Sleep disturbances and poor sleep are a common complaint in the population with multiple sclerosis (MS) disease. The most commonly reported scale is the Pittsburgh Sleep Quality Index (PSQI), measuring seven components of sleep quality. Yet, till today, the PSQI instrument has not been validated in people with multiple sclerosis (pwMS). The objective of our study was to add precision in sleep quality assessment by investigating the psychometric properties of PSQI (factor structure, reliability, validity based on relations with other variables, cut-off scores) in pwMS. The cross-sectional study included data on a total of 87 patients with MS and 216 control subjects. Demographic information, education level, and MS-related variables were ascertained. Psychometric properties were examined by estimating the validity, including factor structure, metric invariance, and relations with other MS- and non-MS-related variables, reliability, and discrimination ability of the PSQI. The Croatian version of the PSQI had a two-factor structure which demonstrated loading and partial intercept invariance between pwMS and the control group. The global score and both subscales had high internal consistencies (McDonald’s omega and Cronbach’s alpha coefficients) in pwMS and showed expected relations with demographic and MS-related variables. PwMS differed significantly in the PSQI global score from the control groups, although receiver operating characteristics (ROC) curve analysis did not indicate a clear cut-off point. The PSQI is a reliable and valid scale and can be applied in clinical settings for assessing sleep quality in pwMS.

SummaryBackgroundThe aim of this study was to examine the impact of intravenous methylprednisolone therapy (IVMP) on the recovery of walking ability in patients experiencing multiple sclerosis (MS) relapses, to compare the responsiveness of walking-based measures, and to estimate the impact of different walking-based measures responsiveness on clinical trials.Material/MethodsThe study included 49 consecutive patients with relapsing-remitting MS who received Solu-Medrol 1000 mg/day over 3 days for relapse with difficulties in walking. The following walking-based measures were administered before and a month after IVMP: the Multiple Sclerosis Walking Scale-12 (MSWS-12), the Expanded Disability Status Scale (EDSS), the 2-minute timed walk (2-minTW), the 25-foot walk test (25FWT), the Six Spot Step Test (SSST). All patients had worn the step activity monitor accelerometer (SAM) 1 week prior to IVMP was applied and wore it again the fourth week upon the corticosteroid therapy was completed. The SAM analysis utilized the average daily step count and data regarding frequency and intensity of walking over a continuous time interval. We examined: (1) the impact of IVMP on the recovery of walking ability; (2) the responsiveness of each walking-based measure; (3) the relative responsiveness of competing walking-based measures; and (4) the impact of different walking-based measures responsiveness on clinical trials.ResultsAll walking-based measures showed significant improvement of walking ability 1 month after the IVMP. The most responsive were MSWS-12 and EDSS. Different responsiveness implied a greater than 6-fold impact on sample size estimates.ConclusionsAll applied walking-based measures showed significant improvement of walking ability 1 month after the IVMP. Responsiveness of various walking-based measures notably differ, thus affecting sample size calculations.

Cognitive impairment is a common complaint in people with multiple sclerosis (pwMS). The study objective was to determine the psychometric properties of the letter digit substitution test (LDST) that measures information processing speed and to investigate the impact of relevant predictors of LDST achievement in pwMS. The design was cross-sectional. The study included 87 pwMS and 154 control subjects. The validity of LDST was examined, and a hierarchical regression model was used to explore relevant predictors of LDST success. The LDST had excellent construct validity, as expressed by differences between pwMS and control subjects. Convergent validity of the LDST was supported by a significant moderate correlation with the expanded disability status scale (EDSS) (ρ = −0.36; p < 0.05) and a significantly strong correlation with the multiple sclerosis impact scale (MSIS-29) physical subscale (r = −0.64; p < 0.01). The LDTS score well differentiated the pwMS considering age, education, EDSS, disease duration, comorbidity, and medication therapy. Using the LDST as a criterion variable in pwMS results showed consistent evidence for the age, education, and EDSS impact on LDST performance. The best cut-off score of ≤35 discriminated the control and MS group. LDST proved to be a valid test for assessing information processing speed in pwMS.

Depression and anxiety are common complaints in patients with multiple sclerosis (MS). The study objective was to investigate the factor structure, internal consistency, and correlates of the Croatian version of the Hospital Anxiety and Depression Scale (HADS) in patients with MS. A total of 179 patients with MS and 999 controls were included in the online survey. All subjects completed the HADS and self-administered questionnaires capturing information of demographic, education level, disease-related variables, and the Multiple Sclerosis Impact Scale-29 (MSIS-29). Psychometric properties were examined by estimating the validity, reliability, and factor structure of the HADS in patients with MS. The two HADS subscales (anxiety and depression) had excellent internal consistencies (Cronbach’s α value 0.82–0.83), and factor analysis confirmed a two-factor structure. The convergent validity of the HADS subscales appeared to be good due to the significant correlations between HADS and MSIS-29. Receiver operating characteristic (ROC) analysis indicates that the HADS subscales have a significant diagnostic validity for group differentiation. Hierarchical regression analysis using MSIS-29 subscales as criterion variables showed consistent evidence for the incremental validity of the HADS. The HADS is a reliable and valid self-assessment scale in patients with MS and is suggested to be used in clinical monitoring of the psychiatric and psychological status of patients with MS.

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