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PubMed2000

Validation of parachlorobenzotrifluoride, benzotrifluoride, and monochlorotoluene on diffusive samplers.

Three solvents (OXSOL 10, monochlorotoluene or mixed isomers of 1- chloro-2-methyl benzene and 1-chloro-4-methyl benzene; OXSOL 100, parachlorobenzotrifluoride or 1-chloro-4-(trifluoromethyl) benzene; and OXSOL 2000, benzotrifluoride or trifluoromethyl benzene) produced by Occidental Chemical Corporation (Niagara Falls, NY) were considered as candidates for SKC, Inc.'s on-going diffusive sampler validation program. The 575-series diffusive sampler contains coconut-shell charcoal (575-001) or Anasorb 747 (575-002). Both samplers were used in this study. Desorption efficiency was tested at loadings equivalent to eight-hour time-weighted average (TWA) exposures to 0.01-2 times the Occidental Chemical Corporation in-house limit values (respectively: 50 ppm, 25 ppm, and 100 ppm,. All results met the National Institute for Occupational Safety and Health (NIOSH) criteria of > 75 percent, and, except for the lower loadings of parachlorobenzotrifluoride, the results were in the range of 90-110 percent. The calculated uptake rates were verified for different periods of exposure, up to eight hours, and found to be within 5 percent of the calculated for all three compounds on both samplers. A detailed comparison of the results from different time periods indicated no significant reverse diffusion effects for any combination of sampler and analyte. Samplers exposed to standard atmospheres of each compound were stored for three weeks at ambient temperatures and reanalyzed with results between 94 and 107 percent of expected. Based on full validation of samplers for the lower homologue (benzene), the bi-level theory of sample validation as endorsed by international validation protocols establishes this as a complete validation of the featured samplers for sampling vapors of these chemicals in air.

Air Pollution↗
PubMed1989

Iron deficiency and behavior: criteria for testing causality.

The association between iron deficiency and poor behavioral-test performance is well established. The question of causality, however, remains unanswered. This paper presents the essential criteria for a valid test of causality. Internal validity is examined in terms of positive and negative findings. Plausibility of the findings requires analyzing the congruency of the results; for example, those who respond to the iron treatment are also those who respond behaviorally. External validity describes the extent to which inferences may be made about other populations or circumstances.

Behavior↗
PubMed1998

IASP diagnostic criteria for complex regional pain syndrome: a preliminary empirical validation study. International Association for the Study of Pain.

OBJECTIVE: To assess the ability of the International Association for the Study of Pain Complex Regional Pain Syndrome (CRPS) diagnostic criteria and associated features to discriminate between CRPS patients and patients with painful diabetic neuropathy. DESIGN: Prospective assessment of signs and symptoms in a series of CRPS and diabetic neuropathy patients. SETTING: University of Washington Multidisciplinary Pain Center. PATIENTS: A consecutive series of 18 CRPS patients and 30 diabetic neuropathy patients. INTERVENTIONS: Patients completed a 10-item patient history questionnaire assessing symptoms of CRPS prior to medical evaluation. The evaluating physician completed a 10-item patient examination questionnaire assessing objective signs of CRPS. OUTCOME MEASURES: The analyses conducted were designed to test the ability of CRPS signs and symptoms and associated features to discriminate between CRPS patients and diabetic neuropathy patients. RESULTS: Data analysis suggested that CRPS decision rules may lead to overdiagnosis of the disorder. Diagnosis based on self-reported symptoms can be diagnostically useful in some circumstances. The addition of trophic tissue changes, range of motion changes, and "burning" quality of pain did not improve diagnostic accuracy, but the addition of motor neglect signs did. Test of a CRPS scoring system resulted in improved accuracy relative to current criteria and decision rules. CONCLUSIONS: Poorly understood disorders lacking prototypical signs/symptoms and diagnostic laboratory testing must rely on the development of reliable diagnostic guidelines. The results of this study should assist in the further refinement of the CRPS diagnostic criteria.

Diabetic Neuropathies↗
PubMed1986

The validity of internal carotid back pressure measurements during carotid endarterectomy for unilateral carotid stenosis.

Peri-operative neurological deficits in 212 patients undergoing carotid endarterectomy for unilateral carotid stenosis were examined to determine whether the internal carotid back pressure (ICBP) correctly predicted the need for a protective shunt during temporary carotid occlusion. Three strokes occurred in 149 patients who were not shunted. In one of these the ICBP indicated the need for a shunt, but shunting was not possible for technical reasons and a stroke due to hypoperfusion occurred. In another patient a stroke occurred as a result of embolism. There was only one patient where the ICBP possibly incorrectly predicted that a shunt would not be necessary. Four strokes due to various causes occurred in the 63 shunted patients. Shunting was not withheld from these patients in order to prove that ICBP would correctly predict their vulnerability to hypoperfusion since to have done so would be unethical. The results indicate that in patients with unilateral carotid stenosis the ICBP is an accurate indicator of which patients can undergo carotid endarterectomy without the need for shunting.

Aged↗
PubMed1986

The Montgomery-Asberg Depression Scale: reliability and validity.

The Montgomery-Asberg Depression Scale was evaluated in 44 depressed inpatients. All items of the scale occurred frequently in the sample; the scale exhibited construct validity (internal homogeneity) and concurrent validity relative to the Hamilton Depression Scale and the concepts of endogenous and nonendogenous depression. Sleep disturbance, reduced appetite, and suicidal thoughts, correlated poorly with the remainder of the scale. Reasons for this finding are discussed. Inter-rater reliability was demonstrated between a psychiatrist and a nurse on individual item and total scale scores.

Adult↗
PubMed2000

A short screening instrument for poststroke dementia : the R-CAMCOG.

BACKGROUND AND PURPOSE: The CAMCOG is a feasible cognitive screening instrument for dementia in patients with a recent stroke. A major disadvantage of the CAMCOG, however, is its lengthy and relatively complex administration for screening purposes. We therefore developed the Rotterdam CAMCOG (R-CAMCOG), based on the original version. Our aim was to reduce the estimated administration time to 15 minutes or less and to retain or perhaps even improve its diagnostic accuracy. METHODS: We analyzed the item scores on the CAMCOG of 300 consecutive stroke patients, after exclusion of patients with a severe aphasia or lowered consciousness level, who were entered in the Rotterdam Stroke Databank. The diagnosis of dementia was made independent of the R-CAMCOG score, on the basis of clinical examination and neuropsychological test results. The R-CAMCOG was constructed in 3 steps. First, items with floor and ceiling effects were removed. Next, subscales with no additional diagnostic value were excluded. Finally, we removed items that did not contribute to the homogeneity of the subscales. The diagnostic accuracy of the R-CAMCOG and the original CAMCOG was determined by means of the area under the receiver operating characteristic (ROC) curve. RESULTS: In the 3 steps, the number of items was reduced from 59 to 25, divided over the subscales orientation, memory (recent, remote, and learning), perception, and abstraction. The subscale orientation did not reach significance in a logistic regression model but was included in the R-CAMCOG because of its high face validity in dementia screening. Internal validation with ROC analysis suggests that the R-CAMCOG and the CAMCOG are equally accurate in screening for poststroke dementia (area under the curve was 0.95 for both tests). CONCLUSIONS: The R-CAMCOG has overcome the disadvantages of the original CAMCOG. It is a promising, short, and easy-to-administer screening instrument for poststroke dementia. It seems to be sufficiently accurate for this purpose, but the test has yet to be validated in a separate, independent study.

Aged↗
PubMed1999

[Internal statistical validation of a quality of life questionnaire].

In this paper we present two different statistical approaches to evaluate the psychometric properties of a quality of life questionnaire. First the study of the factorial structure is briefly exposed. Then we present the unidimensional classical models. They are based on the linear relationship between the observed score and the true score. The definition of the reliability was first addressed in this classical framework. Its estimation with the Cronbach alpha coefficient is one important feature of the evaluation of an instrument. More recently, modern response theory gives a better statistical framework to deal with unidimensional latent traits. These models describe the probability of positive answer to an item as a function of the actual value of the latent trait and an item parameter. We expose the principles of the Rasch model: hypothesis, estimations methods and fit tests. Finally practical applications to the validation process of a questionnaire are explored with data from a study of a short French version of the SIP questionnaire.

Evaluation Studies as Topic↗
PubMed1991

Algorithm to predict triple-vessel/left main coronary artery disease in patients without myocardial infarction. An international cross validation.

Logistic regression was applied to the clinical, risk factor, and exercise data of consecutive angiographic referrals without prior myocardial infarction to determine an algorithm predicting the probability of triple-vessel/left main coronary artery disease. These data were obtained from a total of 1,074 such subjects from patient populations at four centers (Cleveland Clinic Foundation, Cleveland, Ohio; Hungarian Institute of Cardiology, Budapest, Hungary; the university hospitals, Zurich and Basel, Switzerland; and the Veterans Administration Medical Center, Long Beach, Calif.) and used to derive four separate probability algorithms. Each algorithm is based on patient data from study samples at three of the four centers and consists of 272 logistic functions, which are related to linear combinations of 13 variables (age, sex, type of chest pain, systolic blood pressure, resting electrocardiogram, serum cholesterol, fasting blood sugar, achieved exercise work load, achieved heart rate, exercise-induced angina and hypotension, heart rate-adjusted resting ST depression, and exercise ST slope). The four algorithms were cross validated by testing them on the populations not involved in their derivation. The resulting probabilities in the four test groups were then compared with the angiographic findings of triple-vessel/left main coronary artery disease. The discriminatory power of all the algorithms was fair to good (area under receiver operating characteristic curve, 0.68, 0.75, 0.82, 0.85) in the test groups. The algorithm did not significantly underestimate or overestimate disease probability except in one center (Long Beach).(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMedDate not supplied

[Translation and validation of the Revised Social Anhedonia Scale (SAS Social Anhedonia Scale, M.L. Eckblad, L.J. Chapman et al., 1982). Study of the internal and concurrent validity in 126 normal subjects].

The Revised Social Anhedonia Scale (SAS) with 40 items (Eckblad et al., 1982) which studies the social dimension of anhedonia has been validated in the United-States (Mishlove & Chapman, 1985). However, no french translation and validation of this scale has been made to date. This work presents the french translation of the Social Anhedonia Scale and its validation. After a back-translation and final adjustment, it has been submitted to a sample of 126 control subjects from the general population. Furthermore, they were asked to fill two other scales: the Chapman Physical Anhedonia (PAS) with 61 items and the Fawcett Pleasure Scale (36 items), both of them exploring the subjects answer in terms of anhedonia/hedonia towards social, sensorial and/or physical experiences. The internal validity has been determined on the one hand by the Cronbach alpha coefficient which showed a strong unidimensional characteristic (0.80) and the other hand by the correlation of each item with the total score using the point biserial coefficient which ranged from .204 to .559. The concurrent validation has been determined by the Pearson correlation coefficient between the french version of social anhedonia scale and the french version of physical anhedonia scale. The values were .42, p = .001. Furthermore, this two scales are significant inversely correled to the french version of the pleasure scale: r = -.22, p = .0125 for the first, and r = -.26, p = .0027 for the second. The internal and concurrent validity of the french version of the revised social anhedonia scale should allow to improve our understanding of anhedonia in psychiatry and psychopathology.

Adolescent↗
PubMed2003

Prediction of outcome in acute lower-gastrointestinal haemorrhage based on an artificial neural network: internal and external validation of a predictive model.

BACKGROUND: Models based on artificial neural networks (ANN) are useful in predicting outcome of various disorders. There is currently no useful predictive model for risk assessment in acute lower-gastrointestinal haemorrhage. We investigated whether ANN models using information available during triage could predict clinical outcome in patients with this disorder. METHODS: ANN and multiple-logistic-regression (MLR) models were constructed from non-endoscopic data of patients admitted with acute lower-gastrointestinal haemorrhage. The performance of ANN in classifying patients into high-risk and low-risk groups was compared with that of another validated scoring system (BLEED), with the outcome variables recurrent bleeding, death, and therapeutic interventions for control of haemorrhage. The ANN models were trained with data from patients admitted to the primary institution during the first 12 months (n=120) and then internally validated with data from patients admitted to the same institution during the next 6 months (n=70). The ANN models were then externally validated and direct comparison made with MLR in patients admitted to an independent institution in another US state (n=142). FINDINGS: Clinical features were similar for training and validation groups. The predictive accuracy of ANN was significantly better than that of BLEED (predictive accuracy in internal validation group for death 87% vs 21%; for recurrent bleeding 89% vs 41%; and for intervention 96% vs 46%) and similar to MLR. During external validation, ANN performed well in predicting death (97%), recurrent bleeding (93%), and need for intervention (94%), and it was superior to MLR (70%, 73%, and 70%, respectively). INTERPRETATION: ANN can accurately predict the outcome for patients presenting with acute lower-gastrointestinal haemorrhage and may be generally useful for the risk stratification of these patients.

Acute Disease↗
PubMed2007

Paediatric Hepatology Dependency score (PHD score): an audit tool.

BACKGROUND: The aim was to develop a tool that measures patient dependency and disease severity in children with mild to severe liver disease. METHODS: The initial pilot score was based on known markers of disease severity in acute and chronic liver disease. Between 1997 and 2001, the score was modified 4 times and reduced to comprise 10 key parameters: aspartate transaminase, prothrombin time, albumin, bilirubin, ascites, nutritional support, organ dysfunction, blood product support, sepsis and intravenous access. The score's face validity, internal consistency, interobserver agreement and construct validity were evaluated statistically and by the use of endpoints such as survival and transplant after 6 months. RESULTS: The final 10 variable score was tested on 71 children admitted over two 3-month periods. The Cronbach's alpha score (a test for internal consistency) for the total score was 0.72. Serial data paralleled clinical deterioration and response to interventions. A Paediatric Hepatology Dependency score >15 had an odds ratio of 7 (P = 0.0125) for death or transplant at 6 months. The score was also found to agree with the paediatric end-stage liver disease score for the 12 patients being listed for liver transplantation (r = 0.660, P < 0.05). CONCLUSION: The Paediatric Hepatology Dependency score is valid and internally consistent and is a convenient measure of dependency and disease severity in a heterogeneous group of patients with liver disease. It also allows admissions to be audited for comparison between eras and for monitoring the progress of patients while on the ward.

Acute Disease↗
PubMed2004

Development and validation of an acceptability and satisfaction questionnaire for a contraceptive vaginal ring, NuvaRing.

OBJECTIVE: To validate an acceptability questionnaire for NuvaRing, a new combined contraceptive vaginal ring. METHODS: A 21-item questionnaire was developed covering: ease of ring use, ease of package use, clarity of instructions, sexual comfort, cycle-related characteristics, compliance and satisfaction. A total of 2145 women completed the questionnaire after 3, 6 or 13 cycles of NuvaRing use. The psychometric properties and predictive value of the questionnaire were assessed using cycle 3 data (n = 1950). The quality of completed questionnaires, item content analysis, construct validity, internal consistency reliability, known groups validity and predictive validity were evaluated. RESULTS: Excluding non-ordinal items, 0.6% of the data were missing. Principal component analysis of 15 ordinal items indicated that two hypothesised dimensions ('ease of package use' and 'clarity of instructions') were consistently linked and so were combined into a single 'ease of comprehension' scale. Item convergent validity (the degree of correlation between an item and its own scale) was 100% for 'ease of ring use' (r = 0.44) and 'satisfaction' (r = 0.58), 83% for 'ease of comprehension' (r = 0.25-0.62) and 67% (r = 0.38-0.54) for 'sexual comfort', but 0% for 'cycle-related characteristics' (r = 0.31). Item discriminant validity (the degree to which an item correlates with its own scale compared with other scales) was >/=96% for all dimensions. Internal consistency reliability was acceptable for all dimensions (adjusted Cronbach's alpha coefficient >0.70). Satisfaction was higher than in the complementary groups for respondents who had no adverse events, chose NuvaRing as the best method of contraception or completed the study; this indicated good known groups validity. Low satisfaction with the method was a good predictor of early discontinuation after cycle 3, indicating that the questionnaire had good predictive validity. CONCLUSIONS: The acceptability questionnaire has good psychometric properties and can predict early discontinuation of the NuvaRing vaginal ring method of contraception.

Adolescent↗
PubMed2000

Economic evaluation of parasitic diseases: a critique of the internal and external validity of published studies.

It was estimated that in 1990, major parasitic diseases accounted for 11.7% of the disease burden from communicable disease. As advances in the prevention, diagnosis and treatment of parasitic diseases are made and implemented, there is a growing economic literature to help decision-makers choose the most efficient control method. The aim of this paper is to identify, describe and analyse the available published data on the efficiency of control strategies against parasitic diseases. Internal validity is assessed through the quality of economic evaluations over time using a series of standard questions, and external validity is assessed in terms of the potential to extrapolate results to other settings. This leads to a discussion of the legitimacy and feasibility of pooling data or results from studies for priority setting in the health sector, resulting in three recommendations: to increase the coverage of economic evaluations for parasitic diseases and types of interventions; to improve the internal validity of studies through guidelines and review procedures; and to explore the external validity of research results by examining their predictive validity across settings.

Child↗
PubMed2005

Validation of two devices for self-measurement of brachial blood pressure according to the International Protocol of the European Society of Hypertension: the SEINEX SE-9400 and the Microlife BP 3AC1-1.

BACKGROUND: Two electronic devices for self-measurement of blood pressure at the brachial artery -- the Seinex SE-9400 and the Microlife BP 3AC1-1 -- were evaluated in two separate studies according to the International Protocol of the European Society of Hypertension. DESIGN: The international validation protocol is divided into two phases: the first phase is performed on 15 selected participants (45 blood pressure measurements); if the device passes this phase, 18 supplementary participants are included (54 blood pressure measurements) making a total number of 33 participants (99 blood pressure measurements) on whom the final validation is performed. METHODS: The same methodology recommended by the European Society of Hypertension protocol was applied for both studies. In each study and for each participant, four blood pressure measurements were taken simultaneously by two trained observers using mercury sphygmomanometers alternately with three measurements by the tested device. The difference between the blood pressure value given by the device and that obtained by the two observers (mean of the two observers) was calculated for each measure. The 99 differences were classified into three categories (< or =5, < or =10, < or =15 mmHg). The number of differences in each category was compared with the number required by the ESH protocol. An individual analysis was then done to determine, for each participant, the number of comparisons < or =5 mmHg. At least 22 of the 33 participants should have two of their three comparisons < or =5 mmHg. RESULTS: In both studies, the two tested devices passed the first phase of the validation process. For the complete analysis (phase 1 and phase 2), the average differences between the device and mercury sphygmomanometer readings were in the first study for the Seinex SE-9400 device 0.9+/-5.2 and -1.7+/-4.7 mmHg for systolic and diastolic blood pressure, respectively, and -0.2+/-4.5 and -2.0+/-4.8 mmHg for the Microlife BP 3AC1-1 device in the second study. For both devices, readings differing by less than 5, 10 and 15 mmHg for systolic and diastolic blood pressure values fulfill the recommendation criteria of the International Protocol as well as the individual analysis. CONCLUSIONS: The Seinex SE-9400 and the Microlife BP 3AC1-1 devices fulfilled the validation recommendations of the International Protocol.

Adult↗