Measuring the population impact of knee pain and disability with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)

Abstract

This study has used the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) in an unsolicited postal questionnaire to investigate the impact of knee pain and disability in the general older population. The study provides WOMAC population data for those aged over 50 and demographic and psychosocial associations with severity of WOMAC scores. A pilot survey (n=240) and repeatability study (n=80) were undertaken to test completion of the WOMAC in this new setting. The main questionnaire was mailed to 8,995 men and women aged over 50 registered with three general practices in North Staffordshire, UK. Completion rates for WOMAC items were high. Substantial reliability was found for pain and physical function scales (both >0.80). Fourteen percent of the over 50 population in this study had severe knee pain, 20% had severe difficulty with at least one area of physical functioning, 12% had both. The strongest link with severe difficulty with physical functioning was chronicity (odds ratio (OR)=6.49, 95% CI 4.65, 9.04). Other independent links were age over 75 years (odds ratio (OR)=4.11, 95% confidence interval (CI) 3.03, 5.58), depression (OR=2.80, 95% CI 2.22, 3.54), bilateral knee injury (OR=2.23, 95% CI 1.63, 3.06) and body mass index>30 (OR=2.00, 95% CI 1.51, 2.64). Similar associations were found for severe pain. The findings suggest that the WOMAC is a reliable measure for use in postal surveys. It has advantages over other instruments when measuring pain and physical function difficulty related to the knee. Chronicity, older age, injury, obesity and depression were all linked with higher WOMAC scores for knee pain severity and disability among knee pain sufferers in the general older population.

Valgus Bracing for Knee Osteoarthritis: A Meta‐Analysis of Randomized Trials

“…If so, conventional descriptors for effect sizes (37) suggest moderate improvements in both pain and function with valgus bracing, although the relatively large 95% CIs around those point estimates indicate that considerable uncertainty remains (Figure 2). Additionally, when translated into the difference between groups for improvements in WOMAC pain and function scores (8,38), the upper ends of the 95% CIs include values that would likely be considered clinically important (5 of a maximum 20 for pain, and 16 of a maximum 68 for function).…”

“…Previously reported SDs from a typical knee osteoarthritis population were then used to also translate the SMD into a difference between groups in the change score for the WOMAC pain and function subdomains (8,38).…”

Self-reported activity level and knee function in amateur football players: the influence of age, gender, history of knee injury and level of competition

“…[24][25][26] It is known that patient-reported outcomes assessing knee problems vary with age and gender in the general population. [7,14,22] However, only 6% of all Swedish football players were over 40 years of age in 2005 (http://www.svenskfotboll.se) and the influence of age in the age group of 15-40 years have not been sufficiently assessed.…”

“Pain elsewhere” and the impact of knee pain in older people

“…Guidelines for missing data were followed (8). For each subscale (pain, stiffness, and restricted physical function), responders who scored "severe" or "extreme" on at least 1 item on that subscale were defined as "severe" (10).…”