Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Age of Symptomatic Knee OA Onset: Impact on Costs and Quality of Life.

Losina5,  Elena, Reichmann3,  William M., Golovaty2,  Ilya, Yelin6,  Edward H., Gerlovin2,  Hanna, Wright2,  Elizabeth A., Hunter7,  David J.

Brigham & Womens Hosp, Boston, MA
Brigham and Women's Hospital
Brigham and Women's Hospital, Boston University, Boston, MA
Brigham and Women's Hospital, Harvard Medical School
Brigham and Womens Hospital, Boston, MA
University of California, San Francisco, CA
University of Sydney

Background:

Symptomatic knee OA is debilitating and affects >4.5 million US adults. While traditionally viewed as a disease of the elderly, knee OA also affects younger adults, primarily due to history of sport-related injury or occupational exposure. Studies describing the age of patients with knee OA have focused on age at presentation to care or study initiation. Age of onset of symptomatic knee OA and its impact on quality of life and costs have not been described.

Methods:

We used a validated computer simulation model of the natural history and management of knee OA, combined with published population-based estimates of incidence, progression, and impact on quality of life, to determine the age of onset, and the lifetime risk and costs associated with symptomatic knee OA and total knee replacement (TKR). We followed a simulated cohort representative of the US general population from age 45 to death. Knee OA treatment costs were derived from the Medicare reimbursement schedule and the Red Book, ranging from $609/yr for PT, NSAIDs, assistive devices and capsaicin to $20,456/yr for TKR. Costs related to comorbidities ranged from $557/yr for 0–1 to $3,603/yr for > 3 comorbidities. We defined TKR eligibility by Kellgren-Lawrence (K-L) grade 4 radiographic OA in persons with consistent pain. Costs (in 2008 US$) were reported as total direct medical costs and costs attributable to knee OA. Both costs and quality-adjusted life expectancy (QALE) were discounted at 3%/yr.

Results:

The estimated lifetime risk of symptomatic knee OA was 15.3% with a mean age at onset of 68.7 (SD 13.6) years. Nineteen percent of those with symptomatic knee OA (2.9% of the overall population) developed it before the age of 55, 35.6% of those with symptomatic knee OA (5.4% of overall population) developed knee OA before age 65, and 62% (9.5% of overall population) developed symptomatic knee OA by 75 years of age. The discounted QALE in persons with early onset (before age 55) was 16.7 quality-adjusted life years (QALYs) compared to 17.8 for those with late onset (ages 75+). Early onset led to mean discounted lifetime costs attributable to knee OA of $14,156 per-person, compared to $1,658 for those with late onset. (Table) Among those who developed knee OA early, lifetime risk of TKR was 57.6% compared to 9.7% for those who developed knee OA late. Lifetime risk for revision TKR ranged from 12.1% for those with early onset to 0.4% for those with late onset of disease.

Age of symptomatic knee OA onsetQALE, discountedCosts, discountedCosts attributable to knee OA, discountedLifetime risk of TKRLifetime risk of revision TKR
45–5416.7$62,816$14,15657.6%12.1%
55–6417.0$58,007$9,19146.2%6.4%
65–7417.5$52,431$3,71424.6%2.0%
75+17.8$50,375$1,6589.7%0.4%

Conclusions:

Early onset of symptomatic knee OA is prevalent in the general US population. It leads to substantial decrements in QALE and increases OA-associated costs. Early onset of symptomatic knee OA leads to 6- and 25-fold increases in the lifetime risk for primary and revision TKR. Injury prevention and weight management, implemented early in life, may delay the onset of symptomatic knee OA, improve quality of life and decrease the economic burden associated with knee OA.

To cite this abstract, please use the following information:
Losina, Elena, Reichmann, William M., Golovaty, Ilya, Yelin, Edward H., Gerlovin, Hanna, Wright, Elizabeth A., et al; Age of Symptomatic Knee OA Onset: Impact on Costs and Quality of Life. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :2091
DOI: 10.1002/art.29856

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