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PubMed1998

The Danish SF-36 Health Survey: translation and preliminary validity studies.

This article reports on the Danish translation of SF-36 and discusses the procedures used for translation improvement, translation evaluation, and scale evaluation. We followed the standard procedures of the International Quality of Life Assessment (IQOLA) Project including forward and backward translation, independent assessment of translation quality, assessment of response-choice weighting through visual analogue scale (VAS) investigations, and psychometric testing of the translated questionnaire. We found that backward translation, independent quality assessment, and VAS studies provided useful information for translation improvement. The Danish SF-36 received a favorable translation evaluation by independent rating; however, interrater agreement was low. Preliminary validity studies generally supported the internal consistency and homogeneity of the Danish SF-36, and the questionnaire performed satisfactorily in distinguishing depressive patients from nonpatients. On the basis of this and other studies, we recommend use of the Danish SF-36 in research.

Denmark↗

PubMedDate not supplied

Bacterial cell size and surface charge characteristics relevant to filter validation studies.

There are two recognized mechanisms whereby organisms are retained by liquid filters; namely, sieve-retention and adsorption. The efficiency of each may be influenced by the organism, suspending milieu, and by the filtration conditions. Validations of sterilizing filtrations require the use of organism suspensions in product-specific media. However, where the product is bactericidal to the challenge organism(s), surrogate solutions may be required. The ideal surrogate solution would minimize adsorptive retention, ensuring that the sterilizing action of the filter under consideration is the consequence of sieve-retention. This review explores the impact that various physicochemical factors may have on bacterial cell size and cell surface characteristics. An understanding of interactions among challenge bacteria, suspending fluid, and filter medium is essential for the development of surrogate solutions that provide a "worst case" mileu for filter validation studies or a "placebo," non-inhibitory challenge solution.

Adsorption↗

PubMed1989

Conners' Teacher's Rating Scale--a validity study in Hong Kong.

The validity of the Conners' teacher's rating scale (CTRS) in Hong Kong Chinese school children was examined. It was found that CTRS could significantly differentiate a behaviorally deviant group and the normal population; that CTRS has a strong positive correlation with the teacher's decision to refer a child to a mental health professional; that the CTRS by itself is not useful as a diagnostic instrument; and finally, it cannot stand alone as a screening instrument in the epidemiological study of childhood hyperactivity.

Attention Deficit Disorder with Hyperactivity↗

PubMedDate not supplied

International validation study for the determination of chloramphenicol in bovine muscle.

A gas chromatographic (GC) procedure for the quantitation and GC/negative ion chemical ionization mass spectrometric (NICIMS) confirmation of chloramphenicol in calf muscle tissue was the subject of a validation study. Five analysts representing 5 laboratories in 4 countries participated in the quantitative method and analyzed 7 randomly numbered blind triplicates at 4 fortified and 3 incurred tissue concentrations on 3 separate days. The chloramphenicol concentrations ranged from 0 to 2.5 ppb. All data were reported to 3 significant figures. The coefficients of variation were 9.5-28.7% for repeatability and 14.6-38% over the study range for reproducibility. NICIMS data representing 3 laboratories in 3 countries successfully confirmed chloramphenicol in samples at 0.6 ppb or greater with no false positives in blank tissues.

Animals↗

PubMed1994

Accuracy and precision of quantitative arteriography in the evaluation of coronary artery disease after coronary bypass surgery. A validation study.

Computer-assisted quantitative coronary arteriography (QCA) has gained widespread acceptance in assessing changes in coronary dimensions over time, but little is known about the utility of QCA in patients having undergone coronary bypass surgery. As a validation study, we analyzed the accuracy and precision of QCA in a subset of the baseline angiograms of a clinical trial in 395 post-bypass men with low HDL cholesterol concentrations who have been randomized to receive double-blind gemfibrozil or placebo for 2 1/2 years. Based on repeat measurements of the same cineframe, the average diameter of a segment (ADS) had a mean coefficient of variation (CV) of 3.1%. The mean CVs of the minimum luminal diameter (MLD), percent diameter stenosis (PDS) and stenotic flow reserve of an obstruction were 8.6, 10.2 and 9.8%, respectively, but the area of the atherosclerotic plaque had an unacceptably high CV, 24.0%. When the measurements from two contrast injections into a native coronary artery during the same angiographic session were compared, precision (standard deviation of the differences) was 0.198 mm for ADS, 0.192 mm for MLD, and 7.37% for PDS. Variability was not substantially reduced when measurements from 3 or 5 consecutive cineframes were averaged. Comparable repeatability was found when venous bypass grafts were imaged twice, whether the grafts themselves or the grafted native vessels were analyzed. We conclude that QCA has an acceptable accuracy and precision in analyzing coronary dimensions in bypass-grafted patients. A change of 0.40 mm in ADS and MLD, and 20% in PDS represent true progression or regression of coronary atherosclerosis with more than 95% confidence.

Cholesterol, HDL↗

PubMed1993

Localisation of cerebral function using topographical mapping of EEG: a preliminary validation study.

In an attempt to validate the use of topographical mapping of EEG as a method of localising cerebral function, EEG was recorded during a simple motor task. A minimum of 20 sec artifact-free EEG was recorded from 24 healthy right handed subjects in each of 4 conditions: eyes open 1, motor task (left/right, order randomized), eyes open 2. EEG amplitude maps were computed in delta, theta, alpha, and beta (1 and 2). Differences were seen between the eyes open and the motor conditions in alpha, beta 1 and beta 2 localised to the motor and supplementary motor areas. It is argued that topographical mapping of EEG is a valid method of localising cognitive function in healthy individuals for the Luria task.

Adult↗

PubMed1998

Driving behavior in a real and a simulated road tunnel--a validation study.

The aim was to validate driving behaviour in a simulated road tunnel. Speed and lateral position of 20 subjects were measured in a real tunnel and in the same tunnel implemented in the VTI driving simulator. In both situations a left-hand steered and manually geared passenger car was used. Driving speed was higher in the simulated tunnel than in the real tunnel. Elimination of speed information from the speedometer caused a similar small speed increase in both situations. Also, the difference in speed between driving lanes was similar in both cases. The effects on speed variation were similar to that for speed level. Regarding lateral position, subjects positioned the car somewhat further away from the nearest tunnel wall in the real tunnel than in the simulated tunnel. In both situations the distance to the nearest wall was greater when it was located to the left of the driver than on the opposite side. Lateral position deviation was about the same when the road was straight, but in a curved section it was somewhat greater for the simulated tunnel. It is concluded that behavioural validity in absolute terms was not quite satisfactory, especially regarding choice of speed, whereas relative validity was good for both speed and lateral position.

Adult↗

PubMed1995

Acute Physiology and Chronic Health Evaluation II scoring system in acute myocardial infarction: a prospective validation study.

OBJECTIVE: To study the usefulness of the Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring system for prognostication of inhospital mortality in acute myocardial infarction. DESIGN: A prospective validation study. SETTING: A medical intensive care unit (ICU) at a university hospital. PATIENTS: Over a 3-yr period, 2,007 admissions of 1,714 patients with acute myocardial infarction were studied. In readmissions to the medical ICU during the same hospital stay, only the first admission was studied. MEASUREMENTS AND MAIN RESULTS: Mean age of the patients was 72 +/- 10 yrs. The medical ICU mortality rate was 13% and total hospital mortality rate was 16%. Mean APACHE II score was 11.6 +/- 6.5. There was a close correlation between observed and predicted mortality rates in classes of patients with various APACHE II scores. Observed mortality in patients with scores of 20 to 24 was higher than the predicted mortality (p < .03). In this subgroup, 25% of the patients had a length of stay in the medical ICU of < 8 hrs. CONCLUSIONS: Inhospital mortality in patients with acute myocardial infarction could be accurately predicted with APACHE II scores. Prognostication was not as good in patients with a length of stay in the medical ICU of < 8 hrs.

APACHE↗

PubMedDate not supplied

Multiresidue gas chromatographic method for determining organochlorine pesticides in meats: validation study for swine and beef fats.

A validation of a previously studied method for determining organochlorine residues in poultry fat was conducted to extend the usefulness of the method to beef and swine fats. The validation samples consisted of 16 materials all analyzed in duplicate. Fortification levels ranged from 0.02 to 1.2 ppm for alpha-BHC, lindane, cis- and trans-chlordane, octachlor epoxide, o,p'- and p,p'-DDT, p,p'-DDE, p,p'-TDE, hexachlorobenzene, heptachlor epoxide, dieldrin, endrin, methoxychlor, mirex, and toxaphene. The average recovery was 101% with a range of 79-113%, not including toxaphene. The ranges of coefficients of variation were CVo = 0-23.37% and CVx = 3.74-26.19%. The results were comparable to the previous collaborative study of the same method for poultry fat. The extended method has been adopted official first action.

Animals↗

PubMed1996

Algorithms for verbal autopsies: a validation study in Kenyan children.

The verbal autopsy (VA) questionnaire is a widely used method for collecting information on cause-specific mortality where the medical certification of deaths in childhood is incomplete. This paper discusses review by physicians and expert algorithms as approaches to ascribing cause of deaths from the VA questionnaire and proposes an alternative, data-derived approach. In this validation study, the relatives of 295 children who had died in hospital were interviewed using a VA questionnaire. The children were assigned causes of death using data-derived algorithms obtained under logistic regression and using expert algorithms. For most causes of death, the data-derived algorithms and expert algorithms yielded similar levels of diagnostic accuracy. However, a data-derived algorithm for malaria gave a sensitivity of 71% (95% Cl: 58-84%), which was significantly higher than the sensitivity of 47% obtained under an expert algorithm. The need for exploring this and other ways in which the VA technique can be improved are discussed. The implications of less-than-perfect sensitivity and specificity are explored using numerical examples. Misclassification bias should be taken into consideration when planning and evaluating epidemiological studies.

Algorithms↗

PubMed1991

Risk assessment for HIV infection: validation study of a computer-assisted preliminary screen.

Development has been undertaken for microcomputer software intended to assess individual risk for HIV infection by analyzing personal case histories pertinent to drug abuse, receptive blood transfusion, and sexual behavior. The software performs interactive confidential interviews of individuals desiring expert assistance when deciding whether to commit to an antibody test. In the first phase of a validation study, 87 subjects responded to the computer interview. For each subject, human immunodeficiency virus (HIV) antibody status was on clinical record. This sample included 70 subjects, 29 of whom were HIV seropositive, recruited from the clientele of an AIDS antibody testing and counseling facility. In this phase, the software accurately assessed 28 of 29 seropositives (96.6%) to be at risk for HIV. The second phase was based upon participation of an additional 74 subjects who were undergraduates at the University of Oklahoma. In this presumed low-risk sample, 55 members reported never having previously tested for HIV antibodies. Seven members (12.7%) of the untested group were declared at risk in the course of receiving confidential computer screen advice. Of these 7, there were 3 members (42.9%) who were motivated by the computer to voluntarily seek HIV antibody testing. Of the 7 declared at risk, 2 members (3.9%) were among the 51 seronegative subjects classified as heterosexuals without specific and identified risks. All Phase II subjects seeking follow-up antibody tests were found seronegative.

Diagnosis, Computer-Assisted↗

PubMed1990

Validation study methods for estimating exposure proportions and odds ratios with misclassified data.

Two methods for making adjustments to an estimate of exposure when data are possibly misclassified are discussed. One, the indirect method, is widely used but the other, the direct method, seems less well-known, despite it being a rather more obvious approach. To implement either requires some knowledge of misclassification rates and it may be possible to estimate these by a validation study. Depending on how sampling for such a study is done, one has the choice of what method to use. Formulae for the variance of estimates are derived and the precision of the methods compared. The direct approach is found to be more efficient.

Environmental Exposure↗

PubMedDate not supplied

FETAX interlaboratory validation study: phase III--Part 1 testing.

The Frog Embryo Teratogenesis Assay-Xenopus (FETAX) is a 96-h whole embryo developmental toxicity screening assay that can be used in ecotoxicology and in detecting mammalian developmental toxicants when an in vitro metabolic activation system is employed. A standardized American Society for Testing and Materials (ASTM) guide for the conduct of FETAX has been published, along with a companion atlas that aids in embryo staging and identifying malformations. As part of the ASTM process, a three-phase interlaboratory validation study was undertaken to evaluate the repeatability and reliability of FETAX. Seven different participants collaborated in the study. In Phase I, FETAX proved to be more repeatable and reliable than many bioassays. However, some excessive variation was observed in a few laboratories. An initial lack of assay experience by some technicians caused variation. Phase II showed far less intra- and interlaboratory variability than Phase I. Non-teratogens showed the most consistent results, while more variability was observed for the two teratogens tested. Interlaboratory coefficient of variation values for all endpoints ranged from 7.3 to 54.7. Phase III--Part 1, using coded samples and test concentration ranges selected by each laboratory, showed results similar to Phase I. Analysis of the causes of variation suggested that some technicians judged some embryos to be malformed while others consistently judged similar embryos as normal. Concentration ranges tested by some of the laboratories varied greatly and a new protocol for selecting concentrations for initial testing was written to reduce variation from this source. Testing to date suggests that FETAX is as repeatable and reliable as other standard bioassays.

Aminopropionitrile↗

PubMed1989

The anxiety thermometer: a validation study.

The aim of our study was to provide validation and reproducible data for the anxiety thermometer. This thermometer is either a continuous or a 10-point Likert-type scale on which subjects are asked to rate their anxiety feelings at a particular moment. It is a quick way to measure state-anxiety. As a validation criterion the State-Trait Anxiety Inventory (STAI) A-State scale was used. To test the reproducibility of the thermometer, a test-retest correlation coefficient was calculated, with a retrospective second thermometer score. The ego-threatening situation used was a written examination. Two experiments were carried out during different examination conditions. The data consistently indicated that the validity and reproducibility of the anxiety thermometer is fair (correlation coefficients between .60 and .78) In the second study, the possible influence of two factors on the retrospective scores were additionally tested.

Adult↗

PubMed1997

A validation study of home uterine activity monitoring technology in Western Australia.

Home uterine activity monitoring has been developed as an 'early warning' device to detect premature uterine activity, thereby encouraging earlier referral and tocolysis of women at risk of preterm delivery. This ambulatory monitoring system, utilizing a ring-guard tocodynamometer, was piloted in Western Australia to determine if it can reliably record and transmit antenatal uterine activity data in an Australian environment. Pregnant women were readily able to correctly apply and use the ambulatory monitoring device. The information collected was able to be transmitted using standard Australian telecommunications systems within our hospital environment. Validation studies with the ambulatory monitor and current external tocodynamometry hardware were performed. The ring-guard tocodynamometer detected more uterine activity at gestations less than 32 weeks compared with conventional external tocodynamometers. As term approached, however, the sensitivity of the ring-guard tocodynamometer decreased. A cross-sectional profile of antenatal uterine activity was developed for women at low risk of delivering preterm. A gradual increase in the number, duration and amplitude of uterine contractions as pregnancy advanced was observed.

Female↗

PubMed1986

Neurobehavioral screening in rats: validation study.

The usefulness of a neurobehavioral check-list for the detection and characterization of neurotoxic effects of chemical compounds was evaluated in rats. The animals were given single doses of the test compounds, and higher or lower doses of the substances were administered in subsequent weeks, depending on the outcome of the experiments. The testing procedure proved to be useful for detecting the neurobehavioral hazards of psychotherapeutics and other drugs with known neurobehavioral side-effects. However, the investigational technique was less satisfactory for evaluating alcohols and various neurotoxic agents. With these compounds, even repeated dosing did not improve the predictability of the testing scheme. Swimming performance was also investigated and was found to be impaired only in rats treated with neuroleptic drugs. Based on this validation study, the advantages and pitfalls of the neurobehavioral check-list approach are discussed.

Alcohols↗

PubMed1989

A murine local lymph node assay for the identification of contact allergens. Assay development and results of an initial validation study.

The development of an alternative predictive test for the identification of contact sensitizing chemicals is described. The method is based upon the fact that, following epicutaneous application, sensitizing chemicals initiate a primary immunological response in the draining lymph node(s) which is characterized by lymphocyte proliferation. Experimental conditions for the measurement in vitro of the induced lymph node cell proliferative response have been optimized. On the basis of the data presented a local lymph node assay was developed in which CBA/Ca strain mice were exposed daily, for 3 consecutive days, to various concentrations of the test chemical, or to vehicle alone, on the dorsum of the ear. Lymph node activation was measured subsequently as a function of increased node weight, the frequency of large pyroninophilic cells and lymphocyte proliferation in the presence or absence of an exogenous source of interleukin 2 (IL-2). The results of a validation study are reported in which 22 well-characterized sensitizing chemicals of varying potency were examined. With the exception of three chemicals where water was used as the application vehicle, positive responses, defined as a substantial increase in lymphocyte proliferative activity, were recorded with all these test materials. Under the conditions employed non-sensitizing chemicals, including non-sensitizing irritant chemicals, failed to influence the immunological status of the draining lymph node. Taken together, the data suggest that the local lymph node assay provides the basis for a rapid and cost-effective alternative to the currently available guinea pig predictive test methods. The local lymph node assay may be of particular value for the evaluation of coloured or irritant chemicals.

Allergens↗

PubMed1991

HLA class II (DR and DQ) antigen associations in idiopathic dilated cardiomyopathy. Validation study and meta-analysis of published HLA association studies.

We previously reported antigen frequency differences for HLA-DR4 and HLA-DRw6 between idiopathic dilated cardiomyopathy (IDC) patients and healthy controls in a pilot study. To confirm these findings, we undertook an independent study with a prospective hypothesis regarding the frequencies of DR4 and DRw6; typing for a second family of class II antigens (HLA-DQ) was included because of the proximity of the DQ loci to the DR loci and the strong linkage disequilibrium between some of the DR and DQ alleles. Comparing a new consecutive series of IDC patients (n = 41) and healthy blood bank controls (n = 53), we confirmed an increase of DR4 antigen frequency in patients (49% versus 21%, p less than 0.005). A trend toward decreased expression of DRw6 among patients was also noted (10% of patients versus 23% of controls). HLA-DQw4 was significantly elevated in patients compared with controls (27% versus 6%, p less than 0.005; relative risk, 6.1; etiologic fraction, 0.22). We identified the combined DR4-DQw4 haplotype in five of 41 Caucasian IDC patients (12%) and none of 53 controls (p less than 0.007). A comparison of specific antigen frequencies between the preliminary and validation studies did not reveal significant differences; therefore, the data from the two studies were examined in combination. For the combined studies, DR4 was elevated (51% versus 27% in controls, p less than 0.001), and DRw6 was decreased (9% versus 24% in controls, p less than 0.01). The relative risk for DR4 was 2.8, and the etiologic fraction was 0.33.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiomyopathy, Dilated↗