i Background and Purpose. Typically systematic reviews and guidelines consider chronic and acute/sub-acute back pain (< 3 months). However, LBP’s clinical course is often untidy, making this distinction difficult to apply in practice. We did a secondary analysis of the UK BEAM data-set to decide pain duration affected treatment outcome.

ii Method and results: We recruited 1,334 participants with four weeks or more of LBP to a trial of manipulation and exercise for low back pain. We found small sustained benefit from the manipulation package and a small short term benefit for the exercise package. One third of our participants reported that their pain had lasted for less than 90 days (range 4 weeks to 40 years). For this analysis the dependent variable was the Roland Morris Disability Questionnaire score at 12 months. Independent variables were treatment group and episode length, an interaction term between treatment (usual care, exercise, manipulation, and manipulation followed by exercise) and duration of current episode. Preliminary analysis indicates that the significance of the interaction terms for manipulation vs GP care, exercise vs. GP care and manipulation followed by exercise vs GP care are, 0.409, 0.037 and 0.889 respectively. The statistically significant result for the interaction between exercise and episode duration is a positive interaction, indicating that exercise may be more effective for those with shorter episodes of back pain and GP care more effective for longer episodes.

iii Conclusion: It is possible that duration of episode affects effectiveness of the UK BEAM exercise package, but not the UK BEAM manipulation package.