title: Identifying Treatment Effect Modifiers in the STarT Back Trial: A Secondary Analysis.
abstract: Identification of patient characteristics influencing treatment outcomes is a top low back pain (LBP) research priority. Results from the STarT Back trial support the effectiveness of prognostic stratified care for LBP compared with current best care, however, patient characteristics associated with treatment response have not yet been explored. The purpose of this secondary analysis was to identify treatment effect modifiers within the STarT Back trial at 4-month follow-up (n = 688). Treatment response was dichotomized using back-specific physical disability measured using the Roland-Morris Disability Questionnaire (≥7). Candidate modifiers were identified using previous literature and evaluated using logistic regression with statistical interaction terms to provide preliminary evidence of treatment effect modification. Socioeconomic status (SES) was identified as an effect modifier for disability outcomes (odds ratio [OR] = 1.71, P = .028). High SES patients receiving prognostic stratified care were 2.5 times less likely to have a poor outcome compared with low SES patients receiving best current care (OR = .40, P = .006). Education level (OR = 1.33, P = .109) and number of pain medications (OR = .64, P = .140) met our criteria for effect modification with weaker evidence (.20 > P ≥ .05). These findings provide preliminary evidence for SES, education, and number of pain medications as treatment effect modifiers of prognostic stratified care delivered in the STarT Back Trial.
  
  
  
  This analysis provides preliminary exploratory findings about the characteristics of patients who might least likely benefit from targeted treatment using prognostic stratified care for LBP.
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville, Florida; Brooks Rehabilitation-College of Public Health and Health Professions (University of Florida) Research Collaboration, University of Florida, Gainesville, Florida. Electronic address: beneciuk@phhp.ufl.edu.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Beneciuk
authors.affiliation: Arthritis Research UK Primary Care Centre, Research Institute of Primary Care and Health Sciences, Keele University, Staffordshire, United Kingdom.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Hill
authors.affiliation: Arthritis Research UK Primary Care Centre, Research Institute of Primary Care and Health Sciences, Keele University, Staffordshire, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Campbell
authors.affiliation: Arthritis Research UK Primary Care Centre, Research Institute of Primary Care and Health Sciences, Keele University, Staffordshire, United Kingdom.
authors.forename: Ebenezer
authors.initials: E
authors.lastname: Afolabi
authors.affiliation: Department of Physical Therapy, University of Florida, Gainesville, Florida; Brooks Rehabilitation-College of Public Health and Health Professions (University of Florida) Research Collaboration, University of Florida, Gainesville, Florida.
authors.forename: Steven Z
authors.initials: SZ
authors.lastname: George
authors.affiliation: Arthritis Research UK Primary Care Centre, Research Institute of Primary Care and Health Sciences, Keele University, Staffordshire, United Kingdom.
authors.forename: Kate M
authors.initials: KM
authors.lastname: Dunn
authors.affiliation: Arthritis Research UK Primary Care Centre, Research Institute of Primary Care and Health Sciences, Keele University, Staffordshire, United Kingdom.
authors.forename: Nadine E
authors.initials: NE
authors.lastname: Foster
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D017116:Low Back Pain / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D059408:Pain Management / Q000379:methods*; D010147:Pain Measurement / Q000379:methods*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
keywords: Low back pain; socioeconomic status; stratified care; subgrouping; treatment effect modification