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PubMed2006

Is digital image plethysmographic (DIP) acquisition a valid new tool for preoperative body composition assessment? A validation by dual-energy X-ray absorptiometry.

BACKGROUND: The increasing incidence of obesity and the wider acceptance of laparoscopic surgery, have lead to a 10-fold increase in bariatric operations in the last 10 years. Widely used indices of obesity (weight and body mass index - BMI) cannot adequately distinguish between fat mass (FM), represented by the sum of kilograms (kg) of lipid, and fat-free mass (FFM), inclusive of lean (kg of proteins), bone (kg of minerals), glycogen, and total body water (TBW), which are important parameters for clinical and physiological studies. METHODS: Anthropometric variables were measured in 19 Caucasian Italian individuals according to standard methods. Body weight (kg) and height (m) were measured, and BMI was calculated as kg/m(2). Body composition was evaluated, with a mean BMI of 25.95+/-5.04 kg/m(2), by dual X-ray absorptiometry (DXA) and by digital image plethysmographic (DIP) acquisition with a digital camera. The clear-colored body of the subjects was automatically converted into a front and lateral red-shaped figure, and then through algorithms the 2 pictures were transformed into a nominal volume; body weight was then divided by the estimated volume, so that the body density could be obtained. DXA was used as a comparison to assess fat mass and fat-free mass. Radiation exposure was <0.6 mSv. RESULTS: Significant positive correlation (R= 0.971, P<0.001) was found between data of body composition obtained by DXA and DIP. CONCLUSIONS: Body volume assessed using DIP or DXA did not differ. According to this validation study, DIP represents a new promising tool for clinical applications.

Absorptiometry, Photon↗
PubMed2005

Validation of the subtle and overt psychological abuse scale: an examination of construct validity.

The Subtle and Overt Scale of Psychological Abuse (Marshall, 1999a) is a measure designed to examine previously unevaluated forms of psychological abuse. The scale was originally divided into seven subscales (overt: dominance, indifference, monitoring and discrediting; subtle: undermining, discounting, isolating). A sample of 172 women was used to evaluate the construct validity of this measure. In other words, the internal structure of the measure, its relation to other measures of physical and psychological abuse, and its relationship to other psychological outcomes. Empirical and theoretical approaches were used to replicate and examine the dimensions of this scale. Results revealed that this scale represents a unidimensional construct that is highly correlated to other measures of psychological abuse. Implications for future research and practice are discussed.

Adult↗
PubMed1978

The Peer Preference Test as a measure of reward value: item analysis, cross-validation, concurrent validation, and replication.

Thirty-six preschoolers were administered and retested on a 15-item Peer Preference Test designed to measure the reward value of peers for each child. Test-retest reliability was .88, and after item analyses, 12 items were maintained in the test. The revised test was then administered to 29 other preschoolers. Test-retest reliability was .77, and item analyses indicated that each item made a significant contribution to the overall test. Concurrent validation of the test was demonstrated using both a picture sociometric and a behavioral measure. In addition, the Evers-Pasquale and Sherman (1975) study was replicated, using 10 preschool social isolates.

Behavior Therapy↗
PubMed1996

Measurement of menopausal hot flushes: validation and cross-validation.

Specificity and sensitivity of two physiological markers for hot flushes were investigated. One marker, proposed by Freedman, is an increase of sternal skin conductance, the second marker, proposed by Swartzman, is a physiological profile which consists of skin conductance changes in combination with circulation changes. In our laboratory 20 menopausal women, 15 with frequent hot flushes and 5 without hot flushes, and 5 women with regular menstrual cycles were continuously monitored for 2.5 h on subjective hot flush experience, sternal and palmar skin conductance, dorsal and palmar finger temperature and pulse blood volume. Increase in sternal skin conductance proved to be very specific in contrast to Swartzman's physiological profile, although it was less sensitive. Receiver operating characteristics revealed that an increase combined with a preceding decrease in sternal skin conductance as most specific for, and most sensitive to, subjectively reported hot flushes. This was confirmed by a cross-validation with 34 "flushing' menopausal women.

Adult↗
PubMed2006

Cleaning validation 1: development and validation of a chromatographic method for the detection of traces of LpHse detergent.

A high performance liquid chromatography (HPLC) method for the detection of traces of LpHse (4-tert-amylphenol and 2-phenylphenol) has been developed and validated. The method was shown to be linear in the range from 0.5 to 10.00 ppm in solution. The method was also shown to be accurate with a recovery of up to 95% by area response for amylphenol and up to 94% by area response for phenylphenol from metal surfaces (4''x4'' un-polished 304 stainless steel plates) by means of swab material. The reproducibility of the method was determined to be 1.61% by area response and 1.52% by height response for amylphenol and 5.40% by area response and 13.77% by height response for phenylphenol from solutions reported as the pooled relative standard deviation. The developed method was also shown to be rugged by comparisons of different preparations by different analysts. The limit of detection was established to be 0.076 ppm by peak area, 0.079 ppm by peak height for amylphenol and 0.34 ppm by peak area, 0.82 ppm by peak height for phenylphenol from solution, and 1.77 ppb by peak area, 1.23 ppm by peak height for amylphenol and 1.23 ppm by peak area, 1.44 ppm by peak height for phenylphenol from recovery from metal studies. The limit of quantitation was established to be 0.25 ppm by peak area, 0.26 ppm by peak height for amylphenol and 1.14 ppm by peak area, 2.73 ppm by peak height for phenylphenol from solution, and 3.89 ppm by peak area, 4.11 ppm by peak height for amylphenol and 4.11 ppm by peak area, 4.79 ppm by peak height for phenylphenol from recovery from metal plates studies. This method can be employed to determine the presence of LpHse residues in cleaned equipments where the detergent was used.

Biphenyl Compounds↗
PubMed1991

Development and validation of a protocol for field validation of passive dosimeters for ethylene oxide excursion limit monitoring.

An exposure and analysis protocol is described for the field validation of passive dosimeters for ethylene oxide (EtO) excursion limit monitoring. The protocol calls for the use of a field exposure chamber with concurrent sampling using Tedlar air-sampling bags. The bags are analyzed immediately after sampling by gas chromatography with flame ionization detection (GC-FID). The chamber design allows all monitors to be exposed for the exact same time in the field. The sampling and analysis procedure not only determines the actual concentration of EtO present during the monitor's exposure but estimates if concentrations of EtO vary from point to point in the monitor array during the exposure. In chamber operation, the accuracy of the standard generator used to calibrate the GC-FID was independently verified in the field by the standard additions method. The sampling bias of the sampling train was determined to be -3.5% in the 2.4 ppm to 14.3 ppm concentration range. To estimate the stability of collected EtO samples in Tedlar bags, the rate of EtO loss in the bags was determined to be 0.011 ppm/hr at 2.57 ppm and 0.066 ppm/hr at 8.07 ppm. Sampling bias of the passive methods by additional EtO exposure of the monitors in the closed chamber after sampling and during purging was determined to be +1.5%. The Tedlar bag sampling method with subsequent GC-FID determination demonstrated a coefficient of variation of 1.8% at 2.43 ppm.

Air Pollutants, Occupational↗
PubMed1999

Validity of the body mass index as an indicator of the risk and presence of overweight in adolescents.

The validity of the body mass index (BMI) as an indicator of the risk of becoming overweight and of the presence of overweight was evaluated in 6 groups of adolescents comprising several ethnic groups (n = 1570, aged 9-19 y). With use of triceps skinfold thickness and estimated percentage body fat as the criteria for adiposity, BMI had high specificities (86.1-98.8% for risk of overweight and 96.3-100% for presence of overweight) and lower but variable sensitivities (4.3-75.0% for risk of overweight and 14.3-60% for presence of overweight). Thus, almost all adolescents who were not at risk for overweight or who were not overweight were classified correctly. In contrast, many adolescents who were at risk of overweight or who were overweight were not correctly identified as measured by BMI. Partial correlations, controlling for age, between BMI and the triceps skinfold thickness and estimated percentage body fat were generally moderate to moderately high, whereas BMI and triceps skinfold thickness appeared to be equally related to estimated total body fatness and percentage body fat in Mexican American and Austrian white males. BMI was better correlated with trunk skinfold thicknesses, but when relative subcutaneous fat distribu-tion was statistically controlled, the trunk-extremity contrast in the correlations was no longer apparent.

Journal Article↗
PubMed1985

Validation of attenuation-corrected equilibrium radionuclide angiographic determinations of right ventricular volume: comparison with cast-validated biplane cineventriculography.

To determine the accuracy of attenuation-corrected equilibrium radionuclide angiographic determinations of right ventricular volumes, we initially studied 14 postmortem human right ventricular casts by water displacement and biplane cineventriculography. Biplane cineventriculographic right ventricular cast volumes, calculated by a modification of Simpson's rule algorithm, correlated well with right ventricular cast volumes measured by water displacement (r = .97, y = 8 + 0.88x, SEE = 6 ml). Moreover, the mean volumes obtained by both methods were no different (73 +/- 28 vs 73 +/- 25 ml). Subsequently, we studied 16 patients by both biplane cineventriculography and equilibrium radionuclide angiography. The uncorrected radionuclide right ventricular volumes were calculated by normalizing background corrected end-diastolic and end-systolic counts from hand-drawn regions of interest obtained by phase analysis for cardiac cycles processed, frame rate, and blood sample counts. Attenuation correction was performed by a simple geometric method. The attenuation-corrected radionuclide right ventricular end-diastolic volumes correlated with the cineventriculographic end-diastolic volumes (r = .91, y = 3 + 0.92x, SEE = 27 ml). Similarly, the attenuation-corrected radionuclide right ventricular end-systolic volumes correlated with the cineventriculographic end-systolic volumes (r = .93, y = - 1 + 0.91x, SEE = 16 ml). Also, the mean attenuation-corrected radionuclide end-diastolic and end-systolic volumes were no different than the average cineventriculographic end-diastolic and end-systolic volumes (160 +/- 61 and 83 +/- 44 vs 170 +/- 61 and 86 +/- 43 ml, respectively). Comparison of the uncorrected and attenuation-corrected radionuclide right ventricular volumes demonstrated narrower 95% confidence intervals for the attentuation-corrected right ventricular volume determinations over a wide range of cineventriculographic volumes. Thus we conclude that: (1) attenuation-corrected radionuclide right ventricular end-diastolic and end-systolic volumes compare closely with those obtained by a cast-validated biplane cineventriculographic method and (2) attenuation-corrected radionuclide right ventricular volumes correspond more closely to determinations of biplane cineventriculographic right ventricular volumes and are thus likely to be more accurate than uncorrected radionuclide right ventricular volumes.

Adolescent↗
PubMed2003

Validity and representativity in the Danish Breast Cancer Cooperative Group--a study on protocol allocation and data validity from one county to a multi-centre database.

Population-based cancer registries collect basic information on incident cases, whereas clinical databases hold a broad range of variables that make them attractive sources in epidemiological research. Quality, completeness and representativeness of the clinical database in the Danish Breast Cancer Cooperative group (DBCG) were compared with those in a complete population-based database holding detailed information on patients with breast cancer. The study included 1765 patients diagnosed in Aarhus County between 1983 and 1989. Data on tumour characteristics were of high quality. Fifty percent of patients were included in DBCG trials and a total of 83% were notified in the DBCG register, the rest having significantly poorer stage distribution and survival probabilities. However, for patients younger than 70 years of age, the difference in overall survival between all patients and those notified in the DBCG register was only 2%. Follow-up was incomplete in patients treated outside the programme, and this had a major impact on recurrence-free survival. The DBCG database holds high-quality data, but as a population-based database, it is neither comprehensive nor representative.

Adult↗
PubMed2005

Validation of the Bech-Rafaelsen Melancholia Scale and the Hamilton Depression Scale in patients with major depression; is the total score a valid measure of illness severity?

OBJECTIVE: Evaluation of antidepressant drug efficacy requires adequate rating scales for measuring the severity of depression. However, to measure the illness severity by such a total score, the scale needs to fulfil criteria of unidimensionality. On this background, we aimed at comparing the unidimensionality of the Bech-Rafaelsen Melancholia Scale (MES) and the 17-item Hamilton Depression Rating Scale (HAM-D(17)). METHOD: A total of 1629 patients aged between 18 and 65 years with a major depressive episode were treated openly with sertraline at a fixed oral dose of 50 mg daily during 4 weeks. The HAM-D(17) and the MES were applied at baseline and at weeks 2 and 4. Unidimensionality was tested with Mokken and Rasch analysis. RESULTS: Unidimensionality of the HAM-D(17) could not be confirmed. However, the 6-item Hamilton Depression Subscale (HAM-D(6)), was accepted by the Rasch analysis both at baseline and after 2 and 4 weeks of therapy. For the MES (as well as for the HAM-D(6)), a Loevinger coefficient of homogeneity above 0.40 (suggesting acceptance) was found at week 4. CONCLUSION: The HAM-D(6) and the MES did fulfil criteria for unidimensionality while the HAM-D(17) did not. Therefore, the extended use of the HAM-D(17) in drug trials may be questioned.

Adolescent↗
PubMed2006

Analysis and validation of automated skull stripping tools: a validation study based on 296 MR images from the Honolulu Asia aging study.

As population-based epidemiologic studies may acquire images from thousands of subjects, automated image post-processing is needed. However, error in these methods may be biased and related to subject characteristics relevant to the research question. Here, we compare two automated methods of brain extraction against manually segmented images and evaluate whether method accuracy is associated with subject demographic and health characteristics. MRI data (n = 296) are from the Honolulu Asia Aging Study, a population-based study of elderly Japanese-American men. The intracranial space was manually outlined on the axial proton density sequence by a single operator. The brain was extracted automatically using BET (Brain Extraction Tool) and BSE (Brain Surface Extractor) on axial proton density images. Total intracranial volume was calculated for the manually segmented images (ticvM), the BET segmented images (ticvBET) and the BSE segmented images (ticvBSE). Mean ticvBSE was closer to that of ticvM, but ticvBET was more highly correlated with ticvM than ticvBSE. BSE had significant over (positive error) and underestimated (negative error) ticv, but net error was relatively low. BET had large positive and very low negative error. Method accuracy, measured in percent positive and negative error, varied slightly with age, head circumference, presence of the apolipoprotein eepsilon4 polymorphism, subcortical and cortical infracts and enlarged ventricles. This epidemiologic approach to the assessment of potential bias in image post-processing tasks shows both skull-stripping programs performed well in this large image dataset when compared to manually segmented images. Although method accuracy was statistically associated with some subject characteristics, the extent of the misclassification (in terms of percent of brain volume) was small.

Aged↗
PubMed1998

Device implementation, validation, and application assessment of two continuous 12-lead ECG monitors during percutaneous transluminal coronary angioplasty: description of the validation method and implications for clinical trials.

Comparability of clinical and research data sets may be undermined if the instruments used to acquire them vary. Even when standard 12-lead electrocardiographic formats are used for monitoring, proprietary signal processing techniques and sampling intervals may differ among devices. In order to directly compare the two commercially available standard 12-lead devices with monitoring capabilities, bifurcated wires from a single standard lead set were attached to each device in elective angioplasty patients. Neither device was used as a standard; rather, a method was designed to analyze the output from each device independently, and then, if results differed, data from both monitors were reviewed by consensus to determine the source of the differences. Analysis endpoints for each study included study quality, baseline ST-segment levels, the presence of ischemia, number of ischemic episodes, peak lead location, and peak lead amplitude. Sources of differences in these endpoints visible to consensus review included variations between devices in baseline stability, noise/artifact levels, stability of the QRS complex onset, and temporal sampling intervals.

Angioplasty, Balloon, Coronary↗
PubMed1989

Validation of an imaging system: steps to evaluate and validate a microscope imaging system for quantitative studies.

The processing methods described in this article are general and can be used with any computer with adequate software without reference to a specific experimental apparatus. To achieve appropriately corrected images, the operations must be performed correctly and in a specific order to extract meaningful information from digital images. The operations are subtraction of the dark current, a shading correction after low pass filtering of the shading mask, a geometric correction with a reference grid obtained at the longest wavelength of interest, and finally registration. Since the digital data sets are too large for manual evaluation, statistical criteria must be used to define the analytical capabilities and error limits of the system before the more interesting cellular studies can be undertaken.

Algorithms↗