Clinical and Economic Burden Among People with Knee Osteoarthritis and Obesity in the United States: A Retrospective Analysis

Obesity and knee osteoarthritis (KOA) are prevalent conditions that significantly impact public health and healthcare costs. We aimed to quantify the economic burden and explore the relationship between obesity and KOA pain. This study used Optum’s de-identified Market Clarity Data from October 1, 2015, to March 31, 2024. Adults (≥ 45 years) with moderate-to-severe osteoarthritis (MTS-OA) knee pain (index date: first-observed claim with a KOA diagnosis between October 1, 2016, and March 31, 2023), with continuous enrollment in commercial, Medicare, or Medicaid healthcare plans for 1 year before and after post index, were included. The presence of KOA pain was identified using a previously validated algorithm. Adjusted annualized all-cause and KOA-related healthcare resource utilization and costs were assessed in the first year after index date, stratified by body mass index (BMI) categories: normal (≥ 18.5 to < 25 kg/m2), overweight (≥ 25 to < 30 kg/m2), Class 1 obesity (≥ 30 to < 35 kg/m2), Class 2 obesity (≥ 35 to < 40 kg/m2), and Class 3 obesity (≥ 40 kg/m2). Models were adjusted for age, race, sex, payor type, baseline Charlson Comorbidity Index score, and baseline cost. Adjusted costs were winsorized at 1%. The prevalence of obesity-related complications was high, particularly among those with a BMI ≥ 35 kg/m2. Adjusted total healthcare costs (mean [standard deviation]) SD]) were the highest in individuals with Class 3 ($37,698 [$34,239])) and Class 2 ($33,676 [$29,627]) obesity) compared with those in individuals with normal BMI ($32,402 [$32,290]). Similar trends were observed with pharmacy and medical costs (Class 3: $15,040 [$41,754] and $25,493 [$16,927]; Class 2: $11,088 [$33,879] and $24,075 [$15,540]; normal BMI: $9327 [$32,165] and $23,821 [$17,474]). KOA-specific pharmacy, medical, and total costs followed a similar pattern. In people with MTS-OA knee pain, this descriptive analysis revealed higher observed average overall and disease-specific healthcare expenditure in Class 2 and 3 obesity than in other BMI categories.