title: Can we predict which patients with patellofemoral pain are more likely to benefit from exercise therapy? A secondary exploratory analysis of a randomized controlled trial.
abstract: METHODS
  Secondary exploratory analysis of a randomized controlled trial comparing supervised exercise therapy to usual care in patients with patellofemoral pain (PFP).
  
  
  OBJECTIVE
  To explore which patients with PFP are more likely to benefit from exercise therapy.
  
  
  BACKGROUND
  Patellofemoral pain is a common condition for which exercise therapy is effective in reducing pain and improving function. However, not all patients benefit from exercise therapy.
  
  
  METHODS
  The present study explored patient characteristics that might interact with treatment effects of PFP in 131 patients treated with usual care or exercise therapy. These characteristics were tested for interaction with treatment in a regression analysis. The primary outcomes were function and pain on activity at a 3-month follow-up.
  
  
  RESULTS
  None of the tested variables had a significant interaction with treatment. A positive trend was seen for females with PFP: they were more likely to report higher function scores with exercise therapy than with usual care compared to males with PFP (β = 12.1; 95% confidence interval: 0.23, 24.0; P = .05). A positive trend was seen for patients with a longer duration of complaints (greater than 6 months); they were more likely to report higher function scores and to have less pain on activity with exercise therapy than with usual care compared to those with a shorter duration of complaints (β = 12.3; 95% confidence interval: -0.08, 24.7; P = .05 and β = -1.74; 95% confidence interval: -3.90, 0.43; P = .12, respectively).
  
  
  CONCLUSIONS
  Two factors, sex and duration of complaints, may have a predictive value for response to exercise therapy at 3-month follow-up. Due to the exploratory design of the study, future research should confirm this tendency.
authors: Department of General Practice, Erasmus University Medical Center, Rotterdam, the Netherlands.
authors: Nienke E
authors: NE
authors: Lankhorst
authors: Marienke
authors: M
authors: van Middelkoop
authors: Yvonne D M
authors: YD
authors: van Trier
authors: Robbart
authors: R
authors: van Linschoten
authors: Bart W
authors: BW
authors: Koes
authors: Jan A N
authors: JA
authors: Verhaar
authors: Sita M A
authors: SM
authors: Bierma-Zeinstra
mesh_terms: D000293:Adolescent; D000328:Adult; D018771:Arthralgia / Q000628:therapy*; D059350:Chronic Pain / Q000628:therapy; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D007719:Knee Joint; D008297:Male; D012737:Sex Factors; D016896:Treatment Outcome; D055815:Young Adult
keywords: knee; primary care; treatment