Study findings highlight the substantial burden associated with obesity among individuals with moderate to severe knee OA and suggest that strategies targeting both excess weight and osteoarthritis may help improve outcomes while reducing healthcare costs.
Adults with moderate to severe knee osteoarthritis (OA) and obesity — particularly those with higher BMI values — experience a greater clinical and economic burden than their counterparts with lower BMI, according to study results published in Rheumatology and Therapy
Obesity is a well-established modifiable risk factor for the development and progression of knee OA, but less is known about how varying degrees of excess weight affect healthcare utilization and costs among patients with more severe disease. Researchers therefore evaluated the relationship between BMI and healthcare burden among adults with moderate to severe osteoarthritis knee pain in a large real-world US population
For this retrospective analysis, researchers used data from Optum Market Clarity, a database linking administrative claims and electronic health records. Adults aged 45 years and older with moderate to severe knee OA pain, with continuous medical and pharmacy coverage between October 2015 and March 2024, were eligible for inclusion. Participants were categorized according to baseline BMI as normal weight, overweight, or class 1, 2, or 3 obesity
The analysis included 126,052 commercially or Medicare-insured individuals. Of these, 8.1% had a normal BMI and 29.8% were overweight; 28.7% had class 1 obesity, 17.8% had class 2 obesity, and 15.6% had class 3 obesity. Across all BMI categories, most participants were women and approximately 80% were white. Mean age declined with increasing BMI, ranging from 67.7±10.9 years among those with normal BMI to 59.2±8.5 years among those with class 3 obesity
These insights highlight the need for novel treatment approaches that address both the core disease process of knee OA and the overlapping challenges posed by obesity and related comorbidities
Researchers observed a greater burden of obesity-related comorbidities among patients in the higher BMI groups. The prevalence of hypertension increased from 52.4% among those with normal BMI to 73.0% among those with class 3 obesity. Similarly, rates of type 2 diabetes rose from 17.2% to 37.1%, while obstructive sleep apnea increased from 4.8% to 34.7% across the same BMI categories
After adjustment for demographic and clinical characteristics, annual all-cause healthcare costs were highest among patients with class 3 obesity, averaging $37,698 per year, followed by those with class 2 obesity at $33,676. In comparison, adjusted annual costs among individuals with normal BMI were $32,402. Pharmacy expenditures increased substantially with BMI, rising from $9,327 among patients with normal BMI to $15,040 among those with class 3 obesity
A similar pattern emerged for knee OA-related healthcare spending. Mean annual disease-specific costs were approximately $4,900 among patients with class 2 obesity and $4,886 among those with class 3 obesity, compared with $3,299 among individuals with normal BMI. Researchers noted that medical services accounted for most of the disease-related costs across all BMI groups
Although overall healthcare utilization was relatively similar regardless of BMI, patients with class 2 or class 3 obesity tended to have more outpatient visits and incurred higher healthcare expenditures. Knee OA-related outpatient visits also increased progressively with higher BMI categories
Use of pain management therapies — including nonsteroidal anti-inflammatory drugs, opioids, acetaminophen, injectable corticosteroids, and gabapentinoids — was common across all groups and generally increased with BMI. In contrast, obesity-directed interventions — such as glucagon-like peptide-1 receptor agonists, other weight-management medications, and bariatric surgery — were used infrequently, even among patients with severe obesity
The study’s retrospective design and reliance on administrative data meant it was limited by potential coding inaccuracies and missing information, such as socioeconomic status or over-the-counter medication use. Additionally, these findings may not be generalizable to uninsured populations or underrepresented racial and ethnic groups
“These insights highlight the need for novel treatment approaches that address both the core disease process of knee OA and the overlapping challenges posed by obesity and related comorbidities,” the researchers concluded. “Such dual-action treatments could not only improve patient outcomes, but also reduce the burden of multimorbidity and curtail the escalating economic impact on healthcare systems.”
This research was supported by Eli Lilly and Company, Indianapolis, US. Multiple study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures
Schapiro D, Perez-Nieves M, Gonsahn-Bollie S, et al.Clinical and economic burden among people with knee osteoarthritis and obesity in the United States: a retrospective analysis.Rheumatol Ther. doi:10.1007/s40744-026-00856-z
