Abstract
Statement of purposes of the study and background: Validated outcome measures should be an essential tool in clinical practice. The Oswestry Disability Index (ODI), since its publication in 1980, is now a principle measure of condition-specific outcome in spinal management. The Low Back Outcome Score (LBOS), another popular measure, emphasises objective questions and gives a broad based status for low back illness. We have analysed the use of these instruments to see if they were directly comparable.
Method: Fifty five consecutive patients attending our clinic between February and June 2005 for treatment of low back disorders completed the questionnaires. These were then scored in the conventional manner. To directly compare LBOS with ODI the LBOS score was converted to a percentage and inversed. The individual LBOS evaluations were then marked in two ways. Firstly the questions that did not appear to correlate to the ODI were removed. Secondly the weighting system was adjusted to match the ODI weighting. Statistical regression analysis was performed.
Results: Direct comparison of ODI versus an inverse of the LBOS percentage score gave a scatter of results. The R squared result was 0.117
Removing the non-core answers from the LBOS gave an R squared value of 0.130
Removing the weighting of the LBOS gave an R squared value of 0.132
Removing the non-core questions and weighting system of the LBOS gave an R squared value of 0.133
Conclusion: These two validated disease specific outcome tools provide very different results when applied to the same group of patients. This has significant implications for outcome research especially when comparing studies which do not use similar instruments.
Correspondence should be addressed to Ms Alison McGregor, c/o BOA, SBPR at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.