Index > Vol. 39/2007 > Iss. 2/March > pp. 163-169 > Abstract
Original report | Neuromuscular diseases, Methodological studies

Cross-diagnostic validity of the SF-36 physical functioning scale in patients with stroke, multiple sclerosis and amyotrophic lateral sclerosis: A study using rasch analysis

doi: 10.2340/16501977-0024

Abstract:

Objective: The aim of this study was to investigate uni­dimensionality and differential item functioning of the SF-36 physical functioning scale (PF10) in patients with various neurological disorders.
Patients: Patients post-stroke (n = 198), with multiple sclero­sis (n = 151) and amyotrophic lateral sclerosis (n = 193) partici­pated.
Methods: Unidimensionality of the PF10 within the patient groups was investigated by performing a separate Rasch analysis for each group. Differential item functioning was investigated in a pooled Rasch analysis of the 3 groups.
Results: Within each group, all items fitted the Rasch model, except the “bathing/dressing” item in the amyotrophic lateral sclerosis group. The pooled analysis showed inadequate fit to the Rasch model for one item (“walking several hundred metres”). Of the other 9 fitting items, 5 showed differential item functioning for stroke vs multiple sclerosis and amyotrophic lateral sclerosis, while no differential item function­ing was found between multiple sclerosis and amyotrophic lateral sclerosis.
Conclusion: All items of the PF10, except one for the amyotrophic lateral sclerosis group, form a unidimensional scale, supporting the use of a sum score as a measure of physical func­tioning within these diagnostic groups. When comparing the data of patients after stroke, with that of patients with multip­le sclerosis and/or amyotrophic lateral sclerosis patients, adjustments for differential item functioning are required.

Authors:

Annet J. Dallmeijer, Vincent de Groot, Leo D. Roorda, Vera P. M. Schepers, Eline Lindeman, Leonard H. van den Berg, Anita Beelen, Joost Dekker on behalf of the FuPro study group

Key words:

amyotrophic lateral sclerosis, cross-diagnostic validity, differential item functioning, multiple sclerosis, physical functioning, Rasch model, stroke

References

  1. Ware JE, Jr, Sherbourne CD. The MOS 36-item short-form health survey (SF-36). Conceptual framework and item selection. Med Care 1992; 30: 473–483. Link to article
  2. Ware JE, Jr. SF-36 health survey update. Spine 2000; 25: 3130–3139.
  3. McHorney CA, Ware JE, Jr, Raczek AE. The MOS 36-Item Short-Form Health Survey (SF-36): II. Psychometric and clinical tests of validity in measuring physical and mental health constructs. Med Care 1993; 31: 247–263.
  4. McHorney CA, Ware JE, Jr, Lu JF, Sherbourne CD. The MOS 36-item Short-Form Health Survey (SF-36): III. Tests of data quality, scaling assumptions, and reliability across diverse patient groups. Med Care 1994; 32: 40–66. Link to article
  5. Haley SM, McHorney CA, Ware JE, Jr. Evaluation of the MOS SF-36 physical functioning scale (PF-10): I. Unidimensionality and reproducibility of the Rasch item scale. J Clin Epidemiol 1994; 47: 671–684. Link to article
  6. WHO. International Classification of Functioning, Disability and Health. Geneva: WHO; 2001.
  7. Dekker J, Dallmeijer AJ, Lankhorst GJ. Clinimetrics in rehabilitation medicine: current issues in developing and applying measurement instruments. J Rehabil Med 2005; 37: 193–201.
  8. Silverstein B, Kilgore KM, Fisher WP, Harley JP, Harvey RF. Applying psychometric criteria to functional assessment in medical rehabilitation: I. Exploring unidimensionality. Arch Phys Med Rehabil 1991; 72: 631–637.
  9. Nunnally JC, Bernstein IA. Psychometric theory. 3rd edn. New York: McGraw-Hill; 1994.
  10. Haigh R, Tennant A, Biering-Sorensen F, Grimby G, Marincek C, Phillips S, et al. The use of outcome measures in physical medicine and rehabilitation within Europe. J Rehabil Med 2001; 33: 273–278.
  11. Lundgren-Nilsson A, Grimby G, Ring H, Tesio L, Lawton G, Slade A, et al. Cross-cultural validity of functional independence measure items in stroke: a study using Rasch analysis. J Rehabil Med 2005; 37: 23–31.
  12. Roorda LD, Jones CA, Waltz M, Lankhorst GJ, Bouter LM, van der Eijken JW, et al. Satisfactory cross cultural equivalence of the Dutch WOMAC in patients with hip osteoarthritis waiting for arthroplasty. Ann Rheum Dis 2004; 63: 36–42.
  13. Tennant A, Penta M, Tesio L, Grimby G, Thonnard JL, Slade A, et al. Assessing and adjusting for cross-cultural validity of impairment and activity limitation scales through differential item functioning within the framework of the Rasch model: the PRO-ESOR project. Med Care 2004; 42 Suppl 1: I37–I48.
  14. Wright BD, Linacre JM, Smith RM, Heinemann AW, Granger CV. FIM measurement properties and Rasch model details. Scand J Rehabil Med 1997; 29: 267–272.
  15. Tesio L. Measuring behaviours and perceptions: Rasch analysis as a tool for rehabilitation research. J Rehabil Med 2003; 35: 105–115.
  16. Davidson M, Keating JL, Eyres S. A low back-specific version of the SF-36 Physical Functioning scale. Spine 2004; 29: 586–594.
  17. Jenkinson C, Fitzpatrick R, Garratt A, Peto V, Stewart-Brown S. Can item response theory reduce patient burden when measuring health status in neurological disorders? Results from Rasch analysis of the SF-36 physical functioning scale (PF-10). J Neurol Neurosurg Psychiatry 2001; 71: 220–224.
  18. Raczek AE, Ware JE, Bjorner JB, Gandek B, Haley SM, Aaronson NK, et al. Comparison of Rasch and summated rating scales constructed from SF-36 physical functioning items in seven countries: results from the IQOLA Project. International Quality of Life Assessment. J Clin Epidemiol 1998; 51: 1203–1214. Link to article
  19. Bode RK, Lai JS, Cella D, Heinemann AW. Issues in the development of an item bank. Arch Phys Med Rehabil 2003; 84 Suppl 2: S52–S60.
  20. Brooks BR, Miller RG, Swash M, Munsat TL. El Escorial revisited: revised criteria for the diagnosis of amyotrophic lateral sclerosis. Amyotroph Lateral Scler Other Motor Neuron Disord 2000; 1: 293–299.
  21. Andrich D, Sheridan BS, Luo G. RUMM2020: Rasch Unidimensional Models for Measurement. Perth Western Australia: RUMM Laboratory; 2002.
  22. Ware JE, Snow KK, Kosinski M, Gandek B. SF-36 Health survey manual and interpretation guide. Boston MA: New England Medical Center, The Health Institute; 1993.
  23. Aaronson NK, Muller M, Cohen PD, Essink-Bot ML, Fekkes M, Sanderman R, et al. Translation, validation, and norming of the Dutch language version of the SF-36 Health Survey in community and chronic disease populations. J Clin Epidemiol 1998; 51: 1055–1068. Link to article
  24. Failde I, Ramos I. Validity and reliability of the SF-36 Health Survey Questionnaire in patients with coronary artery disease. J Clin Epidemiol 2000; 53: 359–365.
  25. Gandek B, Ware JE, Jr, Aaronson NK, Alonso J, Apolone G, 
Bjorner J, et al. Tests of data quality, scaling assumptions, and reliability of the SF-36 in eleven countries: results from the IQOLA Project. International Quality of Life Assessment. J Clin Epidemiol 1998; 51: 1149–1158. Link to article
  26. Ware JE, Jr, Kosinski M, Gandek B, Aaronson NK, Apolone G, Bech P, et al. The factor structure of the SF-36 Health Survey in 10 countries: results from the IQOLA Project. International Quality of Life Assessment. J Clin Epidemiol 1998; 51: 1159–1165. Link to article
  27. Moorer P, Suurmeije T, Foets M, Molenaar IW. Psychometric properties of the RAND-36 among three chronic diseases (multiple sclerosis, rheumatic diseases and COPD) in The Netherlands. Qual Life Res 2001; 10: 637–645.
  28. McHorney CA, Haley SM, Ware JE, Jr. Evaluation of the MOS SF-36 Physical Functioning Scale (PF-10): II. Comparison of relative precision using Likert and Rasch scoring methods. J Clin Epidemiol 1997; 50: 451–461. Link to article
  29. Stucki G, Daltroy L, Katz JN, Johannesson M, Liang MH. Interpretation of change scores in ordinal clinical scales and health status measures: the whole may not equal the sum of the parts. J Clin Epidemiol 1996; 49: 711–717. Link to article