title: What factors explain the number of physical therapy treatment sessions in patients referred with low back pain; a multilevel analysis.
abstract: BACKGROUND
  It is well-known that the number of physical therapy treatment sessions varies over treatment episodes. Information is lacking, however, on the source and explanation of the variation. The purposes of the current study are: 1) to determine how the variance in the number of physical therapy treatment sessions in patients with non-specific low back pain (LBP) in the Netherlands is distributed over patient level, therapist level and practice level; and 2) to determine the factors that explain the variance.
  
  
  METHODS
  Data were used from a national registration network on physical therapy. Our database contained information on 1,733 patients referred with LBP, treated by 97 therapists working in 41 practices. The variation in the number of treatment sessions was investigated by means of multilevel regression analyses.
  
  
  RESULTS
  Eighty-eight per cent of the variation in the number of treatment sessions for patients with LBP is located at patient level and seven per cent is located at practice level. It was possible to explain thirteen per cent of all variance. The duration of the complaint, prior therapy, and the patients' age and gender in particular are related to the number of physical therapy treatment sessions.
  
  
  CONCLUSIONS
  Our results suggest that the number of physical therapy treatment sessions in patients with LBP mainly depends on patient characteristics. More variation needs to be explained, however, to improve the transparency of care. Future research should examine the contribution of psychosocial factors, baseline disability, and the ability to learn motor behavior as possible factors in the variation in treatment sessions.
authors.affiliation: NIVEL Netherlands Institute for Health Services Research, PO Box 1568, 3500 BN Utrecht, The Netherlands. i.swinkels@nivel.nl
authors.forename: Ilse C S
authors.initials: IC
authors.lastname: Swinkels
authors.forename: Raymond H
authors.initials: RH
authors.lastname: Wimmers
authors.forename: Peter P
authors.initials: PP
authors.lastname: Groenewegen
authors.forename: Wil J H
authors.initials: WJ
authors.lastname: van den Bosch
authors.forename: Joost
authors.initials: J
authors.lastname: Dekker
authors.forename: Cornelia H M
authors.initials: CH
authors.lastname: van den Ende
mesh_terms: D000328:Adult; D000367:Age Factors; D017050:Episode of Care; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis / Q000503:physiopathology / Q000534:rehabilitation*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009426:Netherlands; D026741:Physical Therapy Modalities / Q000193:education / Q000592:standards / Q000706:statistics & numerical data*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D011331:Private Practice / Q000706:statistics & numerical data; D012017:Referral and Consultation / Q000706:statistics & numerical data; D012042:Registries; D012737:Sex Factors; D011795:Surveys and Questionnaires