Sample size and randomisation
LBP
RECURRENCE
A sample size calculation indicated that 349 participants per group (698 total) would provide 80% power to detect a 25% relative reduction in recurrence rates of Randomisation to intervention or control was conducted using a pre-generated schedule and allocation concealment was ensured at the patient level. Randomisation used randomly permuted blocks of 4, 6 and 8 and participants were stratified by history of > 2 previous lifetime episodes of LBP (known to be a prognostic factor for recurrence) [