Should the SCOPA-COG be modified?: a Rasch analysis perspective

Validation of the Spanish version of the Memory Failures of Everyday questionnaire in older adults using Rasch analysis

AIM

The Memory Failures of Everyday (MFE) is a widely used instrument for assessing memory failure. The aim of the study was to analyze the MFE items using the Rasch model in a sample of cognitively older adults in Spain.

METHODS

A cross-sectional validation study in a sample of 214 healthy people aged ≥60 years who used centers for older people in Madrid (Spain). The MFE for the assessment of memory complaints was used. The following properties of the Rasch model were assessed: data fit, reliability, unidimensionality, local dependence and lack of differential item functioning by gender, age and marital status.

RESULTS

The MFE showed a good fit to the Rasch model (χ² (140) = 160.2; P = 0.116) and high reliability (person separation index = 0.808). The questionnaire was unidimensional (6.54% t-test; IC binomial = 0.036-0.095). The items showed lack of local dependence between them and differential item functioning. The MFE scores were transformed into linear interval scores with a median of 44.31 and an observed range of 17.9-89.2 (theoretical range: 0-100).

CONCLUSIONS

The MFE is a unidimensional, reliable instrument to assess memory complaints in cognitively healthy older adults in Spain, with usefulness in clinical research and practice. The construct validity of the MFE linear score could not be fully confirmed and this deserves further investigation. Geriatr Gerontol Int 2022; 22: 332-337.

Quantifying cognition at the bedside: a novel approach combining cognitive symptoms and signs in HIV

Background

Up to half of all people with HIV infection have some degree of cognitive impairment. This impairment is typically mild, but nonetheless often disabling. Although early detection of cognitive impairment offers the greatest hope of effective intervention, there are important barriers to this goal in most clinical settings. These include uncertainty about how self-reported cognitive symptoms relate to objective impairments, and the paucity of bedside measurement tools suitable for mild deficits. Clinicians need guidance in interpreting cognitive symptoms in this population, and a brief cognitive measurement tool targeted to mild impairment. We addressed these two problems together here. The objective of this study was to determine the extent to which performance on cognitive tests and self-reported cognitive symptoms form a unidimensional construct.

Methods

Two hundred three HIV+ individuals completed the Montreal Cognitive Assessment, computerized cognitive tasks and a questionnaire eliciting cognitive symptoms. Rasch measurement theory was applied to determine whether patient-reported and performance items could be combined to measure cognition as a unidimensional latent construct.

Results

Performance-based items and cognitive symptoms are arranged hierarchically along the same continuum of cognitive ability, forming a measure with thresholds covering a broad spectrum of ability that has good internal reliability. The cognitive symptoms that fit the measurement model relate to important aspects of everyday life, providing evidence that the identified construct is meaningful.

Conclusions

This finding lays the foundation for a rapid measure of cognitive ability in people with HIV infection that is feasible for routine clinical use, and shows that some cognitive symptoms are systematically related to performance in this population.

Psychometric properties of the Italian version of the Scales for Outcomes in Parkinson's disease- Cognition (SCOPA-Cog)

The Scales for Outcomes in Parkinson's disease-Cognition (SCOPA-Cog) has been shown to be a clinimetrically rigorous and valid instrument for a disease-oriented neuropsychological assessment of Parkinson's disease (PD) patients. In the present study we evaluated the psychometric properties of the Italian version of the SCOPA-Cog in 121 PD patients. The scale explores memory, attention, and executive and visuospatial functions and takes approximately 20 minutes to administer. Data distribution (skewness= -0.23) and internal consistency (Cronbach's alpha= 0.78) were satisfactory. Standard error of measurement was 3.42. The outcome was significantly worse in patients with an abnormal Psychometric properties of the Italian version of the Scales for Outcomes in Parkinson's disease-Cognition (SCOPA-Cog) score on the Dementia Rating Scale (DRS) (SCOPACog mean score 14.6 ± 5.1 out of a total of 43) with respect to cognitively intact subjects (24.2 ± 4.3) (p<0.0001). The DRS showed good convergent validity (Spearman rho= 0.77, p<0.0001), and a high coefficient of variation (= 0.34). These findings support the goodness of the Italian SCOPA-Cog in terms of metrics and validity.

A psychometric evaluation of the Arm Motor Ability Test

OBJECTIVE

To further examine the psychometric properties of a 9-item version of the Arm Motor Ability Test (AMAT-9) in persons with stroke.

SUBJECTS

Thirty-two community-dwelling persons > 6 months post-stroke undergoing robotics treatment (mean age = 56.0 years, time post-stroke = 4.1 years, National Institutes of Health Stroke Scale score = 4.1, and AMAT-9 score = 1.22).

METHODS

Construct validity (including Rasch analyses) used baseline data prior to treatment (n = 32). Standardized response mean was calculated for subjects completing the protocol (n = 29). The Wolf Motor Function Test (WMFT), Fugl-Meyer Assessment (FMA), Action Research Arm Test (ARAT), and Stroke Impact Scale (SIS) were also administered.

RESULTS

Spearman-rank correlation coefficients between AMAT-9 and the WMFT, FMA, and ARAT were strong (0.78-0.79, all p < 0.001). The correlation between the AMAT-9 and SIS Hand Function sub-score was stronger than that between the AMAT-9 and the Communication sub-score (0.40, p = 0.025 and -0.16, p = 0.39, respectively). Rasch analyses provided evidence for an appropriate hierarchical structure of item difficulties, unidimensionality, and good reliability. The AMAT demonstrated a comparable standardized response mean of 0.98.

CONCLUSIONS

The AMAT-9 is valid and responsive among subjects scoring in the lower range of the scale. It has the advantage of assessing function and by eliminating the standing item from the previous iteration, it may be more easily used with severely impaired patients.