Clinically important improvement in function is common in people with or at high risk of knee OA: the MOST study.
OBJECTIVE
To calculate the frequency of clinically important improvement in function over 30 months and identify risk factors in people who have or are at risk of knee osteoarthritis (OA).


METHODS
Subjects were from the Multicenter Osteoarthritis (MOST), a longitudinal study of persons with or at high risk of knee OA. We defined minimal clinically important improvement (MCII) with the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) physical function using 3 different methods. Baseline risk factors tested for improvement included age, sex, educational attainment, presence of radiographic knee OA (ROA), the number of comorbidities, body mass index (BMI), knee pain, walking speed, isokinetic knee extensor strength, depressive symptoms, physical activity, and medication usage. We used logistic regression to evaluate the association of baseline risk factors with MCII.


RESULTS
Of the 1801 subjects (mean age 63 yrs, BMI = 31, 63% women), most had mild limitations in baseline function (WOMAC = 19 +/- 11). Regardless of how defined, a substantial percentage of subjects (24%-39%) reached MCII at 30 months. Compared to their counterparts, people with MCII were less likely to have ROA and to use medications, and were more likely to have a lower BMI, less knee pain, a faster walking speed, more knee strength, and fewer depressive symptoms. After adjustment, MCII was 40% to 50% less likely in those with ROA, and 1.9 to 2.0 times more likely in those walking 1.0 meters/second faster than counterparts.


CONCLUSIONS
Clinically important improvement is frequent in people with or at high risk of knee OA. The absence of ROA and a faster walking speed appear to be associated with clinically important improvements.
White
Daniel K
DK
Clinical Epidemiology Research and Training Unit, Boston University School of Medicine, 650 Albany Street X 200, Boston, MA 02118, USA. white.daniel@gmail.com
Keysor
Julie J
JJ
Lavalley
Michael P
MP
Lewis
Cora E
CE
Torner
James C
JC
Nevitt
Michael C
MC
Felson
David T
DT
D000368:Aged; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000627:therapeutic use; D003348:Cortisone / Q000627:therapeutic use; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007270:Injections, Intra-Articular; D007719:Knee Joint / Q000000981:diagnostic imaging; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000503:physiopathology* / Q000534:rehabilitation*; D011379:Prognosis; D011446:Prospective Studies; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D020127:Recovery of Function; D012307:Risk Factors; D012720:Severity of Illness Index; D016896:Treatment Outcome
D000894:Anti-Inflammatory Agents, Non-Steroidal; D018501:Antirheumatic Agents; D003348:Cortisone
J Gerontol A Biol Sci Med Sci. 2000 Apr;55(4):M221-31
10811152
J Clin Epidemiol. 2006 Jul;59(7):724-31
16765276
Ann Rheum Dis. 2007 Nov;66(11):1456-61
17456527
J Rheumatol. 1997 Jul;24(7):1344-9
9228135
J Rheumatol. 1991 Apr;18(4):591-8
2066950
J Clin Epidemiol. 1993 Feb;46(2):153-62
8437031
J Gerontol A Biol Sci Med Sci. 2005 Jul;60(7):894-900
16079214
Ann Rheum Dis. 1957 Dec;16(4):494-502
13498604
J Rheumatol. 2002 Jan;29(1):131-8
11824949
J Rheumatol. 2007 Jan;34(1):159-64
17143966
Ann Rheum Dis. 2005 Jan;64(1):29-33
15208174
World Health Organ Tech Rep Ser. 2000;894:i-xii, 1-253
11234459
Osteoarthritis Cartilage. 2000 Mar;8(2):63-8
10772234
JAMA. 1998 Jun 3;279(21):1720-6
9624025
Med Sci Sports Exerc. 2003 Sep;35(9):1529-36
12972873
Arthritis Rheum. 2001 Aug;45(4):331-9
11501720
Arthritis Rheum. 2007 Sep;56(9):2986-92
17763427
Arthritis Rheum. 2008 Dec 15;59(12):1750-5
19035428
J Clin Epidemiol. 2001 Dec;54(12):1204-17
11750189
Rheumatology (Oxford). 2007 May;46(5):877-81
17308312
Ann Rheum Dis. 1995 Nov;54(11):872-80
7492235
J Am Geriatr Soc. 2007 Nov;55(11):1727-34
17916121
J Am Geriatr Soc. 2005 Oct;53(10):1675-80
16181165
Ann Rheum Dis. 2008 Apr;67(4):505-10
17704069
Arch Phys Med Rehabil. 2008 Nov;89(11):2102-7
18996238
Med Care. 1996 Jan;34(1):73-84
8551813
Clin Rehabil. 2004 Nov;18(7):793-800
15573836
J Rheumatol. 2009 Mar;36(3):583-91
19208591
Am J Public Health. 1990 Aug;80(8):945-9
2368855
J Rheumatol. 2007 Sep;34(9):1905-12
17696267
J Am Geriatr Soc. 2003 Mar;51(3):314-22
12588574
Osteoarthritis Cartilage. 1997 Jul;5(4):241-50
9404469
Arthritis Rheum. 2003 Dec;48(12):3359-70
14673987
Osteoarthritis Cartilage. 2009 Oct;17(10):1288-92
19410034
Eur Radiol. 2004 Sep;14(9):1568-73
15150666
Br J Gen Pract. 2005 Mar;55(512):205-11
15808036
BMJ. 2009 Nov 10;339:b4460
19903980
Ann Rheum Dis. 2008 Oct;67(10):1390-8
18245111
J Am Geriatr Soc. 2002 Sep;50(9):1492-7
12383145
Arthritis Rheum. 2005 Dec 15;53(6):920-30
16342106
Am J Ther. 2002 May-Jun;9(3):199-205
11941379