SAMPLE SIZE
The trial aimed to recruit 344 patients with 86 patients in each
of the four interventions. 12 This calculation was based on a
90% chance of detecting a 20% relative improvement in the
ODI corresponding to a between-group difference of eight
points in the ODI and declaring it statistically signifi cant using
a two-sided α = .05. This calculation assumed a SD of 20 in
each group and allowed for loss to follow-up of 23%, as seen
in earlier descriptive work