title: Low back pain and other musculoskeletal pain comorbidities in individuals with symptomatic osteoarthritis of the knee: data from the osteoarthritis initiative.
abstract: OBJECTIVE
  To examine the association of concurrent low back pain (LBP), and other musculoskeletal pain comorbidity, with knee pain severity in symptomatic knee osteoarthritis (OA).
  
  
  METHODS
  Individuals from the Progression Cohort of the Osteoarthritis Initiative (n=1,389, ages 45-79 years) with symptomatic tibiofemoral knee OA were studied. Participants identified pain in the low back, neck, shoulder, elbow, wrist, hand, hip, knee, ankle, or foot. The primary outcome was the pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) applied to the more symptomatic knee. We examined WOMAC pain score in persons with and without LBP, before and after adjusting for other musculoskeletal symptoms.
  
  
  RESULTS
  Of the participants, 57.4% reported LBP. The mean±SD WOMAC pain score (possible range 0-20) was 6.5±4.1 in participants with and 5.2±3.4 in participants without LBP (P<0.0001). In multivariate analyses, LBP was significantly associated with increased WOMAC knee pain score (β [SE]=1.00 [0.21], P<0.0001). However, pain in all other individual musculoskeletal locations demonstrated similar associations with knee pain score. In models including all pain locations simultaneously, only LBP (β [SE]=0.65 [0.21], P=0.002), ipsilateral elbow pain (β [SE]=0.98 [0.40], P=0.02), and ipsilateral foot pain (β [SE]=1.03 [0.45], P=0.02) were significantly associated with knee pain score. Having >1 pain location was associated with greater WOMAC knee pain; this relationship was strongest for individuals having 4 (β [SE]=1.83 [0.42], P<0.0001) or ≥5 pain locations (β [SE]=1.86 [0.36], P<0.0001).
  
  
  CONCLUSIONS
  LBP, foot pain, and elbow pain are significantly associated with WOMAC knee pain score, as are a higher total number of pain locations. This may have implications for clinical trial planning.
authors.affiliation: Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, Massachusetts 02130, USA. psuri@caregroup.harvard.edu
authors.forename: Pradeep
authors.initials: P
authors.lastname: Suri
authors.forename: David C
authors.initials: DC
authors.lastname: Morgenroth
authors.forename: C Kent
authors.initials: CK
authors.lastname: Kwoh
authors.forename: Jonathan F
authors.initials: JF
authors.lastname: Bean
authors.forename: Leonid
authors.initials: L
authors.lastname: Kalichman
authors.forename: David J
authors.initials: DJ
authors.lastname: Hunter
mesh_terms: D000368:Aged; D018771:Arthralgia / Q000150:complications* / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D017116:Low Back Pain / Q000150:complications* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D020370:Osteoarthritis, Knee / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D010147:Pain Measurement; D011379:Prognosis; D012720:Severity of Illness Index
references.citation: J Clin Epidemiol. 1999 Feb;52(2):137-42
references.pmid: 10201654
references.citation: Arthritis Rheum. 2005 Aug;52(8):2350-4
references.pmid: 16052574
references.citation: J Health Serv Res Policy. 1996 Oct;1(4):224-31
references.pmid: 10180875
references.citation: J Bone Joint Surg Am. 2004 May;86(5):902-9
references.pmid: 15118030
references.citation: Spine (Phila Pa 1976). 1980 Mar-Apr;5(2):133-42
references.pmid: 6446158
references.citation: Arthritis Care Res. 1996 Oct;9(5):376-83
references.pmid: 8997927
references.citation: Scand J Rheumatol. 1999;28(4):210-5
references.pmid: 10503556
references.citation: Disabil Rehabil. 2006 Dec 30;28(24):1543-9
references.pmid: 17178617
references.citation: Arthritis Rheum. 2003 Feb 15;49(1):101-13
references.pmid: 12579600
references.citation: Br J Rheumatol. 1998 Aug;37(8):862-9
references.pmid: 9734677
references.citation: Am J Public Health. 1984 Jun;74(6):574-9
references.pmid: 6232862
references.citation: Pain Med. 2003 Dec;4(4):311-20
references.pmid: 14750907
references.citation: Clin Orthop Relat Res. 2009 Oct;467(10):2623-9
references.pmid: 19434467
references.citation: Osteoarthritis Cartilage. 2008 Jun;16(6):647-53
references.pmid: 18207435
references.citation: Pain. 2008 Aug 15;138(1):41-46
references.pmid: 18077092
references.citation: Scand J Public Health. 2002;30(4):288-92
references.pmid: 12680505
references.citation: Arch Intern Med. 2005 May 23;165(10):1117-24
references.pmid: 15911724
references.citation: Spine (Phila Pa 1976). 2008 Jan 1;33(1):95-103
references.pmid: 18165754
references.citation: J Rehabil Med. 2001 Jan;33(1):21-5
references.pmid: 11480465
references.citation: Pain Med. 2009 May-Jun;10(4):693-701
references.pmid: 19254337
references.citation: Rheumatology (Oxford). 1999 Apr;38(4):355-61
references.pmid: 10378714
references.citation: J Am Acad Child Adolesc Psychiatry. 2002 Feb;41(2):199-205
references.pmid: 11837410
references.citation: Arthritis Care Res. 1999 Oct;12(5):331-5
references.pmid: 11081002
references.citation: Spine (Phila Pa 1976). 2008 Dec 1;33(25):2759-66
references.pmid: 19050582
references.citation: J Clin Epidemiol. 1996 Jul;49(7):743-7
references.pmid: 8691223
references.citation: J Rheumatol. 2002 Jan;29(1):131-8
references.pmid: 11824949
references.citation: Med Care. 1996 Nov;34(11):1093-101
references.pmid: 8911426
references.citation: Osteoarthritis Cartilage. 2007;15 Suppl A:A1-56
references.pmid: 17320422
references.citation: J Bone Joint Surg Br. 2003 Jan;85(1):95-9
references.pmid: 12585585
references.citation: J Orthop Sci. 2002;7(5):519-23
references.pmid: 12355123
references.citation: Gerontology. 2005 Nov-Dec;51(6):390-5
references.pmid: 16299420
references.citation: Am J Psychiatry. 1995 Jul;152(7):1026-32
references.pmid: 7793438
references.citation: Rheumatology (Oxford). 2007 Jan;46(1):112-9
references.pmid: 16735451