Concordance between supervised and postal administration of the Mini Asthma Quality of Life Questionnaire (MiniAQLQ) and Asthma Control Questionnaire (ACQ) was very high

BACKGROUND AND OBJECTIVE: There is increasing international interest in using patient-based outcome measures to evaluate interventions. We compared responses to postal administration of Mini Asthma Quality of Life Questionnaire (MiniAQLQ) and Asthma Control Questionnaire (ACQ) with the gold standard of supervised self-completion. STUDY DESIGN AND SETTING: Validation study involving 96 adults, recruited from U.K. general practice, sent the postal questionnaires with an instruction sheet 1 week before supervised self-completion. Responses for those whose quality of life (n=56) or asthma control (n=61) had 'not changed' between postal and supervised completions were compared using paired-sample t-tests, Pearson's correlation coefficient (r), and intraclass correlation coefficient (ICC). RESULTS: For the MiniAQLQ, overall mean scores were similar in both groups: Postal=5.14 (SD=1.42) vs. Supervised=5.17 (SD=1.39), with mean difference of -0.03 (95% CI=-0.14, 0.08; P=.59), with a high degree of correlation (r=.96, P<.001) and concordance (ICC=0.96; 95% CI=0.93, 0.98; P<.001). For the ACQ, overall mean scores (with SD) were also similar in both groups: Postal=1.24 (SD=1.09) vs. Supervised=1.26 (SD=1.10), with mean difference of -0.02 (95% CI=-0.12, 0.08; P=.74), with good correlation (r=.94, P<.01) and concordance (ICC=0.94; 95% CI=0.90, 0.96; P<.01). CONCLUSIONS: Correlation and concordance between supervised and postal administration of the MiniAQLQ and ACQ are very high. Users may confidently choose the mode of administration most appropriate to their needs.     

Using the standard error of measurement to identify important changes on the Asthma Quality of Life Questionnaire

Objectives: To establish a link between the minimal important difference (MID) and the standard error of measurement (SEM) for all responsive dimensions of the Asthma Quality of Life Questionnaire (AQLQ). Methods: Secondary data analysis of baseline and follow-up interview data from 198 outpatients with asthma enrolled in a randomized controlled trial and receiving care at a major urban academic medical center's general medicine clinics. Domain statistics for baseline and follow-up interviews were examined for the AQLQ. The baseline SEM values were compared with established AQLQ MID standards using weighted values. Results: One SEM identified the MID in responsive AQLQ dimensions. Weighted values (0.88–0.93) validated excellent agreement between these two criteria. Conclusion: This is the third study to support using one SEM to identify important individual change in health-related quality of life (HRQoL) measures. However, refinement of the process for determining a measure's clinically meaningful differences is still needed to secure a link between the SEM and the identification of relevant HRQoL change over time.     

Using structural equation models to evaluate the magnitude of measurement error in blood pressure

This article aims to compare alternative methods for estimating the quality of blood pressure measurements. Traditional within-subject variance estimates in mixed analysis of variance models are compared to multiple-group multitrait-multimethod models, which are a particular case of mean-and-covariance-structure confirmatory factor analysis models. Confirmatory factor analysis models belong to the family of structural equation models and were specifically developed to analyse psychosociological traits measured by tests or surveys, but they have also proved suitable for evaluating the quality of blood pressure measurements. Confirmatory factor analysis models are less restrictive and provide more detailed information than traditional approaches, enable researchers to compute weighted averages of individual measures with optimal measurement quality, make it easier to correct the biasing effects of measurement error on the results of substantive studies, and make the use of equivalent replicated measures unnecessary under certain conditions.     

Confirmatory factor analysis of the General Health Questionnaire (GHQ-12) in Spanish adolescents

Purpose

To evaluate the factor structure of the 12-item General Health Questionnaire (GHQ-12) in a population of Spanish adolescents.

Methods

Cross-sectional study among 4,146 individuals (mean age 16.3?years). The students completed a health questionnaire that included the GHQ-12. A confirmatory factor analysis (CFA) was conducted with four factor structure models. Three of the models were theory-driven: unidimensional, two-dimensional (positive and negative questions), model proposed by Graetz (anxiety and depression, social dysfunction, loss of confidence); and the fourth model was based on our exploratory factor analysis (EFA).

Results

The Cronbach??s alpha for internal consistency was 0.82. A three-dimensional structure was identified in the EFA. The first factor included items 1, 2, 5, 6, 7, and 9 of the GHQ-12; the second, items 3, 10, and 11; and the third, items 4, 8, and 12. The three factors together explained 53.7% of the variance. The model with the best fit in the CFA was the three-dimensional model proposed by Graetz, followed by the three-dimensional model derived from the EFA. These two models had acceptable goodness-of-fit indices.

Conclusions

In an adolescent population from Southern Europe, the GHQ-12 showed high internal consistency. The factor structure that best fitted the data was the Graetz three-dimensional model. However, the high correlations observed between factors suggest that the GHQ-12 should be used as a unidimensional scale, as currently done.     

Confirmatory factor analysis of the Child Feeding Questionnaire (CFQ) in Japanese elementary school children

The validity of the Child Feeding Questionnaire (CFQ), one of the measures used to assess parental child feeding practices and attitudes, has been confirmed in American populations. We used confirmatory factor analysis to test the validity and factor structure of the translated version of the CFQ among parents of Japanese elementary school children. The structural equation modelling software Linear Structural Relationships (LISREL) was applied to explore the validity of the translated CFQ to examine child feeding behaviours and attitudes in a sample of 920 parents of Japanese elementary schoolchildren from schools in Koshu City in Yamanashi prefecture (grades 4-6), Japan. The confirmatory factor analysis suggested that after dropping the items with a low factor loading and adding three error covariances between items, the 7-factor model displayed acceptable fit and most items loaded as expected. Of the 24 direct factor-item correlations, 22 were greater than 0.50. Our study confirmed the validity of the translated CFQ to assess child feeding practices and attitudes among parents of elementary schoolchildren brought up in a Japanese eating culture.     

A Rasch and confirmatory factor analysis of the General Health Questionnaire (GHQ) - 12

Background  

The General Health Questionnaire (GHQ) - 12 was designed as a short questionnaire to assess psychiatric morbidity. Despite the fact that studies have suggested a number of competing multidimensional factor structures, it continues to be largely used as a unidimensional instrument. This may have an impact on the identification of psychiatric morbidity in target populations. The aim of this study was to explore the dimensionality of the GHQ-12 and to evaluate a number of alternative models for the instrument.     

Rasch analysis of the Psychiatric Out-Patient Experiences Questionnaire (POPEQ)

Background  

The Psychiatric Out-Patient Experiences Questionnaire (POPEQ) is an 11-item core measure of psychiatric out-patients experiences of the perceived outcome of the treatment, the quality of interaction with the clinician, and the quality of information provision. The POPEQ was found to have evidence for reliability and validity following the application of classical test theory but has not previously been assessed by Rasch analysis.     

Use of stable isotopes to evaluate the functional effects of nutrients

PURPOSE OF REVIEW: Lifestyle, particularly dietary habits, plays a major role in the increasing prevalence of obesity, type 2 diabetes and atherosclerosis. Understanding how diet and specific foods can modify important functions of the body, in a beneficial or detrimental way, is therefore important. This review presents recent advances in the use of stable isotopes to investigate how nutrients can influence pathways of glucose, lipids and protein metabolism, and also intestinal absorption, body composition and fat mass turnover. RECENT FINDINGS: Recent developments have focused mainly on the measurement of intratissular metabolic pathways, particularly in lipids and proteins. Advances in the field of cell proliferation rates, body composition and energy expenditure have also been made. Many of these developments rely on the use of deuterated water to trace multiple metabolic pathways. SUMMARY: Stable isotopes can now be used to measure the kinetics and oxidation rate of circulating metabolites and also body composition, colonic fermentation, intestinal absorption, and important intratissular metabolic pathways, such as gluconeogenesis, lipogenesis, cholesterol synthesis, the turnover rate of triglycerides, individual protein synthesis and cell proliferation. Deuterated water has emerged as a powerful and versatile tool, allowing the simultaneous investigation of several aspects of protein, lipid and glucose metabolism.     

A comparison of estimators to evaluate the discriminatory power of time-to-event models

Discrimination measures for continuous time‐to‐event outcomes have become an important tool in medical decision making. The idea behind discrimination measures is to evaluate the performance of a prediction model by measuring its ability to distinguish between observations having an event and those having no event. Researchers proposed a variety of approaches to estimate discrimination measures from a set of right‐censored data. These approaches rely on different regularity assumptions that are needed to ensure consistency of the respective estimators. Typical examples of regularity assumptions include the proportional hazards assumption in Cox regression and the random censoring assumption. Because regularity assumptions are often violated in practice, conducting a sensitivity analysis of the estimators is of considerable interest. The aim of the paper is to analyze and to compare the most popular estimators of discrimination measures for event time outcomes. On the basis of the results of an extensive simulation study and the analysis of molecular data, we investigate the behavior of the estimators in situations where the underlying regularity assumptions do not hold. We show that violations of the regularity assumptions may induce a nonignorable bias and may therefore result in biased medical decision making. Copyright © 2012 John Wiley & Sons, Ltd.     

Confirmatory factor analysis of the Children's Eating Behaviour Questionnaire in a low-income sample

Although pediatric obesity is prevalent in low-income and African American and Hispanic communities, validated measures of child eating habits are lacking for these communities. In this study, confirmatory factor analysis was used to validate the hypothesized 7-factor structure of the Children's Eating Behaviour Questionnaire (CEBQ). The sample included 229 parent-child pairs, the majority low-income and Hispanic (57%) or African American (25%). The a priori structure of the CEBQ failed to replicate. Exploratory factor analysis revealed 3 factors: Disinhibition, Food interest, and Undereating, none predicting child BMI. Although limited by the observational, cross-sectional design, results indicate that the CEBQ needs additional study.     

Development of the Telemedicine Satisfaction Questionnaire to evaluate patient satisfaction with telemedicine: a preliminary study

We developed a questionnaire for the evaluation of patient satisfaction with telemedicine. Items related to patient satisfaction with telemedicine were identified through a review of the literature. The internal consistency and the intraclass correlation coefficient were used to evaluate the reliability of the proposed instrument. Content validity was examined using a panel of experts. The predictive validity of the proposed instrument was assessed by correlating scores on the Telemedicine Satisfaction Questionnaire (TSQ) with haemoglobin A(1c) levels and adherence to self-management activities among 38 patients with type 2 diabetes, after they had completed a four-session interactive diabetes tele-education programme. A principal-components analysis with varimax rotation was performed to reduce the number of questionnaire items from 15 to 14, and the scree test was used to select significant factors. There were three components with eigenvalues over 1.0, which together explained 68% of the total variance. These were: quality of care provided, similarity to face-to-face encounter and perception of the interaction. The TSQ demonstrated preliminary reliability and validity but more extensive testing will be required before it can be considered generally applicable.     

The Spanish version of the Paediatric Asthma Quality of Life Questionnaire (PAQLQ): Metric characteristics and equivalence with the original version

The Paediatric Asthma Quality of Life Questionnaire (PAQLQ), developed by Juniper etal., assesses the impact of asthma on children's daily life. It contains 23 items, covering three dimensions: symptoms, activities limitation and emotional function. Aims: To develop an equivalent Spanish version of the PAQLQ, and to assess its measurement characteristics. Methods: The forward and back-translation method was used for the adaptation. A longitudinal study (assessments at the 1st and 5th weeks), with patients from the emergency and outpatient departments of three Spanish hospitals, was designed to test the properties of the new adapted version. At each visit, a trained interviewer administered the PAQLQ, a Global Index of Change and a General Health Perception scale. The Peak Expiratory Flow Rate (PEFR) was also recorded daily, together with symptoms, during the prior week. Results: Ninety-nine patients (66.7% males, 42.4% suffering an exacerbation, mean age of 11.3years) with the following types of asthma were evaluated: mild intermittent (31.3%), mild persistent (36.4%), moderate persistent (29.3%) and severe persistent (3%). At the 1st visit, the mean pre-bronchodilator %PEFR was 87.3%. The Cronbach's ranged from 0.86 to 0.95. As expected, correlations between the PAQLQ scores, and the Asthma Control Score (0.53–0.67), the General Health Perception (0.34–0.55), and the %PEFR (0.44–0.55) were moderate. The PAQLQ scores remained unchanged in stable patients while increased significantly in those showing improvements. Conclusions: After a standard cross-cultural adaptation process, the Spanish version of the PAQLQ has shown to be equivalent to the original, with similar internal consistency reliability, validity and sensitivity to clinical changes.