Osteoarthritis (OA) is a common joint condition characterized by the breakdown of cartilage and other joint tissues, leading to pain, stiffness, and swelling. It affects a person’s ability to move freely and can impact overall well-being.
Prevalence of Osteoarthritis
In 2019, approximately 528 million people worldwide were living with osteoarthritis, representing a significant increase of 113% since 1990. By 2020, this number rose to 595 million people globally, accounting for about 7.6% of the world’s population.
In the United States, osteoarthritis is highly prevalent, affecting over 32 million adults. The condition manifests in various joints, with the knee being the most frequently affected, impacting an estimated 365 million people globally. Following the knee, the hip and hand are also commonly affected joint sites.
The global prevalence of knee OA was 16.0% among individuals aged 15 and over in 2020, and 22.9% for those aged 40 and older. This translates to approximately 654.1 million individuals aged 40 and older with knee OA worldwide in 2020. Data from a UK-based study found that clinical OA incidence increased from 29.2 per 1000 person-years in 1992 to 40.5 per 1000 person-years in 2013 for patients aged 45 and older.
Demographic Patterns
Age is a prominent factor in osteoarthritis prevalence. The condition is uncommon in individuals younger than 40 years, unless it results from an underlying metabolic disorder or a prior joint injury. However, about 73% of people living with osteoarthritis are older than 55 years, and its prevalence increases with advancing age.
Sex also plays a role, with women being more frequently affected by osteoarthritis than men. Approximately 60% of people living with osteoarthritis globally are female. This disparity is particularly noticeable after the age of 50, suggesting that physiological changes, such as those occurring post-menopause, may contribute to the elevated risk in women.
Ethnic and racial variations are also observed. Among US adults aged 60 and older, radiographic knee OA prevalence was higher in women (42.1%) compared to men (31.2%). Non-Hispanic Black individuals and men in manual labor occupations also showed significantly higher odds of both radiographic and symptomatic knee OA. Geographic location and socioeconomic status can also influence prevalence, likely due to differences in genetics, anatomy, and environmental exposures.
Economic and Societal Impact
Osteoarthritis imposes a substantial economic and societal burden. The economic cost of OA can amount to 1-2.5% of the Gross National Product in established market economies like the US, UK, Canada, and Australia. In the United States, the direct medical cost of OA was estimated at $72 billion using data from 2008-2011.
Osteoarthritis was the second most costly medical condition treated in US hospitals in 2013, accounting for 4.3% ($18.4 billion) of all hospitalization costs. Lost productivity is another significant economic factor. Individuals with OA pain in the US incurred nearly twofold higher annual indirect costs from lost workplace productivity compared to those without OA. In 2009, workers with OA pain reported losing 31% of productive time while at work due to presenteeism and 8% due to absenteeism.
Societal impact includes reduced quality of life and functional limitations. OA is a significant contributor to years lived with disability globally. Patients experience pain, stiffness, and reduced range of motion, leading to difficulties in daily activities, decreased participation, reduced well-being, and psychological distress.
Future Outlook and Trends
The prevalence of osteoarthritis is projected to continue increasing globally. This trend is largely attributed to aging populations and rising rates of obesity. Obesity is a major modifiable risk factor for OA, particularly in weight-bearing joints like the knee and hip.
Projections suggest that cases of knee osteoarthritis could increase by 74.9% by 2050 compared to 2020. Hand OA cases are projected to rise by 48.6%, and hip OA cases by 78.6% by 2050. The global age-standardized rate of years lived with disability (YLDs) due to osteoarthritis also increased by 9.5% from 1990 to 2020. This indicates a growing long-term significance for the condition.