Prevalent cases of osteoarthritis increased significantly worldwide from 1990 to 2019, based on data from the Global Burden of Disease Study 2019.
OA remains a highly prevalent condition worldwide, with no nonsurgical interventions to prevent progression, wrote Huibin Long, MD, of Capital Medical University, Beijing, and colleagues.
Courtesy National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Data from previous studies show that the prevalence of OA varies depending on the joints involved, with the knee being most frequently affected. However, site-specific data on OA trends and disease burden across regions or territories has not been well documented, they said.
In a study published in Arthritis & Rheumatology, the researchers analyzed data from the Global Burden of Disease Study, an ongoing project involving researchers in approximately 200 countries and territories to provide up-to-date information on the disease burdens of more than 350 types of diseases and injuries.
The Global Burden of Disease study for 2019 (GBD 2019) included data on age- and sex-specific incidence, prevalence, mortality, years of life lost, and disability-adjusted life-years for 369 diseases and injuries in 204 countries and territories. Countries were divided into five groups based on a composite sociodemographic index (SDI) of factors including fertility, income, and educational attainment; the SDI represents the quality and availability of health care, the researchers wrote.
OA was defined as radiologically confirmed Kellgren-Lawrence grade 2-4 and pain for at least 1 month during the past 12 months.
Overall, prevalent OA cases increased by 113.25% worldwide, from 247.51 million in 1990 to 527.81 million in 2019. China had the highest number of cases in 2019 (132.81 million), followed by India (62.36 million), and the United States (51.87 million). The percentage increases for these three countries from 1990 to 2019 were 156.58%, 165.75%, and 79.63%, respectively.
To further calculate trends in OA, the researchers used age-standardized prevalence rates (ASRs). The overall ASRs increased from 6,173.38 per 100,000 individuals in 1990 to 6,348.25 per 100,000 individuals in 2019, for an estimated annual percentage change of 0.12%. The ASR of OA varied substantially across countries in 2019, with the highest level observed in the United States (9,960.88 per 100,000) and the lowest in Timor-Leste (3,768.44 per 100,000). The prevalence of OA was higher in countries with higher SDI levels, such as the United States and the Republic of Korea, and increased life expectancy may play a role, they said.
OA prevalence increased with age; the prevalence of OA among adults peaked at 60-64 years in both 1990 and 2019. The absolute number of cases rose most sharply among individuals aged 95 years and older, increasing nearly fourfold during the 30-year period. The ASR of OA was also highest for people aged 95 years or older.
As for site-specific prevalence in 2019, OA of the knee was the most common site worldwide (60.6% of cases), followed by OA of the hand (23.7%), other joint sites (10.2%), and the hip (5.5%).
The ASR of OA increased for knee, hip, and other joints, with estimated annual percentage changes of 0.32%, 0.28%, and 0.18%, respectively, but decreased by 0.36% for the hand.
OA in large joints, such as the knee and hip, is often associated with higher disease burden, the researchers said. However, this held true for only knee OA because in this study, “globally as well as in most regions and countries, joints with the main disease burden were the knee, followed by the hand, [and] other joints except spine, while OA [of the] hip contributed the least,” they noted.
The study findings were limited by several factors including the adjustments from individual studies in the GBD and the exclusion of spinal symptoms, which might have contributed to an underestimation of disease burden, the researchers noted. Other limitations included the lack of assessment of the effect of health systems as part of the SDI, they said.
Overall, the results support a trend of increasing OA worldwide that is expected to continue in part because of the aging global population and the ongoing epidemic of obesity, the researchers said.
“Public awareness of the modifiable risk factors, and potential education programs of prevention of disease occurrence are essential to alleviate the enormous burden of OA,” they concluded.
The study was supported by the Beijing Postdoctoral Research Foundation and National Natural Science Foundation of China. The researchers had no financial conflicts to disclose.