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PubMedDate not supplied

Overview of the reanalysis of the Harvard Six Cities Study and American Cancer Society Study of Particulate Air Pollution and Mortality.

This article provides an overview of the Reanalysis Study of the Harvard Six Cities and the American Cancer Society (ACS) studies of particulate air pollution and mortality. The previous findings of the studies have been subject to debate. In response, a reanalysis team, comprised of Canadian and American researchers, was invited to participate in an independent reanalysis project to address the concerns. Phase I of the reanalysis involved the design of data audits to determine whether each study conformed to the consistency and accuracy of their data. Phase II of the reanalysis involved conducting a series of comprehensive analyses using alternative statistical methods. Alternative models were also used to identify covariates that may confound or modify the association of particulate air pollution as well as identify sensitive population subgroups. The audit demonstrated that the data in the original analyses were of high quality, as were the risk estimates reported by the original investigators. The sensitivity analysis illustrated that the mortality risk estimates reported in both studies were found to be robust against alternative Cox models. Detailed investigation of the covariate effects found a significant modifying effect of education and a relative risk of mortality associated with fine particles and declining education levels. The study team applied spatial analytic methods to the ACS data, resulting in various levels of spatial autocorrelations supporting the reported association for fine particles mortality of the original investigators as well as demonstrating a significant association between sulfur dioxide and mortality. Collectively, our reanalysis suggest that mortality may be attributable to more than one component of the complex mixture of ambient air pollutants for U.S. urban areas.

Air↗
PubMed2004

Estimating the population burden of injuries: a comparison of household surveys and emergency department surveillance.

BACKGROUND: Injuries represent an important public health problem but their incidence is difficult to estimate. METHODS: We conducted a population-based household survey in Greece covering 4079 interviewed individuals. The interviewees reported, for themselves and for cohabitating adults (age 15 years and older; n = 7157), injuries that occurred during the preceding year. Major injuries were defined as those requiring contact with a health institution. We compared these survey data with data obtained through a national Emergency Department Injury Surveillance System (EDISS). RESULTS: For the month closest to the survey interview, the incidence reported for the responders was 5.9 per 100 person-year, whereas the incidence for cohabitating adults was 3.7 per 100 person-years. These incidence rates declined for months more remote to the interview. Comparison of survey and EDISS data suggested that survey reporting was less accurate for nontraffic-related injuries. Taking into account possible recall and telescoping biases, the best survey estimate of the national annual number of major injuries is 525,000 (5.9 per 100 person-year), whereas the EDISS data yielded an estimate of 1,150,000 major injuries (12.9 per 100 person-years) CONCLUSIONS: Comparison of survey and EDISS data systems provides quantitative assessment of accuracy of the survey data in relation to time of injury before report date, to severity of injury, and to whether the injury is to the interviewee or to a cohabitant. The 2 systems could be used in a complementary way, although EDISS generates information that is medically more accurate and is a more cost-effective data collection system.

Adolescent↗
PubMedDate not supplied

Film dosimetry of megavoltage photon beams: a practical method of isodensity-to-isodose curve conversion.

The central problems of photon beam film dosimetry are the dependence of film response upon photon energy, processing conditions, and film plane orientation. We have overcome these problems by accurately fitting the depth-dependent sensitometric curve of Kodak XV-2 film (exposed parallel to beam axis) to the equation OD(D,d) = ODs(1 - exp [- alpha 0[1 + beta(d-dm)]D]) where OD(D,d) is the optical density for dose D at depth d. ODs, alpha 0, and beta are constants characteristic of the film and beam energy but are independent of field size. Only central axis depth dose data for a single field are required to determine their values. A computer program based upon this equation has been written which successfully generates single field isodose curves from film data for a variety of field sizes (including wedged fields) with an accuracy of +/- 3%. Data are presented for 60Co, and 4 and 10 MV x rays.

Film Dosimetry↗
PubMed2004

The control of aerodynamics, acoustics, and perceptual characteristics during speech production.

One of the most important areas of study in speech motor control is the identification of control variables, the variables controlled by the nervous system during motor tasks. The current study examined two hypotheses regarding control variables in speech production: (1) pressure and resistance in the vocal tract are controlled, and (2) perceptual and acoustic accuracy are controlled. Aerodynamic and acoustic data were collected on 20 subjects in three conditions, normally (NT), with an open air pressure bleed tube in place (TWB), and with a closed bleed tube in place (TNB). The voice recordings collected from the speakers in the production study were used in the perceptual study. Results showed that oral pressure (Po) was significantly lower in the TWB condition than in the NT and TNB conditions. The Po in the TWB condition seemed to be related to maintenance of subglottal pressure (Ps). Examination of the perceptual and acoustic data indicated that perceptual accuracy for [a] was achieved by maintaining Ps to preserve a steady sound pressure level, fundamental frequency, and voicing. Overall, it appeared speakers controlled pressure in compensating, but for the ultimate goal of maintaining acoustic and perceptual accuracy.

Adult↗
PubMed1992

Cost-effectiveness decision analysis of obtaining periapical radiographs of traumatized maxillary incisors.

A long-term decision analysis approach has been applied to the problem of whether or not periapical radiographs should be taken routinely of patients presenting with simple fractures of otherwise asymptomatic maxillary incisors. Information from the literature concerning the accuracy of cold, hot and electrical tests for pulp vitality, combined with data on the accuracy of radiographic diagnosis of periapical pathology, and therefore vitality, has been used in the analysis of the diagnostic problem structured in the form of a decision tree. By adding information concerning the direct costs of examining and treating patients over a 10-year period to the analysis and varying the likely prevalence of periapical lesions in a three-way sensitivity analysis, the following results were arrived at: (1) if the disease prevalence in teenage patients is < 5%, it is economically justifiable to make a visual inspection only and then to proceed with simple restorative treatment; (2) if there is evidence from the clinical examination or patient history that the prevalence of pulp necrosis is between 5% and 50% then, in our case, radiographs were the most appropriate single diagnostic test.

Cost-Benefit Analysis↗
PubMed2002

Myocardial contrast echocardiography yields best accuracy using quantitative analysis of digital data from pulse inversion technique: comparison with second harmonic imaging and harmonic power Doppler during simultaneous dipyridamole stress SPECT studies.

AIMS: This prospective study assesses the (1) feasibility of quantifying ultrasound myocardial perfusion studies based on the densitometric analysis of digital data and the (2) comparison of pulse inversion, second harmonic and harmonic power Doppler modalities with SPECT. METHODS AND RESULTS: Twenty-three patients with suspected ischaemic heart disease had i.v. injections of Tc-Sestamibi and Optison during a dipyridamole stress test for echocardiography in pulse inversion, second harmonic and harmonic power Doppler mode. Analysis was (a) visual by scoring and (b) quantitative by densitometry of digital data for background subtracted myocardial opacification (a.u.) and normalized contrast effect (%). In the nine control patients, myocardial opacification at stress was greater (P< or =0.002) than in the pathologic group (5. +/- 3.3 vs 2.6 +/- 2.5 a.u. in pulse inversion, 5.4 +/- 2.1 vs 2.4 +/- 1.8 in second harmonic and 7.1 +/- 3.7 vs 4.9 +/- 3.7 a.u. in harmonic power Doppler). In the pathologic group, normalized contrast effect decreased significantly during stress (23.7 +/- 18.8 to 11.3 +/- 10.8%, P<0.003) only in pulse inversion. Kappa values for patient based diagnostic agreement with SPECT were 0.75 by pulse inversion, 0.62 by second harmonic and 0.52 by harmonic power Doppler for quantitative analysis, and 0.51, 0.37 and 0.35 respectively, for visual assessment. CONCLUSION: Myocardial contrast echocardiography should be analysed using densitometry of digital data. The new technique pulse inversion demonstrates best agreement with SPECT data.

Albumins↗
PubMed2004

Using computers for intensive care unit research.

A computerized clinical information system (CIS) is potentially a very important information tool for research and improving health care processes as well as for optimizing data management and thereby minimizing health care costs. The newest CISs automatically collect patient data from various sources, including monitors, the laboratory, radiology, and patient notes, and make the data highly organized and readily accessible. In the future CISs may be able to conduct signal analysis, assist in care decisions, provide advanced graphical data presentation, and generate warnings to clinicians. Most CIS systems include large databases, and the advent of relational databases has improved data retrieval and manipulation and thus made the data a powerful tool in outcomes research. On the whole CISs collect more frequent and more accurate data than do clinicians using paper-based data collection systems, but research continues on how accurate CIS data is, how to improve that accuracy, and how much data checking and correction is needed. At my institution we have used CIS data to study changes in patients' code status and to evaluate a protocol for arterial blood gas (ABG) testing. The primary challenges to optimizing a CIS are ensuring accurate data entry, learning to query the data so as to avoid misleading conclusions, and to administer and maintain the hardware and software so as to minimize the chance of data loss and system down time. CISs are in a relatively early stage of their development, and engineering improvements will eventually make CIS data highly accurate and easily accessible and queryable so that CISs become even more valuable for research.

Computer Systems↗
PubMed1993

Assessment of the accuracy of physical activity questionnaire occupational data.

The validity and reliability of occupational physical activity data from survey instruments were determined in 75 men and women (age 23 to 59 years) in white-collar jobs. Data were validated against measures of cardiorespiratory fitness, body fatness, motion detection, pulmonary function, and 12 days of occupational physical activity records. More than 90% of occupational physical activity was spent in light-intensity sitting, standing, and walking. Test-retest reliability was high for most occupational questions (r > or = .63, P < .05). Correlation coefficients between questionnaire data and validation criteria that reflect heavy-intensity physical activity were low (r < .17, P > .05). The modified Tecumseh Occupational Questionnaire and Seven-Day Recall, which classified occupational physical activity in hours per week worked and average level of ratio of associated metabolic rate for a specific activity divided by the resting metabolic rate, on the job, correlated best with physical activity records (r = .11 to .47). Validation of these self-administered questionnaires in populations with a greater diversity of jobs and occupational energy requirements is needed.

Activities of Daily Living↗
PubMed1993

Markers of data quality in computer audit: the Manchester Orthopaedic Database.

This study investigates the efficiency of the Manchester Orthopaedic Database (MOD), a computer software package for record collection and audit. Data is entered into the system in the form of diagnostic, operative and complication keywords. We have calculated the completeness, accuracy and quality (completeness x accuracy) of keyword data in the MOD in two departments of orthopaedics (Departments A and B). In each department, 100 sets of inpatient notes were reviewed. Department B obtained results which were significantly better than those in A at the 5% level. We attribute this to the presence of a systems coordinator to motivate and organise the team for audit. Senior and junior staff did not differ significantly with respect to completeness, accuracy and quality measures, but locum junior staff recorded data with a quality of 0%. Statistically, the biggest difference between the departments was the quality of operation keywords. Sample sizes were too small to permit effective statistical comparisons between the quality of complication keywords. In both departments, however, the poorest quality data was seen in complication keywords. The low complication keyword completeness contributed to this; on average, the true complication rate (39%) was twice the recorded complication rate (17%). In the recent Royal College of Surgeons of England Confidential Comparative Audit, the recorded complication rate was 4.7%. In the light of the above findings, we suggest that the true complication rate of the RCS CCA should approach 9%.

Data Collection↗
PubMed2000

A comparison of data sources for motor vehicle crash characteristic accuracy.

OBJECTIVE: To determine the accuracy of police reports (PRs), ambulance reports (ARs), and emergency department records (EDRs) in describing motor vehicle crash (MVC) characteristics when compared with an investigation performed by an experienced crash investigator trained in impact biomechanics. METHODS: This was a cross-sectional, observational study. Ninety-one patients transported by ambulance to a university emergency department (ED) directly from the scene of an MVC from August 1997 to April 1998 were enrolled. Potential patients were identified from the ED log and consent was obtained to investigate the crash vehicle. Data describing MVC characteristics were abstracted from the PR, AR, and medical record. Variables of interest included restraint use (RU), air bag deployment (AD), and type of impact (TI). Agreements between the variables and the independent crash investigation were compared using kappa. Interrater reliability was determined using kappa by comparing a random sample of 20 abstracted reports for each data source with the originally abstracted data. RESULTS: Agreement using kappa between the crash investigation and each data source was 0.588 (95% CI = 0.508 to 0.667) for the PR, 0.330 (95% CI = 0.252 to 0.407) for the AR, and 0.492 (95% CI = 0.413 to 0.572) for the EDR. Variable agreement was 0.239 (95% CI = 0.164 to 0.314) for RU, 0.350 (95% CI = 0.268 to 0.432) for AD, and 0.631 (95% = 0.563 to 0.698) for TI. Interrater reliability was excellent (kappa > 0.8) for all data sources. CONCLUSIONS: The strength of the agreement between the independent crash investigation and the data sources that were measured by kappa was fair to moderate, indicating inaccuracies. This presents ramifications for researchers and necessitates consideration of the validity and accuracy of crash characteristics contained in these data sources.

Accidents, Traffic↗
PubMed1997

Concurrent coding provides more accurate data for outcomes and performance reports.

Preventing GIGO with concurrent, accurate coding. With so much riding on the accuracy of claims data, including outcomes and performance ratings, more should be done to improve the process of gathering this all-important information. That's the case at the University of Washington Medical Center, where coders actually work on the patient care floors, coding concurrently, interacting with physicians, and actually observing patients' treatment. Here's how the program works.

Abstracting and Indexing↗
PubMed1976

Medical economics survey-methods study: design, data collection, and analytical plan.

This paper describes the background, methodology, data collection, and analytical plan of a pilot investigation conducted under contract for the National Center for Health Statistics during 1975. The objective was to determine the cost effectiveness of a variety of strategies under consideration for national application to develop previously unavailable information on utilization of, and the costs and payments for, health care. Detailed data on health care utilization and expenditures were collected periodically from a panel of 691 Maryland households over a six-month interval. Issues to be tested through a random experimental design include whether periodicity (monthly vs bimonthly interviews) and type of contact (in-person vs telephone) are significant factors in the cost effectiveness of this type of survey. An extensive record check involving all providers and third-party payers identified in the household survey was carried out. Record information will be used to 1) provide a basis for measuring accuracy of household data, 2) fill gaps in household knowledge, and 3) determine whether a subset of the record sources can provide adequate information for correcting household data. The household survey resulted in an initial response rate of 77.5 per cent with a subsequent attrition rate over six months of 13.6 per cent. Signed permission to access record data was obtained for 84.9 per cent of the individuals completing the entire survey. The most intensive survey strategy, monthly, mostly in-person contact, resulted in the lowest participation. The analytical plan presents details of the approaches to be taken in making judgments on the relative accuracy and completeness of data obtained by the various survey strategies and the contribution made by availability of data from record sources.

Adolescent↗
PubMed2000

A comparison of individual and population smoking data from a postal survey and general practice records.

BACKGROUND: Data on smoking held by general practitioners (GPs) may contribute to clinical care and to an assessment of population health. However, these data are prone to several biases and their validity has not been tested. AIM: To examine the accuracy of general practice data as an estimate for population prevalence of smoking and to estimate the accuracy of GP data on individuals' smoking habit compared with self-report. METHODS: A postal questionnaire on smoking habit over the past six years was sent to a random sample of individuals aged 15 to 74 years and registered with five out of seven general practices in one part of Leicester. GP records of those sampled were examined for an entry of smoking status over this period. RESULTS: Response rate to the postal questionnaire was 1906 out of 2490 (76.5%). Reported smoking prevalence was 35.2%. Of those notes sampled, 1784 out of 2432 (73.4%) had an entry about smoking recorded between 1991 and 1996. Patients recorded as smokers were less likely to respond to the postal questionnaire than non-smokers. Using practice data to ascribe smoking status to non-responders produced an estimated prevalence of 38.6%. Using questionnaire data alone as the 'gold standard', the last practice record collected since 1991 overestimated current smoking prevalence by a factor of 1.22; using questionnaire data supplemented by practice data for non-responders as the 'gold standard' meant that the overestimate was by a factor of 1.11. Data from notes and the questionnaire were available for 1398 individuals and 2188 observations. Levels of agreement were high (kappa = 0.83). CONCLUSION: GP-held data are valid for individuals but over-estimate smoking prevalence at a population level.

Adolescent↗
PubMed2003

Operator functional state classification using multiple psychophysiological features in an air traffic control task.

We studied 2 classifiers to determine their ability to discriminate among 4 levels of mental workload during a simulated air traffic control task using psychophysiological measures. Data from 7 air traffic controllers were used to train and test artificial neural network and stepwise discriminant classifiers. Very high levels of classification accuracy were achieved by both classifiers. When the 2 task difficulty manipulations were tested separately, the percentage correct classifications were between 84% and 88%. Feature reduction using saliency analysis for the artificial neural networks resulted in a mean of 90% correct classification accuracy. Considering the data as a 2-class problem, acceptable load versus overload, resulted in almost perfect classification accuracies, with mean percentage correct of 98%. In applied situations, the most important distinction among operator functional states would be to detect mental overload situations. These results suggest that psychophysiological data are capable of such discriminations with high levels of accuracy. Potential applications of this research include test and evaluation of new and modified systems and adaptive aiding.

Adult↗