Rationale Low back pain (LBP) is a leading cause of disability in the United States creating substantial economic hardship through multiple negative social, financial, and health effects. Chronic low back pain (CLBP) accounted for just above half of patients treated in physical therapy (PT) clinics for LBP. However, a systematic review and meta-analysis showed only small benefit from PT in the treatment of CLBP. Preliminary evidence suggests that clinician-level variables such as post-professional education may affect treatment outcomes, but requires further investigation to determine whether patients with CLBP would reap greater benefit from treatment by providers with post-professional training. This study examined the relationship between levels of clinician training and patient-reported outcomes in the treatment of CLBP. Methods PTs were surveyed using a large commercial patient outcome assessment system to determine their level of post-professional education then categorized by education level. Outcomes for 2497 patients with CLBP were extracted from the database. To account for the possibility that clinicians with higher levels of training are referred more clinically complex patients, a machine learning approach was used to identify predictive variables for clinician group, which were then used to construct propensity scores as a means to account for differences between groups. Differences in functional status score change among the pooled data were analyzed using linear models adjusted for propensity scores. Results There were no clinically meaningful differences in patient outcomes when comparing clinicians with post-professional training to those without. The propensity score method proved to be a valuable way to account for differences at baseline between the groups. Conclusion Post-professional training does not appear to contribute to improved patient outcomes in the treatment of CLBP. This study demonstrates that propensity score analysis can be used to ensure that differences observed are true and not due to differences at baseline.