Psychometric properties of a Chinese asthma quality of life questionnaire

Purpose: To assess the acceptability, reliability, validity, and responsiveness of the Chinese Asthma Quality of Life Questionnaire (C-AQLQ) in a sample of Chinese asthma patients. Methods: The C-AQLQ and Short Form 36 Health Survey (SF-36) scales were administered to patients at baseline and 3 months later. Asthma severity condition and lung function were evaluated. Necessary data were gathered to assess the psychometric properties such as the feasibility, internal consistency, test-retest reliability, structural validity, discriminant validity, convergent validity, and responsiveness of the C-AQLQ. Results: One hundred and thirty-seven patients completed the investigation. The Cronbach's alpha coefficient for the total scale was 0.96. Factor analysis yielded five factors that generally corresponded to the five proposed subscales. Patients with mild asthma reported higher scores than patients with moderate/severe asthma on all subscales other than environmental stimuli. Lung function measurement and the asthma severity score correlated significantly with domains of the C-AQOL but with fewer domains of the SF-36. The questionnaire detected within-subject changes in patients' asthma status during follow-up. Conclusions: Results indicated preliminary support that the C-AQLQ is a reliable, valid, discriminating, and responsive measure of quality of life in Chinese asthma patients. It is more sensitive than the generic SF-36 in detecting differences in asthma severity.     

Psychometric testing of a Swedish version of the Apathy Evaluation Scale

Background: Apathy, a prevalent and clinically relevant symptom in neurodegenerative disease, is often evaluated by the instrument Apathy Evaluation Scale (AES). However, this instrument has not been translated into Swedish, halting clinical and research efforts. Furthermore, previous studies lack analyses of some basic properties, such as the legitimacy of a total score, or have analysed dimensionality by questionable methods.

Aim: To translate and psychometrically evaluate a Swedish version of the AES.

Method: The AES was translated, and its psychometric properties were tested in the Swedish BioFINDER study, including cognitively well elderly, and subjects with mild cognitive or parkinsonian symptoms. Psychometric analyses were conducted according to classical test theory (CTT) and aimed to resemble those performed in the English original study by Marin et al. in 1991. Dimensionality was additionally analysed on a matrix of polychoric correlations and parallel analyses.

Results: Data indicate that the Swedish AES performs satisfactorily regarding data completeness, scaling assumptions, targeting, and reliability. Principal component analyses (with parallel analysis) of polychoric correlation matrices identified a single component. Convergent and discriminative validity correlations accorded with a priori expectations.

Conclusions: The study provides initial support that this Swedish AES performs similarly to the English original, and exhibits acceptable psychometric properties according to CTT, including supported unidimensionality, and may be adopted for use in clinical and research settings.     

Psychometric properties of the dimensional anxiety scales for DSM‐5 in a Brazilian community sample

The DSM‐5 highlights the use of dimensional assessments of mental health as a supplement to categorical diagnoses. This study investigated the psychometric properties of the DSM‐5 Dimensional Anxiety Scales in a Brazilian community sample. Dimensional scales for generalized anxiety disorder, social anxiety disorder, panic disorder, agoraphobia, and specific phobia were administered to 930 adults aged 18 to 70, 64.2% female. Psychometric properties investigated were: unidimensionality; measurement invariance; internal consistency; composite reliability; test–retest reliability; convergent and divergent validity; category thresholds and item performance analyses. Analyses revealed unidimensionality for all scales except for specific phobia. Measurement invariance, high internal consistency and composite reliability, and convergent and divergent validity were demonstrated. Test–retest reliability was high for all scales but generalized anxiety disorder. Item‐based analyses evidenced that none of the items were very easy to endorse and that the scales offered more information about subjects with high severity estimates of anxiety. The DSM‐5 Dimensional Anxiety Scales are a valid and reliable alternative to assess anxiety symptomatology in community settings, although further evaluation is needed, especially for specific phobia. The scales seem to be more useful for characterizing dimensionality of symptoms for subclinical or clinical cases than for slight or mildly anxious subjects.     

Sensitivity and specificity should never be interpreted in isolation without consideration of other clinical utility metrics*

Abstract

Objective: The purpose of this paper is to highlight the risks and pitfalls of interpreting sensitivity and specificity in isolation when evaluating the clinical utility of a new test/measure to predict a target behavior, disease, or condition. Method: This paper (a) provides a primer for a set of metrics that can be used to appropriately examine the clinical utility of a test/measure (i.e. test operating characteristics – TOC), and (b) provides a discussion regarding various interpretative considerations when using TOCs that supports the tenet of this paper. Conclusions: There are two primary conclusions. First, sensitivity and specificity should never be interpreted in isolation as a means for evaluating the clinical utility of a test/measure. When sensitivity and specificity are used in this manner, more often than not, this will result in erroneous and/or incomplete conclusions regarding the clinical utility of a new test/measure. Second, sensitivity and specificity values are important, but they must be interpreted in conjunction with other more relevant clinical utility metrics (e.g. positive predictive power and negative predictive power).     

Assessment of an asthma quality of life scale using item-response theory

OBJECTIVE: Health-related quality of life (HRQOL) scores produced by simply summing individual item values have been criticized for lacking linearity and for not being equally discriminating across the range of scores. Differences in summed scores may depend more on their starting point on the scale rather than actual differences in the underlying dimension of HRQOL, making it difficult to judge what a particular score means. We sought to examine the usefulness of an alternative method of scoring questionnaires, item-response theory (IRT), for the clinical interpretation of a modified version of the Marks Asthma Quality of Life Questionnaire (MAQLQ-M). METHODOLOGY: Using the MAQLQ-M, we surveyed 293 adults with moderate to severe asthma, managed at two university teaching hospitals in Adelaide, South Australia. Scores obtained by usual summative Likert-type scores were compared to estimates using the partial credit method of IRT. RESULTS: We found a non-linear relationship between raw, summative scores and the IRT estimates. The departure from linearity was marked for summative scores below 3.0 and above 5.0 (range 1.0-7.0), values that included half of the study patients. Summative scoring did not produce scores at the interval level of measurement. CONCLUSION: For an equivalent difference measured in the underlying dimension of actual HRQOL using IRT, traditional summated scores showed a much smaller difference in scores at both the lower and upper end of HRQOL, than at the mid-range of HRQOL. Caution should be used when interpreting HRQOL surveys scored in the usual summative manner. Advantages may be gained by using IRT as an alternative method of scoring HRQOL questionnaires.     

The development and initial validation of the Terminally Ill Grief or Depression Scale (TIGDS)

Patients often experience 'preparatory-grief' as they cope with the dying process. Some may be depressed. The Terminally Ill Grief or Depression Scale (TIGDS), comprising grief and depression sub-scales, is a new self-report measure designed to differentiate between preparatory-grief and depression in adult inpatients. The initial 100-item inventory was assembled based on literature review, interviews with clinicians and dying patients and then shortened to 42 items based on consensus expert opinion. Validity and reliability were tested in a sample of 55 terminally ill adults. The consensus clinical opinion was used as the gold standard to differentiate between preparatory grief and depression. The intra-class correlation coefficient was high (it was calculated to estimate the test-retest reliability for the 47 patients who had completed the TIGDS twice--retest was administered 2 to 7 days after the initial test), ranging from 0.86 (grief) to 0.97 (depression). The validity of TIGDS was assessed using a receiver operating characteristic curve analysis, comparing the first test with the clinical criterion. The first and only variable and cut-point was the depression score (chi-square = 18.4, p < 0.001, cut point = 3). The sensitivity of the TIGDS was 0.727 and specificity was 0.886 for the depression = 3 cutoff score. The construct validity of the TIGDS was tested by comparing with the Hospital Anxiety and Depression Scale (HADS). The TIGDS depression subscale showed strong convergent validity and the TIGDS grief subscale showed strong discriminant validity with the HADS total score.