The test-retest reliability and concurrent validity of the subjective complaints questionnaire for low back pain

Physiotherapists commonly record detailed patient information regarding subjective complaints for low back pain (LBP), particularly to assist in the process of classifying patients into specific subgroups. A self-administered Subjective Complaints Questionnaire for LBP (SCQ-LBP) measuring such information was developed for the purposes of future clinical research, particularly in the area of LBP classification. The development comprised literature review, feedback from experienced physiotherapists and pilot questionnaire testing in a patient population. Test-retest reliability of the questionnaire in a self administered format as well as concurrent validity against a suitable reference standard was evaluated. The agreement between the self administered questionnaire compared to when administered by a physiotherapist was also tested as the latter method is the most common form of retrieving subjective complaints in clinical practice. Thirty participants with LBP were recruited and at least moderate test-retest reliability was demonstrated in 56 of the 57 self administered questionnaire items. Preliminary evidence was found supporting the concurrent validity of selected items. At least moderate agreement was demonstrated in 51 of the 57 items when comparing between the self administered and physiotherapist administered conditions. The questionnaire is a useful tool for collecting subjective complaints information, particularly for clinical research on the classification of LBP, however, further research regarding validity is required.