Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.
A Population-Based Approach to Establishing the National Burden of Severe Hip and Knee Osteoarthritis In Australia.
Ackerman1, Ilana N., Osborne2, Richard H.
Severe hip and knee osteoarthritis (OA) is an ongoing public health problem in Australia, as evidenced by the growing demand for joint replacement surgery. However, the burden of these conditions has not been evaluated using a national, population-based approach. Rising rates of obesity are also of great concern, similar to many developed countries. This study aimed to investigate the prevalence and impact of severe hip and knee OA in Australia and examine the relationship between obesity and wellbeing in OA.
Five thousand Australians were randomly selected from the federal government electoral roll and invited to participate. Participants completed a questionnaire to identify doctor-diagnosed hip and knee OA and evaluate the severity and burden of these conditions. Pain, stiffness and function were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (range 0100; scored best-worst). Total WOMAC score was used to classify OA severity (<7 = asymptomatic, 738 = mild-moderate, >=39 = severe). Health-Related Quality of Life (HRQoL) was assessed using the Assessment of Quality of Life (AQoL) instrument (range -0.041.00; scored worst to best; minimal important difference 0.06 AQoL units). Body Mass Index (BMI) was used to classify underweight/normal weight (BMI <=24.99 kg/m2), overweight (BMI 2529.99) and obesity (BMI >=30). Analysis of covariance was used to determine the effect of OA severity on HRQoL and the effect of obesity on HRQoL, pain, stiffness and function, after adjusting for age and gender.
Data for analysis were available from 1153 participants (23%). The prevalence of hip OA was 4.9% (n=56) and prevalence of knee OA was 8.2% (n=95). The specific prevalence of severe hip and knee OA was 2.3% (n=27) and 3.2% (n=37), respectively. Reduced HRQoL was seen with increasing OA severity (F=59.02, p<0.01 for hip OA; F=67.40, p<0.01 for knee OA); participants with severe OA had extremely low HRQoL (mean AQoL 0.34 for hip OA, 0.39 for knee OA), compared to those with mild-moderate OA (mean AQoL 0.75 for hip OA, 0.72 for knee OA), those who were asymptomatic (mean AQoL 0.77 for hip OA, 0.81 for knee OA) and those without OA (mean AQoL 0.82 without hip OA, 0.83 without knee OA).
Obesity was strongly associated with poorer wellbeing in OA, even after adjusting for age and gender. Of those with hip OA, participants who were obese had the highest pain (mean WOMAC pain 50.3 vs 24.4 for underweight/normal weight; F=3.69, p=0.03) and lowest HRQoL (mean AQoL 0.33 vs 0.59 for underweight/normal weight; F=3.88, p=0.03). In knee OA, those who were obese had the highest pain (mean WOMAC pain 40.0 vs 27.4 for underweight/normal weight; F=3.99, p=0.02), greatest stiffness (mean WOMAC stiffness 44.3 vs 29.9 for underweight/normal weight; F=3.86, p=0.03) and poorest function (mean WOMAC function 40.6 vs 23.7 for underweight/normal weight; F=5.07, p=0.01).
This study provides the first Australian data on the prevalence of severe hip and knee OA and clearly shows that severe OA is associated with markedly reduced HRQoL. The relationship between obesity and poorer wellbeing in OA highlights the importance of targeted interventions for this patient group.
To cite this abstract, please use the following information:
Ackerman, Ilana N., Osborne, Richard H.; A Population-Based Approach to Establishing the National Burden of Severe Hip and Knee Osteoarthritis In Australia. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :796