Validation of Patient Determined Disease Steps (PDDS) scale scores in persons with multiple sclerosis

BMC Neurology (Impact Factor: 2.49). 04/2013; 13(1):37. DOI: 10.1186/1471-2377-13-37
Source: PubMed

ABSTRACT Background
The Patient Determined Disease Steps (PDDS) is a promising patient-reported outcome (PRO) of disability in multiple sclerosis (MS). To date, there is limited evidence regarding the validity of PDDS scores, despite its sound conceptual development and broad inclusion in MS research. This study examined the validity of the PDDS based on (1) the association with Expanded Disability Status Scale (EDSS) scores and (2) the pattern of associations between PDDS and EDSS scores with Functional System (FS) scores as well as ambulatory and other outcomes.

96 persons with MS provided demographic/clinical information, completed the PDDS and other PROs including the Multiple Sclerosis Walking Scale-12 (MSWS-12), and underwent a neurological examination for generating FS and EDSS scores. Participants completed assessments of cognition, ambulation including the 6-minute walk (6 MW), and wore an accelerometer during waking hours over seven days.

There was a strong correlation between EDSS and PDDS scores (ρ = .783). PDDS and EDSS scores were strongly correlated with Pyramidal (ρ = .578 &ρ = .647, respectively) and Cerebellar (ρ = .501 &ρ = .528, respectively) FS scores as well as 6 MW distance (ρ = .704 &ρ = .805, respectively), MSWS-12 scores (ρ = .801 &ρ = .729, respectively), and accelerometer steps/day (ρ = -.740 &ρ = -.717, respectively).

This study provides novel evidence supporting the PDDS as valid PRO of disability in MS.

Download full-text


Available from: Yvonne C Learmonth, Aug 15, 2015
  • Source
    • "Participants arrived at the Colorado Translational Research Imaging Center during the morning hours following an 8 h fast, and patients with MS were assessed for disability levels utilizing the Patient Determined Disease Steps (PDDS). The PDDS has been validated and shows a high correlation to the Expanded Disability Status Scale (EDSS) (Hohol et al., 1995, 1999; Kobelt et al., 2006; Learmonth et al., 2013; Marrie and Goldman, 2007). Leg spasticity was graded using the MASS. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Difficulties in ambulation are one of the main problems reported by patients with multiple sclerosis. A previous study by our research group showed increased recruitment of muscle groups during walking, but the influence of skeletal muscle properties, such as muscle fiber activity, has not been fully elucidated. The purpose of this investigation was to use the novel method of calculating glucose uptake heterogeneity in the leg muscles of patients with multiple sclerosis and compare these results to healthy controls. Eight patients with multiple sclerosis (4 men) and 8 healthy controls (4 men) performed 15min of treadmill walking at a comfortable self-selected speed following muscle strength tests. Participants were injected with≈8mCi of [(18)F]-fluorodeoxyglucose during walking after which positron emission tomography/computed tomography imaging was performed. No differences in muscle strength were detected between multiple sclerosis and control groups (P>0.27). Within the multiple sclerosis, group differences in muscle volume existed between the stronger and weaker legs in the vastus lateralis, semitendinosus, and semimembranosus (P<0.03). Glucose uptake heterogeneity between the groups was not different for any muscle group or individual muscle of the legs (P>0.16, P≥0.05). Patients with multiple sclerosis and healthy controls showed similar muscle fiber activity during walking. Interpretations of these results, with respect to our previous study, suggest that walking difficulties in patients with multiple sclerosis may be more associated with altered central nervous system motor patterns rather than alterations in skeletal muscle properties. Published by Elsevier Ltd.
    Clinical biomechanics (Bristol, Avon) 12/2014; 30(2). DOI:10.1016/j.clinbiomech.2014.12.005 · 1.88 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The number of steps taken per day (steps/day) provides a reliable and valid outcome of free-living walking behavior in persons with multiple sclerosis (MS). This study examined the clinical meaningfulness of steps/day using the minimal clinically important difference (MCID) value across stages representing the developing impact of MS. This study was a secondary analysis of de-identified data from 15 investigations totaling 786 persons with MS and 157 healthy controls. All participants provided demographic information and wore an accelerometer or pedometer during the waking hours of a 7-day period. Those with MS further provided real-life, health, and clinical information and completed the Multiple Sclerosis Walking Scale-12 (MSWS-12) and Patient Determined Disease Steps (PDDS) scale. MCID estimates were based on regression analyses and analysis of variance for between group differences. The mean MCID from self-report scales that capture subtle changes in ambulation (1-point change in PDSS scores and 10-point change in MSWS-12 scores) was 779 steps/day (14% of mean score for MS sample); the mean MCID for clinical/health outcomes (MS type, duration, weight status) was 1,455 steps/day (26% of mean score for MS sample); real-life anchors (unemployment, divorce, assistive device use) resulted in a mean MCID of 2,580 steps/day (45% of mean score for MS sample); and the MCID for the cumulative impact of MS (MS vs. control) was 2,747 steps/day (48% of mean score for MS sample). The change in motion sensor output of ∼800 steps/day appears to represent a lower-bound estimate of clinically meaningful change in free-living walking behavior in interventions of MS.
    PLoS ONE 09/2013; 8(9):e73247. DOI:10.1371/journal.pone.0073247 · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Depressive symptoms are common in multiple sclerosis (MS), yet there is little information about the pattern and predictors of changes in depressive symptoms over time. We examined changes in depressive symptoms over a 30-month period and the demographic, clinical and behavioral predictors of such changes in relapsing-remitting MS (RRMS). 269 persons with RRMS completed the Hospital Anxiety and Depression Scale (HADS) and a demographic/clinical scale, Godin Leisure-Time Exercise Questionnaire (GLTEQ) and Patient Determined Disease Steps (PDDS) scale every 6 months over a 30-month period. Data were analyzed using latent class growth modeling (LCGM). LCGM identified a two-class model for changes in HADS depression scores over time. Class 1 involved lower initial status (i.e. fewer depressive symptoms) and linear decreases in depressive symptoms over time (i.e. improving HADS scores), whereas Class 2 involved higher initial status (i.e. more depressive symptoms) and linear increases in depressive symptoms over time (i.e. worsening HADS scores). LCGM further indicated that being older (OR = 2.46; p < .05), married (OR = 2.62; p < .05), employed (OR = 4.29; p < .005) and physically active (OR = 2.71; p < .05) predicted a greater likelihood of belonging to C1 than C2. Depressive symptoms change over time in persons with RRMS, and the pattern of change can be predicted by modifiable and non-modifiable factors.
    Multiple Sclerosis 09/2013; 20(5). DOI:10.1177/1352458513504251 · 4.86 Impact Factor
Show more