A Critical Appraisal of the responsiveness of a patient specific outcome measure compared with the Oswestry Disability Index v2.1 and Roland and Morris Disability Questionnaire
P: For patients with at least a six week history of back and/or leg pain
I: is the patient specific outcome measure
C: as compared to the Oswestry Disability Index and Roland and Morris Disability Questionnaire
O: as responsive
Vincent Gutierrez, PT, MPT, cert. MDT
Ovidsp with title term of “Oswestry”. The results were limited to full text. 73 citations were found with no limit to year published.
Date of Search: February 22,2014
Frost H, Lamb S, Stewart-Brown S. Responsiveness of a Patient Specific Outcome Measure Compared With the Oswestry Disability Index v2.1 and Roland and Morris Disability Questionnaire for Patients With Subacute and Chronic Low Back Pain. Spine 2008;33(22):2450-2457.
The purpose of this study is to assess the responsiveness of the Patient Specific Activity Questionnaire compared to the Oswestry Disability Index v2.1 and the Roland and Morris Disability Questionnaire.
The inclusion criteria were subjects at least 18 years old, with at least a 6-week history of low back pain. Subjects with or without leg pain and/or neurological signs were also included. Subjects were excluded for the following: serious pathologies, gynecological problems, ankylosing spondylitis, tumors, infection, past spinal operations, pregnancy, serious spinal pathology, unable or unwilling to complete questionnaires independently, received physical therapy in the previous month or were referred for intensive functional restoration.
The subjects were randomized to either a physiotherapy advice group or an advice with additional physiotherapy intervention group, which was not described. The subjects completed the following measures both prior to intervention and after 12 months: the Patient Specific Activity Questionnaire (PSAQ), the Oswestry Disability Index v2.1 (ODI), the Roland and Morris Disability Questionnaire (RMDQ), and the Global Transition Rating Scale (GTRS).
Subjects were divided into three groups, based on the GTRS, after 12 months: better, same or worse. The change score was calculated by subtracting the baseline scores from the follow-up scores for the ODI, RMDQ and the PSAQ. A relationship was established between the GTRS and each of the latter three outcome measures using 1 way analysis of variance (ANOVA).
Of the 286 subjects randomized initially, 201 completed the follow-up questionnaire. The PSAQ is responsive among subjects noting improvement, but is less sensitive to those reporting no improvement, when compared to the ODI and RMDQ.
The validity of the study is questionable, as there are flaws in the design. The authors do not account for the patient’s lost to follow-up, which may alter the results of the study. The authors fail to note the differences between the two groups at baseline, with regards to demographics. The authors note that a P value of <0.01 was utilized to differentiate among the outcome measures, which provides for a more limited confidence interval to detect true change.
The authors note the area under an operating receiver operator curve as follows: ODI as 0.752, PSAQ as 0.751 and RMDQ as 0.689. This indicates the order of responsiveness to change respectively.
Because the study results indicate that the tested outcome measure (PSAQ) is less sensitive to those patient’s with little change in status pre-post intervention, it would be prudent to utilize an outcome measure than can assess both small and large changes in status, such as the ODI and RMDQ.
With patients presenting to the clinic with complaints of at least a six week history of low back pain, with or without leg symptoms, the ODI would be the most effective to assess change.