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PubMed1987

An analysis of the validity of self reported occupational histories using a cohort of workers exposed to PCBs.

An investigation was conducted to examine the validity of self reported work histories obtained from a sample of 326 capacitor manufacturing workers who had participated in an epidemiological study relating health abnormalities to exposure to polychlorinated biphenyls. Based on objective personnel records obtained for 288 members of the sample group, validity scores ranged from 20% to 100% with most falling between 70% and 75%. This validity range corresponded to misclassification proportions ranging from 13% to 29%. Exposure misclassification tended to be random for men but non-random for women (overestimation of exposure). By means of multiple regression analysis, the diversity of the job categorical pattern was found to be a significant independent predictor of validity. The factors sex, duration, and time lapse were also significant validity predictors but only interactively with job diversity. There were also indications that interviewer skill could be an important factor. Knowledge of the magnitude of these factor effects could be critical in planning retrospective epidemiological studies.

Data Collection↗

PubMed2004

[Confirmatory factor analysis. Its role on the validation of health related questionnaires].

Researchers who use questionnaires in the health sciences tacitly base themselves (often inadvertently) in Classical Test Theory, the suppositions of which are unrealistic and frequently violated, leading to defective evaluation of the reliability and validity of the instrument.The present article emphasizes the need for precise definition of essential terms of measurement (reliability and validity) by clarifying the deficiencies that traditional methodology incurs in their use. The limitations of evaluation of reliability through Chronbach's alpha and laxity in quantitative evaluation of validity through exploratory factor analysis are described. As an alternative, a sequential and integrated approach to validity and reliability within the framework of confirmatory factor analysis models is proposed. These models provide the appropriate statistical framework to evaluate the validity and reliability of each item, instead of carrying out overall evaluations only. The confirmatory approach guides researchers to optimize the process of designing or adapting a questionnaire, freeing them from the largely unfounded ritual laid down by classical methodology.

Factor Analysis, Statistical↗

PubMed2006

[Validation of a scale to measure ill-treatment of women].

OBJECTIVES: To analyse the validity of content and of structure and the reliability of a questionnaire designed to measure ill-treatment (IT) of women by their partners. DESIGN: Descriptive, transversal, multi-centre study. SETTING: Four urban health centres in Granada, Spain. PARTICIPANTS: Three hundred and ninety one women of 14 and over who consulted in primary care and had a stable partner for at least 3 months. MAIN MEASUREMENTS: Questionnaire by means of interviews between December 2000 and May 2001, with 10 Likert-like questions on physical, psychological, and sexual mistreatment, social and demographic questions and various health indicators. We analysed content validity by means of exploratory factorial analysis, reliability of alpha-Cronbach factors and of corrected scale-item correlation coefficients, and structure validity. RESULTS: We obtained 2 empirical IT factors that did not correspond to the theoretical dimensions of physical, psychological, and sexual mistreatment and explained 64.21% of variance. The first included all the questions on psychological abuse, one on physical abuse and the sexual abuse dimension. The second covered the remaining questions on physical IT and "breaking things in the home". The factors gave reliability coefficients of 0.8688 and 0.7072. Comparison by means of extreme groups technique showed that the questionnaire's structure is valid. CONCLUSION: We found this was a reliable and valid questionnaire for evaluating ill-treatment of women. Its use, particularly in primary care, could help expand and deepen understanding of the problem.

Adult↗

PubMed2000

Characterization and validation of diagnostic methods.

Diagnosis is defined as the determination of disease, but not as the determination of the signs and symptoms thereof. The use of modern diagnostic methodology in the clinic is hampered by cost considerations and by the still widespread belief that, e.g. caries lesions and periodontal breakdown are irreversible processes that need to be detected and treated invasively as early as possible, their measurement thus being irrelevant. Modern instrumental and quantitative methods allow early detection and introduction of noninvasive preventive measures to control the development of the disease. Such methods are also very beneficial in clinical research as they may describe the speed of progress or regress of disease. In epidemiology, such methods reduce the classical problem of calibration of observers. Repeatability, reproducibility, accuracy and validity are defined as method-characterizing quantities, for which examples are given. To express the validity of quantitative methods compared with a quantitative gold standard, the use of scatter plots and correlation and regression methods is suggested. Validation of a dichotomous method with a dichotomous gold standard in terms of sensitivity and specificity is discussed. To validate a quantitative method with a dichotomous gold standard, the receiver operating characteristic curve is suggested, with the requirement that the cutoff value should be determined in relation to the use of the method. However, preferably a quantitative method should not be reduced to a dichotomous one by using a cutoff value, but instead all available information should be used by the diagnostician. It is argued that the use of a secondary standard instead of the accepted gold standard usually leads to inadequate results, even when the validity of the secondary standard is known. Finally, it is argued that the choice of a gold standard is a matter of reasoning and weighing of arguments and not of following a prescribed procedure.

Calibration↗

PubMed2003

Validation study of a CT-based weighted rating scale for subcortical ischemic vascular disease in patients with mild cognitive deterioration.

OBJECTIVES: Subcortical ischemic vascular disease (SIVD) is frequently associated with cognitive impairment. Rating scales to grade cerebrovascular disease are available, but their sensitivity to the clinical features of mild SIVD is unclear. The aim of the study is to devise and validate a computed tomography (CT)-based visual rating scale sensitive to SIVD in patients with mild cognitive deterioration. METHODS: Subjects were 122 consecutive outpatients of a memory clinic (mean age +/- SD 77 +/- 8 years, 71% females, mean +/- SD score of mental state exam 22 +/- 3, 61% with clinical dementia rating of 0.5 and 39% of 1). Diffuse leukoaraiosis, fuzzy and patchy lesions, and lacunes were assessed on ordinary CT films and weights were computed based on clinical indicators of SIVD. A continuous score and an ordinal class (0-3) with higher values indicating higher vascular damage were derived. RESULTS: Intraclass correlation coefficients for intra- and interrater reliability of the subcortical vascular score and class ranged from 0.84 to 0.88. Convergent validity versus the scale of Wahlund et al. was good (Spearman's correlation coefficient between 0.53 and 0.73, p < 0.0005). Known-group validity was assessed versus clinical diagnoses of degenerative (mild cognitive impairment determined by Petersen et al. and NINCDS-ADRDA probable Alzheimer's disease; n = 58), mixed (possible Alzheimer's disease with cerebrovascular disease; n = 21), and vascular cognitive impairment (criteria of Erkinjuntti et al. for subcortical vascular dementia and cognitive impairment; n = 43). Patients with degenerative cognitive impairment were more often in the lower subcortical vascular classes (43% in class 0, 43% in class 1, 14% in class 2, and 0% in class 3), while patients with mixed (0, 24, 24, and 52%) and vascular cognitive impairment were in increasingly higher subcortical vascular classes (0, 12, 35, 53%; p < 0.00005). Criterion-related validity was assessed versus clinical indicators of cerebrovascular disease. Hypertension, platelet aggregation inhibitor use, balance, gait, and bradykinesia increased linearly with increasing subcortical vascular class (p for trend <0.02). CONCLUSIONS: This rating scale is valid and sensitive to capture different degrees of SIVD associated with mild cognitive deterioration.

Aged↗

PubMed1995

Factors involved in validity measurements of diagnostic tests for approximal caries--a meta-analysis.

In this study, a meta-analysis was performed on published validity parameters of visual inspection, radiographic examination and visual inspection upon fibreoptic transillumination (FOTI) in approximal caries diagnosis. It was the objective to investigate the influence of the diagnostic test, the study design and the validation method on reported validity. Sensitivities and specificities reported in the literature were transformed into D2 values, representing the performance of a diagnostic method above chance, or of the observer using it, in a single parameter. Dz values were neither statistically significantly different between visual inspection, radiographic examination and FOTI nor between 'weak' and 'strong' validation methods (p > 0.05). Dz values obtained from in vivo studies were significantly different from those obtained from in vitro studies (p < 0.05), indicating that study design had a significant impact on the measurement of the validity of the evaluated test for approximal caries diagnosis.

Dental Caries↗

PubMed1996

The WHO (Ten) Well-Being Index: validation in diabetes.

BACKGROUND: In a European trial in 8 countries, the subjective well-being of patients on alternative forms of treatment for insulin-dependent diabetes was compared using the 28-item WHO Well-Being Questionnaire, covering four dimensions of depression, anxiety, energy and positive well-being. The objective of the analysis reported here has been to identify the items of the WHO questionnaire which belong to an overall index of negative and positive well-being. METHODS: Adult patients at 10 study centres in 8 countries who had been on insulin for at least 2 years were invited to participate in a randomised, cross-over trial to compare insulin pump treatment with injection therapy. At each phase, patients completed questions on well-being and general health. Internal validity of the well-being index was evaluated by Cronbach's alpha and Loevinger's and Mokken's homogeneity coefficients, as well as factor analysis. External validity was evaluated by comparisons with results of the general assessment questions and by the ability to discriminate between the alternative forms of treatment. RESULTS: 358 patients had sufficient data for analysis. Ten items were found to constitute a valid index of well-being with respect to internal and external validity. Coefficients of homogeneity were acceptable and there was evidence for both concurrent and discriminant validity. CONCLUSIONS: The WHO (Ten) well-being index includes negative and positive aspects of well-being in a single uni-dimensional scale. Its advantage lies in its ability to show overall change along the continuum of well-being, thus facilitating comparisons between patient groups and treatments. It is not specific to diabetes, and therefore may be useful as a disease-independent index of well-being in a broad range of health care studies.

Adaptation, Psychological↗

PubMed2002

Modified National Institutes of Health Stroke Scale for use in stroke clinical trials: prospective reliability and validity.

BACKGROUND AND PURPOSE: To prospectively evaluate the reliability and validity of this previously developed stroke scale in an independently collected cohort. The National Institutes of Health Stroke Scale (NIHSS) has been criticized for its complexity and variability. Prior formal clinimetric analyses were used to obtain a modified version of NIHSS (mNIHSS), which retrospectively demonstrated improved reliability and validity. We sought to prospectively measure the reliability and validity of the mNIHSS. METHODS: Forty-five patients with a history of stroke or intracerebral hemorrhage were evaluated at the University of California, San Diego, Stroke Center from September 2000 through March 2001. Each patient was tested by 2 NIHSS-certified neurologists using the NIHSS, mNIHSS, Barthel Index, and Modified Rankin scales. RESULTS: There were a large percentage of high kappa values using the mNIHSS. Only 10 (66.67%) of 15 NIHSS kappa scores showed excellent agreement, whereas 10 (90.91%) of 11 mNIHSS kappa scores showed excellent agreement. As predicted, the mNIHSS was more reliable than the NIHSS because of the exclusion of items with low kappa values. With the use of correlation coefficient analysis, the mNIHSS was as valid as the NIHSS. CONCLUSIONS: This prospective study found high reliability and continued validity by using a previously developed mNIHSS. Items found to have low kappa values were consistent with the previously derived retrospective mNIHSS. The resulting mNIHSS scale has much higher kappa values. The mNIHSS showed improved agreement between examiners and was also easier to administer, having fewer and simpler items. Further prospective evaluation should assess whether the mNIHSS could be used in lieu of the NIHSS.

Academic Medical Centers↗

PubMed2003

Stroke and Aphasia Quality of Life Scale-39 (SAQOL-39): evaluation of acceptability, reliability, and validity.

BACKGROUND AND PURPOSE: Health-related quality of life (HRQL) is a key outcome in stroke clinical trials. Stroke-specific HRQL scales (eg, SS-QOL, SIS) have generally been developed with samples of stroke survivors that exclude people with aphasia. We adapted the SS-QOL for use with people with aphasia to produce the Stroke and Aphasia Quality of Life Scale (SAQOL). We report results from the psychometric evaluation of the initial 53-item SAQOL and the item-reduced SAQOL-39. METHODS: We studied 95 people with long-term aphasia to evaluate the acceptability, reliability, and validity of the SAQOL and SAQOL-39 using standard psychometric methods. RESULTS: A total of 83 of 95 (87%) were able to complete the SAQOL by self-report; their results are reported here. Results supported the reliability and validity of the overall score on the 53-item SAQOL, but there was little support for hypothesized subdomains. Using factor analysis, we derived a shorter version (SAQOL-39) that identified 4 subdomains (physical, psychosocial, communication, and energy). The SAQOL-39 demonstrated good acceptability, internal consistency (Cronbach's alpha=0.74 to 0.94), test-retest reliability (intraclass correlation coefficient=0.89 to 0.98), and construct validity (corrected domain-total correlations, r=0.38 to 0.58; convergent, r=0.55 to 0.67; discriminant, r=0.02 to 0.27 validity). CONCLUSIONS: The SAQOL-39 is an acceptable, reliable, and valid measure of HRQL in people with long-term aphasia. Further testing is needed to evaluate the responsiveness of the SAQOL-39 and to investigate its usefulness in evaluative research and routine clinical practice.

Adult↗

PubMed1998

Diagnosis of stroke by the nonneurologist. A validation study.

BACKGROUND AND PURPOSE: The first medical contact of an acute stroke victim is often a nonneurologist. Validation of stroke diagnosis made by these medical doctors is poorly known. The present study seeks to validate the stroke diagnoses made by general practitioners (GPs) and hospital emergency service physicians (ESPs). METHODS: Validation through direct interview and examination by a neurologist was performed for diagnoses of stroke made by GPs in patients under their care and doctors working at the emergency departments of 3 hospitals. RESULTS: Validation of the GP diagnosis was confirmed in 44 cases (85%); 3 patients (6%) had transient ischemic attacks and 5 (9%) suffered from noncerebrovascular disorders. Validation of the ESP diagnosis was confirmed in 169 patients (91%); 16 (9%) had a noncerebrovascular diagnosis. Overall, the most frequent conditions misdiagnosed as stroke were neurological in nature (cerebral tumor, 3; subdural hematoma, 1; seizure, 1; benign paroxysmal postural vertigo, 1; peripheral facial palsy, 2; psychiatric condition, 6; and other medical disorders, 7). CONCLUSIONS: In the majority of cases, nonneurologists (either GPs or ESPs) can make a correct diagnosis of acute stroke. Treatment of acute stroke with drugs that do not cause serious side effects can be started before evaluation by a neurologist and CT scan.

Adult↗

PubMed2003

The Activities of Daily Vision Scale for cataract surgery outcomes: re-evaluating validity with Rasch analysis.

PURPOSE: The Activities of Daily Vision Scale (ADVS) has been extensively validated by traditional methodology. In the current study, Rasch analysis was used to explore further the validity of the ADVS and to determine whether improvements could be made. METHODS: Forty-three patients with cataract underwent visual acuity (VA) and contrast sensitivity (CS) testing and completed the ADVS. The data were Rasch analyzed and the value of response scale and item reduction explored. A shortened version and the original ADVS were tested for criterion validity by determining correlations with VA and CS. RESULTS: The ADVS data contained abnormally distributed items and items with ceiling effects and empty response categories. Therefore, items benefited from shortening the response scale, the optimum length being three responses. There was poor targeting of item difficulty to patient ability, because many patients with cataract were sufficiently able that they had no difficulty with many activities. Items were eliminated if the task was too easy or did not fit with the overall concept of visual disability determined by the Rasch model. A reduced ADVS version was established that had adequate precision, equivalent criterion validity, and improved targeting of item difficulty to patient ability, but this version was still not ideal. CONCLUSIONS: Despite careful traditional validation, the ADVS data contained inadequacies exposed by Rasch analysis. Through Rasch scaling, particularly with response scale reduction, the ADVS can be improved, but additional questions seem to be needed to suit the more able, including patients undergoing second eye cataract surgery. There remains a need to develop Rasch-scaled measures of visual disability for use in ophthalmic outcomes research.

Activities of Daily Living↗

PubMed1994

Diagnostic validity of schizophreniform disorder.

OBJECTIVE: The author examined the validity of schizophreniform disorder as defined in DSM-III and DSM-III-R by critically reviewing the current literature. METHOD: Thirty publications that met specific inclusion criteria were identified and reviewed. To organize information relevant to the question of validity, the data were divided into three general classes of validators: antecedent, concurrent, and predictive. When possible, meta-analyses of specific validators were performed according to the summary odds ratio method of Mantel-Haenszel. RESULTS: The findings of this review failed to provide support for the validity of schizophreniform disorder, as it is currently defined, as a distinct diagnostic entity. In addition, the review did not provide strong support for schizophreniform disorder as representing a subtype of schizophrenia or affective illness. Instead, the data suggest that the current diagnostic criteria for schizophreniform disorder identify a heterogeneous group of patients with new-onset schizophrenia, schizoaffective disorder, and atypical affective disorder and a small subgroup with a remitting nonaffective psychosis. CONCLUSIONS: This review suggests that the diagnosis of schizophreniform disorder has limited clinical utility. Patients meeting criteria for schizophreniform disorder should instead be diagnosed as having psychotic disorder not otherwise specified until additional clinical information (e.g., course of illness) becomes available. Future research will require prospective longitudinal follow-up of patients with new-onset affective and nonaffective psychoses to identify the subgroup with "true" schizophreniform disorder, i.e., a remitting nonaffective psychosis.

Confidence Intervals↗

PubMed1994

Development and validation of a scale for rating mood states of psychiatric inpatients.

OBJECTIVE: The authors assessed reliability and validity of a scale developed for use with inpatients on a mood disorders unit. The scale is used to rate a patient's mood along a quantitative continuum from -5, depressive stupor, through 0, euthymic, to 5, full mania. The scale lists behaviors that constitute criteria for each rating point. Mixed states and idiosyncratic behavior can also be assessed. METHODS: Assessment of the scale's reliability and validity was based on data for 53 psychiatric inpatients. The scale's reliability was assessed by comparing nurses' ratings. Validity was assessed by comparing nurses' ratings with patients' self-ratings using previously validated self-report instruments as well as a patient self-report version of the scale. RESULTS: Interrater reliability for the instrument was high (r = .84). Estimates of validity obtained using patient self-report measures ranged from .54 to .85. CONCLUSIONS: The psychometric properties of the scale are comparable to and in some cases are superior to those reported for instruments that include more items and that take longer to complete.

Adult↗

PubMed1998

A ten-year review of the validity and clinical utility of depression screening.

OBJECTIVE: Use of depression screening instruments in primary care is controversial. The authors reviewed research studies published since the development of national practice guidelines to determine whether new evidence might favor screening. The review focused on evidence-related validity and clinical utility of depression screening instruments. METHODS: Silver Platter MEDLINE was searched for English-language studies of depression screening instruments published between 1986 and 1995. Studies were classified by type--reviews of studies, outcome studies, validation studies. RESULTS AND CONCLUSIONS: Fifty-nine studies met criteria for review. Validation studies were the most frequent type (39 studies) and were subclassified according to population, type of comparison, and analytical method. These studies documented the validity of screening instruments compared with formal criteria and demonstrated consistently better performance for systematic approaches compared with clinical impressions. Thirteen studies were reviews; those reviewing evidence for effectiveness disagreed in their conclusions. Only seven outcome studies related to depression screening instruments were found, and none showed measurable benefit in a screened population. Several studies showed that very brief instruments performed about as well as longer, well-validated questionnaires for screening in general populations.

Depressive Disorder↗

PubMed1981

Influence of antisera, purification procedures, and tracers on validity of a testosterone radioimmunoassay.

The levels of testosterone in pooled plasma from men and from women were measured by radioimmunoassay. Testosterone was isolated from plasma either by ether extraction (direct procedure) or by chromatography of the ether extract (chromatographic procedure). Three different antisera (all raised against testosterone-3-oxime albumin) were employed. An additional variable was the use of two tracers, [3H] testosterone and [125I] histamine testosterone. The latter tracer was employed in both a freshly prepared form and two months after labelling. The old tracer was used both in a nonpurified and repurified form. The results were compared with those given by one of the antisera using the assay with chromatography. The validity of this assay was verified earlier using a test of radiochemical purity. In the statistical evaluation of the data, it was found that the assays of both plasma pools gave the same results as the validated assay, even with two other antisera, but only when the chromatographic purification was used. The direct assays gave significantly increased values for testosterone in the male plasma pool with one antiserum, and in the female plasma pool with all three antisera. It is concluded that those assays maybe considered valid which give results statistically indistinguishable from those obtained by the valid assay. These were all chromatographic assays and, in the man, also two direct assays. The comparison of [3H] testosterone and [125I] histamine testosterone as tracers did not indicate any major differences in the validity of the assays. When the 125I-tracer was employed, a moderate (1.5-2 fold) increase of sensitivity was seen with all three antisera, and the antisera could be used in a 10-40 times higher dilution. Furthermore, it was possible to use [125I] histamine testosterone and obtain practically the same results after two months, whether repurified or not.

Adult↗

PubMed2004

Social identity and worldview validation: the effects of ingroup identity primes and mortality salience on value endorsement.

In this article, the authors report an investigation of the relationship between terror management and social identity processes by testing for the effects of social identity salience on worldview validation. Two studies, with distinct populations, were conducted to test the hypothesis that mortality salience would lead to worldview validation of values related to a salient social identity. In Study 1, reasonable support for this hypothesis was found with bicultural Aboriginal Australian participants (N = 97). It was found that thoughts of death led participants to validate ingroup and reject outgroup values depending on the social identity that had been made salient. In Study 2, when their student and Australian identities were primed, respectively, Anglo-Australian students (N = 119) validated values related to those identities, exclusively. The implications of the findings for identity-based worldview validation are discussed.

Adolescent↗

PubMed2002

A short dutch questionnaire to measure fruit and vegetable intake: relative validity among adults and adolescents.

A short food frequency questionnaire (FFQ) to assess fruit and vegetable (F&V) intake was validated. Forty-nine adults and fifty-one adolescents (12-18 years old) completed the FFQ at home, and subsequently kept diet records for seven successive days. Mean daily intake of F&V was overestimated by the FFQ as compared to the 7-day diet records. For adults, spearman correlations of at least 0.5 were observed between the two methods for intake of total fruit and intake of citrus fruit. For adolescents, acceptable spearman correlations (0.53-0.64) were observed between the two methods for total F&V intake, total fruit intake and consumption of fruit juice. Low correlations (0.22-0.35) between the FFQ and the diet records were found for vegetable intake. Relatively large percentages (22-37%) of respondents were incorrectly classified by the short FFQ as eating according to the Dutch recommendations for fruit and vegetable intake. Based on the results of the present study as well as an overview of the results of 34 earlier validation studies of F&V FFQ's, it is concluded that the available FFQ's have only limited capability to make valid assessment of F&V intake levels. In spite of the practical advantages of the short FFQ tested in the present study and the similar validity scores as compared with other often used F&V FFQ's, it needs further revision, especially to be used for valid measurement of vegetable intake as well as total F&V intake among adults.

Adolescent↗

PubMedDate not supplied

A new scale for assessing perceptions of chance: a validation study.

BACKGROUND: Clinicians and researchers often wish to know how patients perceive the likelihoods of health risks. Little work has been done to develop and validate scales and formats to measure perceptions of event probabilities, particularly low probabilities (i.e., <1%). OBJECTIVE: To compare a new visual analog scale with three benchmarks in terms of validity and reliability. DESIGN: Survey with retest after approximately two weeks. Respondents estimated the probabilities of six events with the new scale, which featured a "magnifying glass" to represent probabilities between 0 and 1% on a logarithmic scale. Participants estimated the same probabilities on three benchmarks: two linear visual analog scales (one labeled with words, one with numbers) and a "1 in x" scale. SUBJECTS: 100 veterans and family members and 107 university faculty and students. MEASURES: For each scale, the authors assessed: 1) validity-the correlation between participants' direct rankings (i.e., numbering them from 1 to 6) and scale-derived rankings of the relative probabilities of six events; 2) test-retest reliability-the correlation of responses from test to retest two weeks later; 3) usability (missing/ incorrect responses, participant evaluation). RESULTS: Both the magnifier and the two linear scales outperformed the "1 in x" scale on all criteria. The magnifier scale performed about as well as the two linear visual analog scales for validity (correlation between direct and scale-derived rankings = 0.72), reliability (test-retest correlation = 0.55), and usability (2% missing or incorrect responses, 65% rated it easy to use). 62% felt the magnifier scale was a "very good or good" indicator of their feelings about chance. The magnifier scale facilitated expression of low-probability judgments. For example, the estimated chance of parenting sextuplets was orders of magnitude lower on the magnifier scale (median perceived chance 10(-5)) than on its linear counterpart (10(-2)). Participants' assessments of high-probability events (e.g., chance of catching a cold in the next year) were not affected by the presence of the magnifier. CONCLUSIONS: The "1 in x" scale performs poorly and is very difficult for people to use. The magnifier scale and the linear number scale are similar in validity, reliability, and usability. However, only the magnifier scale makes it possible to elicit perceptions in the low-probability range (<1%).

Adult↗