Generating Rasch-based activity of daily living measures from the Spinal Cord Injury Longitudinal Aging Study

Study design: Retrospective Longitudinal Study. Objectives: (1) To determine whether the Spinal Cord Injury Activities of Daily Living (SCI-ADL) measure shows adequate item-level and precision psychometrics; (2) to investigate whether the SCI-ADL measure effectively detects ADL changes across time; (3) to describe self-care task(s) participants can and cannot do across time. Setting: Two Midwestern hospitals and 1 Southeastern specialty hospital in 1993. Methods: All participants were adults with traumatic SCI of at least 1-year duration at enrollment. We used 20-year (1993-2013) retrospective longitudinal data and categorized participants into three injury levels: C1-C4 (cervical; n=50), C5-C8 (n=126) and T1-S5 (thoracic, lumbar and sacral; n=168). We first examined psychometrics of the SCI-ADL with factor and Rasch analyses; then we investigated longitudinal change of SCI-ADL scores at three time points over 20 years (1993, 2003 and 2013) using generalized linear mixed modeling and post hoc analyses. Results: The SCI-ADL measure demonstrated unidimensionality, person strata of 2.9, high Cronbach's α (0.93) and fair person reliability (0.76). T1-S5 had the highest measures, following C5-C8 and C1-C4 at three time points (Po0.05). The C1-C4 and T1-S5 groups showed significant decreases from 2003 to 2013; however, none of the three groups showed significant differences from 1993 to 2003 (Po0.05). Conclusions: The SCI-ADL measure could detect longitudinal ADL changes of the population with SCI across time. The C1-C4 group decreased the most in ADLs, indicating higher need of long-term services and rehabilitation.