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Results for “external validation”

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At least 163 records · Page 9Linked to original sources
PubMed2002

External validation of a modified model of Acute Physiology and Chronic Health Evaluation (APACHE) II for orthotopic liver transplant patients.

INTRODUCTION: The purpose of the study was to validate the newly derived postoperative orthotopic liver transplantation (OLTX)-specific diagnostic weight for the Acute Physiology and Chronic Health Evaluation (APACHE) II mortality prediction system in independent databases. METHODS: Medical records of 174 liver transplantation patients admitted postoperatively to the adult intensive care units at King Fahad National Guard Hospital and the University of Wisconsin were reviewed, and data on age, sex, the underlying liver disease, APACHE II scores and the hospital outcome were collected. Predicted mortality was calculated using: 1) the original APACHE II diagnostic weight of postoperative other gastrointestinal surgery and 2) the newly derived OLTX-specific diagnostic category weight. Standardized mortality ratio and 95% confidence intervals were calculated. Calibration was evaluated with the Hosmer-Lemeshow goodness-of-fit C-statistic. Discrimination was tested by 2 x 2 classification matrices and by computing the areas under the receiver operating characteristic curves. Patient characteristics and outcome data were compared between the two hospitals. RESULTS: APACHE II significantly overestimated mortality when the original diagnostic weight was used, but provided a closer estimate of mortality with the OTLX-specific diagnostic weight. The C-statistic analysis showed better calibration for the new approach; discrimination was also improved. The performances of the prediction systems were similar in the two hospitals. The new model provided more accurate estimates of hospital mortality in each hospital. DISCUSSION: APACHE II provided an accurate estimate of mortality in liver transplant patients when the OLTX-specific diagnostic weight was used. With the new model, APACHE II can be used as a valid mortality prediction system in this group of patients.

APACHE↗
PubMed1999

External validation of the equivalence of two computational formulas for a WAIS-R seven-subtest short form.

The usefulness of an abbreviated form of the Wechsler Adult Intelligence Scale-R (WAIS-R) has been noted by several researchers. A 7-subtest short form yielding estimates of Verbal, Performance, and Full Scale IQs (FSIQs) has shown good reliability and validity. Both weighted and prorated formulas have been used interchangeably to compute estimated IQs derived from this short form. The purpose of this study was to compare the equivalence of these formulas with the full WAIS-R in a mixed clinical sample. Results show that both formulas produce nearly identical results, with neither formula emerging as clearly superior over the other; validity coefficients for WAIS-R IQs ranged from .95 to .97. A very slight absolute advantage was noted for the prorated over the weighted formula in that it resulted in fewer IQ differences greater than 2 standard errors of measurement, fewer misclassifications of FSIQ, and stronger correlations with WAIS-R Verbal, Performance, and FSIQs.

Adolescent↗
PubMedDate not supplied

Randomized controlled trials: do they have external validity for patients with multiple comorbidities?

PURPOSE: Many randomized controlled trials (RCTs) exclude patients who have multiple comorbidities. The aim of this study was to illustrate the prevalence of comorbidities among patients followed up in primary care who would have met the inclusion criteria of selected RCTs focusing on treatment of a particular condition. We used hypertension as an example of a particular chronic condition. METHODS: We used an existing database of 980 patients (660 women) that was representative of a population consulting primary care family doctors and that contained information about all chronic conditions. We randomly selected 5 RCTs that focused on patients with hypertension. The inclusion and exclusion criteria used in each of the 5 RCTs were applied (1 study at a time) to the patients in our database. The patients from our data set who met the inclusion criteria of a given RCT were considered eligible for that RCT. RESULTS: Of the patients from our data set who were eligible for each of the RCTs, 89% to 100% had multiple chronic conditions. The mean number of chronic conditions of patients eligible for each RCT ranged from 5.5 +/- 3.3 to 11.7 +/- 5.3. CONCLUSIONS: Results from this study suggest that RCTs targeting a chronic medical condition such as hypertension could find that, in a sample taken from family practice, most eligible patients have comorbid conditions. Whether these patients are sampled or excluded should be reported. Research results intended to be applied in medical practice should take the complex reality of effective treatment of these patients into consideration.

Adult↗
PubMed2006

Risk of pregnancy and external validity in clinical trials of emergency contraception.

OBJECTIVES: To compare women who enroll in emergency contraception (EC) trials to those who decline and to understand why eligible women decline to participate. METHODS: Data were collected from all women seeking EC (n = 5,787) at three clinics in the USA and UK during a period of nearly 1 year (from September 1997 to August 1998). The main outcome measures were pregnancy risk calculated by adjusted cycle day of ovulation. RESULTS: Enrolled and non-enrolled women had similar mean ages and similar mean cycle lengths. However, the enrolled and non-enrolled groups were different with respect to adjusted cycle day of unprotected sexual intercourse (UPSI), the regularity of their cycles, recent hormone use, breastfeeding, the number of other acts of UPSI they had engaged in during the same cycle, and their willingness to participate in the study. Expected pregnancy risk among enrolled patients was higher than among non-enrolled EC seekers (6.5% vs 5.0%, p<0.001, calculated using Dixon conception probabilities, and 5.4% vs 4.6%, p = 0.086, calculated using Trussell conception probabilities). Unwillingness to take part in the study was the most common reason women did not enrol in the trial. Otherwise-eligible women most often declined to enrol because they were concerned about the effectiveness of the trial regimen. CONCLUSIONS: Women in EC trials are likely to face higher pregnancy risk than the general population. Clinical trials might overestimate the number of pregnancies averted by treatment because the number of expected pregnancies in trial populations is not representative of the population of all EC seekers. This information could be useful in projecting the public health impact of expanded EC access.

Adolescent↗
PubMed1999

External validation of the Ottawa knee rules in an urban trauma center in the United States.

OBJECTIVE: We evaluated the Ottawa knee rules in a high-volume teaching hospital in the United States to determine whether the rules could be safely used to decide whether patients with acute blunt knee trauma should undergo radiography. SUBJECTS AND METHODS: During a 13-month period, 378 patients with acute blunt knee trauma were prospectively examined using the Ottawa knee rules. Data collected included the presence or absence of fracture predictors and the results of radiography. RESULTS: A fracture was seen in 43 (11%) of the 378 patients who met inclusion criteria. The knee rules predicted 42 of the 43 fractures; sensitivity was 98%, and specificity was 19%. Radiography of 65 patients (17%) who had no predictors for fracture could have been avoided if the knee rules had been used to screen for radiography. CONCLUSION: The Ottawa knee rules are highly sensitive for fracture in this setting and may safely be used to decide whether patients with acute blunt knee trauma should undergo radiography.

Adult↗
PubMed1985

Lateralization in attainment and maintenance of neonatal head posture: further external validation.

Consistencies in lateral head turning of 50 healthy, term neonates were examined to determine relations between attainment and maintenance of lateral head position. The majority showed lateral consistencies, typically rightward, in initial head turn from midline per trial, in direction of the majority of all head turns from midline per trial and in direction turned for the majority of time per trial. Head position prior to testing was related to the three indices. The results of work to date, including the current study, have proven very consistent in nature, yielding the most reliable measure of an element of lateralized behavior in the neonate.

Female↗
PubMed2000

The external validity of Asperger disorder: lack of evidence from the domain of neuropsychology.

The present study compared individuals with high-functioning autism (HFA) and Asperger disorder (AD) in intellectual, motor, visuospatial, and executive function domains. Participants with AD demonstrated significantly higher Verbal and Full Scale IQ scores, significantly larger Verbal-Performance IQ discrepancies, and significantly better visual-perceptual skills than those with HFA. Once the superior intellectual abilities of the AD group were controlled (both statistically through analysis of covariance and by examining IQ-matched subgroups of HFA and AD participants), no significant group differences in motor, visuospatial, or executive functions were evident, save a marginally significant trend toward poorer fine motor performance in the AD group. This suggests that AD may simply be "high-IQ autism" and that separate names for the disorders may not be warranted. The relation of these findings to theories of autism and AD are discussed.

Asperger Syndrome↗
PubMedDate not supplied

[External validity, reliability and basic score determination of the Toronto Alexithymia Scales (TAS and TAS-20) in a group of alcoholic patients].

The criterion validity of the Toronto Alexithymia Scales (TAS and TAS-20) was assessed by administering the scales to 47 alcoholic inpatients. The 47 subjects were inpatients meeting the Research Diagnostic Criteria for alcoholism. The subjects were assessed by two raters using the Beth Israël Questionnaire in the first week following their hospitalization. They filled out the TAS and one week later the TAS-20. Among the 47 alcoholics, 31 were alexithymic and 16 were non-alexithymic. The TAS and the TAS-20 scores of the alexithymics were significantly higher than that of the non alexithymics. The mean (sd) of the TAS in the alexithymics and the non alexithymics were respectively (m = 76.13, sd = 9.56; m = 64.2, sd = 13.88; t = 3.38, df = 45, p = 0.0015). The mean (sd) of the TAS-20 in the alexithymics and the non alexithymics were respectively (m = 54.1, sd = 8.81; m = 43.18, sd = 11.5; t = 3.62, df = 45, p = 0.0007). The one-week test-retest was r = 0.17, p < 0.001. On the basis of these findings, TAS and TAS-20 cutoff scores were suggested. A range of potential cutoff scores around the mean TAS or TAS-20 score were tested using four methods to assess the goodness of a diagnostic test (sensitivity, specificity, Younden's coefficient, positive predictive value). The best scores that maximizes the diagnostic validity of the TAS and TAS-20 in identifying alexithymic subjects were respectively 73 and 56. On the basis of the mean TAS and TAS-20 score for the non alexithymic group and the means that we have obtained with normal groups, scores of 64 and 44 were respectively selected as the cutoff level for the identification of non alexithymic subjects.

Adult↗
PubMed1995

How to evaluate measuring methods in the case of non-defined external validity.

In the clinical routine of chronic diseases, a new measurement has to be compared to an established criterion to see whether there is agreement on assessing disease progress. Because of the nonexistence of established criteria for rheumatoid arthritis the evaluation of grading systems for radiological assessment needs an alternative approach. Using the measurement error as a measure for repeatability and rater agreement in comparison to the progress of the grading score might be a solution to this dilemma.

Arthritis, Rheumatoid↗
PubMed1998

Physical self-concept: assessment and external validity.

This chapter summarized knowledge about the physical SC, a variable that has assumed great importance in studying how self-esteem is related to physical activity participation. It discussed the advantages of employing component scales such as physical SCs, and reviewed research and theory on the development of the physical SC, age and sex differences, and relationships with life adjustment. Skill development and self-enhancement research were summarized. Leading physical SC scales were briefly reviewed. A thesis of the chapter is that SE and its associations with physical activity participation can be studied best by the employment of models that are hierarchical in their structure, and which contain SC components ranging from very specific to very broad constructs. This has implications for item and inventory selection and for an ultimate understanding of how physical activity leads to mental and emotional benefits.

Adult↗