1982 - Relationship Between Aspects of the Pain Experience in Knee Osteoarthritis and Function and Disability

Tuesday, November 8, 2011: 9:00 AM-6:00 PM
Hall F2 - Poster Hall (McCormick Place West)
September Cahue, Joan Chmiel, Karen W. Hayes, Orit Almagor, Kirsten Moisio, Carmelita J. Colbert, Clifton Saurel, Yunhui Zhang and Leena Sharma, Northwestern University, Chicago, IL
Presentation Number: 1982


It is widely accepted that knee pain influences physical functioning in knee osteoarthritis (OA), but how specific aspects of the pain experience relate to function impairment and disability is unclear. Our goal was to analyze separate aspects of the pain experience to determine which is most closely associated with measures of function and disability in persons with knee OA.


All participants had knee OA (osteophyte presence in at least one knee). Four aspects of the pain experience were evaluated: pain intensity (0-10 numeric rating scale); how much pain affected sleep (ICOAP item); pain after 20 m walk (0-10 rating scale); pain catastrophizing (Pain Catastrophizing Scale). Function was evaluated by: WOMAC function scale; Late Life Function Instrument (LL-FI), basic and advanced lower extremity function scales; 20 m walk time; time to complete 5 chair stands. Disability was evaluated by: Late Life Disability Instrument (LL-DI), activity frequency and activity limitation scales. Lower LL-FI and LL-DI scores are worse; higher WOMAC function, 20 m walk time, and chair stand time are worse. We used linear regression with function or disability as dependent variable, including each pain measure and age, gender, and BMI in each model, after screening for problematic multicollinearity. We calculated standardized regression coefficients [i.e., estimate of the expected change in standard deviation (SD) units in average value of dependent variable per SD change in predictor, after considering all other variables in the model] to compare the strength of association of different predictors with the outcome variable within the same model.


The sample was 250 persons (mean age 64.8 yrs, BMI 28.6, 76% women). The table shows standardized coefficients for each model (bold and italicized when significant). Row variables and gender were included in each model. Pain intensity was associated with WOMAC function but no other measure, pain affecting sleep with almost all function measures but no disability measure, and pain after 20 m walk with self-report function measures. Pain catastrophizing was the only aspect to be associated with disability measures.


When the four aspects of the pain experience were considered concurrently, pain catastrophizing was most consistently associated with measures of function and disability. Most closely associated with function measures were: pain affecting sleep, for WOMAC function; pain catastrophizing, for LL-basic function, chair stand time, and disability; and pain after 20 m walk, for LL-advanced function. These findings suggest that different aspects of the pain experience in knee OA may have unique relationships with function and disability. Ultimately, specific multidisciplinary attention to these aspects of pain may yield a more meaningful approach for the person with painful knee OA, and potentially have greater impact on function and disability over time.

Table. Standardized Coefficients from Multipredictor Regression Models



LL-FI, basic LE function

LL-FI, advanced LE function

20 m walk time

Chair stand time

LL-DI, activity frequency

LL-DI, activity limitation

Pain intensity








Pain affecting sleep








Pain after 20 m walk








Pain catastrophizing
























Keywords: disability, functional status and pain

Disclosure: S. Cahue, None; J. Chmiel, None; K. W. Hayes, None; O. Almagor, None; K. Moisio, None; C. J. Colbert, None; C. Saurel, None; Y. Zhang, None; L. Sharma, None.