Revolutionizing Self-Report Measurement of Physical Function: Spinal Function Sort (SFS)

Pictorial Activity Task Sorts, Dr. Leonard Matheson's groundbreaking innovation [1] demonstrates the advantages of pairing text and pictorial descriptions of tasks to measure self-perceived physical abilities and sets the stage for Structured Task Self-Appraisal (STSA). The Spinal Function Sort (SFS) offers distinct benefits over text-based self-report measures.

In the SFS, spine and lower extremity tasks are supplemented by drawings depicting everyday activities of daily living and work tasks. Rehabilitation experts selected the drawings from among hundreds of tasks that individuals with spinal and/or lower extremity impairments report as presenting significant challenges. A simple task description accompanies each of the 50 drawings. The evaluee is instructed to “Look at each drawing and read the description. Indicate your current ability to perform the task”. The SFS is calibrated to the Dictionary of Occupational Titles and the Epic Lift Capacity Test [2,3] through both the Metabolic Physical Demand Characteristics (PDC-METs) chart and the Graduated Physical Demand Characteristics (PDC-G) chart [4].

Benefits of the Pictorial Approach to Self-Report Measures

  • Practicality in Data Collection: PATS, which includes the SFS, allows for the swift collection of information about the ability to perform various work activities and tasks. The pictorial format not only speeds up processing and response but also instills confidence in its practicality for occupational rehabilitation professionals.
  • Enhanced Communication and Understanding: Pictures enhance the text, aiding comprehension for individuals with lower literacy levels, brain injuries, or receptive aphasia. This is particularly empowering for the SFS, often used with individuals recovering from spinal injuries who may have cognitive or language difficulties, enabling more effective communication and understanding in occupational rehabilitation.
  • Broader Occupational Relevance: Using pictures allows PATS to include a more extensive set of items representing tasks and activities across a broader range of occupations than text-based measures. This allows for more detailed information about an individual's capacity to perform specific occupations, and their responses can be generalized to a broader range of jobs.
  • Facilitates Performance Validity Testing: The visual depictions of tasks allow the debriefing challenge: “As you see yourself performing this task, what causes you to be (slightly, moderately, severely restricted)?” during the Structured Task Self-Appraisal so that cognitive and performance inconsistencies are identified.
  • Identification of Psychological Factors: Differences between self-reported abilities on the SFS and actual performance on functional capacity evaluations can provide insight into an individual's psychological status, such as symptom magnification or overestimating of their abilities, both of which impede rehabilitation.

SFS Research References

  • Matheson, Matheson & Grant [5] describes the development of the SFS. The study demonstrated the SFS's reliability across various application sites using split-half and test-retest reliability in a large sample of disabled adults at six industrial rehabilitation centers in the United States.
  • Robinson [6] investigated the clinical utility of the SFS in patients with low back pain undergoing a multidisciplinary pain treatment program. It found that the SFS detected significant improvement in perceived functional capacity scores. The study also highlighted the need to measure perceived functional capacity using the SFS throughout treatment.
  • Oesch [7] studied the validity of the SFS in a European rehabilitation setting involving patients with non-specific low back pain. Results showed high internal consistency and reasonable evidence for unidimensionality.
  • Trippolini [8] analyzed the measurement properties of the SFS in patients with sub-acute whiplash-associated disorders (WAD). The study examined internal consistency, test-retest reliability, agreement, construct validity, and predictive validity for work status. The authors concluded that the SFS is a reliable tool for assessing perceived functional ability in individuals with WAD.
  • Janssen [9] developed a modified version of the original SFS, the M-SFS, to address limitations of the original SFS, such as its length and outdated images. Using a mixed-methods approach, including interviews with patients, data analysis, and expert opinions, they created a shorter, 20-item questionnaire. The study emphasized the need for further research to assess the modified version's feasibility, reliability, and validity.
  • Trippolini [10] examined the reliability and validity of the M-SFS in workers with chronic musculoskeletal disorders. They found the M-SFS to be a reliable and valid tool for assessing perceived self-efficacy for work-related tasks, supporting its use in patients with chronic musculoskeletal disorders. The study also highlighted the importance of further research to evaluate the predictive validity of the M-SFS for return to work and its responsiveness to change.
  • Edelaar [11] presented findings that combining self-reported work ability, such as the SFS, with performance-based tests improved the prediction of sustainable return to work.
  • Tuscher [12] examined the relationship between fear-avoidance behaviors and performance on FCEs among patients with chronic musculoskeletal pain. The researchers found that higher self-reported disability, as measured by the SFS, was associated with poorer performance on the FCE lifting tasks across both groups of patients—those with self-limited effort and those without.
  • Schindl [13]  investigated whether FCE can improve patients' perceptions of their ability to function and positively impact their recovery and return to work. The study found that patients' self-reported functional ability, as measured by the SFS, significantly improved after the FCE. This finding suggests that FCE might serve as a diagnostic tool and have a therapeutic effect by encouraging patients to evaluate their functional abilities. This shift in self-perception, in turn, could potentially contribute to better rehabilitation outcomes.
  • Lassfolk [14] explored the application of the International Classification of Functioning, Disability and Health (ICF) Comprehensive Core Set for Vocational Rehabilitation (ICF CSVR) in classifying functional capacity tests, focusing on the SFS. The analysis revealed that the SFS and FCE tests described 39 distinct ICF categories.
  • Bühne [15] examined a new classification system for the Modified Spinal Function Sort (M-SFS) as a predictive tool. Their findings revealed that when the M-SFS category aligned with or exceeded the actual physical demands of the job, patients with MSDs had a considerably higher likelihood of successfully returning to work following rehabilitation.
  • Burrus [16] defined the perceived work demand capacity associated with different scores on the M-SFS. The study established perceived work demand thresholds for the M-SFS by first determining the percentiles for these thresholds by transposing SFS norms to the M-SFS. The study confirmed the reliability of the M-SFS, finding a strong correlation between M-SFS and SFS scores (0.89) and a moderate correlation based on the PILE (0.60). They emphasize the need for further research to determine the questionnaire's responsiveness.

References

  1. Matheson, L., History, design characteristics, and uses of the pictorial activity and task sorts. Journal of Occupational Rehabilitation, 2004. 14(3): p. 175-195.
  2. Matheson, L., Mooney, V., Grant, J., Affleck, M., Hall, H., Melles, T., Lichter, R., & McIntosh, G. (1995). A test to measure the lift capacity of physically impaired adults. Part 1 Development and reliability testing. Spine, 20, 2119-2129.
  3. Matheson, L., Mooney, V., Holmes, D., Leggett, M., Grant, J., Negri, S., & Holmes, B. (1995). A test to measure the lift capacity of physically impaired adults. Part 2 Reactivity in a patient sample. Spine, 20, 2130-2134.
  4. Matheson, L., et al., Work Hardening: Occupational Therapy in Industrial Rehabilitation. American Journal of Occupational Therapy, 1985. 39(5): p. 314-321.
  5. Matheson, L., M. Matheson, and J. Grant, Development of a measure of perceived functional ability. Journal of Occupational Rehabilitation,1993. 3(1): p. 15-30.
  6. Robinson, R.C., et al., Improvement in postoperative and nonoperative spinal patients on a self-report measure of disability: the Spinal Function Sort (SFS). Journal of Occupational Rehabilitation, 2003. 13: p. 107-113.
  7. Oesch, P., et al., Perceived functional ability assessed with the spinal function sort: is it valid for European rehabilitation settings in patients with non-specific non-acute low back pain? European Spine Journal, 2010. 19: p. 1527-1533.
  8. Trippolini, M.A., et al., Measurement properties of the spinal function sort in patients with sub-acute whiplash-associated disorders. Journal of Occupational Rehabilitation, 2015. 25: p. 527-536.
  9. Janssen, S., et al., Development of a modified version of the spinal function sort (M-SFS): a mixed method approach. Journal of Occupational Rehabilitation, 2016. 26: p. 253-263.
  10. Trippolini, M.A., et al., Measurement properties of the modified spinal function sort (M-SFS): is it reliable and valid in workers with chronic musculoskeletal pain? Journal of Occupational Rehabilitation, 2018. 28: p. 322-331.
  11. Edelaar, M., et al., Functional capacity evaluation research: report from the Third International Functional Capacity Evaluation research meeting. Journal of Occupational Rehabilitation, 2018. 28: p. 130-134.
  12. Tüscher, J., et al., Predictive value of the fear-avoidance model on functional capacity evaluation. Journal of Occupational Rehabilitation, 2018. 28: p. 513-522.
  13. Schindl, M., H. Zipko, and M. Bethge, Reproducibility of improvements in patient-reported functional ability following functional capacity evaluation. BMC Musculoskeletal Disorders, 2022. 23(1): p. 258.
  14. Lassfolk, M., et al., Linking the spinal function sort and functional capacity evaluation tests to the international classification of functioning, disability and health core set of vocational rehabilitation. Journal of Occupational Rehabilitation, 2021. 31: p. 166-174.
  15. Bühne, D., et al., Matching Perceived Physical Capacity and Work Demands: A New Classification of the Modified Spinal Function Sort (M-SFS). Journal of Occupational Rehabilitation, 2021: p. 1-7.
  16. Burrus, C., et al., Determination of Perceived Levels of Physical Work Demand Thresholds, and Reliability and Responsiveness of the Modified-Spinal Function Sort Questionnaire in a Multidisciplinary Occupational Rehabilitation Setting. Journal of Occupational Rehabilitation, 2021: p. 1-9.