Does Kinesiophobia Modify the Effects of Physical Therapy on Outcomes in Patients With Sciatica in Primary Care? Subgroup Analysis From a Randomized Controlled Trial

Background. A higher level of kinesiophobia appears to be associated with poor recovery in patients with sciatica. Objective. The aim of this study was to investigate whether kinesiophobia modifies the effect of physical therapy on outcomes in patients with sciatica. Design. This was a subgroup analysis from a randomized controlled trial. Setting. The study was conducted in a primary care setting. Patients. A total of 135 patients with acute sciatica participated. Intervention. Patients were randomly assigned to groups that received (1) physical therapy plus general practitioners' care (intervention group) or (2) general practitioners' care alone (control group). Measurements. Kinesiophobia at baseline was measured with the Tampa Scale for Kinesiophobia (TSK) and a single substitute question for kinesiophobia (SQK). Pain and recovery were assessed at 3- and 12-month follow-ups. Regression analysis was used to test for interaction between the level of kinesiophobia at baseline and treatment allocation. Subgroup results were calculated for patients classified with high fear of movement and for those classified with low fear of movement. Results. Kinesiophobia at baseline interacted with physical therapy in the analysis with leg pain intensity at 12-month follow-up. Kinesiophobia at baseline did not interact with physical therapy regarding any outcome at 3-month follow-up or recovery at 12-month follow-up. When comparing both treatment groups in the subgroup of patients with high fear of movement (n = 73), the only significant result was found for leg pain intensity difference from baseline at 12-month follow-up (intervention group: (X) over bar = -5.0, SD = 2.6; control group: (X) over bar = -3.6, SD = 2.7). Limitations. The post hoc study design and relatively small sample size were limitations of the study. Conclusions. In 135 patients with sciatica, evidence shows that patients with a higher level of kinesiophobia at baseline may particularly benefit from physical therapy with regard to decreasing leg pain intensity at 12-month follow-up.