title: Short-term improvements in disability mediate patient satisfaction after epidural corticosteroid injections for symptomatic lumbar spinal stenosis.
abstract: METHODS
  Secondary analysis of data from a double-blind randomized controlled trial.
  
  
  OBJECTIVE
  To identify mediators of the effect of lumbar epidural injections of corticosteroid plus lidocaine on patient satisfaction at 6 weeks postinjection in patients with lumbar spinal stenosis. We hypothesized that short-term (≤3 wk) change in leg pain would be a significant mediator of satisfaction.
  
  
  BACKGROUND
  No prior studies have identified mediators of effects of epidural injections on patient satisfaction with treatment of lumbar spinal stenosis.
  
  
  METHODS
  We used mediation analysis methods to examine selected intermediate variables (adverse events and change in leg pain, back pain, disability, depression, and fatigue at 3 wk) as potential mediators of the effect of lumbar epidural injections of corticosteroid plus lidocaine on patient satisfaction with treatment. We used the overall satisfaction item from the Swiss Spinal Stenosis Questionnaire as our primary outcome to measure patient satisfaction with the injection procedure at 6 weeks.
  
  
  RESULTS
  Among 400 patients randomized to receive epidural injections with corticosteroid plus lidocaine or with lidocaine alone, 369 had complete data for the satisfaction outcome and potential mediators and served as the analysis sample. Contrary to our expectations, 3-week change in leg pain intensity did not have significant mediation effects on patient satisfaction. Three-week change in disability as measured by the Roland-Morris Disability Questionnaire was a significant mediator of the effects of lumbar epidural corticosteroid injections on patient satisfaction at 6 weeks, explaining 48% to 60% of the treatment effect on satisfaction. Changes in pain intensity in the leg and back together explained very little of the treatment effect on satisfaction beyond the information contributed by disability change alone. We did not find other intermediate variables to be mediators of patient satisfaction.
  
  
  CONCLUSIONS
  These findings support the current approach of examining disability as a primary patient-reported outcome in comparative effectiveness studies of lumbar spinal stenosis.
  
  
  METHODS
  2.
authors.affiliation: *Division of Rehabilitation Care Services and Seattle Epidemiologic Research and Information Center (ERIC), VA Puget Sound Health Care System, Seattle, WA †Department of Rehabilitation Medicine, University of Washington, Seattle, WA ‡Department of Biostatistics, University of Washington, Seattle, WA §Comparative Effectiveness, Cost and Outcomes Research Center, University of Washington, Seattle, WA ¶Department of Radiology, University of Washington, Seattle, WA ‖Department of Health Services, University of Washington, Seattle, WA **Department of Psychiatry & Behavioral Sciences, University of Washington, Seattle, WA ††Department of Physical Medicine and Rehabilitation, VA North Texas Health Care System and UT Southwestern Medical Center, Dallas, TX ‡‡Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, MA §§Spine Unit, Harvard Vanguard Medical Associates, Boston, MA; and ¶¶ Departments of Anesthesiology and Psychiatry, University of Pittsburgh, Pittsburgh, PA.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Suri
authors.forename: Hristina
authors.initials: H
authors.lastname: Pashova
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Heagerty
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Jarvik
authors.forename: Judith A
authors.initials: JA
authors.lastname: Turner
authors.forename: Bryan A
authors.initials: BA
authors.lastname: Comstock
authors.forename: Zoya
authors.initials: Z
authors.lastname: Bauer
authors.forename: Thiru M
authors.initials: TM
authors.lastname: Annaswamy
authors.forename: Srdjan S
authors.initials: SS
authors.lastname: Nedeljkovic
authors.forename: Ajay D
authors.initials: AD
authors.lastname: Wasan
authors.forename: Janna L
authors.initials: JL
authors.lastname: Friedly
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000627:therapeutic use*; D001416:Back Pain / Q000188:drug therapy*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007268:Injections, Epidural / Q000379:methods; D008012:Lidocaine / Q000008:administration & dosage / Q000627:therapeutic use*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D017060:Patient Satisfaction; D013130:Spinal Stenosis / Q000150:complications / Q000188:drug therapy*
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine