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Osteoarthritis (OA)

I. Background

  • Also known as degenerative joint disease.
  • Most common form of arthritis.
  • Classified as: Idiopathic (localized or generalized) or Secondary (traumatic, congenital, metabolic/endocrine/neuropathic and other medical causes).
  • Characterized by focal and progressive loss of the hyaline cartilage of joints, underlying bony changes.
  • Usually defined by symptoms, pathology or combination 1
    • Pathology = radiographic changes (joint space narrowing, osteophytes, and bony sclerosis.)
    • Symptoms = pain, swelling, and stiffness.
  • The American College of Rheumatology (ACR) has published clinical classification guidelines for OA of the hand [PDF - 1.31MB], hip [PDF - 2.93MB], and knee [PDF-3.22MB].

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II. Prevalence

  •  Overall, in the United States,  OA affects 13.9% of adults aged 25 years and older and 33.6% (12.4 million) of those 65+ in 2005; an estimated 26.9 million US adults in 2005 up from 21 million in 1990 (believed to be conservative estimate).2
  • Average annual prevalence of OA in the ambulatory health care system in the United States, from 2001–2005, was estimated to be 3.5%  which amounts to 7.7 million with OA.3
    • Knee
      • Age ≥60 years=  37.4 (42.1 female; 31.2 male).4
      • Age ≥60 years=  47.8.5
      • Age ≥45 years= 19.2 (19.3 female; 18.6 male).6
      • Age ≥45 years= 37.4 (42.1 female; 31.2 male).7
      • Age ≥26 years=4.9 (4.9 female; 4.6 male).6
    • Hip
      • Age ≥45 years = 28.0 (29.5 female; 25.4 male).8
  • Symptomatic radiographic OA—prevalence per 100
    • Hand
      • Age ≥26 years = 6.8 (9.2 female; 3.8male).9
      • Age ≥60 years= 8.0 overall.10
  •  Radiographic knee and hp OA—prevalence per 100
    • Knee
      • Age ≥60 years=  12.1 (10.0 female; 13.6 male).4
      • Age ≥45 years= 6.7 (7.2 female; 5.9 male).6 
      • Age ≥45 years= 16.7 (18.7 female; 13.5 male).
      • Age ≥26 years= 4.9 (4.9 female; 4.6 male).6 
    • Hip 
      • Age ≥45 years = 8.7 (9.3 female; 9.2 male).6

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III. Incidence

  • Age and sex-standardized incidence rates of symptomatic radiographic OA in the in adults aged ≥20 years and older:
    • Hand OA = 100 per 100,000 person years.11
    • Hip OA = 88 per 100,000 person years.11
    • Knee OA = 240 per 100,000 person years.11
  • Among women in the adult population:
    • Incident radiographic knee OA 2-2.5% per year.5, 12, 13
    • Incident symptomatic radiographic knee OA 1% per year.12
    • Progressive radiographic knee OA 3-4% per year.5,12,13
  • Incidence rates of OA increased with age, and level off around age 80.14
  • Women had higher rates than men, especially after age 50.14
    • Men have 45% lower risk of incident knee OA and 36% reduced risk of hip OA than women.15

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IV. Mortality

  • OA is associated with excess mortality.16
    • Deaths from all causes, cardiovascular deaths, and dementia deaths among adults with OA were 1.6,1.7, and 2.0 times higher compared with the general population.16
  • Annual average of 0.2 to 0.3 deaths per 100,000 population due to OA (1979–1988).17
  • OA accounts for ~6% of all arthritis-related deaths.17
  • ~ 500 deaths per year attributed to OA; numbers increased during the past 10 years.17
  • OA deaths are likely highly underestimated. For example, gastrointestinal bleeding due to treatment with NSAIDs is not counted. 17

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V. Hospitalizations

  • OA accounts for 47.4% of all arthritis-related hospitalizations; 3,161,100 hospitalizations for OA as principal diagnosis in 2011.18
  • Knee and hip joint replacement procedures (usually for OA) accounted for 35% of total arthritis-related procedures during hospitalization.19
  • Nationally, from 1992 to 2011 the rate (per 100,000) of total knee replacement increased 217% from 203.6 to 645.1. In addition, the rate (per 100,000) of total hip replacement increased 119% from 139.9 to 306.6.18
  • Non-Hispanic Blacks and persons with low income have lower rates of total knee replacement but higher complications and mortality than Non-Hispanic whites.20,21

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VI. Ambulatory Care

  • OA accounted for an annual prevalence of 21.7 million (21.7%) of all arthritis-related ambulatory medical care visits in 2010.3
  • About 39% of people with OA report inability to access needed health care rehabilitative services.22

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VII. Costs

  • Estimated costs due to hospital expenditures of total knee and hip joint replacements, respectively, $28.5 billion and $13.7 billion in 2009.23
  • Average direct costs of OA per patient ~$2,600 per year.19
  • Total (direct and indirect) annual costs of OA per patient = $5700 (US dollars FY2000).24
  • Job-related OA costs $3.4 to $13.2 billion per year.14

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VIII. Impact on Health-Related Quality of Life (HRQOL) 

  • OA of the knee is 1 of 5 leading causes of disability among non-institutionalized adults. 25
  • About 80% of patients with OA have some degree of movement limitation.
    • 25% cannot perform major activities of daily living (ADL's), 11% of adults with knee OA need help with personal care and 14% require help with routine needs.
  • About 40% of adults with knee OA reported their health "poor" or "fair."
  • In 1999, adults with knee OA reported more than 13 days of lost work due to health problems.
  • Hip/knee OA ranked high in disability adjusted life years (DALYs)27 and years lived with disability (YLDs).26

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IX. Unique Characteristics

  • Disease in weight bearing joints has greater clinical impact.
  • About 20%–35% of knee OA and ~50% of hip and hand OA may be genetically determined.27,28
  • Established modifiable and non-modifiable risk factors7,27,28,29,30,31:
    • Modifiable
      • Excess body mass (especially knee OA).
      • Joint injury (sports, work, trauma).
      • Knee pain.
      • Hand OA is a risk factor for knee OA.
      • Occupation (due to excessive mechanical stress: hard labor, heavy lifting, knee bending, repetitive motion).
        • Men—often due to work that includes construction/mechanics, agriculture, blue collar laborers, and engineers.
        • Women—often due to work that includes cleaning, construction, agriculture, and small business and retail.
      • Structural malalignment, muscle weakness.
    • Non-modifiable.
      • Gender (women higher risk).
      • Age (increases with age and levels around age 75).
      • Race (some Asian populations have lower risk).
      • Genetic predisposition.
  • Other possible factors:
    • Estrogen deficiency (estrogen replacement therapy (ERT) may reduce risk of knee/hip OA).
    • High bone density may increase risk of knee).
    • Vitamins C, E, and D—equivocal reports.
    • C-reactive protein (increased risk with higher levels).

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X. References

  1. American Academy of Orthopaedic Surgeons. Osteoarthritis.  Accessed 04-07-2014
  2. Lawrence RC, Felson DT, Helmick CG, et al. Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part II. Arthritis Rheum. 2008;58(1):26-35.
  3. Sacks JJ, Luo Y-H, Helmick CG. Prevalence of specific types of arthritis and other rheumatic conditions in the ambulatory health care system in the   
    United States, 2001–2005.  Arthritis Care & Research. 2010;62 (4):460-464.
  4. Dillon CF, Rasch EK, Gu Q, Hirsch R. Prevalence of knee osteoarthritis in the United States: arthritis data from the Third National Health and Nutrition Examination Survey 1991–1994. J Rheumatol, 2006;33(11):2271-2279.
  5. Leyland KM, Hart DJ, Javaid MK, Judge A, et al. The natural history of radiographic knee osteoarthritis: a fourteen-year population-based cohort study. Arthritis Rheum 2012;64(7):2243-51.
  6. Felson DT, Naimark A, Anderson J, Kazis L, Castelli W, Meenan RF. The prevalence of knee osteoarthritis in the elderly. The Framingham Osteoarthritis Study. Arthritis Rheum. 1987;30(8):914-918.
  7. Jordan JM, Helmick CG, Renner JB, et al. Prevalence of knee symptoms and radiographic and symptomatic knee osteoarthritis in African Americans and Caucasians: The Johnston County Osteoarthritis Project. J Rheumatol. 2007;34(1):172-180.
  8. Jordan JM, Helmick CG, Renner JB, et al. Prevalence of hip symptoms and radiographic and symptomatic hip osteoarthritis in African Americans and Caucasians: the Johnston County Osteoarthritis Project. J Rheumatol 2009;36(4):809-15.
  9. Zhang Y, Niu J, Kelly-Hayes M, et al. Prevalence of symptomatic hand osteoarthritis and its impact on functional status among elderly: the Framingham Study. Am J Epidemiol.2002;156:1021-7.
  10. Dillon CF, Hirsch R, Rasch EK, Gu Q. Symptomatic hand osteoarthritis in the United States: prevalence and functional impairment estimates from the third U.S. National Health and Nutrition Examination Survey, 1991–1994. Am J Phys Med Rehabil, 2007;86(1):12-21.
  11. Oliveria SA, Felson DT, Reed JI, et al. Incidence of symptomatic hand, hip, and knee osteoarthritis among patients in a health maintenance organization. Arthritis Rheum. 1995;38(8):1134-1141.
  12. Felson DT, Zhang Y, Hannan MT, et al. The incidence and natural history of knee osteoarthritis in the elderly. The Framingham Osteoarthritis Study. Arthritis Rheum. 1995;38(10):1500-1505.
  13. Cooper C, Snow S, McAlindon TE, et al .Risk factors for the incidence and progression of radiographic knee osteoarthritis. Arthritis Rheum. 2000;43(5):995-1000.
  14. Buckwalter JA, Saltzman C, Brown T. The impact of osteoarthritis. Clin Orthoped Rel Res. 2004:427S: S6-S15.
  15. Srikanth VK, Fryer JL, Zhai G, Winzenberg TM, Hosmer D, Jones G. A meta-analysis of sex difference prevalence, incidence and severity of osteoarthritis. Osteoarthritis Cartilage. 2005;13:769-781.
  16. Nüesch E, Dieppe P, Reichenbach S, et al. All cause and disease specific mortality in patients with knee or hip osteoarthritis: population based cohort study. BMJ. 2011;342:d1165.
  17. Sacks JJ, Helmick CG, Langmaid G. Deaths from arthritis and other rheumatic conditions, United States, 1979–1998. J Rheumatol. 2004;31:1823-1828.
  18. Arthritis and Related Conditions Chapter 4. Accessed 07-23-2015.
  19. Gabriel SE, Crowson CS, Campion ME, et al. Direct medical costs unique to people with arthritis. J Rheumatol. 1997;24(4):719–725.
  20. Mahomed NN, Barrett J, Katz JN Baron JA, Wright J, Losina E. Epidemiology of total knee replacements in the United States Medicare population. J Bone Joint Surg Am. 2005;87(6):1222-1228.
  21. CDC. Racial disparities in total knee replacement among Medicare enrollees--United States, 2000–2006. MMWR. 2009;58(6):133-8.
  22. Hagglund KJ, Clark MJ, Hilton SA, Hewett JE. Access to healthcare services among persons with osteoarthritis and rheumatoid arthritis. Am J Phys Med Rehabil. 2005;84(9):702-711.
  23. Murphy L, Helmick CG.The impact of osteoarthritis in the United States: a population-health perspective. Am J Nurs. 2012;112(3 Suppl 1):S13-9.
  24. Maetzel A, Li LC, Pencharz J, Tomlinson F Bombardier C. The economic burden associated with osteoarthritis, rheumatoid arthritis, and hypertension: a comparative study. Ann Rheum Dis. 2004;63(4):395-401.
  25. Guccione AA, Felson DT, Anderson JJ, et al. The effects of specific medical conditions on the functional limitations of elders in the Framingham Study. Am J Pub Health. 1994;84(3):351-358.
  26. Michaud CM, McKenna MT, Begg S, et al. The burden of disease and injury in the United States 1996. Popul Health Metr. 2006;4:11. Accessed July, 19, 2007.
  27. Felson DT, Zhang Y. An update on the epidemiology of knee and hip osteoarthritis with a view to prevention. Arthritis Rheum. 1998;41(8):1343-1355.
  28. Felson DT. Risk factors for osteoarthritis. Clin Orthoped Rel Res. 2004;427S:S16-S21.
  29. Rossignol M, Leclerc A, Allaert FA, et al. Primary osteoarthritis of hip, knee and hand in relation to occupational exposure. Occup Environ Med. 2005;62:772-777.
  30. Cooper C, Snow S, McAlindon TE, et al. Risk factors for the incidence and progression of radiographic knee osteoarthritis. Arthritis Rheum. 2000;43(5):995-1000.
  31. Blagojevic M, Jinks C, Jeffery A, et al. Risk factors for onset of osteoarthritis of the knee in older adults: a systematic review and meta-analysis. Osteoarthritis Cartilage. 2010;18(1):24-33.

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XI. Resources