Rasch analysis of the living with chronic illness scale in Parkinson's disease

Validation of the Ocular Pain Assessment Survey Instrument With Rasch Analysis

Purpose

The Ocular Pain Assessment Survey (OPAS) has been used to quantify chronic ocular pain and quality of life (QOL). We aim to investigate the psychometric properties of individual OPAS items with the Rasch analysis in an Asian population of dry eye disease and neuropathic corneal pain (NCP).

Methods

Question responses were obtained from 196 patients; 138 with dry eye disease (DED) and 58 with NCP, at the Singapore National Eye Centre. Item hierarchy, item fit statistics, item separation, reliability indices, and Yen's Q3 values were calculated.

Results

Individual dimensions that quantify eye pain levels in the past 24 hours and QOL showed good discriminative ability according to their person separation index values. However, individual dimensions that measured eye pain in the past 2 weeks, non-eye pain, as well as aggravating and associated factors showed suboptimal person separation index values. Significant correlations were found between the individual item pairs of the aggravating factors dimension as well as between some of the items in the QOL and associated factors dimensions.

Conclusions

Two dimensions of the OPAS questionnaire were validated with the Rasch analysis. Based on these findings, we shorten the number of questions in some dimensions to improve the performance of the tool in similar Asian populations.

Translational Relevance

Our study provides insights to improve the existing OPAS for real-world clinical applications and clinical trials.

Rasch analysis of the beck depression inventory in a homeless and precariously housed sample

The approach to analysis of and interpretation of findings from the Beck Depression Inventory (BDI), a self-report questionnaire, depends on sample characteristics. To extend work using conventional BDI scoring, the BDI's suitability in assessing symptom severity in a homeless and precariously housed sample was examined using Rasch analysis. Participants (n=478) recruited from an impoverished neighbourhood in Vancouver, Canada, completed the BDI. Rasch analysis using the partial credit model was done, and the structural validity, unidimensionality, and reliability of the BDI were studied. A receiver operating characteristic curve determined a Rasch cut-off score consistent with clinical depression, and Rasch scores were correlated with raw scores. Good fit to the Rasch model was observed after rescoring all items and removing Item 19 (Weight Loss), and unidimensionality and reliability were satisfactory. Item 9 (Suicidal Wishes) represented the most severe symptom. Rasch-based scores detected clinical depression with moderate sensitivity and specificity, and were positively correlated with conventional scores. The BDI in a community-based sample of homeless and precariously housed adults satisfied Rasch model expectations in a 20-item format, and is suitable for assessing symptom severity. Future research on depression in similar samples may reveal more information on using specific symptoms to determine clinical significance.

First validation study of the living with long term conditions scale (LwLTCs) among English-speaking population living with Parkinson's disease

INTRODUCTION

Parkinson's disease is the second most prevalent neurodegenerative disease, affecting 10 million people worldwide. Health and social care professionals need to have personalised tools to evaluate the process of living with Parkinson's disease and consequently, plan individualised and targeted interventions. Recently, the English version of the Living with Long term conditions (LwLTCs) scale has been developed filling an important gap related to person-centred tools to evaluate the process of living with long term conditions among English-speaking population. However, no validation studies for testing its psychometric properties have been conducted.

AIM

To analyse the psychometric properties of the LwLTCs scale in a wide English-speaking population living with Parkinson's disease.

METHODS

Validation study, with an observational and cross-sectional design. The sample was composed of individuals living with Parkinson's disease from non-NHS services in the community. Psychometric properties including feasibility and acceptability, internal consistency, reproducibility, and construct, internal and known-groups validity were tested.

RESULTS

A total sample of 241 people living with Parkinson's disease were included. 6 individuals did not complete 1 or 2 items on the scale. Ordinal alpha was 0.89 for the total scale. The intraclass correlation coefficient for the total scale was 0.88. The LwLTCs scale is strongly correlated with scales measuring satisfaction with life (r_s=0.67), quality of life (r_s=0.54), and moderately correlated with social support (r_s=0.45). Statistically significant difference just for therapy and co-morbidity, yet no for gender, employment situation, or lifestyle changes.

CONCLUSIONS

The LwLTCs scale is a valid scale to evaluate how the person is living with Parkinson's disease. Future validation studies to prove the repeatability of the total scale and particularly, domains 3-Self-management, and 4-Integration and internal consistency will be needed. Developing further studies on the English version of the LwLTC in people with other long term conditions is also proposed.

Acetylation Rather than H50Q Mutation Impacts the Kinetics of Cu(II) Binding to α-Synuclein

The interaction between α‐synuclein (αSyn) and Cu²⁺ has been suggested to be closely linked to brain copper homeostasis. Disruption of copper levels could induce misfolding and aggregation of αSyn, and thus contribute to the progression of Parkinson's disease (PD). Understanding the molecular mechanism of αSyn‐Cu²⁺ interaction is important and controversies in Cu²⁺ coordination geometry with αSyn still exists. Herein, we find that the pathological H50Q mutation has no impact on the kinetics of Cu²⁺ binding to the high‐affinity site of wild type αSyn (WT‐αSyn), indicating the non‐involvement of His50 in high‐affinity Cu²⁺ binding to WT‐αSyn. In contrast, the physiological N‐terminally acetylated αSyn (NAc‐αSyn) displays several orders of magnitude weaker Cu²⁺ binding affinity than WT‐αSyn. Cu²⁺ coordination mode to NAc‐αSyn has also been proposed based on EPR spectrum. In addition, we find that Cu²⁺ coordinated WT‐αSyn is reduction‐active in the presence of GSH, but essentially inactive towards ascorbate. Our work provides new insights into αSyn‐Cu²⁺ interaction, which may help understand the multifaceted normal functions of αSyn as well as pathological consequences of αSyn aggregation.

Validation of living with chronic illness scale in a type 2 diabetes mellitus population

Background

Worldwide, type 2 diabetes mellitus (T2DM) is one of the most prevalent chronic diseases and one of those producing greatest impact on patients’ day-to-day quality of life. Our study aim is to validate the “Living with Chronic Illness Scale” for a Spanish-speaking T2DM population.

Methods

In this observational, international, cross-sectional study, 582 persons with T2DM were recruited in primary care and outpatient hospital consultations, in Spain and Colombia, during the period from May 2018 to June 2019. The properties analysed were feasibility/acceptability, internal consistency, reliability, precision and (structural) content-construct validity including confirmatory factor analysis. The COSMIN checklist was used to assess the methodological/psychometric quality of the instrument.

Results

The scale had an adequate internal consistency and test retest reliability (Cronbach’s alpha = 0.90; intraclass correlation coefficient = 0.96, respectively). In addition, the instrument is precise (standard error of measurement = 3.34, with values < ½SD = 8.52) and correlates positively with social support (DUFSS) (r_s = 0.56), quality of life (WHOQOL-BREF) (r_s = 0.51–0.30) and ssatisfaction with life (SLS-6) (r_s = 0.50–0.38). The original 26-items version of the scale did not support totally the confirmatory factor analysis. The COSMIN checklist is favourable for all the properties analysed, although weaknesses are detected for structural validity.

Conclusions

The LW-CI-T2DM is a valid, reliable and accurate instrument for use in clinical practice to determine how a person’s life is affected by the presence of diabetes. This instrument correlates well with the associated constructs of social support, quality of life and satisfaction. Additional research is needed to determine how well the questionnaire structure performs when robust factor analysis methods are applied.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12955-021-01715-x.