title: Revisiting classification of pain from bone metastases as mild, moderate, or severe based on correlation with function and quality of life.
abstract: OBJECTIVE
  The objective of our study was to determine the optimal cut points for classification of pain scores as mild, moderate, and severe based on interference with function and quality of life (QOL).
  
  
  METHODS
  We evaluated 822 patients who completed the Brief Pain Inventory (BPI) and/or the European Organization for Research and Treatment of Cancer (EORTC) QOL Questionnaire Core 30 (QLQ-C30) prior to receiving repeat radiation therapy for previously irradiated painful bone metastases. Optimal cut points for mild, moderate, and severe pain were determined by the MANOVA that yielded the largest F ratio for the between category effect on the seven interference items of BPI and the six functional domains of QOL (physical, role, emotional, cognitive, social functioning, and global QOL) as indicated by Pillai's Trace, Wilk's λ, and Hostelling's Trace F statistics.
  
  
  RESULTS
  For BPI and for QOL domains separately, the two largest F ratios for Wilk's λ, Pillai's Trace, and Hotelling's Trace F statistics were from the cut points 4, 8 and 6, 8. When combining both, the optimal cut points were 4, 8 with 1-4 (mild), 5-8 (moderate), and 9-10 (severe). With this classification, the mean scores of all the seven interference items in BPI and the six functional domains were all highly statistically different. Patients with severe pain survived significantly shorter than those with mild and moderate pain (p < 0.0001).
  
  
  CONCLUSIONS
  Our analysis supports the classification of pain scores as follows: 1-4 as mild pain, 5-8 as moderate pain, and 9-10 as severe pain. This may facilitate conduct of future clinical trials.
authors.affiliation: Sunnybrook Odette Cancer Centre, University of Toronto, Toronto, ON, Canada. Edward.Chow@sunnybrook.ca.|Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON, M4N 3M5, Canada. Edward.Chow@sunnybrook.ca.
authors.forename: Edward
authors.initials: E
authors.lastname: Chow
authors.affiliation: NCIC Clinical Trials Group, Cancer Research Institute, Queen's University, Kingston, ON, Canada.
authors.forename: Keyue
authors.initials: K
authors.lastname: Ding
authors.affiliation: NCIC Clinical Trials Group, Cancer Research Institute, Queen's University, Kingston, ON, Canada.
authors.forename: Wendy R
authors.initials: WR
authors.lastname: Parulekar
authors.affiliation: Princess Margaret Cancer Centre, Radiation Medicine Program, Ontario Cancer Institute, University of Toronto, Toronto, ON, Canada.
authors.forename: Rebecca K S
authors.initials: RK
authors.lastname: Wong
authors.affiliation: Leiden University Medical Centre, Leiden and Radiotherapy Institute Friesland, Leeuwarden, Netherlands.
authors.forename: Yvette M
authors.initials: YM
authors.lastname: van der Linden
authors.affiliation: Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Roos
authors.affiliation: Central DuPage Hospital Cancer Center, Warrenville, IL, USA.
authors.forename: William F
authors.initials: WF
authors.lastname: Hartsell
authors.affiliation: Mount Vernon Hospital Cancer Centre, Middlesex, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Hoskin
authors.affiliation: Tom Baker Cancer Centre, University of Calgary, Calgary, AB, Canada.
authors.forename: Jackson S Y
authors.initials: JS
authors.lastname: Wu
authors.affiliation: Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada.
authors.forename: Abdenour
authors.initials: A
authors.lastname: Nabid
authors.affiliation: Medisch Spectrum Twente, Enschede, Netherlands.
authors.forename: Francisca
authors.initials: F
authors.lastname: Ong
authors.affiliation: Academic Medical Center, Amsterdam, Netherlands.
authors.forename: Geertjan
authors.initials: G
authors.lastname: van Tienhoven
authors.affiliation: Christchurch Hospital, Christchurch, New Zealand.
authors.forename: Scott
authors.initials: S
authors.lastname: Babington
authors.affiliation: Akron City Hospital, Northeast Ohio Medical University, Akron, OH, USA.
authors.forename: William F
authors.initials: WF
authors.lastname: Demas
authors.affiliation: NCIC Clinical Trials Group, Cancer Research Institute, Queen's University, Kingston, ON, Canada.
authors.forename: Carolyn F
authors.initials: CF
authors.lastname: Wilson
authors.affiliation: Queen's University, Kingston, ON, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Brundage
authors.affiliation: NCIC Clinical Trials Group, Cancer Research Institute, Queen's University, Kingston, ON, Canada.
authors.forename: Liting
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Juravinski Hospital and Cancer Centre and McMaster University, Hamilton, ON, Canada.
authors.forename: Ralph M
authors.initials: RM
authors.lastname: Meyer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000150:complications* / Q000556:secondary; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000145:classification* / Q000209:etiology; D010147:Pain Measurement / Q000379:methods*; D011788:Quality of Life; D012720:Severity of Illness Index; D055815:Young Adult
keywords: Bone metastases; Functional interference; Pain severity; Quality of life; Re-irradiation; Survival