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PubMed1987

Accuracy of fetal death reports: comparison with data from an independent stillbirth assessment program.

We evaluated the completeness and accuracy of reporting on Wisconsin fetal death report forms (FDF) through case by case comparison with data from the Wisconsin Stillbirth Service Project (WiSSP), which uses extensive protocols for etiologic investigation of stillborns. Fetal deaths are underreported: no FDF was submitted for 17.8 per cent of fetal deaths evaluated through the WiSSP. For those for whom FDF were submitted, fetal anomalies were often unrecognized or unreported: only 60 per cent of stillborns identified by the WiSSP as having fetal anomalies had any indication of the presence of such anomalies on FDF. When causes of death were classified into fetal, placental/cord, maternal/environmental, and unknown, comparison of reported underlying cause of death revealed marked inaccuracies on FDF. Placental/cord causes reported on FDF often could not be documented subsequently while, in contrast, fetal causes of death were underreported. Few accurate fetal diagnoses were present on FDF. Even among common lethal malformations misdiagnosis occurred frequently.

Autopsy↗
PubMed1995

Optimization of Applied Biosystems 373 sequencer stretch modification.

We have optimized the conditions for using the Stretch modification for the Applied Biosystems 373 Automated DNA Sequencers for sequencing double-stranded DNA using 34-cm well-to-read and 48-cm well-to-read configurations. With the manufacturer's recommended settings, uneven spacing within the first 100 bases was observed, which led to miscalls, insertions and deletions in the analyzed data. A significant decrease in accuracy for reads greater than 400 bases was also observed. Various gel concentrations were tested to improve the base spacing for the first 100 bases while maintaining accuracy and usable length of data. A longer average usable length and better resolution of smaller fragments were achieved by increased acrylamide concentration coupled with increased wattage. Using the Applied Biosystems CATALYST 800 Molecular Biology LabStation, Taq dye primer cycle sequencing reactions were optimized for -21 M13 and M13RP1 primers to produce a more even distribution of dye-labeled fragments that increased the overall signal strengths and decreased background signal. These reaction products, run on the Stretch sequencers using the new gel conditions, provided longer reads with increased reliability and accuracy of the data.

Acrylamides↗
PubMed1987

Estimation of myocardial infarction mortality from routinely collected data in Western Australia.

The accuracy of routinely collected mortality data for ischemic heart disease (IHD) as indicators of death from acute myocardial infarction (AMI) was assessed in ages 25-64 years, according to the WHO criteria defined in 1983. Cases were identified from computer records (linked for individuals) of all death certificates and hospital discharges in Western Australia between 1971 and 1982. Where the official cause was IHD about 90% of deaths fulfilled the WHO criteria for definite or possible AMI. Up to 10% of fatal cases of definite or possible AMI were coded to other causes in the official death statistics, however it appeared that variations in this figure with changes in coding practices could cause appreciable bias in the estimation of secular trends in IHD mortality. This problem could largely be overcome by reviewing fatal events where the death certificate was coded to one of a limited number of other ICD rubrics.

Adult↗
PubMed2004

Quality of patient-reported outcome data captured using paper and interactive voice response diaries in an allergic rhinitis study: is electronic data capture really better?

BACKGROUND: Accuracy and reliability of diary data collected in allergic rhinitis trials depends on how and when the information is recorded by the subjects. OBJECTIVE: To compare diary data collected by using paper (optical mark readable) and electronic [telephone, interactive voice response system (IVRS)] tools. METHODS: There was a randomized, 3-week, 3-way, crossover trial, in 87 adults with allergic rhinitis recording diary data at home. Outcome measures were (1) comparison of symptom data during weeks when both or only 1 instrument was used; (2) missing data: and (3) ease of use and participant preference. RESULTS: More than 40,000 symptom data elements were recorded by 72 protocol-correct subjects. Symptoms recorded during the week that both instruments were used and when the 2 instruments were used alone were indistinguishable. Overall, 0.45% of paper and 4.12% of IVRS symptom data were missing. Of 10,080 paired data collected on paper and IVRS diaries during the week in which subjects used both, 94.44% were identical. Using IVRS, 63.2% of protocol-correct data were entered within the designated time and 87.6% within 1 half-day of the time specified; 85% of subjects preferred the paper instrument, 4% preferred IVRS, and 11% had no preference. CONCLUSIONS: A paper-based instrument can capture data indistinguishable from data captured from an electronic product. Processes to collect diary data should be evaluated for each study rather than simply to use the "latest" technology. Another interpretation is that frequency of recording diary data does not have a significant impact on outcomes.

Adult↗
PubMed2004

Using administrative data to measure ambulatory mental health service provision in primary care.

OBJECTIVE: We sought to determine the accuracy of administrative data for identifying mental health service provision in primary care. STUDY DESIGN: This was a chart abstraction study measuring agreement between billing data and clinical data on the binary variable "mental health visit." Data were collected from the charts and billing records of 5 academic family practice clinics in Toronto, Ontario (1999 to 2000). Billing claims (n = 952) were selected from the billings for all visits by a stratified random sampling technique. A blinded data abstractor reviewed the clinical charts and assigned diagnostic codes for each patient visit associated with the selected claims. Any visit with at least 1 abstracted mental health diagnostic code was defined as a mental health visit. The test characteristics of 4 administrative measures of mental health service provision, based on different combinations of billing codes, were calculated. RESULTS: The accuracy of the administrative data was 86.8% when compared with clinical data. The sensitivity of the 4 administrative measures ranged from 22.3% to 80.7%. The specificity ranged from 97.0% to 99.5%. CONCLUSIONS: This is the first study to establish the performance of administrative data in measuring mental health service provision in a primary care setting. In our setting, broadly defined administrative measures of mental health have excellent specificity and adequate sensitivity for exploring and understanding mental health service utilization.

Adult↗
PubMed2004

The accuracy of various tests for bacterial vaginosis in predicting preterm birth: a systematic review.

OBJECTIVE: To determine the accuracy with which various types of tests for bacterial vaginosis predict spontaneous preterm birth in pregnant women. DATA SOURCES: Studies were identified without language restrictions through nine different databases, and manual searching of bibliographies of known primary and review articles. STUDY SELECTION AND DATA EXTRACTION: There are four different bacterial vaginosis testing methods: Gram staining tests using either Nugent's or Spiegel's criteria, and gas liquid chromatography are laboratory based, and the fourth method uses clinical (Amsel's) criteria to diagnose bacterial vaginosis. Two reviewers independently selected studies and extracted data on their characteristics, quality and accuracy. Accuracy data were used to form 2 x 2 contingency tables of the bacterial vaginosis test results with spontaneous preterm birth as the reference standard. DATA SYNTHESIS: Data on asymptomatic women and women with symptoms of threatened preterm labour were analysed separately. Data were pooled to produce summary estimates of likelihood ratios for positive (LR+) and negative (LR-) test results for the various types of tests. RESULTS: There were 18 primary articles, involving altogether 17,868 women. There was unexplained heterogeneity in the meta-analyses of the accuracy results, which requires caution in their interpretation. Meta-analyses of studies testing asymptomatic women in the second trimester showed that clinical criteria had a LR+ of 0.98 (95% confidence interval 0.59 to 1.6) and a LR- of 1.00 (0.93 to 1.1), Gram staining (Nugent's criteria) had a LR+ of 1.6 (1.4 to 1.9) and a LR- of 0.9 (0.8 to 0.9), and Gram staining (Spiegel's criteria) had a LR+ of 2.4 (1.4 to 4.9) and a LR- of 0.81 (0.64 to 1.0). Among symptomatic women, Gram staining (Spiegel's criteria) had a LR+ of 1.3 (1.0 to 1.6) and LR- of 0.9 (0.7 to 1.0). CONCLUSION: There was a lack of difference in the accuracy of the various bacterial vaginosis tests for predicting preterm birth in both asymptomatic and symptomatic women of threatened preterm labour.

Bacteriological Techniques↗
PubMed1994

How accurate are Scottish cancer registration data?

In order to assess the accuracy of Scottish cancer registration data, a random sample of 2,200 registrations, attributed to the year 1990, was generated. Relevant medical records were available for review in 2,021 (92%) cases. Registration details were reabstracted from available records and compared with data in the registry. Discrepancies in identifying items of data (surname, forename, sex and date of birth) were found in 3.5% of cases. Most were trivial and would not disturb record linkage. Discrepancy rates of 7.1% in post code of residence at the time of diagnosis (excluding differences arising through boundary changes), 11.0% in anniversary date (excluding differences of 6 weeks or less), 7.7% in histological verification status, 5.4% in ICD-9 site codes (the first three digits) and 14.5% in ICD-O morphology codes (excluding 'inferred' morphology codes) were recorded. Overall, serious discrepancies were judged to have occurred in 2.8% of cases. In many respects, therefore, Scottish cancer registration data show a high level of accuracy that compares favourably to the reported accuracy of the few other cancer registries undertaking such analyses.

Female↗
PubMed1993

Field molecular epidemiology. Feasibility of monitoring for the malignant bladder cell phenotype in a benzidine-exposed occupational cohort.

Modern molecular and cellular biology have provided powerful new approaches to study cancer in the research laboratory, but these techniques have not been used extensively in field studies or in screening of high-risk occupational cohorts. The primary objective of this study was to demonstrate the use of cellular and molecular methods in combination with medical and epidemiologic methods to identify cancer cases, risk factors, and markers in a previously identified and defined cohort of Chinese workers exposed to benzidine. The screening of exposed workers included occupational, medical, and smoking histories to identify exogenous risk factors, a limited physical examination, Papanicolaou (PAP) urinary cytology, measurement of urine pH, quantitative fluorescence image analysis (QFIA) cytology to detect DNA hyperploidy, and quantitative fluorescence to detect expression of a low-grade bladder tumor-associated antigen (p300) by exfoliated urothelial cells and elevated expression of the neu oncogene product (p185). Detailed analysis of the accuracy of epidemiologic data and the adequacy of samples and accuracy of molecular techniques was carried out. Three groups were included in this study: group 1 included 23 bladder cancer cases who had previously been exposed to benzidine and served as two surrogates for late-emerging disease; group 2 consisted of 20 subjects with previous exposure history but not previously diagnosed with bladder cancer; and group 0 was the nonexposure and nonbladder cancer controls. The results showed that accurate questionnaire data and urine samples can be obtained at remote sites. Among the 20 group 2 subjects, two displayed abnormal findings by both QFIA cytology and p300 expression and were later confirmed to have bladder cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

Benzidines↗
PubMed1989

A comparison of interview data and medical records for previous medical conditions and surgery.

Although interview information is usually the sole source of data in case-control studies, the accuracy of such data is infrequently assessed. We compared interview data on selected medical conditions and surgical procedures with medical records of subjects with chronic lymphocytic leukemia. We examined agreement by type of respondent (self or surrogate), age, sex, race, and type of hospital. The strength of agreement between the two data sources (as measured by kappa statistics) was substantial kappa greater than 0.6) for splenectomy, appendectomy, asthma, and systemic lupus erythematosus; moderate kappa greater than 0.4) for tonsillectomy/adenoidectomy, tuberculosis, diverticulitis, hepatitis, rheumatic fever, and drug allergy; and poor kappa less than 0.3) for chronic bronchitis, chronic sinusitis, psoriasis, rheumatoid arthritis, and most other types of allergy. In general, self respondents had more accurate recall than surrogate respondents. Among self respondents the strength of agreement tended to be greater for males than females, for whites than blacks, and for subjects from referral hospitals than for community hospitals. No consistent patterns were apparent by age. Despite a number of limitations, the findings of the study provide an addition to the scant epidemiologic literature on this topic, and suggest that for certain conditions medical record data collection may be needed to supplement interview information.

Aged↗
PubMed1996

Methodological considerations in participant event monitoring of low-base-rate events in health psychology: children's injuries as a model.

The present article outlines the advantages of the participant event monitoring methodology for the investigation of unpredictable, low-base-rate events in children. Several methods for assessing the quality of participant event monitoring data are advanced with a data set showing participant event monitoring of children's minor injuries by 61 children and their mothers. Child-mother correspondence and debriefing data suggest good accuracy for frequency estimates. Home- and laboratory-based simulations illustrate the participant event monitors' accuracy for major details. Traditional measures of data quality show good overall coder and test-retest reliability, and cross-observer reports show acceptable estimates of validity for objective aspects of the events and the expected lower estimates for the more subjective aspects. Conceptual and pragmatic difficulties of the method are considered, and suggestions for future research are advanced.

Accident Prevention↗
PubMed1999

A strategy for rapid sequencing of heparan sulfate and heparin saccharides.

Sulfated glycosaminoglycans (GAGs) are linear polysaccharides of repeating disaccharide sequences on which are superimposed highly complex and variable patterns of sulfation, especially in heparan sulfate (HS). HS and the structurally related heparin exert important biological functions, primarily by interacting with proteins and regulating their activities. Evidence is accumulating that these interactions depend on specific saccharide sequences, but the lack of simple, direct techniques for sequencing GAG saccharides has been a major obstacle to progress. We describe how HS and heparin saccharides can be sequenced rapidly by using an integrated strategy with chemical and enzymic steps. Attachment of a reducing-end fluorescent tag establishes a reading frame. Partial selective chemical cleavage at internal N-sulfoglucosamine residues with nitrous acid then creates a set of fragments of defined sizes. Subsequent digestion of these fragments with combinations of exosulfatases and exoglycosidases permits the selective removal of specific sulfates and monosaccharides from their nonreducing ends. PAGE of the products yields a pattern of fluorescent bands from which the saccharide sequence can be read directly. Data are presented on sequencing of heparin tetrasaccharides and hexasaccharides of known structure; these data show the accuracy and versatility of this sequencing strategy. Data also are presented on the application of the strategy to the sequencing of an HS decasaccharide of unknown structure. Application and further development of this sequencing strategy, called integral glycan sequencing, will accelerate progress in defining the structure-activity relationships of these complex GAGs and lead to important insights into their biological functions.

Carbohydrate Sequence↗
PubMed1997

Diagnostic accuracy of a rural live video telepathology system.

Accuracy of diagnoses rendered using a live video telepathology network was assessed for permanent sections of surgical pathology specimens. To determine accuracy, telepathology diagnoses were compared with those obtained by directly viewing the glass slide using a standard microscope. A total of 294 cases were read via both telepathology and glass slide by attending pathologists at a tertiary care medical center. Overall accuracy was defined as exact concordance between diagnoses. Clinically insignificant differences in diagnoses were excluded to determine clinically significant accuracy. For the 285 cases with complete data, the overall accuracy for telepathology was 0.912 (95% confidence interval [CI], 0.872-0.941), whereas the overall accuracy for glass slide readings was 0.968 (95% CI, 0.939-0.985). This difference is statistically significant (p = 0.009). When focusing on clinically significant discrepancies, where the difference in diagnosis might affect therapeutic decisions, the video accuracy was only slightly less than the glass slide accuracy (0.965 [95% CI, 0.934-0.982] vs. 0.982 [95% CI, 0.957-0.994], respectively), but this difference is not statistically significant (p = 0.302). Most of the cases with clinically significant differences involved lesions with inherently high interobserver variation. Certainty of diagnosis did not differ between video and glass slide readings (p = 0.911), but there was an association between certainty of diagnosis and diagnostic accuracy for video (p = 0.003 for clinically significant accuracies). Based on these findings, we recommend when using this telepathology system that only preliminary diagnoses should be given in the following situations: for diagnostic areas with known high interobserver variability; when the consultant has any degree of uncertainty about the presence or absence of the lesion in question; and when there is insufficient experience using telepathology as a diagnostic medium.

Crohn Disease↗
PubMed1995

Comparison of different X-ray data-collection systems using the crystal structure of octreotide.

The octapeptide octreotide crystallizes with three peptide molecules and about 20% water in the asymmetric unit, and in many ways possesses diffraction properties similar to those of a 'mini-protein' consisting of 24 amino-acid residues. It diffracts to about 1.0 A but data in the range 1.4-1.0 A are weak. It provides a suitable test of different macromolecular X-ray data-collection techniques, especially of their ability to measure weak reflections accurately. In contrast to typical proteins it is possible to perform a full anisotropic refinement, that we believe provides a more objective test of the quality of the data than the internal consistency of equivalent reflections. We have collected a total of six data sets. The X-ray sources included synchrotron radiation, Cu Kalpha rotating anodes and Mo Kalpha sealed tubes; position-sensitive two-dimensional detectors from four manufacturers and a four-circle diffractometer with scintillation counter were employed. Two of the six data sets were collected at low temperature. Reasonable anisotropic refinement was possible with all area-detector data sets, although significant differences in the precision of the final model were observed. In addition we tested the ability of automated Patterson interpretation to solve the structure using the six independent data sets. The structure solution was only successful using the synchrotron or rotating-anode data sets, i.e. for the more intense sources. It appears that for structure solution the maximum resolution of the data is critical, whereas for refinement the accuracy of the data is more important.

Journal Article↗
PubMed1991

Correlation dimension of heartbeat intervals is reduced in conscious pigs by myocardial ischemia.

A reduced standard deviation of RR intervals (SDRR) predicts increased mortality in groups of survivors of myocardial infarction. Like SDRR, the correlation dimension (D2) describes variation within a sampled time series, but uniquely it reveals 1) the epoch's geometric structure and 2) the degrees of freedom of the generator. These unique features may be more sensitive predictors of mortality than SDRR. We developed a new algorithm for estimating D2 (i.e., the "point-D2"), tested it with known data, and found that it had greater accuracy for finite data than other published algorithms. Analysis of RR intervals from eight conscious pigs undergoing acute occlusion of the left anterior descending coronary artery revealed a drop in the point-D2 from a control mean and standard deviation of 2.50 +/- 0.81 to 1.58 +/- 0.64 during the first minute of ischemia (p less than 0.01) and to 1.07 +/- 0.18 during the last minute preceding ventricular fibrillation (p less than 0.01). Partial occlusions (50-90% reduction of coronary blood flow) evoked point-D2 reductions only 25-30% of control (p less than 0.01). The point-D2 means were correlated between pigs with the magnitude of the respiratory sinus arrhythmia (p less than 0.01), but during ischemia this correlation was replaced by one between the standard deviation of the point-D2s and SDRRs. Because the simultaneous reduction in the mean point-D2 and its standard deviation to 1.07 +/- 0.18 occurred in every case, was unique to the few minutes preceding ventricular fibrillation, and never reached these low values during other conditions in which it was reduced, we conclude that the point-D2 may be an accurate prospective predictor of mortality within the individual subject.

Algorithms↗
PubMedDate not supplied

Accuracy of enteral pumps: in vitro performance.

There are few data on the accuracy of pumps used to deliver enteral formulas. Enteral pump manufacturers claim that accuracy is within 10% of the selected flow rate. We evaluated 15 pumps: Flexiflo Companion (n = 5), Travenol 2100 (n = 5), and Kangaroo 324 (n = 5). Three types of formula at room temperature were infused at 10, 100, and 300 mL/h. The formulas used were Jevity, Ensure Plus, and Suplena with added Promod. The Flexiflo Companion and Kangaroo 324 pumps delivered 90% to 110% of the expected volume using the ready-to-feed formulas. The Travenol 2100 pumps averaged less than 90% of the selected flow rates for the three formulas infused. All three pumps delivered less than 90% of the expected volume using a formula with an added powder, but the Travenol 2100 delivered the highest volume of this same formula. There was no significant difference in the delivery of Jevity with the Flexiflo Companion (104% +/- 5% SD) and the Kangaroo 324 pumps (99% +/- 4% SD), but the flow rate was significantly lower with the Travenol 2100 pumps (80% +/- 6% SD). There was no significant difference in the flow rate of Ensure Plus with the Kangaroo 324 (95% +/- 7% SD) and the Travenol 2100 pumps (89% +/- 4% SD). The flow rate of Ensure Plus with the Flexiflo Companion pumps was significantly higher (107% +/- 4% SD).(ABSTRACT TRUNCATED AT 250 WORDS)

Enteral Nutrition↗
PubMed1976

Comparison of nonretarded and mentally retarded children on a perceptual learning task.

The performances of 12 EMR and 12 nonretarded sixth-grade children on a perceptual learning task were compared to investigate the information processing of visually presented stimuli in individuals with different intelligence levels. A minicomputer flashed either familiar (lowercase) or unfamiliar letters (Gibson-like figures) in either a stimultaneous or successive mode on a same-different matching task. The computer automatically calculated accuracy and latency data for each subject. Results showed that accuracy was superior in the nonretarded group and that mean latencies for the EMR group was consistently higher than those of the nonretarded group. However, when latencies were corrected for differences in basic reaction time, there were no significant differences between the groups in the speed of processing the information.

Attention↗
PubMed1997

Supercritical fluid extraction of selected pharmaceuticals from water and serum.

Selected drugs from benzodiazepine, anabolic agent and non-steroidal anti-inflammatory drug (NSAID) therapeutic classes were extracted from water and serum using a supercritical CO2 mobile phase. The samples were extracted at a pump pressure of 329 MPa, an extraction chamber temperature of 45 degrees C, and a restrictor temperature of 60 degrees C. The static extraction time for all samples was 2.5 min and the dynamic extraction time ranged from 5 to 20 min. The analytes were collected in appropriate solvent traps and assayed by modified literature HPLC procedures. Analyte recoveries were calculated based on peak height measurements of extracted vs. unextracted analyte. The recovery of the benzodiazepines ranged from 80 to 98% in water and from 75 to 94% in serum. Anabolic drug recoveries from water and serum ranged from 67 to 100% and 70 to 100%, respectively. The NSAIDs were recovered from water in the 76 to 97% range and in the 76 to 100% range from serum. Accuracy, precision and endogenous peak interference, if any, were determined for blank and spiked serum extractions and compared with classical sample preparation techniques of liquid-liquid and solid-phase extraction reported in the literature. For the benzodiazepines, accuracy and precision for supercritical fluid extraction (SFE) ranged from 1.95 to 3.31 and 0.57 to 1.25%, respectively (n = 3). The SFE accuracy and precision data for the anabolic agents ranged from 4.03 to 7.84 and 0.66 to 2.78%, respectively (n = 3). The accuracy and precision data reported for the SFE of the NSAIDs ranged from 2.79 to 3.79 and 0.33 to 1.27%, respectively (n = 3). The precision of the SFE method from serum was shown to be comparable to the precision obtained with other classical preparation techniques.

Anabolic Agents↗
PubMedDate not supplied

Artifacts and thresholding in X-ray CT of a cortical bone and titanium composite.

PURPOSE: X-Ray CT has the potential to provide precise and accurate data from which the mechanical properties of bone can be calculated. Such data would be useful in understanding the response of bone tissue to implants. Various artifacts can, however, degrade accuracy of the data. The aim of this study was to measure the artifactual errors produced in CT of a simulated femoral bone-titanium composite and to propose a method to correct for them. METHOD: A composite phantom that simulates cortical bone and a titanium implant was designed and constructed. The phantom was scanned and the image data were analyzed over a range of thresholds with image analysis software developed for this study. The outer (OD) and inner (ID) diameter and the CT number of the cortical bone, with and without titanium, were measured over a range of cortical thicknesses. RESULTS: While ID can be accurately measured by choosing the proper threshold (800 HU), OD, even at optimal threshold, will be underestimated by approximately 2%. If a proper threshold is selected, CT number can also be accurately determined. Errors of up to 5%, however, are produced by titanium unless corrected by proper threshold selection. CONCLUSION: Intramedullary titanium is not a deterrent to obtaining accurate measurements of cortical bone dimensions and properties. Proper choice of thresholds for image analysis of CT scan data can yield accuracy and precision of < or = 2%.

Artifacts↗