Randomized cohort trial was shown to be feasible for evaluating treatments in low back pain

To investigate the feasibility of conducting a cohort, factorial randomized controlled trial (RCT) in the treatment of patients with low back pain (LBP).

Pragmatic feasibility factorial RCT nested within an observational cohort study in two general practices in York, United Kingdom.

Eight hundred forty-five patients aged between 18 and 65 years who had consulted their general practitioner about LBP within the preceding 12 months were mailed an invitation to participate in a cohort trial, with the possibility of later joining a treatment RCT. One hundred twenty-four patients consented to participate in the cohort and treatment trial, and one consented only to the cohort only. Ultimately, 59 patients were randomized into the nested RCT. Outcomes included recruitment, acceptability, and attrition rates as measures of the feasibility of the design and Roland Morris Disability Questionnaire. No statistically significant differences in outcome between treatment groups and usual care were found.

The design was feasible for the evaluation of different back pain treatments. We found zero attrition after randomization and showed that for a remitting relapsing condition, the design allows us to recruit initially ineligible patients from the cohort. Additional statistical analysis using regression discontinuity can also be used with this design.