involved in data collection. Although data were used primarily for statistical reports (93% of nurseries), quality assurance (73%) and research activities (61%) were also enhanced by database information. Neonatal databases were used to generate reports for the permanent medical record in 38% of centers. Satisfaction with the database was dependent on how useful the database information was to centers which collected and actually used a large volume of information. Overall, nurseries expressed a high degree of confidence in the data they collected, and 65% felt their neonatal database information could be used directly in publication of research. It was disturbing that accuracy of data was not monitored formally by the majority of nurseries. Only 27% of centers followed a routine schedule of data quality assurance, and only 53% had built in error messages for data entry. We caution all who receive database information in the form of morbidity and mortality statistics, clinical reports on patients cared for in neonatal units, and published manuscripts to be attentive to the quality of the data they consume. We feel that future database design efforts need to better address data quality control. Our findings stress the importance and need for immediate efforts to better address database quality control.

Data Collection↗
PubMed1989

[Three dimensional shape measurement of teeth (Part 2). The accuracy of the three dimensional measurement using a laser displacement meter].

The three dimensional shape measurement system of teeth was improved. The system was assembled by using a high precision laser displacement meter and computer controlled scanning machine (CAMM-3). At the fissure of the occlusal plane, the abnormal data caused by multiple scattering of the reflected beam were observed, but they were dissolved by painting the stone model teeth gray and measured by using a laser displacement meter of MD-40 type with a short measurement length. Another error observed when the reflected beam was shielded by the model tooth itself, was corrected by connecting some data which were measured by rotating the teeth model on the gonio stage. A software program was composed to connect the data. The accuracy of measurement of this system was examined on the slope of a 7 abutment tooth. When the model teeth were measured without tilting, the difference between the true value and the measured value was -240 microns (-2.8%). However, by tilting the model teeth +/- 20 degrees on the gonio stage and connecting a couple of data obtained with two tilting angles by means of the software program, the difference was considerably decreased into + 10 microns and the accuracy was + 0.1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Lasers↗
PubMedDate not supplied

Self-measurement of blood glucose. Accuracy of self-reported data and adherence to recommended regimen.

Reflectance meters containing memory chips were used in a study that addressed several questions concerning routine use of self-monitoring of blood glucose (SMBG), including accuracy of patient blood glucose (BG) diaries, reliability of self-reported frequency of SMBG, and adherence to recommended SMBG regimen. Thirty adults with insulin-dependent diabetes used memory meters and recorded test results in diaries for 2 wk while performing their normal SMBG regimen. Analysis of glucose diaries showed that only 23% of the subjects had no diary errors and 47% had clinically accurate diaries (less than 10% error rate). The most common types of errors were omissions of values contained in meter memory and additions of values not contained in meter memory, with significantly more omissions than additions. Alterations of test values (e.g., changing a 300-mg/dl reading to 200 mg/dl) were extremely rare. There was no difference in the rate of errors that resulted in a more positive clinical profile (omitting unacceptable values and adding acceptable values) or a more negative clinical profile (omitting acceptable values and adding unacceptable values). Examination of the actual frequency of SMBG showed that most subjects (56.6%) measured their BG an average of two to three times each day. Self-report of SMBG frequency correlated with both actual frequency and HbA1. Although actual frequency of SMBG was not related to physicians' recommendations, the majority (64%) of subjects were self-testing as often or more often than they had been instructed.

Adult↗
PubMedDate not supplied

Identifying diagnostic errors with induced decision trees.

OBJECTIVE: The purpose of this article is to compare the diagnostic accuracy of induced decision trees with that of pruned neural networks and to improve the accuracy and interpretation of breast cancer diagnosis from readings of thin-needle aspirate by identifying cases likely to be misclassified by induced decision rules. METHOD: Using an online database consisting of 699 cases of suspected breast cancer and their corresponding readings of fine-needle aspirate, decision trees were induced from half of the cases, randomly selected. Accuracy was determined for the remaining cases in successive partitions. The pattern of errors in the multiple decision trees was examined. A smaller data set was created with 2 classes: (1) correctly classified and (2) misclassified by a decision tree, rather than the original benign and malignant classes. From this data set, decision trees that describe the misclassified cases were induced. RESULTS: Larger, less severely pruned decision trees were more accurate in breast cancer diagnosis for both training and test data. The accuracy of the induced decision trees exceeded that reported for the smaller pruned neural networks. Combining classifications from 2 trees was effective in identifying malignancies missed by a single tree. Induced decision trees were able to identify patterns associated with misclassified cases, but the identification of errors inductively did not improve the overall error rate. CONCLUSION: In this application, a model that is too compact identifies fewer cases of the minority class, malignancy. New methods that combine models and examine classification errors can improve diagnosis by identifying more malignancies and by describing ambiguous cases.

Breast Neoplasms↗
PubMed1993

Comparison of the quality of patient data collected by hospital and departmental computer systems.

The quality of patient data routinely collected in hospitals is rarely assessed, though by repute it may often be incomplete and inaccurate. To explore their completeness and accuracy, patient data separately collected by a hospital Patient Administration System (PAS) and by a departmental Clinical Information System (CIS) used by clinicians were compared. The results indicate that, although both systems appear to record reliably demographic and administrative data, PAS data are more complete than CIS data. Moreover clinicians and medical records staff seem to use classifications of diagnoses and procedures in profoundly different ways. More attention should be paid to the need to assess and improve data quality. The development of a shared database, used and validated by medical records staff and clinicians alike, may be the best way to achieve this.

Abstracting and Indexing↗
PubMed1993

Colposcopic accuracy in a residency training program: defining competency and proficiency.

BACKGROUND: The determination of proficiency in procedural skills has evoked keen interest, but meaningful guidelines are limited by the absence of pertinent clinical data. Colposcopic accuracy is defined as the clinical correlation between a colposcopic impression and a histologic report. The colposcopic accuracy of physicians in a university-based family practice residency colposcopy program was evaluated. METHODS: Demographic information, clinical findings, and laboratory results of patients evaluated by colposcopy were prospectively recorded. Colposcopic accuracy was calculated based on the agreement of the colposcopic impression with the histologic interpretation within one histologic grade. RESULTS: Colposcopic examinations were performed on 282 patients. Histologic evidence of premalignant cervical disease was identified in 115 patients as follows: mild dysplasia, 72; moderate dysplasia, 24; and severe dysplasia, 19. The colposcopic impression agreed within one histologic grade in 188 of 205 patients for a colposcopic accuracy rate of 91.7% (95% CI = 87.1% to 95.1%). CONCLUSIONS: Given an acceptable latitude of clinical correlation between the colposcopic impression and histologic interpretation, the colposcopic accuracy of family physicians compared favorably with that reported by other colposcopists. The more common colposcopic errors were overestimation of low-grade disease and underestimation of high-grade disease. Colposcopic accuracy at an essential minimal proficiency level of 80% should form the basis for assessing specialized perceptual ability and therefore determining colposcopic competency.

Adolescent↗
PubMed1998

Estimation of the accuracy of a surface matching technique for registration of EEG and MRI data.

OBJECTIVES: We developed a method to register EEG and MRI data used for the source reconstruction of electric brain activity. METHODS: The method is based on matching of the head surfaces as obtained by 3D scanning after the EEG recording, and by segmentation of MRI data. The registration accuracy was estimated by calculating the residual error of the surface matching and its intra-individual and inter-individual variability. In addition, the test-retest reliability concerning the transformation of electrode positions was studied, to estimate how inaccuracies resulting from the 3D scanning of the head surface translate into registration uncertainty. RESULTS: For 61 measurements, performed on 20 subjects, the average root mean square of the Euclidean distances between the 3D-scanned and the MRI-derived head surfaces amounted to 3.4 mm. An inter-individual standard deviation of 0.24 mm, and an intraindividual standard deviation of 0.003-0.31 mm proved a high inter- and intra-subject stability of the surface matching technique. The variation of transformation results when studying the test-retest reliability amounted to 1.6 mm on average. The maximum error of transformation was smaller than the diameter of the electrodes. CONCLUSIONS: The findings suggest that the surface matching technique is a precise method for determination of the transformation of electrode positions and MRI data into a single co-ordinate system and can successfully be used in a routine laboratory setting.

Brain↗
PubMed1993

Accuracy of recall of hip fracture, heart attack, and cancer: a comparison of postal survey data and medical records.

Accuracy of recall of hip fracture, heart attack, and cancer was evaluated by comparing data obtained from postal surveys and medical records of participants in the Leisure World Disease Prevention Study. The study cohort comprised 13,897 residents of Leisure World Laguna Hills who responded to a questionnaire first mailed in 1981. Follow-up questionnaires requesting information on recent disease history were mailed in 1983 and 1985 to all living cohort members and were returned by 9,734 (86%) and 8,884 (82%) persons, respectively. The proportion of false-positive answers was about 40% for acute myocardial infarction, but less than 10% for hip fracture and cancer. Many of those who gave a false-positive answer on the questionnaire had a condition that the lay population might easily confuse with the condition of interest (e.g., heart attack vs. other cardiovascular disease). Among persons with the disease of interest recorded in the medical record, the percentage who failed to report their events on the questionnaires was highest for those who had an acute myocardial infarction, followed by those who had cancer and those who had hip fracture. The highest rates of confirmation of cancer were for cancers of the breast, bladder, prostate, and uterus. For closely related sites (e.g., colon and rectum), the reliability of reports decreased. The amount of information obtained varied according to the wording of the questionnaire and the specificity of the questions asked. Improved accuracy of recall was observed when the occurrence of specific diseases was asked in addition to a general question about recent hospitalizations.

California↗
PubMed2000

Tympanometry interpretation by primary care physicians. A report from the International Primary Care Network (IPCN) and the Ambulatory Sentinel Practice Network (ASPN).

BACKGROUND: The accuracy of data gathered by primary care clinicians in practice-based research networks (PBRNs) has been questioned. Tympanometry, recently recommended as a means of improving accuracy of diagnosing acute otitis media, was included as an objective diagnostic measure in an international PBRN study. We report the level of agreement of interpretations of tympanograms between primary care physicians in PBRNs and experts. METHODS: Primary care physicians in PBRNs in the Netherlands, United Kingdom, United States, and Canada enrolled 1773 children aged 6 to 180 months who contributed 6358 tympanograms during 3179 visits. The physicians were trained in the use and interpretation of tympanometry using the Modified Jerger Classification. We determined the level of agreement between physicians and experts for interpretation of tympanograms. One comparison used the 6358 individual ear tracings. A second comparison used the 3179 office visits by children as the unit of analysis. RESULTS: The distribution of expert interpretation of all tympanograms was: 35.8% A, 30% B, 15.5% C1, 12% C2, and 6.8% uninterpretable; for visits, 37.8% were normal (A or C1), 55.6% abnormal (B or C2), and 6.6% could not be classified. There was a high degree of agreement in the interpretation of tympanograms between experts and primary care physicians across networks (kappa=0.70-0.77), age groups of children (kappa=0.69-0.73), and types of visits (kappa=0.66-0.77). This high degree of agreement was also found when children were used as a unit of analysis. CONCLUSIONS: Interpretations of tympanograms by primary care physicians using the Modified Jerger Classification can be used with confidence. These results provide further evidence that practicing primary care physicians can provide high-quality data for research purposes.

Acoustic Impedance Tests↗
PubMed2004

Screening, library-assisted identification and validated quantification of 23 benzodiazepines, flumazenil, zaleplone, zolpidem and zopiclone in plasma by liquid chromatography/mass spectrometry with atmospheric pressure chemical ionization.

A liquid chromatographic/mass spectrometric assay with atmospheric pressure chemical ionization (LC/APCI-MS) is presented for fast and reliable screening and identification and also for precise and sensitive quantification in plasma of the 23 benzodiazepines alprazolam, bromazepam, brotizolam, camazepam, chlordiazepoxide, clobazam, clonazepam, diazepam, flunitrazepam, flurazepam, desalkylflurazepam, lorazepam, lormetazepam, medazepam, metaclazepam, midazolam, nitrazepam, nordazepam, oxazepam, prazepam, temazepam and tetrazepam, triazolam, their antagonist flumazenil and the benzodiazepine BZ1 (omega 1) receptor agonists zaleplone, zolpidem and zopiclone. It allows confirmation of the diagnosis of an overdose situation and monitoring of psychiatric patients' compliance. The analytes were isolated from plasma using liquid-liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. After screening and identification in the scan mode using the authors' LC/MS library, the analytes were quantified in the selected-ion monitoring mode. The quantification assay was fully validated. It was found to be selective proved to be linear from sub-therapeutic to over therapeutic concentrations for all analytes, except bromazepam. The corresponding reference levels the assay's accuracy and precision data for all studied substances are listed. The accuracy and precision data were within the required limits with the exception of those for bromazepam. The analytes were stable in frozen plasma for at least 1 month. The validated assay was successfully applied to several authentic plasma samples from patients treated or intoxicated with various benzodiazepines or with zaleplone, zolpidem or zopiclone. It has proven to be appropriate for the isolation, separation, screening, identification and quantification of the drugs mentioned above in plasma for clinical toxicology, e.g. in cases of poisoning, and forensic toxicology, e.g. in cases of driving under the influence of drugs.

Anti-Anxiety Agents↗
PubMed1996

Effects of motion on the performance of pulse oximeters in volunteers.

BACKGROUND: Pulse oximetry is considered a standard of care in both the operating room and the postanesthetic care unit, and it is widely used in all critical care settings. Pulse oximeters may fail to provide valid pulse oximetry data in various situations that produce low signal-to-noise ratio. Motion artifact is a common cause of oximeter failure and loss of accuracy. This study compares the accuracy and data dropout rates of three current pulse oximeters during standardized motion in healthy volunteers. METHODS: Ten healthy volunteers were monitored by three different pulse oximeters: Nellcor N-200, Nellcor N-3000, and Masimo SET (prototype). Sensors were placed on digits 2, 3, and 4 of the test hand, which was strapped to a mechanical motion table. The opposite hand was used as a stationary control and was monitored with the same pulse oximeters and an arterial cannula. Arterial oxygen saturation rate varied from 100% to 75% by changing the inspired oxygen concentration. While pulse oximetry was both constant and changing, the oximeter sensors were connected before and during motion. Oximeter errors and dropout rates were digitally recorded continuously during each experiment. RESULTS: If the oximeter was functioning before motion began, the following are the percentages of time when the instrument displayed a pulse oximetry value within 7% of control: N-200 = 76%, N-3000 = 87%, and Masimo = 99%. When the oximeter sensor was connected after the beginning of motion, the values were N-200 = 68%, N-3000 = 47%, and Masimo = 97%. If the alarm threshold was chosen as pulse oximetry less than 90%, then the positive predictive values (true alarms/ total alarms) are N-200 = 73%, N-3000 = 81%, and Masimo = 100%. In general, N-200 had the greatest pulse oximetry errors and N-3000 had the highest dropout rates. CONCLUSIONS: The mechanical motions used in this study significantly affected oximeter function, particularly when the sensors were connected during motion, which requires signal acquisition during motion. The error and dropout rate performance of the Masimo was superior to that of the other two instruments during all test conditions. Masimo uses a new paradigm for oximeter signal processing, which appears to represent a significant advance in low signal-to-noise performance.

Adult↗
PubMed1997

The effects of motion on the performance of pulse oximeters in volunteers (revised publication).

BACKGROUND: Pulse oximetry is considered a standard of care in both the operating room and the postanesthetic care unit, and it is widely used in all critical care settings. Pulse oximeters may fail to provide valid SpO2 data in various situations that produce low signal-to-noise ratio. Motion artifact is a common cause of oximeter failure and loss of accuracy. This study compares the accuracy and data dropout rates of three current pulse oximeters during standardized motion in healthy volunteers. METHODS: Ten healthy volunteers were monitored by three different pulse oximeters: Nellcor N-200, Nellcor N-3000, and Masimo SET (prototype). Sensors were placed on digits 2, 3, and 4 of the test hand, which was strapped to a mechanical motion table. The opposite hand was used as a stationary control and was monitored with the same pulse oximeters and an arterial cannula. Arterial oxygen saturation was varied from 100% to 75% by changing the inspired oxygen concentration. While SpO2 was both constant and changing, the oximeter sensors were connected before and during motion. Oximeter errors and dropout rates were digitally recorded continuously during each experiment. RESULTS: If the oximeter was functioning before motion began, the following are the percentages of time when the instrument displayed an SpO2 value within 7% of control: N-200 = 76%, N-3000 = 87%, and Masimo = 99%. When the oximeter sensor was connected after the beginning of motion, the values were N-200 = 68%, N-3000 = 47%, and Masimo = 97%. If the alarm threshold was chosen SpO2 less than 90%, then the positive predictive values (true alarms/total alarms) are N-200 = 73%, N-3000 = 81%, and Masimo = 100%. In general, N-200 had the greatest SpO2 errors and N-3000 had the highest dropout rates. CONCLUSIONS: The mechanical motions used in this study significantly affected oximeter function, particularly when the sensors were connected during motion, which requires signal acquisition during motion. The error and dropout rate performance of the Masimo was superior to that of the other two instruments during all test conditions. Masimo uses a new paradigm for oximeter signal processing, which appears to represent a significant advance in low signal-to-noise performance.

Adult↗
PubMed2004

Spectral polarimetry with a differential group delay bias.

We show that the addition of a polarization controller and bias differential group delay to a spectral polarimeter increases the amount of polarization information that can be extracted from a Stokes spectrum measurement. We use this biased spectral polarimetry on 40-Gbit/s signals to measure the polarization mode dispersion of the optical fiber through which they propagate. Our measurements do not require any control of the polarization at the fiber input. Averaging measurements from several settings of the polarization controller yields improved accuracy, and, after data rejection is applied, both the accuracy and the number of valid data points is increased when using several measurements.

Journal Article↗
PubMed1994

Effects of data structure on variance of prediction error and accuracy of genetic evaluation.

Several features of data structure were studied to determine their effects on variance of prediction error and accuracy of evaluation. Assigning 50 sires with progeny to a portion of 10, 25, or 50 contemporary groups according to a sire model with and without additive genetic relationships, or assigning 50 individuals with their own record to one of 2, 5, or 10 contemporary groups according to an animal model, established the designs. Additive genetic relationships were based on stimulated pedigree files. Low, medium, and high heritabilities (.10, .25, and .40, respectively) were considered. The inverse of coefficient matrices gave variances of prediction error. Populations derived from the sire model (n = 8,100) consisted solely of progeny-tested individuals. For them, number of progeny had a quadratic (P < .001) association with variance of prediction error (R2 = 56 to 82%), which selection index theory underestimated when there were < 100 progeny. Number of direct connections (sires of contemporaries of progeny) together with progeny numbers explained variance of prediction error (R2 = 76 to 90%) better than either variable alone. With no direct connections, variance of prediction error was maximum unless a relative with at least one direct connection itself existed. Populations derived from the animal model (n = 900) consisted of animals with designs representing a progeny test, performance test, or a combination of both (34, 41, and 25% of the total, respectively). For performance-tested animals (without progeny), number of genetic connections was not highly correlated with variance of prediction error (r = -.10, across h2), but relatives prevented zero accuracies when contemporary groups consisted of one animal. Even when animals had no relatives, more than five members per contemporary group gave little additional increase in accuracy. For other than a progeny test, designs were complex, being described by many variables that were confounded.

Animals↗
PubMed2001

The diagnostic accuracy of mammography in the evaluation of male breast disease.

BACKGROUND: The role of mammography in the evaluation of male patients presenting with breast disease is controversial. This controversy is a function of the lack of specific data concerning the diagnostic accuracy of mammography when used in this clinical setting. The purpose of this study was to define the diagnostic accuracy of mammography in the evaluation of male breast disease. METHODS: One hundred and four prebiopsy mammograms from 100 patients with tissue diagnoses were read blindly by two independent radiologists, and placed into one of five predetermined categories: definitely malignant, possibly malignant, gynecomastia, benign mass, and normal. Radiologic/pathologic correlation was performed and the sensitivity (Sn), specificity (Sp), positive (Ppv) and negative predictive value (Npv), and accuracy (Ac) for each of the mammographic diagnostic category determined. RESULTS: The pathologic diagnoses were 12 cancers, including 1 patient with bilateral breast cancer, 70 cases of gynecomastia, 16 benign masses, and 6 normals. The accuracy data for the mammographic diagnostic categories are as follows: malignant (combined definitely and possibly malignant), Sn 92%, Sp 90%, Ppv 55%, Npv 99%, Ac 90%; and overall benignity (combined gynecomastia, benign mass, and normal), Sn 90%, Sp 92%, Ppv 99%, Npv 55%, Ac 90%. Six cancers (50%) coexisted with gynecomastia. CONCLUSIONS: Mammography can accurately distinguish between malignant and benign male breast disease. Although not a replacement for clinical examination, its routine use could substantially reduce the need for biopsy in patients whose mammograms and clinical examination suggest benign disease.

Breast Neoplasms, Male↗
PubMedDate not supplied

Methodological considerations for research on late life future temporal perspective.

Several complications may be encountered by the investigator who wishes simply to "plug a future time perspective measure or two" into highly quantitative analyses. Difficulties in data collection appear to arise both from the complex nature of time perspective and from characteristics sometimes associated with older respondents themselves. Although an accompanying data base for empirically determining the most appropriate procedures is currently absent, it appears that an awareness of certain basic points can enhance the quality and accuracy of data collection. A number of these generic methodological considerations are discussed, and various suggestions are offered. Time perspective should not be considered a universal solution for every researchable issue in gerontology. Its strong face validity and literature to date should, however, encourage our addressing the methodological difficulties that exist.

Aged↗