Baseline physical exam predicts final self-reported pain outcomes from a randomized trial on chronic cervicogenic headache

Purpose: The goal of this analysis is to find which baseline physical exam (PE) measures best predict clinically relevant self-reported outcomes at 24 weeks.

Methods: This is an exploratory analysis of data generated by baseline PE from an open-label randomized controlled study. 80 subjects were randomized to 8 or 16 treatments of spinal manipulative therapy or light massage control over 8 weeks. Self-reported outcomes of interest included headache and neck pain and disability, and number of headaches and related disability days in the last four weeks. PE included motion palpation of the cervical and upper thoracic regions, inclinometric evaluation of active cervical range of motion (ROM) and associated pain, and algometric pain threshold (PPT) over articular pillars. The association between PE variables and outcomes were evaluated using forwards then backwards stepwise generalized linear models, adjusting for baseline outcome and treatment group. The resulting prediction models identify independent PE predictors of self-reported outcomes.

Results: Restricted cervical lateral bending ROM (p=.010) was predictive of lower week 24 neck disability. Pain on flexion (p=.004) and cervical flexion ROM (p=.002) were independently predictive of number of headaches at 24 weeks. Other predictors of week 24 self-reported outcomes include pain on extension, cervical extension ROM, and pain pressure threshold.

Conclusions: We noted a number of baseline PE findings that predict measures of 24 week headache and neck pain and disability. This is an important step towards establishing and understanding objective measures of outcomes for clinical studies.

Funded by NCCAM/NIH (R21AT002324)