title: Nortriptyline in knee osteoarthritis (NortIKA Study): study protocol for a randomised controlled trial.
abstract: BACKGROUND
  Osteoarthritis (OA) is a common cause of pain and disability. Currently available analgesics are often insufficiently effective or have unacceptable adverse effects. Tricyclic antidepressants may offer a useful centrally-acting analgesic. Nortriptyline is a readily-available, cheap and comparatively well-tolerated tricyclic antidepressant.
  
  
  METHODS
  We will conduct a parallel group, two-arm, participant and investigator-blinded, randomised controlled superiority trial comparing nortriptyline with placebo. Two hundred participants with primary knee OA will be enrolled. Participants will take study medication for 14 weeks. The primary outcome is difference between treatment arms in mean pain score measured on the Western Ontario and McMaster Universities (WOMAC) pain scale at 14 weeks.
  
  
  CONCLUSIONS
  This protocol describes the first randomised controlled trial of a tricyclic antidepressant in the treatment of OA. The results of the study may have significant implications for the management of this common and painful condition.
  
  
  BACKGROUND
  The trial was registered with the Australian New Zealand Clinical Trials Registry on 27 June 2014. The trial registration number is: ACTRN12614000683639 .
authors.affiliation: Department of General Practice, University of Otago, Christchurch, PO Box 4345, Christchurch, 8140, New Zealand. ben.hudson@otago.ac.nz.
authors.forename: Ben
authors.initials: B
authors.lastname: Hudson
authors.affiliation: Biostatistics and Computational Biology Unit, University of Otago, Christchurch, PO Box 4345, Christchurch, 8140, New Zealand. jonathan.williman@otago.ac.nz.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Williman
authors.affiliation: Department of Medicine, University of Otago, Christchurch, PO Box 4345, Christchurch, 8140, New Zealand. Lisa.stamp@cdhb.health.nz.|Canterbury District Health Board, Christchurch, New Zealand. Lisa.stamp@cdhb.health.nz.
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Stamp
authors.affiliation: Pain Management Centre, Canterbury District Health Board, Christchurch, New Zealand. John.alchin@cdhb.health.nz.
authors.forename: John S
authors.initials: JS
authors.lastname: Alchin
authors.affiliation: Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, PO Box 4345, Christchurch, 8140, New Zealand. gary.hooper@otago.ac.nz.|Canterbury District Health Board, Christchurch, New Zealand. gary.hooper@otago.ac.nz.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Hooper
authors.affiliation: Department of General Practice, University of Otago, Christchurch, PO Box 4345, Christchurch, 8140, New Zealand. dee.mangin@otago.ac.nz.
authors.forename: Dee
authors.initials: D
authors.lastname: Mangin
authors.affiliation: Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, PO Box 4345, Christchurch, 8140, New Zealand. bronwyn.thompson@otago.ac.nz.
authors.forename: Bronwyn F
authors.initials: BF
authors.lastname: Thompson
authors.affiliation: Department of General Practice, University of Otago, Christchurch, PO Box 4345, Christchurch, 8140, New Zealand. les.toop@otago.ac.nz.
authors.forename: Les
authors.initials: L
authors.lastname: Toop
mesh_terms: D000700:Analgesics / Q000009:adverse effects / Q000627:therapeutic use*; D018771:Arthralgia / Q000175:diagnosis / Q000188:drug therapy*; D002985:Clinical Protocols; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D009661:Nortriptyline / Q000009:adverse effects / Q000627:therapeutic use*; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000188:drug therapy*; D010147:Pain Measurement; D012107:Research Design; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000700:Analgesics; D009661:Nortriptyline