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Results for “validation studies”

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PubMed2005

Effect of the addition of a "help" question to two screening questions on specificity for diagnosis of depression in general practice: diagnostic validity study.

OBJECTIVE: To determine the validity of two written screening questions for depression with the addition of a question inquiring if help is needed. DESIGN: Cross sectional validation study. SETTING: 19 general practitioners in six clinics in New Zealand. PARTICIPANTS: 1025 consecutive patients receiving no psychotropic drugs. MAIN OUTCOME MEASURES: Sensitivity, specificity, and likelihood ratios of the two screening questions, the help question, combinations of the screening and help questions, and diagnosis by general practitioners. RESULTS: The help question alone had a sensitivity of 75% (95% confidence interval 60% to 85%) and a specificity of 94% (93% to 96%). The positive likelihood ratio for the help question was 13.0 (9.5 to 17.8) and the negative likelihood ratio was 0.27 (0.17 to 0.44). The likelihood ratio for patients wanting help today was 17.5 (11.8 to 31.9). The general practitioner diagnosis had a sensitivity of 79% (65% to 88%) and a specificity of 94% (92% to 95%). CONCLUSION: Adding a question inquiring if help is needed to the two screening questions for depression improves the specificity of a general practitioner diagnosis of depression.

Depressive Disorder↗

PubMed2002

Evaluation of different methods for assessing intracellular fluid in healthy older people: a cross-validation study.

OBJECTIVES: To cross-validate existing anthropometric and bioimpedance equations to establish their validity and accuracy for estimating intracellular water (ICW) in healthy older Germans and to develop a new equation with improved accuracy and precision for predicting ICW from multifrequency bioimpedance analysis (MFBIA). DESIGN: Cross-validation study. SETTING: University of Mainz. PARTICIPANTS: One hundred fifty-five healthy volunteers aged 60 to 80 years (77 men, 78 women; mean ages +/- standard deviation 67.7 +/- 4.8 and 68.6 +/- 5.5 years, respectively). MEASUREMENTS: ICW was measured by whole-body counting of (40)potassium ((40)K) ((40)K method) as the reference method and compared by cross-validation techniques against five existing bioimpedance and three anthropometric prediction equations. A new equation for estimating ICW from MFBIA was developed using the (40)K method as criterion method. RESULTS: Compared with the (40)K method, the existing bioimpedance and anthropometric equations showed large prediction errors in ICW estimates for older men (-32.3% to +37.7%) and women (-34.2% to +26.6%), depending significantly and positively on ICW volume and inversely on weight. A new equation for estimating ICW from MFBIA was developed (R(2)=0.933, standard error of the estimate (SEE)=0.92 L) involving phase angle at 5 kHz, impedance, height, and gender, with data from 100 subjects chosen at random. Cross-validation on an independent group (n=55, R(2)=0.958, SEE=0.68 L) showed no significant bias (0.013 +/- 1.52 L). CONCLUSIONS: Published bioimpedance and anthropometric prediction equations are not applicable to older Germans because they might be population-specific. The bioimpedance equation of the manufacturer of the bioimpedance analyzer used in this study provides accurate estimates of ICW for normal weight, but not overweight, older men. The newly developed equation improves accuracy and precision of ICW estimates by MFBIA.

Aged↗

PubMed1994

Screening for cognitive impairment in older individuals. Validation study of a computer-based test.

OBJECTIVE: This study examined the validity of a computer-based cognitive test that was recently designed to screen the elderly for cognitive impairment. DESIGN: Criterion-related validity was examined by comparing test scores of impaired patients and normal control subjects. Construct-related validity was computed through correlations between computer-based subtests and related conventional neuropsychological subtests. SETTING: University center for memory disorders. PARTICIPANTS: Fifty-two patients with mild cognitive impairment by strict clinical criteria and 50 unimpaired, age- and education-matched control subjects. Control subjects were rigorously screened by neurological, neuropsychological, imaging, and electrophysiological criteria to identify and exclude individuals with occult abnormalities. RESULTS: Using a cut-off total score of 126, this computer-based instrument had a sensitivity of 0.83 and a specificity of 0.96. Using a prevalence estimate of 10%, predictive values, positive and negative, were 0.70 and 0.96, respectively. Computer-based subtests correlated significantly with conventional neuropsychological tests measuring similar cognitive domains. Thirteen (17.8%) of 73 volunteers with normal medical histories were excluded from the control group, with unsuspected abnormalities on standard neuropsychological tests, electroencephalograms, or magnetic resonance imaging scans. CONCLUSIONS: Computer-based testing is a valid screening methodology for the detection of mild cognitive impairment in the elderly, although this particular test has important limitations. Broader applications of computer-based testing will require extensive population-based validation. Future studies should recognize that normal control subjects without a history of disease who are typically used in validation studies may have a high incidence of unsuspected abnormalities on neurodiagnostic studies.

Aged↗

PubMed1995

Follow-up validation study of the Victorian Congenital Malformations Register.

OBJECTIVE: To determine whether there has been an improvement in ascertainment of malformations in the Victorian Congenital Malformations Register (VCMR). METHODOLOGY: The medical records of 500 children under 4 years of age admitted consecutively to two paediatric teaching hospitals in Victoria in 1992 were viewed to determine whether these cases had been notified to the Register. RESULTS: Over three-quarters of the defects recorded had been notified to VCMR. There was 100% ascertainment of chromosomal anomalies and a high proportion of major structural malformations were notified. CONCLUSION: This study repeats the validation study completed in 1986 and shows marked improvement in ascertainment of malformations in the VCMR by 1992.

Child, Preschool↗

PubMed2001

Review of validation studies of the Edinburgh Postnatal Depression Scale.

OBJECTIVE: To review validation studies of the Edinburgh Postnatal Depression Scale (EPDS). METHOD: A systematic search was performed in Medline and the Science Citation Index Expanded (ISI) from the period 1987-2000. For sensitivity and specificity of the EPDS presented in each study, 95% confidence intervals were estimated. Positive and negative predictive values were estimated assuming prevalences of postpartum depression ranging from 5% to 20%. RESULTS: Eighteen validation studies were identified. The study design varied between studies. The sensitivity and specificity estimates also varied: 65-100% and 49-100%, respectively. The confidence intervals were estimated to be wide. Our estimates suggest a lower positive predictive value in a normal population than in the validation study samples. CONCLUSION: Most studies show a high sensitivity of the EPDS. Because of the differences in study design and large confidence intervals, uncertainty remains regarding the comparability between the sensitivity and specificity estimates of the different EPDS versions.

Confidence Intervals↗

PubMed2000

Development of prediction models for three in vitro embryotoxicity tests in an ECVAM validation study.

Since 1997 the National Center for Documentation and Evaluation of Alternative Methods to Animal Experiments, ZEBET, in Berlin, has been coordinating a validation study aimed at prevalidation and validation of three in vitro embryotoxicity tests, funded by the European Center for the Validation of Alternative Methods (ECVAM) at the Joint Research Center (JRC, Ispra, Italy). The tests use the cultivation of postimplantation rat whole embryos (WEC test), cultures of primary limb bud cells of rat embryos (micromass or, MM, test), and cultures of a pluripotent mouse embryonic stem cell line (embryonic stem cell test or EST). Each of the tests was performed in four laboratories under blind conditions. In the preliminary phase of the validation study 6 out of 20 test chemicals comprising different embryotoxic potential (non, weakly, and strongly embryotoxic) were tested. The results were used to define biostatistically based prediction models (PMs) to identify the embryotoxic potential of test chemicals for the WEC test and the MM test. The PMs developed with the results of the preliminary phase of the validation study (training set) will be evaluated with the results of the remaining 14 test chemicals (definitive phase) by the end of the study. In addition, the existing, improved PM (iPM) for the EST, which had been defined previously, was evaluated using the results of the preliminary phase of this study. Applying the iPM of the EST to the results of this study, in 79% of the experiments, chemicals were classified correctly according to the embryotoxic potential defined by in vivo testing. For the MM and the WEC test, the PMs developed during the preliminary phase of this validation study provided 81% (MM test) and 72% (WEC test) correct classifications. Because the PM of the WEC test took into account only parameters of growth and development, but not cytotoxicity data, a second PM (PM2) was developed for the WEC test by incorporating cytotoxicity data of the differentiated mouse fibroblast cell line 3T3, which was derived from the EST. This approach, which has previously never been used, resulted in an increase to 84% correct classifications in the WEC test.

3T3 Cells↗

PubMed2002

Virtual reality flexible cystoscopy: a validation study.

OBJECTIVES: To validate a flexible cystoscopy simulator by determining if it could differentiate between expert and novice cystoscopists. SUBJECTS AND METHODS: Seventeen subjects (10 novices with no previous endoscopic experience and seven urologists who had all carried out > 1000 flexible cystoscopies each) were asked to undertake a flexible cystoscopy task on the URO Mentor (Simbionix, Israel) virtual reality (VR) machine. In the task used the bladder mucosa has 10 flags (numbered 1-10) at key positions in the bladder; by visualizing each of the 10 flags and photographing them the subject will have indirectly visualized the entire mucosa. Subjects were asked to carry out the task 10 times, to allow their rate of acquisition of skill to be assessed. The total time taken for the task and the number of flags visualized were used as measures of performance. RESULTS: The experienced urologists were significantly better at flexible cystoscopy than the medical students on the first trial for the mean number of flags seen (9.57 vs 8.0, P = 0.01) and the mean time to complete the task (2.33 vs 4.89 min, P = 0.03). At the 10th trial there was still a significant difference for the time taken, between the medical students and the urologists (2.33 vs 0.81 min, P = 0.01) but not for the number of flags seen (9.2 vs 9.6, P = 0.46). The medical students improved between the first and the 10th attempt, being significantly quicker for trial 10 than trial 1 (P = 0.005). However, although the medical students appeared to see more flags (8.0 vs 9.2) this was not significant (P = 0.05). The urologists did not differ in the number of flags visualized between the first and 10th trial, although they were significantly quicker in completing the task (P = 0.02). The urologists were significantly faster in trial 2 than trial 1, but no faster thereafter (P = 0.04). CONCLUSIONS: Using the URO Mentor simulator, it was possible to assess the level of experience of flexible cystoscopy, and therefore the system has construct validity. As in the real situation there is a period of learning during which the subject becomes familiar with the computer/machine/human interface, the task and the handling of the instruments. These results support the view that there is a role for VR simulators in urological training.

Clinical Competence↗

PubMed2004

MergeMaid: R tools for merging and cross-study validation of gene expression data.

Cross-study validation of gene expression investigations is critical in genomic analysis. We developed an R package and associated object definitions to merge and visualize multiple gene expression datasets. Our merging functions use arbitrary character IDs and generate objects that can efficiently support a variety of joint analyses. Visualization tools support exploration and cross-study validation of the data, without requiring normalization across platforms. Tools include "integrative correlation'' plots that is, scatterplots of all pairwise correlations in one study against the corresponding pairwise correlations of another, both for individual genes and all genes combined. Gene-specific plots can be used to identify genes whose changes are reliably measured across studies. Visualizations also include scatterplots of gene-specific statistics quantifying relationships between expression and phenotypes of interest, using linear, logistic and Cox regression.

Journal Article↗

PubMed2004

Determination of cardiac output with multislice spiral computed tomography: a validation study.

OBJECTIVE: To validate and to determine the reproducibility of cardiac output (CO) measurements based on a test-bolus examination in multislice spiral computed tomography (MSCT) in comparison with invasively measured CO using the thermal dilution technique. MATERIAL AND METHODS: In 8 swine, CO was determined by invasive thermal dilution technique and by analysis of enhancement data from dynamic MSCT test-bolus examinations. To assess reproducibility, all MSCT examinations were performed twice. Results were compared using Pearson's correlation coefficient and Bland-Altman plots. RESULTS: Measure by thermal dilution technique CO was 3.71 +/- 1.12 L/min, whereas CO was 3.67 +/- 1.30 L/min using MSCT. Pearson's correlation coefficient was 0.89. The average deviation between MSCT and thermal dilution technique was 0.04 L/min with a standard deviation of 0.59 L/min. There was a good agreement between both MSCT measurements with a mean deviation of -0.03 L/min and a standard deviation of 0.51 L/min. CONCLUSION: CO can reliably be determined from MSCT by means of indicator dilution technique. Measurements are reproducible and provide valuable information on the overall cardiovascular performance without application of additional contrast material or radiation. As this technique does not require time-consuming postprocessing it can be added to routine reporting.

Animals↗

PubMed2005

Diagnostic reference frames for seizures: A validation study.

INTRODUCTION: We developed structured descriptions of signs and symptoms for specific seizure types (called Diagnostic Reference Frames-DRFs-by us) that can serve as a frame of reference in the process of classifying patients with epileptic seizures. In this study the validity of the DRFs for clinical use is evaluated and described. MATERIAL AND METHODS: In this study we use a decision support system based on the DRFs and using Bayes's rule for the validation of the DRFs. Patient's manifestations are entered in the decision support system and by successively applying Bayes's rule posterior probabilities are calculated. The DRFs with the highest posterior probability gives an indication of the classification of the seizure. The validation of the DRFs was performed by comparing the seizure type with the highest posterior probability with the classification of experienced epileptologists on a series of test cases with known epileptic seizures. In this way we assessed the accuracy of the DRFs in classifying patients with epileptic seizures. RESULTS: We included sixty-six patients in this efficacy study. The patients and/or their relatives described the manifestations occurring during a seizure. Sixty cases (91%) were correctly classified using the decision support system. DISCUSSION: The accuracy of 91 % indicates that the knowledge encoded in the DRFs for the included seizure types is valid. The next step is to test the DRFs in a clinical setting to evaluate the applicability in daily practice.

Adolescent↗

PubMed2006

The use of a self-reported pain measure, a nurse-reported pain measure and the PAINAD in nursing home residents with moderate and severe dementia: a validation study.

OBJECTIVES: To assess the construct validity of three measures of pain and to determine a categorical version of the Pain Assessment in Advanced Dementia (PAINAD) scale. DESIGN: Validation study determining the concurrent validity of a self-reported pain score (SRPS), a nurse-reported pain score (NRPS) and the PAINAD; the divergent validity of the three pain measures with the Abbreviated Mental Test (AMT) and the Cornell Scale for Depression in Dementia (CSDD). SETTING AND SUBJECTS: eighty-eight nursing home residents with moderate and severe dementia. METHODS: Residents were asked to rate the severity of their pain in the previous week on a verbal descriptor scale (VDS). Nurses rated the resident's pain on a VDS, scored the PAINAD scale and the CSDD scale. Research assistants administered the AMT. RESULTS: The PAINAD correlated with the NRPS (Kendall's tau [tau] = 0.842); both scales correlated poorly with the SRPS (tau = 0.304 for both correlations). The PAINAD was significantly different for each level of the NRPS. On the SRPS, the PAINAD for the group with moderate+ pain was significantly different from the groups with mild pain and no pain. There was a difference between the SRPS and the NRPS when residents were depressed, but no difference when they were not. Our categorical version of the PAINAD showed good agreement with the NRPS. CONCLUSION: The NRPS and the PAINAD measure pain differently from the SRPS, especially in the presence of depression. Our categorical version of the PAINAD shows good agreement with the NRPS.

Aged↗

PubMedDate not supplied

[Index for a pulmonary postoperative complication after upper abdominal surgery: a validation study].

OBJECTIVE: To validate a previous prognostic index (Pereira et al.) to postoperative pulmonary complication in elective upper abdominal surgery, and observe the risk factor for mortality in this population. METHODS: 283 patients were followed from pre to postoperative period. They were followed in a protocol including a clinical questionnaire, physical examination, thoracic radiogram and spirometry at pre operative period. The main variables measured were: clinical and functional subjects characteristics at pre operative, type of surgery, duration of surgery, time spent in intensive care unit and hospitalization and the occurrence of pulmonary complication. RESULTS: 69 patients had pulmonary complications (24.4%), in 87 events registered. These occurred because some patients had more than one complication. Pneumonia was the most freqüent event 34% (30/87) followed by atelectasis 24% (21/87), bronchoconstriction 17% (15/87), acute respiratory failure 13% (11/87), prolonged mechanical ventilation 9% (8/87) and bronchial infection 2% (2/87). The multiple logistic regression (MLR) showed the association between age above 56 years old (p = 0.0039); DS > 210 (p = 0.0044) and previous chronic pneumopathy (p = 0.0257) and postoperative pulmonary complication. The frequency of postoperative pulmonary complication observed in each categorical classis based on previous index (Pereira equation) did not differ statistically from the prognostic rate calculated, showing the validity of the prognostic index. When FEV1/FVC was included in MLR, the patients with VEF1/FVC<70% and DS> 210 minutes showed a statistically lower number of pulmonary postoperative compared with estimated by the previous Pereira index. The mortality analyses showed significant association with comorbidity, number of days in care unit and postoperative pulmonary complication, however in the MLR only postoperative pulmonary complication had a significant association with death (p = 0.003). CONCLUSIONS: The index based on Pereira equation is valid to estimate the prognosis of postoperative pulmonary complication after elective upper abdominal surgery. Age higher 56 years old, duration of surgery more than 210 minutes and pneumopathy are important markers of postoperative pulmonary complication. The only significant marker for mortality was the post operative pulmonary complication.

Abdomen↗

PubMed2006

Conventional energy and macronutrient variables distort the accuracy of children's dietary reports: illustrative data from a validation study of effect of order prompts.

OBJECTIVE: Validation-study data are used to illustrate that conventional energy and macronutrient (protein, carbohydrate, fat) variables, which disregard accuracy of reported items and amounts, misrepresent reporting accuracy. Reporting-error-sensitive variables are proposed which classify reported items as matches or intrusions, and reported amounts as corresponding or overreported. METHODS: 58 girls and 63 boys were each observed eating school meals on 2 days separated by > or =4 weeks, and interviewed the morning after each observation day. One interview per child had forward-order (morning-to-evening) prompts; one had reverse-order prompts. Original food-item-level analyses found a sex-x-order prompt interaction for omission rates. Current analyses compared reference (observed) and reported information transformed to energy and macronutrients. RESULTS: Using conventional variables, reported amounts were less than reference amounts (ps<0.001; paired t-tests); report rates were higher for the first than second interview for energy, protein, and carbohydrate (ps< or =0.049; mixed models). Using reporting-error-sensitive variables, correspondence rates were higher for girls with forward- but boys with reverse-order prompts (ps< or =0.041; mixed models); inflation ratios were lower with reverse- than forward-order prompts for energy, carbohydrate, and fat (ps< or =0.045; mixed models). CONCLUSIONS: Conventional variables overestimated reporting accuracy and masked order prompt and sex effects. Reporting-error-sensitive variables are recommended when assessing accuracy for energy and macronutrients in validation studies.

Bias↗

PubMedDate not supplied

Reliability and validity studies of the WHO--Composite International Diagnostic Interview (CIDI): a critical review.

This paper reviews reliability and validity studies of the WHO - Composite International Diagnostic Interview (CIDI). The CIDI is a comprehensive and fully standardized diagnostic interview designed for assessing mental disorders according to the definitions of the Diagnostic Criteria for Research of ICD-10 and DSM-III-R. The instrument contains 276 symptom questions many of which are coupled with probe questions to evaluate symptom severity, as well as questions for assessing help-seeking behavior, psychosocial impairments, and other episode-related questions. Although primarily intended for use in epidemiological studies of mental disorders, it is also being used extensively for clinical and other research purposes. The review documents the wide spread use of the instrument and discusses several test-retest and interrater reliability studies of the CIDI. Both types of studies have confirmed good to excellent Kappa coefficients for most diagnostic sections. In international multicenter studies as well as several smaller center studies the CIDI was judged to be acceptable for most subjects and was found to be appropriate for use in different kinds of settings and countries. There is however still a need for reliability studies in general population samples, the area the CIDI was primary intended for. Only a few selected aspects of validity have been examined so far, mostly in smaller selected clinical samples. The need for further procedural validity studies of the CIDI with clinical instruments such as the SCAN as well as cognitive validation studies is emphasized. The latter should focus on specific aspects, such as the use of standardized questions in the elderly, cognitive probes to improve recall of episodes and their timing, as well as the role of order effects in the presentation of diagnostic sections.

Cross-Cultural Comparison↗

PubMed1998

Adult female twins' recall of childhood social class and father's education: a validation study for public health research.

To assess recall of childhood socioeconomic position for public health research, the authors conducted a cross-sectional study of 352 adult women twin pairs enrolled in Examination II of the Kaiser Permanente Women Twins Study carried out in 1989-1990 in Oakland, California. Among twin pairs, 91% (95% confidence interval (CI) 89-94%) agreed on their father's educational level and 81% (95% CI 77-85%) on their childhood social class. Recall did not differ by adult socioeconomic position, zygosity, race/ethnicity, or age. Thus, epidemiologic studies can validly use retrospective data on childhood socioeconomic position to study its relation to adult health status.

Adolescent↗

PubMed2007

Procalcitonin to reduce the number of unnecessary cystographies in children with a urinary tract infection: a European validation study.

OBJECTIVE: To validate high serum procalcitonin (PCT) as a predictor of vesicoureteral reflux (VUR) in children with a first febrile urinary tract infection (UTI). STUDY DESIGN: This secondary analysis of prospective hospital-based cohort studies included children ages 1 month to 4 years with a first febrile UTI. RESULTS: Of the 398 patients included in 8 centers in 7 European countries, 25% had VUR. The median PCT concentration was significantly higher in children with VUR than in those without: 1.6 versus 0.7 ng/mL (P = 10(-4)). High PCT (> or =0.5 ng/mL) was associated with VUR (OR: 2.3; 95% CI, 1.3 to 3.9; P = 10(-3)). After adjustment for all cofactors, the association remained significant (OR: 2.5; 95% CI, 1.4 to 4.4; P = 10(-3)). The strength of the relation increased with the grade of reflux (P = 10(-5)). The sensitivity of procalcitonin was 75% (95% CI, 66 to 83) for all-grade VUR and 100% (95% CI, 81 to 100) for grade > or =4 VUR, both with 43% specificity (95% CI, 37 to 48). CONCLUSIONS: High PCT is a strong, independent and now validated predictor of VUR that can be used to identify low-risk patients and thus avoid one third of the unnecessary cystourethrographies in children with a first febrile UTI.

Calcitonin↗

PubMed2001

Quality indicators in postoperative pain management: a validation study.

Quality indicators in postoperative pain management: a validation study. In a previous study, strategic and clinical quality indicators were developed from a tentative model to assess high quality in postoperative pain management. The aim of the present study was to investigate the content validity of these 15 indicators. The indicators were compiled in a questionnaire, and two groups of nurses (n=210, n=321) scored each indicator on a 5-point scale (strongly disagree to strongly agree) from three different standpoints: whether it was essential for achieving high quality, whether it was realistic to carry out, and whether it was possible for nurses to influence management. The respondents were also asked to choose the most crucial indicators for the quality of care. The results showed that both groups of nurses judged the 15 indicators to have content validity from all three standpoints. Both groups also found the same six indicators to be the most crucial. These indicators concerned detecting and acting on signs and symptoms, performing prescriptions, informing and educating, acting on behalf of patients, competence/knowledge, and attitudes. The validated indicators should be useful to consider when implementing a strategy for postoperative pain management and when planning to evaluate the quality of care.

Adult↗

PubMed1998

Validity study of the EDI-2 in Israeli population.

This study was designed to validate the EDI-2 (1) in an Israeli population. The sample consisted of 29 anorectic patients and 18 recovering anorectics, recruited from six hospitals, and 67 female control subjects matched by age. Results of the validity study indicate that the translated EDI-2 was reliable and valid. Anorectic patients scored higher than the recovering anorectics on most scales. Recovering anorectics resembled the control subjects on most scales except Perfectionism.

Adolescent↗