text: Methods 
  Dataset and patient population 
  This study used data from the Orthopedic Physical Ther- 
  apy – Investigative Network’s (OPT-IN) Optimal Screen- 
  ing for Prediction of Referral and Outcome (OSPRO) 
  validation cohort study, a longitudinal prospective study 
  of individuals with knee, shoulder, back or neck pain seek- 
  ing Physical Therapy in the US. A convenience sample 
  was recruited from December 2014 and December 2015 
  by participating OPT-IN clinics. The OPT-IN clinics that 
  participated in data collection represented multiple geo- 
  graphic regions in the US including the Mideast, South- 
  east, Great Lakes, Rocky Mountain States and Far West, 
  with an attempt to balance recruitment between urban 
  and rural settings over the entire OPT-IN network. Phys- 
  ical therapists practicing in these clinics identified eligible 
  participants at initial evaluation and directed them to a se- 
  cure study website for the informed consent process and 
  baseline self-report assessment. Eligibility criteria have 
  been thoroughly reported elsewhere [19] and were 
  that was 
  intentionally broad to develop a cohort 
  generalizable to those seeking physical therapy for com- 
  mon musculoskeletal conditions in the US. Participants 
  completed follow-up self-reported assessments on the 
  study website at 4 weeks, 6 months and 12 months. Partic- 
  ipants were notified of a pending assessment by an email 
  that directed them back to the study website to complete 
  their follow-up assessment. For additional details of the 
  dataset and cohort, readers are directed to the published 
  cohort profile [19]. 