Expectations about the benefit of exercise, not surgery, are associated with future pain and physical function in patients with non-specific low back pain

Beliefs can affect perceived harms and benefits of a treatment. The purpose of this study was to assess the relationship between beliefs about exercise and surgery effectiveness and pain interference and physical function in patients with non-specific low back pain. This was a cohort of 629 pooled clinical trial participants receiving non-pharmacological pain management. Participants either agreed (somewhat or completely) or disagreed that surgery would be beneficial or that exercise would make their symptoms worse. Those that agreed were categorized as having high expectations about the treatment. The influence of high expectations on short-term (6week) and long-term (6-month) PROMIS Pain Interference scores was modeled with generalized linear (Gaussian) models. In a subset of 510 patients, the same analysis was conducted using PROMIS Physical function scores. The cohort was 28.8% female, mean(SD) age of 33.4(8.3) years and 83.1% active-duty. In all 67.1% had low expectations of exercise and 11.0% had high expecations of surgery. High expectations for surgery were not a significant predictor of pain interference or physical function. High expectations for exercise predicted lower pain interference (beta=-2.146, 95CI -3.366, -0.926; P<0.001) and higher physical function (beta=1.807, 95CI 0.586, 3.027; P=0.004) at 6 weeks and 6 months. High expectations for exercise were uncommon (about 33%) but associated with better outcomes out to six months. One in 10 patients had high expectations for surgery but this was not associated with outcomes. A better understanding of treatment expectations may present opportunities to improve engagement and education strategies for patients with low back pain. Perspective: The results of this study show that exercise expectations predict outcomes for those that get exercise, but expectations about treatment in general may not be as helpful as asking specifically about a given treatment. These finding can potentially help clinicians better understand how to improve patient engagement and education strategies.