title: The effect of waiting time on pain intensity after elective surgical lumbar discectomy.
abstract: BACKGROUND
  Waitlists are commonly used in Canada to manage access to surgical procedures such as elective surgical lumbar discectomy (ESLD). The timing of enrollment onto the waitlist is important as this is a proxy measure for the concordance of preferences for surgery between a patient and surgeon. After enrollment, the waiting time to actual surgery extends the duration of preoperative symptoms, which possibly affects the outcome of ESLD. Waiting time also specifically reflects the delay in service delivery imposed by the limited capacity of the health-care system.
  
  
  OBJECTIVE
  To determine if a system-imposed delay in treatment, that is, longer waiting time, for ESLD is associated with a higher odds of experiencing residual postoperative pain.
  
  
  METHODS
  Ambidirectional cohort study with 2-year retrospective and 3-year prospective components, conducted at a major tertiary care center serving a metropolitan area in Canada.
  
  
  METHODS
  Patients aged 16 years or older with sciatica because of herniated lumbar disc, confirmed on advanced imaging, were recruited at the time of waitlist enrollment for ESLD. Patients with significant comorbidity or emergency indications for surgery were excluded. Of 391 participants, 291 had complete follow-up information at 6 months postoperatively.
  
  
  METHODS
  Intensity of the predominant symptom (worse of either back or leg pain) was assessed on the 11-point numerical rating scale at waitlist enrollment and 6 months postoperatively. Pain scores were highly skewed and therefore categorized into four ordinal levels defined by quartiles.
  
  
  METHODS
  For the primary analysis, time to surgery from waitlist enrollment was dichotomized based on a predetermined clinically meaningful cut-point of 12 weeks. Ordinal logistic regression was used to compare the odds of experiencing higher pain intensity between wait groups. Control of confounders was achieved using both propensity scores and conventional multivariable modeling.
  
  
  RESULTS
  In unadjusted analyses, long-wait patients were 80% more likely than short-wait patients to experience higher ordinal pain intensity at 6 months; unadjusted proportional odds ratio (POR)=1.8 (95% confidence interval [CI], 1.2-2.8). The association held after controlling for all imbalances in measured confounders, with long-wait patients still being 70% more likely to report worse pain; adjusted POR=1.7 (95% CI, 1.0-2.8).
  
  
  CONCLUSIONS
  A waiting time of 12 weeks or more after waitlist enrollment for ESLD is associated with a modest likelihood of experiencing worse pain at 6 months postoperatively. This result was not because of differences in measured confounders. Future studies are encouraged to identify other, as-of-yet unmeasured, variables that might be associated with both longer waiting times and worse outcomes among ESLD patients. Until then, in jurisdictions where highly constrained access to ESLD is managed through waitlists, the expected waiting time for the operation could be an informative deciding criterion for patients with otherwise unresolved preferences for operative treatment.
authors.affiliation: School of Population and Public Health, Faculty of Medicine, University of British Columbia, 2206 East Mall, Vancouver, British Columbia, Canada V6T 1Z3; International Collaboration on Repair Discoveries (ICORD), Blusson Spinal Cord Centre, University of British Columbia, 6133-818 W. 10th Ave., Vancouver, British Columbia, Canada V5Z 1M9; Combined Neurosurgical and Orthopaedic Spine Program, Division of Spine, Department of Orthopaedics, Vancouver Hospital and Health Sciences Centre, University of British Columbia, 3114 - 910 West 10th Ave., Vancouver, British Columbia, Canada V5Z 1M9. Electronic address: quon@mail.ubc.ca.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Quon
authors.forename: Boris G
authors.initials: BG
authors.lastname: Sobolev
authors.forename: Adrian R
authors.initials: AR
authors.lastname: Levy
authors.forename: Charles G
authors.initials: CG
authors.lastname: Fisher
authors.forename: Paul B
authors.initials: PB
authors.lastname: Bishop
authors.forename: Jacek A
authors.initials: JA
authors.lastname: Kopec
authors.forename: Marcel F
authors.initials: MF
authors.lastname: Dvorak
authors.forename: Martin T
authors.initials: MT
authors.lastname: Schechter
mesh_terms: D000328:Adult; D002170:Canada; D015331:Cohort Studies; D017586:Diskectomy / Q000009:adverse effects* / Q000379:methods*; D017558:Elective Surgical Procedures / Q000009:adverse effects / Q000379:methods; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000453:epidemiology*; D013995:Time; D014850:Waiting Lists
keywords: Acute sciatica; Cohort study; Discectomy; Propensity scores; Waiting time