Functional Independence Domains in Patients Receiving Rehabilitation in Skilled Nursing Facilities: Evaluation of Psychometric Properties

Abstract

Jette DU, Warren RL, Wirtalla C. Functional independence domains in patients receiving rehabilitation in skilled nursing facilities: evaluation of psychometric properties. Arch Phys Med Rehabil 2005;86:1089–94. Objective To provide evidence for the validity of using FIM items to derive 4 domains of functional independence (mobility, activities of daily living [ADLs], sphincter management, executive function) in patients receiving rehabilitation in skilled nursing facilities (SNFs). Design A retrospective analysis of secondary data using data from a privately owned administrative dataset. Setting Seventy SNFs under contract with SeniorMetrix Inc health plan clients. Participants Patients (N=7536) with a variety of conditions, covered by Medicare+Choice plans, and admitted to an SNF in 2002. Interventions Not applicable. Main Outcome Measures Item score distributions, corrected item-total correlations, factor correlations, internal consistency, and stage ceiling and floor effects for each hypothesized functional independence domain. Results With the exception of 2 items, the items within a domain had similar standard deviations and distributions of items were not highly skewed. Four factors accounted for 73.4% of the variance in functional independence. Corrected item-total correlations ranged from .58 to .80 for the ADL domain, from .23 to .71 for the mobility domain, and from .78 to .88 for the executive function domain. The correlation between bowel and bladder management items was .84. Cronbach α coefficients ranged from .76 for the mobility domain to .96 for the executive function domain. At admission, there were substantial floor effects for the sphincter management (34.4%) and mobility domains (43.1%) and ceiling effects for the executive function domain (26.7%). Conclusions With a few exceptions, the items proposed for each functional independence domain met the criteria for supporting the validity of the domains.