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PubMed1998

Herd-level test performance based on uncertain estimates of individual test performance, individual true prevalence and herd true prevalence.

A generalized model was derived for understanding the performance of herd-testing protocols when there is uncertainty and variability in individual-level sensitivity, specificity, prevalence of infection within infected herds, and prevalence of infected herds in the population. The model uses Monte-Carlo techniques to provide estimates of test performance for a dichotomous classification of herd-disease status. Uncertainty and variability in input assumptions are described using empirical and parametric probability distributions. The model permits both cluster-correlated behavior of inputs and sampling of animals without replacement. Disease due to obligate parasites is modeled differently from that due to organisms that persist for long periods in the environment. Dependence among model outcomes is assessed using Spearman's rank correlation. Model output is suitable for inclusion in risk-assessment models requiring probabilistic estimates of herd-level test performance, such as those developed for food-safety decision making and import-export risk assessment. The model was demonstrated using an example scenario based on Shiga-like toxin (SLT) producing Escherichia coli O157 in Ontario beef-cattle herds. Inputs were derived from the literature and Statistics Canada agricultural census data. Where appropriate, these data were subjected to distribution-fitting techniques. Otherwise, subjective interpretation was used to select input distributions and their parameters. Simulation revealed that the distribution of herd-level sensitivity for detecting herds infected with SLT producing E. coli O157 has a large range (0.003-0.99) and a median of 0.19. Herd-level specificity also had a large range (0.58-1) and a median of 0.94. Distributions of herd-level positive and negative predictive values exhibited similar degrees of uncertainty. In combination with poor likelihood ratios for positive and negative herd tests, results indicate that the testing protocol investigated has limited ability to discriminate between herds infected and not infected with SLT producing E. coli O157.

Algorithms↗

PubMed1996

Exercise intolerance and poor performance in western performance and sprint horses.

This article deals with the presenting histories, clinical examinations, and therapies of the causes of poor performance and exercise intolerance in the western performance horse and the sprint racehorse. The veterinarian's ability to diagnose and treat various pathophysiologic conditions that affect these horses is crucial to the major goals of a return to optimal performance and a long athletic career. Although these horses are a significant portion of most veterinary practices, there exists a minimal amount of information on their clinical evaluation and treatment. This article intends to fill this void.

Animals↗

PubMed1999

Clinical performance improvement series. Classic CQI integrated with comprehensive disease management as a model for performance improvement.

BACKGROUND: In recent years, health and disease management has emerged as an effective means of delivering, integrating, and improving care through a population-based approach. Since 1997 the University of Pennsylvania Health System (UPHS) has utilized the key principles and components of continuous quality improvement (CQI) and disease management to form a model for health care improvement that focuses on designing best practices, using best practices to influence clinical decision making, changing processes and systems to deploy and deliver best practices, and measuring outcomes to improve the process. Experience with 28 programs and more than 14,000 patients indicates significant improvement in outcomes, including high physician satisfaction, increased patient satisfaction, reduced costs, and improved clinical process and outcome measures across multiple diseases. DIABETES DISEASE MANAGEMENT: In three months a UPHS multidisciplinary diabetes disease management team developed a best practice approach for the treatment of all patients with diabetes in the UPHS. After the program was pilot tested in three primary care physician sites, it was then introduced progressively to additional practice sites throughout the health system. The establishment of the role of the diabetes nurse care managers (certified diabetes educators) was central to successful program deployment. Office-based coordinators ensure incorporation of the best practice protocols into routine flow processes. A disease management intranet disseminates programs electronically. Outcomes of the UPHS health and disease management programs so far demonstrate success across multiple dimensions of performance-service, clinical quality, access, and value. DISCUSSION: The task of health care leadership today is to remove barriers and enable effective implementation of key strategies, such as health and disease management. Substantial effort and resources must be dedicated to gain physician buy-in and achieve compliance. The challenge is to provide leadership support, to reward and recognize best practice performers, and to emphasize the use of data for feedback and improvement. As these processes are implemented successfully, and evidence of improved outcomes is documented, it is likely that this approach will be more widely embraced and that organizationwide performance improvement will increase significantly. CONCLUSIONS: Health care has traditionally invested extraordinary resources in developing best practice approaches, including guidelines, education programs, or other tangible products and services. Comparatively little time, effort, and resources have been targeted to implementation and use, the stage at which most efforts fail. CQI's emphasis on data, rapid diffusion of innovative programs, and rapid cycle improvements enhance the implementation and effectiveness of disease management.

Delivery of Health Care, Integrated↗

PubMed1998

Swimming performance, venous oxygen tension and cardiac performance of coronary-ligated rainbow trout, Oncorhynchus mykiss, exposed to progressive hypoxia.

We performed in vivo studies to examine the idea that cardiac work is impaired in rainbow trout (Oncorhynchus mykiss) below a certain venous PO2 threshold. We hypothesized that coronary-ligated fish, swimming continuously at a reasonably high water velocity (1.5 body lengths x s(-1)) and exposed to progressive hypoxia, would fatigue at higher venous PO2 and ambient water PO2 compared with sham-operated fish. However, we found that both the lowest venous PO2 that supported hypoxic swimming (9.9 torr for coronary-ligated fish and 11.1 torr for sham-operated fish) and the venous PO2 at fatigue (7.8 torr and 8.6 torr, respectively) were the same for coronary-ligated and sham-operated fish. Also, both groups quit swimming at the same water PO2 heart rate and hematocrit. Nevertheless, significant differences in cardiac performance did exist between the two groups. Whereas ventral aortic blood pressure (Pva) increased significantly with hypoxic swimming in sham-operated fish, there was no such increase in coronary-ligated fish. In addition, cardiac arrhythmias occurred in coronary-ligated fish at fatigue, and these fish were slower to recover from exhaustion. We believe that the venous PO2 threshold to support cardiac performance in the absence of a coronary supply was between 7.8 and 9.9 torr. Furthermore, we suspect that the low PO2 in coronary-ligated fish effectively lowered their myocardial O2 demand. Uncertainty still exists regarding whether or not the venous PO2 threshold lies between 8.6 and 11.1 torr in sham-operated fish.

Animals↗

PubMed2007

Solid-phase extraction combined with high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry analysis of pesticides in water: method performance and application in a reconnaissance survey of residues in drinking water in Greater Cairo, Egypt.

Monitoring of water resources for pesticide residues is often needed to ensure that pesticide use does not adversely impact the quality of public water supplies or the environment. In many rural areas and throughout much of the developing world, monitoring is often constrained by lack of testing facilities; thus, collection of samples and shipment to centralized laboratories for analysis is required. The portability, ease of use, and potential to enhance analyte stability make solid-phase extraction (SPE) an attractive technique for handling water samples prior to their shipment. We describe performance of an SPE method targeting a structurally diverse mixture of 25 current-use pesticides and two common degradates in samples of raw and filtered drinking water collected in Greater Cairo, Egypt. SPE was completed in a field laboratory in Egypt, and cartridges were shipped to the United States for elution and high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry analysis. Quantitative and reproducible recovery of 23 of 27 compounds (average = 96%; percent relative standard deviation = 21%) from matrix spikes (1 microg L-1 per component) prepared in the field and from deionized water fortified similarly in the analytical laboratory was obtained. Concurrent analysis of unspiked samples identified four parent compounds and one degradate in drinking water samples. No significant differences were observed between raw and filtered samples. Residue levels in all cases were below drinking water and "harm to aquatic-life" thresholds, indicating that human and ecological risks of pesticide contamination were relatively small; however, the study was limited in scale and scope. Further monitoring is needed to define spatial and temporal variation in residue concentrations. The study has demonstrated the feasibility of performing studies of this type using SPE to extract and preserve samples in the field. The approach should be broadly applicable in many settings.

Chromatography, High Pressure Liquid↗

PubMed2003

Relations between Continuous Performance Test performance measures and ADHD behaviors.

The Conners' Continuous Performance Test (CPT) is a neuropsychological task that has repeatedly been shown to differentiate ADHD from normal groups. Several variables may be derived from the Conners' CPT including errors of omission and commission, mean hit reaction time(RT), mean hit RT standard error, d', and beta. What each CPT parameter actually assesses has largely been based upon clinical assumptions and the face validity of each measure (e.g., omission errors measure inattention, commission errors measure impulsivity). This study attempts to examine relations between various CPT variables and phenotypic behaviors so as to better understand the various CPT variables. An epidemiological sample of 817 children was administered the Conners' CPT. Diagnostic interviews were conducted with parents to determine ADHD symptom profiles for all children. Children diagnosed with ADHD had more variable RTs, made more errors of commission and omission, and demonstrated poorer perceptual sensitivity than nondiagnosed children. Regarding specific symptoms, generalized estimating equations (GEE) and ANCOVAs were conducted to determine specific relationships between the 18 DSM-IV ADHD symptoms and 6 CPT parameters. CPT performance measures demonstrated significant relationships to ADHD symptoms but did not demonstrate symptom domain specificity according to a priori assumptions. Overall performance on the two signal detection measures, d' and beta, was highly related to all ADHD symptoms across symptom domains. Further, increased variability in RTs over time was related to most ADHD symptoms. Finally, it appears that at least 1 CPT variable, mean hit RT, is minimally related to ADHD symptoms as a whole, but does demonstrate some specificity in its link with symptoms of hyperactivity.

Algorithms↗

PubMed2003

Continuous performance test performance in a normative epidemiological sample.

A 14-min continuous performance test (CPT) requiring a high rate of responding was administered to a probability-weighted random sample of 816 9-17-year-old children drawn from a population of 17,117 children in an ongoing epidemiological and longitudinal study in Western North Carolina. Systematic main effects of improved performance with older age were found in this age range for all variables, including reaction time (RT), RT standard error, errors of omission, errors of commission, and signal detection parameters (d' and beta). Significant gender main effects included more impulsive errors, less variability, and faster RT by males, with no interactions between age and gender. There were no main effects of ethnicity or interactions of ethnicity with age and/or gender. Large main effects of interstimulus interval (ISI; 1, 2, or 4-s intervals) and time block were present for most CPT performance measures. The normative data from the CPT should provide a useful framework for interpreting similar data in future studies of child and adolescent psychopathology.

Adolescent↗

PubMed1991

Age, activity, and physical performance: an evaluation of performance models.

Two performance models relating age, physical activity, and physical performance were evaluated on 5 age cohorts involving more than 6,000 persons ranging in age from 20 to 69 years. Significant age and activity main effects, without 1 Age X Activity interaction, were obtained on 5 fitness measures and 2 activity indexes. These results are inconsistent with predictions from the moderation model, but they fit predictions from a recently formulated tonic and overpractice model of physical performance.

Activities of Daily Living↗

PubMed2004

Sports and performing arts medicine. 1. General considerations for sports and performing arts medicine.

UNLABELLED: This self-directed learning module highlights general considerations in sports and performing arts medicine. It is part of the study guide on sports and performing arts medicine in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. OVERALL ARTICLE OBJECTIVE: To discuss similarities and differences of injuries sustained in sports and performing arts using case vignettes.

Anxiety↗

PubMed2003

Is static spatial performance distinguishable from dynamic spatial performance? A latent-variable analysis.

There is disagreement among researchers about the distinction between dynamic and static spatial performance. Given that dynamic spatial performance is supposed to be important for some occupations, such as air traffic control (ATC), it is germane to have evidence about the likelihood of that distinction. In the present study, a battery of printed static spatial and reasoning tests were applied to 480 applicants for an ATC training course. Two dynamic spatial tests were also applied. Confirmatory factor analyses were performed for testing three models. In Model A, static and dynamic spatial tests were grouped, whereas in Model B, spatial tests were separated according to their static or dynamic character, and in Model C, spatial tests were segregated according to the construct they tapped (visualization or spatial relations). The authors found that Model B, which distinguished static and dynamic spatial tests, showed the best fit. They also discuss some implications of the findings.

Adult↗

PubMed1981

Social reinforcement as a determinant of performance, performance expectancy, and attributions.

The effects of positive, negative, and nonreinforcement were examined during performance of a fine motor task to observe any expectancy and performance differences. Female high school subjects first learned the task and then were given a series of 30 trials in which social reinforcement was administered noncontingently. Positive social reinforcement had a significant effect on performance, while both positive and negative reinforcement had significant effects on expectancy. In addition, disparate attributions were made by each treatment group.

Journal Article↗

PubMed2005

Measures of performance in nonlinear estimation tasks: prediction of estimation performance at low signal-to-noise ratio.

Maximum-likelihood (ML) estimation is an established paradigm for the assessment of imaging system performance in nonlinear quantitation tasks. At high signal-to-noise ratio (SNR), ML estimates are asymptotically Gaussian-distributed, unbiased and efficient, thereby attaining the Cramer-Rao bound (CRB). Therefore, at high SNR the CRB is useful as a predictor of the variance of ML estimates and, consequently, as a basis for measures of estimation performance. At low SNR, however, the achievable parameter variances are often substantially larger than the CRB and the estimates are no longer Gaussian-distributed. These departures imply that inference about the estimates that is based on the CRB and the assumption of a normal distribution will not be valid. We have found previously that for some tasks these effects arise at noise levels considered clinically acceptable. We have derived the mathematical relationship between a new measure, chi2(pdf-ML), and the expected probability density of the ML estimates, and have justified the use of chi2(pdf-ML)-isocontours in parameter space to describe the ML estimates. We validated this approach by simulation experiments using spherical objects imaged with a Gaussian point spread function. The parameters, activity concentration and size, were estimated simultaneously by ML, and variances and covariances calculated over 1000 replications per condition from 3D image volumes and from 2D tomographic projections of the same object. At low SNR, where the CRB is no longer achievable, chi2(pdf-ML)-isocontours provide a robust prediction of the distribution of the ML estimates. At high SNR, the chi2(pdf-ML)-isocontours asymptotically approach the analogous chi2(pdf-F)-contours derived from the Fisher information matrix. The chi2(pdf-ML) model appears to be suitable for characterization of the influence of the noise level and characteristics, the task, and the object on the shape of the probability density of the ML estimates at low SNR. Furthermore, it provides unique insights into the causes of the variability of estimation performance.

Algorithms↗

PubMed1993

Relationships of interns' performances to their self-assessments of their preparedness for internship and to their academic performances in medical school.

This study addressed the questions of whether medical students' cumulative grade-point averages (GPAs) correlate with the performance assessments (overall and in specific areas of competency) that they receive as interns from their internship program directors, and whether the students' self-assessments of preparedness for internship correlate with their internship directors' overall assessments. A questionnaire to assess interns' competencies was developed and sent to the directors of the internship programs of the 283 1990 and 1991 graduates of the Medical College of Georgia School of Medicine who consented to participate in the study (82% of the graduates). Eighty percent of the program directors responded. A similar questionnaire was sent to all 342 of the 1990 and 1991 graduates; 38% provided self-assessments of their competencies and also stated their views on how well prepared they were for their internships. Considering the classes as a group, the mean ratings of the interns' overall competencies by the program directors ranged from 3.7 to 4.3 on a five-point Likert scale (1, unsatisfactory, to 5, outstanding), whereas the interns' ratings of how well they were prepared for their internships (that is, their sense of overall competency) were somewhat lower, ranging from 3.4 to 4.0. The correlations of GPAs with the specific areas of competencies ranged from .28 to .51. The correlation between the mean ratings of the program directors and the mean self-ratings of the interns was .58. The data support the conclusions that medical school academic performance relates significantly to performance in internship and that interns do not rate themselves as highly as their program directors do.

Achievement↗

PubMed1999

Global ratings of videotaped performance versus global ratings of actions recorded on checklists: a criterion for performance assessment with standardized patients.

PURPOSE: To test whether global ratings of checklists are a viable alternative to global ratings of actual clinical performance for use as a criterion for standardized-patient (SP) assessment. METHOD: Five faculty physicians independently observed and rated videotaped performances of 44 medical students on the seven SP cases that comprise the fourth-year assessment administered at The Morchand Center of Mount Sinai School of Medicine to students in the eight member schools in the New York City Consortium. A year later, the same panel of raters reviewed and rated checklists for the same 44 students on five of the same SP cases. RESULTS: The mean global ratings of clinical competence were higher with videotapes than checklists, whereas the mean global ratings of interpersonal and communication skills were lower with videotapes. The correlations for global ratings of clinical competence showed only moderate agreement between the videotape and checklist ratings; and for interpersonal and communication skills, the correlations were somewhat weaker. CONCLUSION: The results raise serious questions about the viability of global ratings of checklists as an alternative to ratings of observed clinical performance as a criterion for SP assessment.

Adult↗

PubMed2003

Correlates of performance of the ECFMG Clinical Skills Assessment: influences of candidate characteristics on performance.

PURPOSE: Since 1998, over 30,000 international medical graduates (IMGs) have taken the ECFMG CSA. Although candidate background variables have been shown to predict basic and clinical science performance, little work has focused on the relationships between candidate characteristics and clinical skills performance. The purpose of this study was to investigate whether candidate characteristics were related to CSA pass/fail status. METHOD: Logistic regression analyses were conducted to explore the relationships between candidate characteristics and CSA pass/fail status for a sample of 11,690 IMGs over a two-year period. RESULTS: Results indicated that gender, English language proficiency, recent medical school graduation, and clinical science performance (USMLE Step 2) were all related to clinical skills proficiency. CONCLUSIONS: The results provide additional support for the validity of CSA pass/fail decisions.

Adult↗

PubMed1992

Effects of coenzyme athletic performance system as an ergogenic aid on endurance performance to exhaustion.

This study examined the effects of the Coenzyme Athletic Performance System (CAPS) on endurance performance to exhaustion. CAPS contains 100 mg coenzyme Q10, 500 mg cytochrome C, 100 mg inosine, and 200 IU vitamin E. Eleven highly trained male triathletes were given three daily doses of either CAPS or placebo (dicalcium phosphate) for two 4-week periods using a double-blind crossover design. A 4-week washout period separated the two treatment periods. An exhaustive performance test, consisting of 90 minutes of running on a treadmill (70% VO2max) followed by cycling (70% VO2max) until exhaustion, was conducted after each treatment period. The mean (+/- SEM) time to exhaustion for the subjects using CAPS (223 +/- 17 min) was not significantly different (p = 0.57) from the placebo trial (215 +/- 9 min). Blood glucose, lactate, and free fatty acid concentrations at exhaustion did not differ between treatments (p < 0.05). CAPS had no apparent benefit on exercise to exhaustion.

Adolescent↗

PubMedDate not supplied

Management of severe lower abdominal or inguinal pain in high-performance athletes. PAIN (Performing Athletes with Abdominal or Inguinal Neuromuscular Pain Study Group).

The purpose of this study was to gain insight into the pathophysiologic processes of severe lower-abdominal or inguinal pain in high-performance athletes. We evaluated 276 patients; 175 underwent pelvic floor repairs. Of the 157 athletes who had not undergone previous surgery, 124 (79%) participated at a professional or other highly competitive level, and 138 patients (88%) had adductor pain that accompanied the lower-abdominal or inguinal pain. More patients underwent related adductor releases during the later operative period in the series. Evaluation revealed 38 other abnormalities, including severe hip problems and malignancies. There were 152 athletes (97%) who returned to previous levels of performance. The syndrome was uncommon in women and the results were less predictable in nonathletes. A distinct syndrome of lower-abdominal/adductor pain in male athletes appears correctable by a procedure designed to strengthen the anterior pelvic floor. The location and pattern of pain and the operative success suggest the cause to be a combination of abdominal hyperextension and thigh hyperabduction, with the pivot point being the pubic symphysis. Diagnosis of "athletic pubalgia" and surgery should be limited to a select group of high-performance athletes. The consideration of other causes of groin pain in the patient is critical.

Abdominal Pain↗

PubMed1997

Radiology Cases in Pediatric Emergency Medicine: amplifying the benefits of performance improvement by sharing a hospital performance improvement program with the world via the Internet.

A hospital performance improvement project to improve the quality of x-ray interpretations in the emergency department is described. To amplify the benefits of this project, a multimedia computer program containing this information was created and distributed via the mail and over the internet. Users are encouraged to copy the program disks and distribute them to others (no fees or royalties). The advantages of this method over conventional journals in print are described. Successful distribution of this program, known as Radiology Cases in Pediatric Emergency Medicine (RCPEM), and positive feedback from users, stimulated the continuation of this project, which has now released its fifth volume with two more volumes planned. RCPEM (a hospital performance improvement project) now continues to expand as the knowledge gained is disseminated over the internet to improve the quality of care rendered to children all over the world. Amplifying the benefits of other performance improvement projects can be done in a similar manner.

Computer Communication Networks↗