Background/Purpose:  Osteoarthritis (OA) is the most common form of arthritis and leading cause of working age disabilities. Over 27 million US adults have clinical OA, and different types of burdens exist based on the disease stages and locations. The burden of OA by joint location, age, or comorbidity has not been well studied. The objective of this study was to assess the excess healthcare resource use and costs attributable to OA by joint location, age, and comorbidity in a privately insured population.

Methods: 428,084 OA patients aged 18+ were selected from a US-based employer claims database (1999–2011). Controls were selected from the same database by matching OA patients 1:1 by age, gender, index date, and follow-up, to patients who never had OA in their claims histories. Descriptive analyses were used to compare baseline characteristics and study period medical resource use and costs, inflated to 2011 USD using annual medical CPI data (Bureau of Labor Statistics). Statistical comparisons were made using McNemar’s test for categorical variables and the Wilcoxon signed-rank test for continuous variables.

Results:  Among all the OA patients studied, 181,379 had a primary claim of knee OA; 48,617 had hip OA; 29,340 had hand OA; and 30,549 had spine OA. The average age of OA patients was 63 years and 59% were female. At baseline, OA patients tended to have a greater comorbidity burden than controls (P< 0.001). The occurrence of the 4 most common comorbidities between the OA group and controls were hypertension (45% vs 30%, respectively), cardiovascular disease (16% vs 9%, respectively), diabetes (16% vs 10%, respectively), and depression (8% vs 4%, respectively). OA patients aged 18+ incurred total annual medical costs of $8,644 vs $2,273 in controls (P< 0.001). 20% of all OA patients had at least 1 primary joint arthroplasty, 1% had a revision joint arthroplasy, and 2% had arthrodesis. The cost per surgery ranged from $16,000 to $25,000. On average, a hip arthroplasty cost $18,425 and a knee arthroplasty cost $17,433. Annual pharmacy cost was $2,179 for OA patients and $1,096 for controls. OA-related healthcare costs are summarized by joint locations, age, and comorbidity in Table 1.

Conclusion:  Patients with OA incur greater medical and pharmacy costs than those without OA. The burden of OA varies substantially by joint location. Surgical procedures are the most significant cost among all categories, and therefore is also the main driver of the total cost. In contrast, pharmacy costs are rather small due to no disease-modifying OA drug (DMOAD) available. Hand OA had lower cost than knee and hip due to lack of DMOAD and effective surgery. In summary, OA presents a great disease and economic burden. The current treatment options are limited to generic symptom-modifying drugs and late-stage surgical management of the disease, but the latter is only available for certain joints.

Table 1. OA-Related Mean Cumulative One-Year Costs by Joint Location, Age, and Comorbidity

Subgroup	Total Medical*	Inpatient	Outpatient	Physical or Occupational Therapy	Pharmacy
Overall	$8,644	$3,533	$4,921	$265	$2,179
Joint location
Knee	$9,466	$4,178	$5,093	$292	$2,086
Hip	$12,478	$7,473	$4,818	$295	$2,047
Hand	$6,705	$1,505	$5,004	$221	$2,256
Age group, y
18–44	$10,857	$3,398	$7,070	$440	$1,794
45–64	$12,799	$5,400	$7,144	$395	$2,258
65+†	$3,510	$1,429	$2,002	$84	$2,156
Comorbidity
Hypertension	$8,917	$3,855	$4,857	$232	$2,519
CVD	$10,844	$4,993	$5,575	$157	$3,150
Diabetes	$10,815	$4,709	$5,859	$242	$3,358
CVD=cardiovascular disease; OA=osteoarthritis. *Total medical costs are equal to the sum of inpatient, outpatient, and emergency room costs. †Costs for 65+ may be underestimated because payments observed here are supplements to   Medicare.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-economic-burden-of-osteoarthritis-in-americans-analysis-from-a-privately-insured-population/