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PubMedDate not supplied

Evaluation of an occupational health and safety management system performance measurement tool-III: measurement of initiation elements.

With the proliferation of occupational health and safety management systems (OHSMS) in the 1990s, an assessment instrument was developed at the University of Michigan to measure a wide range of OHSMSs. Due to the range of systems it was designed to measure, the instrument is referred to as a universal assessment instrument (UAI). Initial evaluation of the instrument's first four sections is reported here. This study shows that the UAI's initiation measurement criteria and measurement scales could make distinctions between the OHS management systems at three test sites. This was particularly evident in the case in an organization in which a standards-based OHSMS was not implemented. In this case the UAI's two measurement scales could distinguish between areas that were being developed (development scale) and areas that were in conformance with the measurement criteria (conformance scale). The score totals were consistent with the qualitative assessment using case study methods during field pilot testing; with the exception of Section 2.0, Employee Participation, in which scoring at one test site was not consistent with case study findings. It is suggested that the variables/measures presented in the UAI's OHSMS initiation organizing category may contain performance measures that may serve as key leading indicators of overall OHS performance.

Community Participation↗

PubMed1999

Factors affecting in vivo measurement precision and accuracy of 109Cd K x-ray fluorescence measurements.

109Cd K x-ray fluorescence (XRF) measurement systems from two research centres were used to measure tibia lead content in a population (n = 530) of young adults. The group mean bone lead contents (+/-SEM) determined by McMaster University (n = 214) and the University of Maryland (n = 316) were 2.80 +/- 0.51 and 2.33 +/- 0.50 microg Pb/(g bone mineral) respectively. The mean difference of 0.47 +/- 0.71 microg Pb/(g bone mineral) was not significant. There was no evidence of a systematic difference between measurements from the two systems. Measurement uncertainties for the young adults were poorer overall than uncertainties for a population of occupationally exposed men. This was because obese subjects and women were included in the study. Regressions of precision against body mass index (BMI, defined as weight/height2) determined that uncertainties increased with BMI and were poorer for women than men. Measurement uncertainties (1sigma) were >8 microg Pb/(g bone mineral) for women with a BMI > 0.004 kg cm(-2). Poor-precision data affected population estimates of bone lead content; an inverse correlation was found between precision and bone lead content. A small number (0.4%) of individual measurements with poor uncertainties were inaccurate to within the precision. It is suggested that obese subjects, whose BMI > 0.004 kg cm(-2), should be excluded from 109Cd K XRF studies, as the measurement provides limited information and may be inaccurate.

Adult↗

PubMed2006

Measuring covariation in RNA alignments: physical realism improves information measures.

MOTIVATION: The importance of non-coding RNAs is becoming increasingly evident, and often the function of these molecules depends on the structure. It is common to use alignments of related RNA sequences to deduce the consensus secondary structure by detecting patterns of co-evolution. A central part of such an analysis is to measure covariation between two positions in an alignment. Here, we rank various measures ranging from simple mutual information to more advanced covariation measures. RESULTS: Mutual information is still used for secondary structure prediction, but the results of this study indicate which measures are useful. Incorporating more structural information by considering e.g. indels and stacking improves accuracy, suggesting that physically realistic measures yield improved predictions. This can be used to improve both current and future programs for secondary structure prediction. The best measure tested is the RNAalifold covariation measure modified to include stacking. AVAILABILITY: Scripts, data and supplementary material can be found at http://www.binf.ku.dk/Stinus_covariation

Algorithms↗

PubMed1990

Correction of logistic regression relative risk estimates and confidence intervals for measurement error: the case of multiple covariates measured with error.

If several risk factors for disease are considered in the same multiple logistic regression model, and some of these risk factors are measured with error, the point and interval estimates of relative risk corresponding to any of these factors may be biased either toward or away from the null value. A method is provided for correcting point and interval estimates of relative risk obtained from logistic regression for measurement error in one or more continuous variables. The method requires a separate validation study to estimate the coefficients from the multivariate linear regression model relating the surrogate variables to the vector of true risk factors. Similar methods have been suggested by other authors, but none provides a means of correcting the confidence intervals which include a component of variability due to estimation of the measurement error parameters from a validation study. An example is provided from a prospective study of dietary fat, calories, and alcohol in relation to breast cancer, and from a validation study of the questionnaire used to assess these nutrients. Before correcting for measurement error, the age-adjusted relative risk for a 25 g increment in alcohol intake was 1.33 (95% confidence interval (CI) 1.14-1.55); after correcting for measurement error, the relative risk increased to 1.62 (95% CI 1.23-2.12). Similarly, for a 10 g increment in saturated fat intake, the age-adjusted relative risk was 0.94 (95% CI 0.83-1.06); after correcting for measurement error, the relative risk was 0.84 (95% CI 0.59-1.20). These results indicate that the failure to find a substantial positive association between breast cancer risk and saturated fat intake cannot be explained by measurement error in fat, calories, or alcohol.

Bias↗

PubMed2001

Methods and materials for the measurement of subjective and objective measurements of image quality.

The evaluation of medical imaging systems may be performed using both subjective (e.g. high contrast limiting resolution, and low contrast detail detectability), and objective/physical (e.g. characteristic curve, signal-to-noise ratio, modulation transfer function, and Wiener spectra) indices of image quality. For the purposes of Quality Assurance subjective measurements currently have a wider usage in the clinical environment due to the inherent simplicity of the measurements; however, more rigorous objective approaches are gaining acceptability, and represent a paradigm for possible future QA measurements. Both approaches have their advantages and disadvantages. There is currently wide debate as to the interpretation of these measurements. However, there appears to be a lack of standardisation among scientists in the various approaches to making these measurements, and especially so in the case of objective indices; furthermore, the measurement protocol used must have a bearing on the interpretation of subsequent results. The purpose of this paper is to (i) present the most fundamental indices in the characterisation of 'image quality', and (ii) recommend approaches to the measurement of these indices.

Humans↗

PubMed1994

Interrater reliability of craniosacral rate measurements and their relationship with subjects' and examiners' heart and respiratory rate measurements.

BACKGROUND AND PURPOSE: The evaluation of craniosacral motion is an approach used by physical therapists and other health professionals to assess the causes of pain and dysfunction, but evidence for the existence of this motion is lacking and the reproducibility of the results of this palpatory technique has not been studied. This study examined the interexaminer reliability of craniosacral rate and the relationships among craniosacral rate and subjects' and examiners' heart and respiratory rates. SUBJECTS: Participants were 12 children and adults with histories of physical trauma, surgery, or learning disabilities. Three physical therapists with expertise in craniosacral therapy were the examiners. METHODS: One of three nurses recorded heart and respiratory rates of both subject and examiner. The examiner then palpated the subject to determine craniosacral rate and reported the findings to the nurse. Each subject was examined by each of the three examiners. RESULTS: Reliability was estimated using a repeated-measures analysis of variance and the intraclass correlation coefficient (2,1). Significant differences among examiners and the scatter plot of rates showed lack of agreement among examiners. The ICC was -.02. The correlations between subject craniosacral rate and subject and examiner heart and respiratory rates were analyzed with Pearson correlation coefficients and were low and not statistically significant. DISCUSSION AND CONCLUSIONS: Measurements of craniosacral motion did not appear to be related to measurements of heart and respiratory rates, and therapists were not able to measure it reliably. Measurement error may be sufficiently large to render many clinical decisions potentially erroneous. Further studies are needed to verify whether craniosacral motion exists, examine the interpretations of craniosacral assessment, determine the reliability of all aspects of the assessment, and examine whether craniosacral therapy is an effective treatment. [Wirth-Pattullo V. Hayes KW. Interrater reliability of craniosacral rate measurements and their relationship with subjects' and examiners' heart and respiratory rate measurements.

Adolescent↗

PubMed2000

The reliability of the three-dimensional FASTRAK measurement system in measuring cervical spine and shoulder range of motion in healthy subjects.

OBJECTIVES: To assess the inter-observer and intra-observer reliability of a new three-dimensional measurement system, the FASTRAK, in measuring cervical spine flexion/extension, lateral flexion and rotation and shoulder flexion/extension, abduction and external rotation in healthy subjects. METHODS: The study was conducted in two parts. One part assessed inter-observer reliability with two observers measuring 40 subjects. The other part assessed intra-observer reliability with one observer measuring 32 subjects on three occasions. All subjects had unrestricted, pain-free cervical spine and shoulder movement. Reliability was measured by the intraclass correlation coefficient [ICC(2,1)]. RESULTS: The inter-observer ICCs for the cervical spine ranged from 0.61 to 0.89 and for the shoulder from 0.68 to 0.75. After removal of outliers, all ICCs were above 0.70. Intra-observer ICCs for the cervical spine ranged from 0.54 to 0.82 and for the shoulder from 0.62 to 0.81. After removal of outliers, all ICCs were above 0.70 except for shoulder abduction (0.62). CONCLUSIONS: Whilst all movements measured by the FASTRAK showed good reliability, the reliability of the whole movement in a plane (e.g. left plus right lateral flexion) was better than for the separate movements (e.g. left and right lateral flexion taken separately). Inter-observer reliability was generally better than intra-observer reliability for most cervical spine movements, suggesting that variability of movement within subjects (e.g. over a period of days) for these movements was greater than variability between measures on the same occasion.

Adult↗

PubMed2006

QT interval measurement: evaluation of automatic QTc measurement and new simple method to calculate and interpret corrected QT interval.

BACKGROUND: Assessment of repolarization duration is often recommended to avoid administration of QT-prolonging drugs in patients with prolonged QTc interval, a frequent situation in the postoperative period. Bazett QT correction inappropriately increases QTc when heart rate is increased, and the use of the Fridericia formula may avoid a falsely prolonged QTc interval. The authors assessed automatic QT interval measurement to detect prolonged QTc interval (women >450 ms; men >440 ms) in the postoperative setting. METHODS: Automatic and manual electrocardiograms were performed in 108 patients after anesthesia. Automatic electrocardiographic measurement used the Bazett formula. Manual measurements were made from each electrocardiogram and used as the reference. Agreement between the two methods was analyzed. Bazett and Fridericia QT corrections were compared in this population. RESULTS: Agreement between automatic and manual measurements was low. The Fridericia correction, but not the Bazett correction, was independent from heart rate and allowed adequate QT correction. Sensitivity of automatic measurements to detect prolonged QTc-Bazett interval was 54%. Automatic QTc-Bazett interval less than 430 ms ruled out a manual prolonged QTc interval. When automatic QTc-Bazett was greater than 430 ms, this value was converted according to Fridericia. Automatic QTc-Fridericia greater than 430 ms identified all patients with prolonged manual QTc with a negative predictive error of 0% (95% confidence interval, 0-7%). QTc-Fridericia can be approximated by respectively adding or subtracting 5% to the uncorrected QT for each increase or decrease by 10 beats/min in heart rate from 60 beats/min. CONCLUSIONS: Automatic QTc-Bazett measurement, if abnormal, associated with calculation of QTc-Fridericia reliably identifies patients in whom manual QTc measurement must be performed to confirm postoperative prolonged QTc interval.

Adult↗

PubMed1998

Home blood pressure measurement has a stronger predictive power for mortality than does screening blood pressure measurement: a population-based observation in Ohasama, Japan.

OBJECTIVE: To compare the predictive powers of self-measurement of blood pressure at home (home blood pressure measurement) and casual (screening) blood pressure measurement for mortality. DESIGN: A prospective cohort study. SUBJECTS AND METHODS: We obtained home and screening blood pressure measurements for 1789 subjects aged > or = 40 years who were followed up for a mean of 6.6 years. The prognostic significance of blood pressure for mortality was determined by the Cox proportional hazards regression model adjusted for age, sex, smoking status, past history of cardiovascular disease, and the use of antihypertensive medication. RESULTS: When the home blood pressure values and the screening blood pressure values were simultaneously incorporated into the Cox model as continuous variables, only the average of multiple (taken more than three times) home systolic blood pressure values was significantly and strongly related to the cardiovascular mortality risk. The average of the two initial home blood pressure values was also better related to the mortality risk than were the screening blood pressure values. CONCLUSIONS: Home blood pressure measurement had a stronger predictive power for mortality than did screening blood pressure measurement for a general population. This appears to be the first study in which the prognostic significances of home and screening blood pressure measurements have been compared.

Adult↗

PubMed1983

Quantitative measurement of continuity of care. Measures in use and an alternative approach.

Continuity of care is a frequently used concept without a commonly accepted definition. Proposed measures reflect different aspects of continuity, the concentration-of-care aspect playing a key role. Almost all previously proposed measures are individual-based. As an alternative we propose a visit-based approach. The visit-based measures are easy to handle technically and, because of immediate interpretations, conceptually. They are more flexible than individual-based measures regarding time perspective and ways of forming subpopulations for different kinds of comparisons. Furthermore, it is possible to derive every individual-based measure hitherto proposed from visit-based measures. When forming population measures from visit-based ones, equal weighting of visits rather than individuals seems natural. We argue that the same weighting scheme is appropriate in many situations when equal weighting of individuals has been used.

Continuity of Patient Care↗

PubMed1999

The validity in persons with spinal cord injury of a self-reported functional measure derived from the functional independence measure.

STUDY DESIGN: A cross-sectional, mailed survey on impairment and function using 6361 respondents to the Spinal Cord Dysfunction National Veterans Survey who reported spinal cord injury as the sole cause of their spinal cord dysfunction. OBJECTIVES: To establish the concurrent and construct validities of a Self-Reported Functional Measure appropriate for use in patients with spinal cord injuries. SUMMARY OF BACKGROUND DATA: Functional assessment is of increasing importance in clinical care, quality assurance, and national health-care planning. There is a conspicuous need for validated functional assessment measures that are rapid, reliable, and appropriate for use in the disabled population. METHODS: The correlation was examined of hours of personal assistance, number of affected limbs, amount of motor impairment, and amount of combined limb-motor impairment to Self-Reported Functional Measure response tertile (scores, 13-32, 33-45, 46-52; lower scores indicated worse function). RESULTS: There were statistically significant correlations between Self-Reported Functional Measure score and hours of personal assistance (P < 0.001), the number of affected limbs (P < 0.001), the amount of motor impairment (P < 0.001), and the amount of combined limbmotor impairment (P < 0.001). For example, 87% of people with the most limb-motor impairment (four affected limbs and no useful movement) were in the lowest Self-Reported Functional Measure tertile, compared with 3% of people in the least-affected category of limb-motor impairment. Furthermore, visual, sensory, or memory impairment did not influence the correlation between limbmotor impairment and Self-Reported Functional Measure score. CONCLUSION: The Self-Reported Functional Measure shows good concurrent and construct validities.

Activities of Daily Living↗

PubMed2005

A comparison of traditional protractor versus Oxford Cobbometer radiographic measurement: intraobserver measurement variability for Cobb angles.

STUDY DESIGN: A comparison between measurement of radiographs using a traditional protractor method and the Oxford Cobbometer, which has the potential to reduce error. OBJECTIVE: To assess measurement variability of Cobb angles using the Oxford Cobbometer and to compare it to that of measurements made using the traditional protractor method. SUMMARY OF BACKGROUND DATA: Studies of the Cobb method have multiple sources of error and subsequent intraobserver variability. Estimates of intraobserver variability are from 2.8 degrees to 10 degrees. METHOD: Fifty-three scoliosis curves were measured by 3 examiners. Two measurement sets were performed using the traditional protractor method and two measurement sets performed using the Oxford Cobbometer. RESULTS: For the protractor method, intraobserver variability was 9.01 degrees (95% confidence interval 7.32-10.88). For the Cobbometer method, the value was 5.77 degrees (95% confidence interval 3.25-7.63). The difference between error for construction and Cobbometer methods was significant (P < 0.001). CONCLUSIONS: This study demonstrates a lower intraobserver variability for the Oxford Cobbometer compared to the traditional construction method. The Oxford Cobbometer, besides being quick and easy to use, does not require the drawing of lines on films or the use of wide diameter radiographic markers and hence removes some sources of intrinsic error incurred during the traditional method of measuring Cobb angles.

Adolescent↗

PubMed2004

Blood pressure measurement in obese patients: comparison between upper arm and forearm measurements.

BACKGROUND: It is well known that blood pressure measurement with a standard 12-13 cm wide cuff is erroneous for large arms. OBJECTIVE: To compare arm blood pressure measurements with an appropriate cuff and forearm blood pressure measurements (BPM) with a standard cuff, and both measurements by the Photopletismography (Finapres) method. METHODS: One hundred and twenty-nine obese patients were studied (body mass index=40+/-7 kg/m2). The patients had three arm BPM taken by an automatic oscillometric device using an appropriate cuff and three forearm BPM with a standard cuff in the sitting position after a five-minute rest. Data were analysed by the analysis of variance. The correction values were obtained by the linear regression test. RESULTS: Systolic and diastolic arm BPM with an appropriate cuff were significantly lower (p<0.05) than forearm BPM with a standard cuff. The measurements obtained by Finapres were significantly lower (p<0.05) than those found for forearm systolic and diastolic blood pressures and upper arm diastolic blood pressure. The equation to correct BPM in forearm in obese patients with arm circumference between 32-44 cm was: systolic BPM=33.2+/-0.68 x systolic forearm BPM, and diastolic BPM=25.2+0.59 x forearm diastolic BPM. CONCLUSION: This study showed that forearm blood pressure measurement overestimates the values of arm blood pressure measurement. In addition, it is possible to correct forearm BPM with an equation.

Arm↗

PubMed1989

Relationships between alveolar bone levels measured at surgery, estimated by transgingival probing and clinical attachment level measurements.

Alveolar bone level measurements obtained by transgingival probing were compared with alveolar bone levels measured during surgery at 178 sites in 9 patients. Probing depth measurements using constant loads of 30 g and 60 g were also compared with bone levels measured at surgery at the above sites. The effects of inflammation, location of the site on the tooth surface and tooth type were also investigated. Transgingival probing was unaffected by these factors and proved to be an accurate method of measuring alveolar bone levels (r = 0.975). Probing depth measurements were affected by the presence of inflammation, assessed by the bleeding response to probing, and variation in probing load. The effect of inflammation was to reduce the mean distance between the probe tip and the alveolar bone from 2.4 mm to 1.9 mm. None of the relationships between the measurements were significantly affected by the location of the site on the tooth surface, or by tooth type.

Adult↗

PubMed1978

Effects of recording speed on precision of time-based polycardiographic measurements. Optimal paper speeds for measuring points and intervals.

Optimal paper speeds have not been established for all time-based measurements of the cardiac cycle by appropriately designed observer performance studies. In 10 subjects (5 normals and 5 cardiac patients) carotid pulse, phonocardiogram, and electrocardiogram were recorded on magnetic tape for measurement of all fiducial points for systolic time intervals, the systolic time intervals themselves, the pulse transmission time, cycle length (RR), qR time, and R-to-point versus q-to-point measurements at recording speeds of 25, 50, 75, 100, and 200 mm/s. Tracings were coded numerically and randomised. Three observers measured all points and calculated intervals in a sequence determined by individual tables of random numbers. Left ventricular ejection time was the only calculation that could be made at 25 mm/s statistically equally well as at all other speeds. The smallest numerical observer differences occurred uniformly at 100 mm/s paper speed when all recording speeds were considered. However, after excluding the 25 mm/s speed there were no significant differences among point measurements. Measurements of points from R (rather than q) reduced observer variability. We conclude that for point measurements, for systolic time intervals, pulse transmission time, and RR interval, recording speed between 50 and 200 mm/s showed no statistical differences, though smallest numerical differences occurred at 100 mm/s. For LVET, 25 mm/s was satisfactory.

Adult↗

PubMed1999

Measuring change in disability after inpatient rehabilitation: comparison of the responsiveness of the Barthel index and the Functional Independence Measure.

BACKGROUND: The importance of evaluating disability outcome measures is well recognised. The Functional Independence Measure (FIM) was developed to be a more comprehensive and "sensitive" measure of disability than the Barthel Index (BI). Although the FIM is widely used and has been shown to be reliable and valid, there is limited information about its responsiveness, particularly in comparison with the BI. This study compares the appropriateness and responsiveness of these two disability measures in patients with multiple sclerosis and stroke. METHODS: Patients with multiple sclerosis (n=201) and poststroke (n=82) patients undergoing inpatient neurorehabilitation were studied. Admission and discharge scores were generated for the BI and the three scales of the FIM (total, motor, and cognitive). Appropriateness of the measures to the study samples was determined by examining score distributions, floor and ceiling effects. Responsiveness was determined using an effect size calculation. RESULTS: The BI, FIM total, and FIM motor scales show good variability and have small floor and ceiling effects in the study samples. The FIM cognitive scale showed a notable ceiling effect in patients with multiple sclerosis. Comparable effect sizes were found for the BI, and two FIM scales (total and motor) in both patients with multiple sclerosis and stroke patients. CONCLUSION: All measures were appropriate to the study sample. The FIM cognitive scale, however, has limited usefulness as an outcome measure in progressive multiple sclerosis. The BI, FIM total, and FIM motor scales show similar responsiveness, suggesting that both the FIM total and FIM motor scales have no advantage over the BI in evaluating change.

Activities of Daily Living↗

PubMed1986

Uroflow measurements: their information yield in a long-term investigation of pre- and postoperative measurements.

This investigation shows that the reproducibility of uroflow measurements is limited. For their evaluation, anamnesis and the measured results have to be taken into account equally. We found correspondence of both parameters in about 50% only. One single measurement cannot provide precise information, as psychogenic, social, and other factors influence the measurement. In our study 3 subjects had their micturitions registered over a period of 2 months. We found an increase of the maximum flow with increasing bladder volume. The maximum bladder volume was reached in only four micturitions. Normal values range at about 25% of the maximum bladder volume. Analyzing the micturitions in regard to the time of day, we found maximum flow rates in the morning hours. Under clinical conditions the altered surroundings lead to a measured result which is psychogenically influenced and can only be balanced after repeated measurements. The curves of all 3 patients were equal and inconspicuous. In cases of infravesical obstruction, surgical success could be documented by comparing the pre- and postoperative uroflows. In all cases of neurogenic bladder disorders and unclear findings, uroflow measurements are, however, not sufficient, and diagnosis is accomplished by a complete urodynamic examination. In spite of certain restrictions, uroflowmetry yields a high level of information, besides being a simple, at any time reproducible, and noninvasive procedure. Due to its low costs, it should be the primary step in diagnostics in the clinic as well as for practitioners.

Adult↗

PubMed2003

An applanation resonator sensor for measuring intraocular pressure using combined continuous force and area measurement.

PURPOSE: For diagnostic purposes and for follow-up after treatment, it is important to have simple and reliable methods for measuring intraocular pressure (IOP). The purpose of this study was to develop a new applanation method for IOP measurement that uses combined continuous force and area measurement and to develop and evaluate an applanation resonator sensor (ARS) tonometer based on that method. METHODS: The tonometer was developed and evaluated in an in vitro porcine eye model, in which enucleated eyes were pressurized with a saline column. A model assuming that the applanation principle is valid over a certain interval of contact area was proposed. Continuous contact area was measured with a resonator sensor device, and contact force was measured with a force transducer, both mounted together in one probe. Reference IOP was measured in the vitreous chamber (IOP(VC)) with a standard fluid pressure transducer. RESULTS: An optimization algorithm determined the applanation interval that was optimal for calculating IOP(ARS). The corresponding time interval was 30 +/- 3 to 77 +/- 4 ms (mean +/- SD, n = 418) after initial contact. The proposed model showed a degree of explanation of R(2 [supi]) = 0.991 (n = 410, six eyes), corresponding to a correlation of r = 0.995 (n = 410) between IOP(ARS) and IOP(VC). The within-eyes precision (i.e., 95% confidence interval for the residuals between IOP(ARS) and IOP(VC)) was +/- 1.8 mm Hg (n = 410, six eyes). CONCLUSIONS: In this study, the ARS method for measuring IOP was evaluated in an in vitro porcine eye model and showed high precision. The ARS method is, to the authors' knowledge, the first to combine simultaneous, continuous sampling of both parameters included in the applanation principle: force and area. Consequently, there is a potential for reducing errors in clinical IOP tonometry.

Algorithms↗