title: Sex differences in lumbar degenerative disc disease.
abstract: OBJECTIVE
  A growing number of studies focus on sex differences in the pre- and postoperative setting in patients with degenerative disc disease (DDD). The exact pathomechanism behind this phenomenon, however, remains unclear. The objective of this study was to investigate pre- and postoperative sex differences in patients with lumbar DDD.
  
  
  METHODS
  In a prospective two-center study, back and leg pain (Visual Analogue Scale (VAS)), functional disability (Oswestry Disability Index (ODI) and Roland-Morris Disability Index) and health-related quality of life (HRQoL) (EuroQol 5D and Short-Form (SF12)) were collected for patients scheduled for lumbar spine surgery. In addition to the subjective functional impairment (SFI), objective functional impairment (OFI) was estimated using age- and sex-adjusted cut-off values for the timed-up-and-go (TUG) test. The 6-week responder status was defined using minimally clinically important differences of the ODI, SF12 PCS, VAS back and leg pain in all patients. Six months and one year follow-up (FU) was available in n=127 and n=87 patients, respectively.
  
  
  RESULTS
  The patient cohort comprised of n=214 patients (41.6% females). Preoperatively, female patients scored significantly worse on VAS back and leg pain, ODI and SF12 PCS (p<0.033), while OFI was similar (p=0.334). At the 6 week FU, sex-related differences had resolved for SFI and OFI was similar as well (p=0.333). There were no sex differences in the mean improvement after 6 weeks for all measures of pain intensity, functional impairment and HRQoL (p>0.182). Male and female patients profited equally on measures of SFI and HRQoL up to six months and one year after surgery (p>0.091).
  
  
  CONCLUSIONS
  Preoperatively, female patients scored worse in terms of SFI, while OFI was similar. Consecutively, OFI appears to be less prone to sex bias and may thus serve as a valuable surrogate-marker of disability. The disadvantageous preoperative SFI-status did not translate into worse postoperative results, as no sex differences were present at the 6-week, 6-months and 1-year follow-up.
authors.affiliation: Department of Neurosurgery and Faculty of Medicine, University Hospital Geneva, Geneva, Switzerland. Electronic address: ogautschi@gmail.com.
authors.forename: Oliver P
authors.initials: OP
authors.lastname: Gautschi
authors.affiliation: Department of Neurology, John Hunter Hospital, Newcastle, Australia.
authors.forename: Nicolas R
authors.initials: NR
authors.lastname: Smoll
authors.affiliation: Department of Neurosurgery and Faculty of Medicine, University Hospital Geneva, Geneva, Switzerland.
authors.forename: Marco V
authors.initials: MV
authors.lastname: Corniola
authors.affiliation: Department of Neurosurgery, Cantonal Hospital St.Gallen, St.Gallen, Switzerland.
authors.forename: Holger
authors.initials: H
authors.lastname: Joswig
authors.affiliation: Department of Neurosurgery and Faculty of Medicine, University Hospital Geneva, Geneva, Switzerland.
authors.forename: Karl
authors.initials: K
authors.lastname: Schaller
authors.affiliation: Department of Neurosurgery, Cantonal Hospital St.Gallen, St.Gallen, Switzerland.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Hildebrandt
authors.affiliation: Department of Neurosurgery and Faculty of Medicine, University Hospital Geneva, Geneva, Switzerland.
authors.forename: Martin N
authors.initials: MN
authors.lastname: Stienen
mesh_terms: D000368:Aged; D001416:Back Pain / Q000209:etiology* / Q000601:surgery; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000150:complications* / Q000601:surgery; D007866:Leg / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000601:surgery; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010146:Pain / Q000209:etiology* / Q000601:surgery; D010147:Pain Measurement; D011446:Prospective Studies; D012737:Sex Factors
keywords: Degenerative disc disease; Functional impairment; Health-related quality of life; Sex differences; Timed-up-and-go test