Living with chronic illness scale in Parkinson's disease: Longitudinal metric properties and meaningful change.

AIM: To analyze the responsiveness and interpretability of the Living with Chronic Illness Scale in patients with Parkinson's disease (LW-CI-PD). METHODS: Longitudinal, international study, with a convenience sample of 153 PD Spanish and Latin-American patients assessed at baseline and one year later. The LW-CI-PD and other clinical measures were applied. For responsiveness, Wilcoxon-Mann-Whitney test of differences, correlation of change between rating scales, standard error of difference, relative change, Cohen's effect size and standardized response mean of LW-CI-PD were computed. The minimally clinical important difference was calculated using anchor- (applying the Patient Global Impression of Severity) and distribution-based methods. A triangulation of interpretability indexes was performed to determine the range of the minimally clinical important difference values. RESULTS: The LW-CI-PD scored 65.7 (11.7, range: 33-101) at baseline, and 68.6 (10.3, range: 33-102) one year later (p < 0.001). Change in LW-CI-PD correlated -0.26 with change in psychosocial status, 0.18 with change in motor function and -0.15 with change in social support. Responsiveness statistics were: relative change = 4.5%; effect size = 0.25; standardized response mean = 0.46. Using PGI-S as anchor, 29 patients worsened, and the value of minimally clinical important difference for worsening in LW-CI-PD total score was 4.7. Minimally clinical important difference values using distribution-based methods were between 4.5 (1 standard error of measurement) and 10.4 (10% of total score), with a mean of 6.9. CONCLUSIONS: Our study suggest the LW-CI-PD is responsive to changes over time. The use of different methods for calculating the minimally clinical important difference allows to determine a range of the real change for the LW-CI-PD.

Analysis of four scales for global severity evaluation in Parkinson's disease.

Global evaluations of Parkinson's disease (PD) severity are available, but their concordance and accuracy have not been previously tested. The present international, cross-sectional study was aimed at determining the agreement level among four global scales for PD (Hoehn and Yahr, HY; Clinical Global Impression of Severity, CGIS; Clinical Impression of Severity Index, CISI-PD; and Patient Global Impression of Severity, PGIS) and identifying which of them better correlates with itemized PD assessments. Assessments included additional scales for evaluation of the movement impairment, disability, affective disorders, and quality of life. Spearman correlation coefficients, weighted and generalized kappa, and Kendall's concordance coefficient were used. Four hundred thirty three PD patients, 66% in HY stages 2 or 3, mean disease duration 8.8 years, were analyzed. Correlation between the global scales ranged from 0.60 (HY with PGIS) to 0.91 (CGIS with CISI-PD). Kendall's coefficient of concordance resulted 0.76 (P<0.0001). HY and CISI-PD showed the highest association with age, disease duration, and levodopa-equivalent daily dose, and CISI-PD with measures of PD manifestations, disability, and quality of life. PGIS and CISI-PD correlated similarly with anxiety and depression scores. The lowest agreement in classifying patients as mild, moderate, or severe was observed between PGIS and HY or CISI-PD (58%) and the highest between CGIS and CISI-PD (84.3%). The four PD global severity scales agree moderately to strongly among them; clinician-based ratings estimate PD severity, as established by other measures, better than PGIS; and the CISI-PD showed the highest association with measures of impairment, disability, and quality of life.

Living with chronic illness scale: international validation of a new self-report measure in Parkinson's disease.

Understanding how a person lives with a chronic illness, such as Parkinson's disease (PD), is necessary to provide individualized care and professionals role in person-centered care at clinical and community levels is paramount. The present study was aimed to analyze the psychometric properties of the Living with Chronic Illness-PD Scale (EC-PC) in a wide Spanish-speaking population with PD. International cross-sectional study with retest was carried out with 324 patients from four Latin American countries and Spain. Feasibility, acceptability, scaling assumptions, reliability, precision, and construct validity were tested. The study included 324 patients, with age (mean±s.d.) 66.67±10.68 years. None of the EC-PC items had missing values and all acceptability parameters fulfilled the standard criteria. Around two-third of the items (61.54%) met scaling assumptions standards. Concerning internal consistency, Cronbach's alpha values were 0.68-0.88; item-total correlation was >0.30, except for two items; item homogeneity index was >0.30, and inter-item correlation values 0.14-0.76. Intraclass correlation coefficient for EC-PC stability was 0.76 and standard error of measurement (s.e.m.) for precision was 8.60 (for a EC-PC s.d.=18.57). EC-PC presented strong correlation with social support (rS=0.61) and moderate correlation with life satisfaction (rS=0.46). Weak and negligible correlations were found with the other scales. Internal validity correlations ranged from 0.46 to 0.78. EC-PC total scores were significantly different for each severity level based on Hoehn and Yahr and Clinical Impression of Severity Index, but not for Patient Global Impression of Severity. The EC-PC has satisfactory acceptability, reliability, precision, and validity to evaluate living with PD.