Development and Validation of a Functional Status-Based Pain Assessment Tool

Introduction: Sickle cell disease (SCD) vaso-occlusive crisis (VOC) often requires hospitalization, but SCD pain may be present prior to admission and persist past discharge, similar to many acute-on-chronic painful conditions. In practice, readiness for discharge during VOC is a judgment and/or negotiation between patients and their caregivers. Subjective pain intensity, rated on a unidimensional continuous or numeric rating scale, communicates neither readiness for discharge, nor patients' multidimensional pain experience. Inpatient multidimensional pain scales that incorporate concepts like physical function may require too much time and/or impose a high, daily respondent burden on uncomfortable SCD respondents. We found no well-established brief daily adult inpatient multidimensional assessment scale for SCD, but found a pediatric daily function SCD scale, as well as scales used in systemic lupus erythematous and fibromyalgia. We therefore developed and validated the functional status-based pain-assessment (FSPA) survey meant to improve evaluation of readiness for discharge during VOC.

Methods: FSPA was created using concepts from the above scales, plus input from inpatient management experts familiar with SCD, including physicians, nurse practitioners, pharmacists, and bedside nurses. FSPA helps assess the full spectrum of a patient's functional limitations due to pain. FSPA consists of tasks that are recorded using the patient's self-reported ability (5 point Likert scale ranging from "very easy" to "very difficult") to complete activities including sleeping, watching TV, walking around the room, or eating a meal in a chair. FPSA was designed to be on a health literacy grade of one. Patients were asked to complete FSPA daily at approximately the same time of day. Concurrently, they were asked to rate their pain using a Numeric Rating Scale (NRS, 0-10). Surveys were administered on a preselected nursing unit from January 2018 to June of 2019. Means (standard deviations) or frequencies were used to summarize data. Pearson's correlation was used to examine the relationship between the two continuous variables. Believing readiness for discharge to be a single factor, we performed confirmatory factor analysis (CFA) using structural equation modeling for determining the empirical validity of having a one-factor solution for the FSPA tool. We used item response theory analysis to determine the characteristics of each item using graded response model within a 2-parameter framework. All analyses were performed using Stata 14.0.

Results:

During the study period, 504 assessments from 86 unique patients over 170 distinct admissions were completed. Of the 86 unique patients, 54% were females with mean age of 31.5 (SD8.0) years. The length of stay was 7.1 (SD6.9) days; minimum 0 days, max 38 days. NRS mean was 6.8 ±1.9 and FSPA mean was 27±8.0. Correlation was moderate and highly significant (Pearson's r = -.4342, p <.0001). The CFA indicated that the one-factor structure was a good fit for the data using routine diagnostic statistics (Figure). Using item response theory analysis, we found that the item discrimination varied from 0.56 to 4.1 while difficulty of the items covered broadly the latent variable of the functional status with pain with values ranging from -2.8 to 7.5.

Conclusions:

Development and validation of FPSA, while not complete, has yielded a brief assessment tool which may be used daily to improve communication between adult SCD VOC patients and their inpatient clinicians. FPSA may aid the judgment and negotiation of readiness for discharge of these patients, in order to prevent unnecessarily short or long hospital lengths of stay as well as improve patient and provider satisfaction. Future validation could compare FSPA to other longer-term pain and functional assessment tools, determine its ability to predict VOC discharge, and determine whether its use changes VOC discharge behavior.

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