The assessment of symptoms and functional limitations in low back pain patients: validity and reliability of a new questionnaire
- 179 Downloads
Many of the existing low back pain (LBP) questionnaires of function and symptoms have a content of different domains of disability presented as a single sum score, making it difficult to derive changes within a specific domain. The present study describes the development of a clinically derived back-specific questionnaire incorporating both a functional limitation and a symptom scale, with a further subdivision of the symptom scale in separate indices for severity and temporal aspects. The aims of the study were to assess the overall reliability and validity of the new questionnaire, named the Profile Fitness Mapping questionnaire (PFM). A total of 193 chronic LBP patients answered the PFM together with five validated criterion questionnaires. For the internal consistency of the questionnaires, the three indices of the PFM had the highest Cronbach’s alpha (0.90–0.95) and all items had item–total correlations above 0.2. The correlation coefficients between the PFM and the back-specific criterion questionnaires ranged between 0.61 and 0.83, indicating good concurrent criterion validity. The best discriminative ability between patients with different pain severities was demonstrated by the functional limitation scale of the PFM. Well centered score distribution with no patient’s score at the floor or the ceiling level indicates that the PFM has the potential to detect the improvement or worsening of symptoms and functional limitations in chronic LBP patients. Classification according to the International Classification of Functioning, Disability and health (ICF) of WHO revealed a high degree of homogeneous item content of the symptom scale to the domain of impairments, and of the functional limitation scale to the domain of activity limitations. The present study suggests that the PFM has a high internal consistency and is a valid indicator of symptoms and functional limitations of LBP patients. It offers the combination of a composite total score and the possibility of evaluations within specific domains of disability. Complementary evaluation of test–retest reliability and responsiveness to change is warranted.
KeywordsDisability Back pain Condition-specific questionnaire Outcome measure
The authors would like to direct a special thank to physiologist Henrik Cyrén for most valuable help during the development of the Profile Fitness Mapping scales, Maria Frykman and Nisse Larson for valuable assistance during data collection, processing and analyses, and Margaretha Marklund for graphical work. The present study complies with the Swedish laws and was performed after obtaining advisory pronouncement by the Regional Ethical Review Board in Uppsala, Sweden, and informed consent from each subject.
- 1.Altman DG (1991) Practical statistics for medical research. Chapman and Hall, LondonGoogle Scholar
- 5.Brown FG (1983) Principles of educational and psychological testing, 3rd edn. Holt, Rinehart and Winston, New YorkGoogle Scholar
- 9.Dworkin RH, Turk DC, Farrar JT, Haythornthwaite JA, Jensen MP, Katz NP, Kerns RD, Stucki G, Allen RR, Bellamy N, Carr DB, Chandler J, Cowan P, Dionne R, Galer BS, Hertz S, Jadad AR, Kramer LD, Manning DC, Martin S, McCormick CG, McDermott MP, McGrath P, Quessy S, Rappaport BA, Robbins W, Robinson JP, Rothman M, Royal MA, Simon L, Stauffer JW, Stein W, Tollett J, Wernicke J, Witter J (2005) Core outcome measures for chronic pain clinical trials: IMMPACT recommendations. Pain 113:9–19PubMedCrossRefGoogle Scholar
- 15.Jensen MP, Karoly P (2001) Self-report scales and procedures for assessing pain in adults. In: Turk DC, Melzack R (eds) Handbook of pain assessment. Guilford Press, New York, pp 15–34Google Scholar
- 16.Kjellberg A (1989) Att ställa frågor om arbetsmiljön: en kort handledning i konstruktion av frågeformulär [Swedish]. Arbetsmiljöinstitutet, Förlagstjänst, SolnaGoogle Scholar
- 24.Nunally JC (1967) Psychometric theory. McGraw-Hill, New YorkGoogle Scholar
- 32.Streiner GL, Norman DR (1990) Health measurement scales: a practical guide to their development and use. Oxford University Press, OxfordGoogle Scholar
- 37.WHO (2001) International Classification of Functioning, Disability and Health: ICF. Short version. World Health Organization, GenevaGoogle Scholar