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PubMed1991

Data compression: effect on diagnostic accuracy in digital chest radiography.

High-resolution digital images make up very large data sets that are relatively slow to transmit and expensive to store. Data compression techniques are being developed to address this problem, but significant image deterioration can occur at high compression ratios. In this study, the authors evaluated a form of adaptive block cosine transform coding, a new compression technique that allows considerable compression of digital radiographs with minimal degradation of image quality. To determine the effect of data compression on diagnostic accuracy, observer tests were performed with 60 digitized chest radiographs (2,048 x 2,048 matrix, 1,024 shades of gray) containing subtle examples of pneumothorax, interstitial infiltrate, nodules, and bone lesions. Radiographs with no compression, with 25:1 compression, and with 50:1 compression ratios were presented in randomized order to 12 radiologists. The results suggest that, with this compression scheme, compression ratios as high as 25:1 may be acceptable for primary diagnosis in chest radiology.

Humans↗
PubMed1997

Accuracy of birth certificate data regarding the amount, timing, and adequacy of prenatal care using prenatal clinic medical records as referents.

This study compared birth certificate data on the amount, timing, and adequacy of prenatal care with the same data abstracted from the prenatal clinic records of 2,032 women who attended a health department prenatal clinic in northeast Georgia from 1980 to 1988. Overall accuracy was poor. Only 14.3% (n = 291) of the records completely agreed on the total number of visits, while approximately 36% (n = 738) and 53% (n = 1,081) agreed within one visit and two visits, respectively. Complete agreement for month and trimester prenatal care began was 31.1% (n = 632) and 50.6% (n = 1,202), respectively. Because of the small geographic region included in the current study, the generalizability of these findings to other populations may be limited.

Adult↗
PubMed2007

Accuracy of Medicare claims data in identifying Parkinsonism cases: comparison with the Medicare current beneficiary survey.

STUDY PURPOSE: Administrative databases are commonly used to examine use of healthcare service, with researchers relying on diagnostic codes to identify medical conditions. This study evaluates the accuracy of administrative claims in identifying Parkinsonism cases compared to the self-reported Parkinson's disease (PD). METHODS: The reference cases were identified based on the self-reported PD status and the use of PD drugs collected by the 1992-2000 Medicare Current Beneficiary Survey that contained 72,922 observations from 30,469 individuals. Using ICD-9 CM, cases with PD were extracted from the corresponding Medicare claims. We compared prevalence of PD obtained using different types of claims. RESULTS: The sensitivities were the highest when all claims were used (66%). All the specificities were greater than 99%. When drug use information was included in the gold standard, the sensitivities became lower, while the specificities and positive predictive values (PPVs) increased. Using more diagnostic codes improved the sensitivity of the identification process but reduced PPVs. CONCLUSIONS: Administrative claims can provide fairly accurate and practical approach to "rule in" patients with PD. Depending on the purpose of evaluation, researchers may consider using more categories of claims to improve the sensitivity of the identification algorithm or use fewer diagnoses to minimize number of false positive cases.

Aged↗
PubMed1997

Is congruence between data partitions a reliable predictor of phylogenetic accuracy? Empirically testing an iterative procedure for choosing among phylogenetic methods.

The relationship between phylogenetic accuracy and congruence between data partitions collected from the same taxa was explored for mitochondrial DNA sequences from two well-supported vertebrate phylogenies. An iterative procedure was adopted whereby accuracy, phylogenetic signal, and congruence were measured before and after modifying a simple reconstruction model, equally weighted parsimony. These modifications included transversion parsimony, successive weighting, and six-parameter parsimony. For the data partitions examined, there is a generally positive relationship between congruence and phylogenetic accuracy. If congruence increased without decreasing resolution or phylogenetic signal, this increased congruence was a good predictor of accuracy. If congruence increased as a result of poor resolution, the degree of congruence was not a good predictor of accuracy. For all sets of data partitions, six-parameter parsimony methods show a consistently positive relationship between congruence and accuracy. Unlike successive weighting, six-parameter parsimony methods were not strongly influenced by the starting tree.

Animals↗
PubMed2005

Evaluating diagnostic accuracy in appendicitis using administrative data.

BACKGROUND: Research techniques using administrative data have been used to assess quality of care in the management of appendicitis, but their validity has not been assessed. This study assessed the validity of a research technique using administrative data to determine whether patients undergoing an appendectomy actually had appendicitis or if they had a negative appendectomy (NA). MATERIALS AND METHODS: A retrospective study of patients at Group Health Cooperative of Puget Sound undergoing appendectomy from 1991-1999 was conducted to compare the accuracy of administrative codes with data abstracted from medical records. RESULTS: Of 1823 nonincidental appendectomies (mean age 31 +/- 18.6 years, 49.6% female), 280 did not have appendicitis by criteria applied to administrative data (15.4%). The accuracy of this method for determining appendicitis was determined by medical record evaluation revealing sensitivity (98.6%), specificity (48.6%), positive predictive value for appendicitis (83.8%), and negative predictive value for NA (70.4%). When the administrative-data technique did not classify a patient as having had appendicitis, chart-abstracted data indicated appendicitis in 6.4%, and an incorrectly labeled incidental appendectomy in 23.2%. The administrative-data technique for detecting NA erroneously included many cases of incidental appendectomy and missed many cases of clinically confirmed NA. More than half of clinical NAs were missed by the administrative technique. CONCLUSIONS: In this setting, the sensitivity of administrative-data techniques for the detection of appendicitis was excellent, but their adequacy for identifying patients undergoing NA was limited. The use of this technique as a quality measure should be reconsidered.

Adolescent↗
PubMed2003

Assessment of clinical utility of 18F-FDG PET in patients with head and neck cancer: a probability analysis.

The purpose of this study was to calculate disease probabilities based on data of patients with head and neck cancer in the register of our institution and to perform a systematic review of the available data on the accuracy of PET in the primary assessment and follow-up of patients with head and neck cancer. The pre-test probability of head and neck cancer among patients in our institutional data registry was assessed. Then the published literature was selected and appraised according to a standard protocol of systematic reviews. Two reviewers independently selected and extracted data on study characteristics, quality and accuracy. Accuracy data were used to form 2 x 2 contingency tables and were pooled to produce summary receiver operating characteristic (ROC) curves and summary likelihood ratios for positive and negative testing. Finally post-test probabilities were calculated on the basis of the pre-test probabilities of this patient group. All patients had cytologically or histologically proven cancer. The prevalence of additional lymph node metastases on PET in staging examinations was 19.6% (11/56), and that of locoregional recurrence on restaging PET was 28.6% (12/42). In the primary assessment of patients, PET had positive and negative likelihood ratios of 3.9 (2.56-5.93) and 0.24 (0.14-0.41), respectively. Disease probabilities were therefore 49.4% for a positive test result and 5.7% for a negative test result. In the assessment of recurrence these values were 3.96 (2.8-5.6) and 0.16 (0.1-0.25), resulting in probabilities of 49.7% and 3.8%. PET evaluation for involvement of lymph nodes had positive and negative likelihood ratios of 17.26 (10.9-27.3) and 0.19 (0.13-0.27) for primary assessment and 11.0 (2.93-41.24) and 0.14 (0.01-1.88) for detection of recurrence. The probabilities were 81.2% and 4.5% for primary assessment and 73.3% and 3.4% for assessment of recurrence. It is concluded that in this clinical setting the main advantage of PET is the ability to reliably rule out the presence of disease in both staging and restaging. Further research is required to derive probabilities for individual patients from sequential testing as applied in the diagnostic work-up of patients with head and neck cancer.

Adult↗
PubMed1979

Accuracy of birth certificate data for detecting facial cleft defects in Arkansas children.

A comparison of facial cleft defects reported on birth certificates during the period 1943 to 1974 that were reported on birth certificates was made with records maintained by the Arkansas Crippled Childrens Services (CCS). A total of 506 cases were reported of which 331 (65%) were recorded on the birth certificate. Moreover, the accuracy of the reporting was not good. Only 243 (48%) cleft malformations were correctly classified on the birth certificate. Birth certificate information is an inadequate measure of the true facial cleft occurrence in Arkansas. Caution must be exercised when this data source is used in epidemiological surveys because over one-third of such defects were not recorded. These findings serve to reemphasize the national need to improve the quality of such vital health statistics sources.

Arkansas↗
PubMed1980

Accuracy of bone mineral data.

The reliability of data obtained from the Norland-Cameron Bone Mineral Analyzer has been questioned and the possibility of an inherent calibration error in the machine has been raised. To make an absolute measurement of the instrumental accuracy, bone mineral content measured by the bone mineral analyzer was compared with an absolute value obtained by the ashing method. The instrument bone mineral content values were found to be higher by about 6.5%. The ash content (%), bone mineral density, and compact bone density in these same bone samples were 62.9%, 1.346 g/cm3, and 2.140 g/cm3, respectively, as determined by direct measurement.

Bone and Bones↗
PubMedDate not supplied

Determination of niacin in infant formula by solid-phase extraction/liquid chromatography: peer-verified method performance-interlaboratory validation.

This paper reports the results of the interlaboratory peer validation study of AOAC Peer-Verified Method (PVM) 1:2,000 for the determination of niacin in infant formula by solid-phase extraction/liquid chromatography. We have used a Data Quality Objectives (DQO) approach to address not only method variability and robustness but also accuracy of data through the use of an appropriate reference material in conjunction with the interlaboratory validation study. Our DQO included the following: (1) statistical agreement of analytical results and quantitative recovery between 2 collaborating laboratories; (2) the repeatability relative standard deviation (RSDr) values and the HORRAT (Horwitz ratio) obtained (1.07), which satisfied the criteria of the Horwitz "limits of acceptability" at the analyte level present; (3) validation of lack of interference; and (4) accuracy agreement within assigned values for a certified reference material. National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1846 Infant Formula, with a certified value of 63.3 +/- 7.6 microg/g for niacin content, was used as a test material for collaborative study and accuracy assessment. Niacin values obtained by the originating laboratory were 59.7 +/- 4.0 microg/g (95% confidence interval [CI] = 1.4 microg/g with a relative standard deviation [RSD] of 6.7%) and by the peer laboratory were 56.6 +/- 6.6 microg/g (95% CI = 4.1 microg/g, with an RSD of 11.7%). Statistical evaluation using the means equivalence test showed that nicotinic acid values obtained by the peer laboratory were equivalent to those values obtained by the originating laboratory. Linear calibration curves and quantitative recovery were obtained. Integration of the PVM process with a readily available certified reference material gives the user confidence in the accuracy of the data generated by the method through traceability to the reference material used.

Chromatography, Liquid↗
PubMed1992

The accuracy of Medicare's hospital claims data: progress has been made, but problems remain.

BACKGROUND: Health care databases provide a widely used source of data for health care research, but their accuracy remains uncertain. We analyzed data from the 1985 National DRG Validation Study, which carefully reabstracted and reassigned ICD-9-CM diagnosis and procedure codes from a national sample of 7050 medical records, to determine whether coding accuracy had improved since the Institute of Medicine studies of the 1970s and to assess the current coding accuracy of specific diagnoses and procedures. METHODS: We defined agreement as the proportion of all reabstracted records that had the same principal diagnosis or procedure coded on both the original (hospital) record and on the reabstracted record. We also evaluated coding accuracy in 1985 using the concepts of diagnostic test evaluation. RESULTS: Overall, the percentage of agreement between the principal diagnosis on the reabstracted record and the original hospital record, when analyzed at the third digit, improved from 73.2% in 1977 to 78.2% in 1985. However, analysis of the 1985 data demonstrated that the accuracy of diagnosis and procedure coding varies substantially across conditions. CONCLUSIONS: Although some diagnoses and all major surgical procedures that we examined were accurately coded, the variability in the accuracy of diagnosis coding poses a problem that must be overcome if claims-based research is to achieve its full potential.

Abstracting and Indexing↗
PubMed1991

Predictors of the accuracy of telephoned dietary recall data in a group of free-living elderly subjects.

As part of a study evaluating the accuracy of dietary intake data from telephoned 24-hour dietary recalls, an attempt was made to predict, on the basis of their health, social, demographic and dietary characteristics, which subjects would provide data containing the greatest error. Unexpectedly, the statistical model for the overall error score was predictive of smaller rather than larger errors. All variables it contained were reasons why an individual might have a heightened awareness of their food consumption. Work should be undertaken to determine whether this model also has predictive ability in face-to-face dietary interview settings and with non-elderly subjects.

Aged↗
PubMed2003

MMR vaccine uptake rates: a data validation study.

As part of our investigation into the decrease in the measles, mumps and rubella (MMR) vaccine uptake rates, we validated MMR vaccination records of all children born between 01/09/1998 and 31/08/1999 in our area (North Cheshire, South Cheshire, and Wirral). A significant number of children had received their MMR vaccine but were not recorded as such by the Child Health Computer System (CHCS). Reported COVER (cover of vaccination evaluated rapidly) data uptake (combined) for North Cheshire, South Cheshire, and Wirral Health Authorities for the period covered by the data validation study was 90.5%, the corrected uptake following the validation was 92.6%, 2.1% higher than the reported coverage. If the coverage data were to continue to form part of the NHS indicators of PCT performance, action by all PCTs to improve accuracy of immunisation data would be highly desirable. Electronic transfer of information from practices to the CHCS and between CHCSs, i.e. across boundaries, could improve data accuracy.

Child↗
PubMed2005

Automatic scoring and quality assessment using accuracy bounds for FP-TDI SNP genotyping data.

BACKGROUND: Human diversity, namely single nucleotide polymorphisms (SNPs), is becoming a focus of biomedical research. Despite the binary nature of SNP determination, the majority of genotyping assay data need a critical evaluation for genotype calling. We applied statistical models to improve the automated analysis of 2-dimensional SNP data. METHODS: We derived several quantities in the framework of Gaussian mixture models that provide figures of merit to objectively measure the data quality. The accuracy of individual observations is scored as the probability of belonging to a certain genotype cluster, while the assay quality is measured by the overlap between the genotype clusters. RESULTS: The approach was extensively tested with a dataset of 438 nonredundant SNP assays comprising >150,000 datapoints. The performance of our automatic scoring method was compared with manual assignments. The agreement for the overall assay quality is remarkably good, and individual observations were scored differently by man and machine in 2.6% of cases, when applying stringent probability threshold values. CONCLUSION: Our definition of bounds for the accuracy for complete assays in terms of misclassification probabilities goes beyond other proposed analysis methods. We expect the scoring method to minimise human intervention and provide a more objective error estimate in genotype calling.

Algorithms↗
PubMed1989

Using microcomputers to improve the timeliness, accuracy, and accessibility of clinical data.

This article presents a microcomputer system as a solution to achieve timely, accurate and accessible clinical data. The article describes the components of the clinical data system as well as its functionality. The advantages of automated encoders for coding, editing and grouping of clinical data are outlined, as well as the advantages of relational database software for clinical data management. Clinical data support a myriad of activities within the health care facility. The microcomputer system provides the departmental user with flexibility and customization to meet and manage the ever-changing clinical data requirements. Client hospital experience demonstrate, not only an increase in the accuracy and availability of data, but also an increase in the productivity of the data collection process itself.

Abstracting and Indexing↗
PubMed1994

Evaluating the accuracy of transcribed computer-stored immunization data.

OBJECTIVE: To evaluate the accuracy of immunization records transcribed into a computer-based immunization tracking system and to assess factors that contribute to inaccurate or incomplete immunization record keeping. DESIGN: Computer-stored immunization records were analyzed for 2098 children up to 2 years of age at the time of their most recent well-child visit to the UCLA Children's Health Center over a 12-month period. For children whose immunizations were not up to date, the computer-stored records were analyzed for sources of inaccuracy by comparison with the handwritten records from which the computer-stored data were transcribed. RESULTS: An underimmunization rate of 22.5% (472 of 2098) was observed based on analysis of the computer-stored records. Comparison of the computer-stored and handwritten records revealed an overall transcription error rate of at least 10.2%. In addition, 38.4% of these apparently underimmunized children had received unrecorded immunizations from providers outside UCLA. When transcription errors were corrected and other available sources of immunization data were taken into account, the estimated rate of underimmunization decreased from 22.5% to 10.9%. CONCLUSION: Unavoidable inaccuracies can diminish the utility of the data recorded in an immunization tracking system. Some inaccuracies are related to the process of transcription, but failures to record and communicate immunization data consistently also contribute to the inaccuracy of computer-stored immunization records.

Child Health Services↗
PubMed2001

Reliability and accuracy of environmental analytical data on moss samples: an interlaboratory comparison.

An inter-comparison exercise was performed between two laboratories on mineralised moss samples. Ten samples, together with three certified reference materials (CRM 61, CRM 62 and CRM 482) and five blanks were mineralised independently in the two laboratories and then analysed by both with different techniques (AAS, ICP-MS, and INAA). The elements analysed were: Cd, Cr, Cu, Fe, Ni, and Pb. Accuracy tests showed that, for AAS, the relative standard deviations for five repetitions of the same sample were between 0.2% for Cd and 2.9 % for Cr and that the concentration values found reference materials were withn one standard deviation from the certified values, with the exception of Cr and Cd for CRM 482. The statistical analysis was performed first with a simple linear regression and a Student t-test taking into account the possible influence of the mineralisation procedure and of the analytical technique, in order to evaluate their reliability. The results showed that more than 78% of the regressions had a correlation coefficient higher than 0.750, and that 83% of the slopes were not different from one with a level of significance of 0.01. Afterwards, the precision of the measurements were evaluated using maximum likelihood; the normalised errors showed that ICP-MS had a better performance on most of the elements analysed (with the exception of Fe) and that both the mineralisation procedures gave satisfactory results. The two laboratories were then found to produce reliable results.

Bryopsida↗
PubMed1987

Using administrative data for longitudinal research: comparisons with primary data collection.

This paper discusses the advantages and disadvantages of using administrative data for longitudinal research, focusing on loss to follow-up. Comparisons between research relying on primary data collection and that using data bases are made. After development of a suitable framework, follow-up in several well-known projects based on primary data collection (the Seven Countries project on coronary heart disease, the Massachusetts research on long-term care and the Pittsburgh clinical trial of tonsillectomy) is compared with follow-up using the Health Services Commission data base in Manitoba, Canada. Overall follow-up in the Manitoba research compares favorably with participation and follow-up rates in other studies based on primary data collection. Initial nonresponse and nonlocation are major problems with studies using primary data; failure to locate earlier respondents in subsequent waves results in a wide range of overall response rates. Data bases do not require researchers to contact individuals and hence follow-up is simplified. Eight year follow-up rates in the Manitoba data base are almost always over 80% and often over 90%. Because records can be flexibly summarized for each individual over time, data bases facilitate certain types of longitudinal studies which would be difficult, if not impossible, to perform using other methodologies. If the desired data are available and recorded with acceptable accuracy, administrative data banks hold considerable promise for the health care researcher.

Adolescent↗
PubMed2004

COPD exacerbations: the importance of a standard definition.

Efforts to assess the efficacy of new therapies in the treatment of acute exacerbations of chronic obstructive pulmonary disease (COPD) have been hampered by the lack of a widely agreed and consistently used definition. A variety of definitions have been used in clinical studies, based on changes in patient symptoms or the requirement for antibiotic therapy, oral steroids or hospitalisation. To date, none of these definitions have been assessed in detail for their reliability, responsiveness and validity determined. Considerable heterogeneity in the aetiology and manifestation of COPD exacerbations makes identification and quantification of defining symptoms extremely difficult. New approaches are therefore being sought with a view to identifying a serum or tissue marker that can be used as a valuable diagnostic tool. Improvements in data recording will also contribute to the accuracy of data retrieval and assessment. If we are to progress to a level of sophistication seen in the diagnosis and management of other diseases, it is evident that considerable research efforts will be required to improve our understanding of COPD exacerbations and develop a standard definition for these events, thereby facilitating the assessment of therapeutic approaches.

Ambulatory Care↗