- Background The impact of risk adjustment on clinic quality ranking for patients treated in physical therapy outpatient clinics is unknown. Objectives To compare clinic ranking, based on unadjusted versus risk-adjusted outcomes for patients with low back pain (LBP) who are treated in physical therapy outpatient clinics. Methods This retrospective cohort study involved a secondary analysis of data from adult patients with LBP treated in outpatient physical therapy clinics from 2014 to 2016. Patients with complete outcomes data at admission and discharge were included to develop the risk-adjustment model. Clinics with complete outcomes data for at least 50% of patients and at least 10 complete episodes of care per clinician per year were included for ranking assessment. The R2 shrinkage and predictive ratio were used to assess overfitting. Agreement between unadjusted and adjusted rankings was assessed with percentile ranking by deciles or 3 distinct quality ranks based on uncertainty assessment. Results The primary sample included 414 125 patients (mean ± SD age, 57 ± 17 years; 60% women) treated by 12 569 clinicians from 3048 clinics from all US states; 82% of patients from 2107 clinics were included in the ranking assessment. The R2 shrinkage was less than 1%, with a predictive ratio of 1. Risk adjustment impacted ranking for 70% or 31% of clinics, based on deciles or 3 distinct quality levels, respectively. Conclusion Important changes in ranking were found after adjusting for basic patient characteristics of those admitted to physical therapy for treatment of LBP. Risk-adjustment profiling is necessary to more accurately reflect quality of care when treating patients with LBP. Level of Evidence Therapy, level 2b. J Orthop Sports Phys Ther 2018;48(8):637-648. Epub 22 May 2018. doi:10.2519/jospt.2018.7981.