# Criterion validity of the functional status and pain assessment scale versus pain and length of stay in hospitalized adults with SCD

## TL;DR

This study tested if a new 10-item scale for measuring pain and function in hospitalized adults with sickle cell disease (SCD) accurately predicted hospital length of stay or pain levels, but found it did not.

## Contribution

The study provides evidence that the Functional Status Pain Assessment (FSPA) scale lacks criterion validity in predicting pain or hospital length of stay in SCD patients.

## Key findings

- FSPA scores on admission or discharge explained less than 20% of the variance in pain intensity or hospital length of stay.
- No significant relationship was found between changes in pain intensity and hospital length of stay.
- Unmeasured factors like psychosocial or economic variables likely have a greater impact on hospital length of stay in SCD patients.

## Abstract

In prior research we demonstrated face, construct, discriminant, and preliminary convergent validity of the newly developed, 10-item Functional Status Pain Assessment (FSPA) scale (0-50) in adult SCD patients hospitalized with VOC. We aimed in this study to further demonstrate criterion validity of the FSPA.

This was a prospective observational study of 561 daily functional and pain assessments from 91 hospitalized adults with SCD from January 2018 to June of 2019. Principal Component Analysis (PCA) Partial Least Squares (PLS) models determined the relationship between LOS, pain intensity, and FSPA. A Generalized Linear Model (GLM) to quantified the impact of changes in pain intensity on LOS.

The population mean age was 34 ± 12.2 years, and 59.3% were female. A little over half were genotype SS. Neither admission nor discharge FSPA scores were significant determinants of LOS. Specifically, no component or factor of FSPA score on day of admission explained the LOS. In addition, FSPA score on day of discharge explained only 5.69% of the variance in LOS. Similarly, FSPA score explained only 19.66% of the variance in pain intensity on any pain day. There was no relationship between LOS and pain intensity changes from admission to discharge (P = .92).

The FSPA score did not demonstrate criterion validity with respect to NRS pain intensity changes from admission to discharge, nor to the LOS for SCD admissions. Instead, unmeasured, perhaps environmental, psychosocial, and economic variables, exerted a far more substantial influence on hospital LOS.