New Projections for the Global Burden of Osteoarthritis Through 2050

One of the leading causes of chronic pain and long-term disability in adults is osteoarthritis (OA), which contributes to billions of dollars in annual health care costs and other forms of associated spending. According to a recent study published in The Lancet Rheumatology, the economic and physical burdens of OA will only rise as the size of aging populations continues to grow across the globe.

Factors like joint anatomy or previous joint injury, BMI, line of work, experience in high-impact sports, as well as muscle weakness all influence individual risks for developing OA. Those over the age of 60 are impacted at higher rates; however, OA is not age-specific and can begin affecting individuals well before the age of 50. Finding solutions to alleviate symptoms—or prevent OA altogether—could assuage decades of individual suffering. To effectively implement intervention and prevention tactics, clinicians and health experts need to know where and who to target their efforts toward.

To uncover more vulnerable groups and track global trends, researchers accessed PubMed to evaluate OA cases from 1980-2019. Their examinations sought to uncover OA incidence patterns over time, report its burden as of 2020, determine the contributions of high BMI, and predict the disease’s prevalence to 2050. They conducted a Global Burden of Diseases, Injury, and Risk Factors (GBD) study to stratify health data for specific sites of OA (hip, knee, hand, and “other”) by geographic location, sex, and age to paint a bigger picture of OA’s toll on public health.

Data from state-level US insurance claims and cross-sectional, population-based surveys from around the world were analyzed. OA in males and females above the age of 30 were examined and ranked according to the Kellgren Lawrence grade system: grade 2 indicates the presence of 1 osteophyte in a joint; grade 3 signifies the presence of several osteophytes that coincides with observable joint-space narrowing; grade 4 follows the same criteria as grade 3 but with the addition of bone deformity. The prevalence of each severity level was multiplied by the associated disability weight of the health state to measure years lived with disability (YLD). Additionally, a socio-demographic regression model—accounting for age, sex, location, and total incidence of OA—was applied to predict the course of OA to 2050.

A total of 53 non-insurance-claims sources spanning 22 countries, 95 sources throughout 26 countries, and 69 sources across 12 countries provided data for hip, knee, and hand OA estimations, respectively. Over 600 sources from US state-specific insurance claims data contributed to the hip, knee, and hand models, while estimations for “other” OA solely relied on US insurance claims (totaling 624 sources).

In 2020, the authors esitmated that 7.6% of the global population was living with OA (approximately 595 million people), compared with 4.8% in 1990 (256 million people). These figures constitute over a 132% increase in cases. According to the researchers’ analysis, by 2050, cases of knee OA are projected to increase by nearly 75% (59.4-89.9 per 100,000 people), hand OA by over 48% (35.9-67.1), hip OA by over 76% (57.7-105.3), and approximately 95% (68.1-135) for other forms of OA.

Globally, the 2020 rate of age-standardized YLDs for total arthritis was 255 per 100,000 people, which is a 9.5% increase compared with 1990 (233). In this time frame, site-specific OA increases were observed in the hip (6% higher incidence), knee (8.2%), hand (14.1%), and “other” (5.4%) categories. Overall, the global figures of YLDs for total OA grew by 134% (9.28 million in 1990 to 21.7 million in 2020). The authors note that OA affects women at higher rates than men, the prevalence of total OA increases with age, and OA of the knee has been the most common. Higher BMI was deemed a contributor to over 20% of OA cases.

Among the important limitations encountered throughout their study, the authors noted that most surveys were conducted in subpopulations and therefore cannot always be considered nationally representative. Additionally, they acknowledge that risk and risk factors can vary between urban, metropolitan, or rural communities. The authors also made sure to mention that their heavy use of US claims data could skew their global figures and that BMI was the only reliable, predictive covariant in their GBD modeling.

The study’s findings portray the increasing economic and physical burden OA will have. As things stand in the year 2020, higher-income regions of North America and Southeast Asia register the highest number of cases; however, projections for population growth show that areas like sub-Saharan Africa will be most affected by OA by 2050. In the researchers’ estimations, global prevalence for each site of OA will increase by 48.6-95.1% in the coming decades. Steinmetz et al. urge for future studies that incorporate fatality-burden, the genetic, metabolic, and behavioral differences between regions, as well as other prominent risks factors like occupation and previous injury to develop better approaches and prepare for the future of OA.

References

Steinmetz JD, Culbreth GT, Haile LM, et al. Global, regional, and national burden of osteoarthritis, 1990-2020 and projections to 2050: a systematic analysis for the global burden of disease study 2021. Lancet Rheumatol. Published online August 21, 2023. doi: 10.1016/S2665-9913(23)00163-7