Lifetime medical costs of knee osteoarthritis management in the United States: impact of extending indications for total knee arthroplasty

Abstract

Objective: The impact of increasing utilization of total knee arthroplasty (TKA) on lifetime costs in persons with knee osteoarthritis (OA) is understudied.

Methods: We used the Osteoarthritis Policy Model to estimate total lifetime costs and TKA utilization under a range of TKA eligibility criteria among US persons with symptomatic knee OA. Current TKA utilization was estimated from the Multicenter Osteoarthritis Study and calibrated to Health Care Cost and Utilization Project data. OA treatment efficacy and toxicity were drawn from published literature. Costs in 2013 dollars were derived from Medicare reimbursement schedules and Red Book Online. Time costs were derived from published literature and the US Bureau of Labor Statistics.

Results: Estimated average discounted (3% per year) lifetime costs for persons diagnosed with knee OA were $140,300. Direct medical costs were $129,600, with $12,400 (10%) attributable to knee OA over 28 years. OA patients spent a mean ± SD of 13 ± 10 years waiting for TKA after failing nonsurgical regimens. Under current TKA eligibility criteria, 54% of knee OA patients underwent TKA over their lifetimes. Estimated OA-related discounted lifetime direct medical costs ranged from $12,400 (54% TKA uptake) when TKA eligibility was limited to Kellgren/Lawrence grades 3 or 4 to $16,000 (70% TKA uptake) when eligibility was expanded to include symptomatic OA with a lesser degree of structural damage.

Conclusion: Because of low efficacy of nonsurgical regimens, knee OA treatment-attributable costs are low, representing a small portion of all costs for OA patients. Expanding TKA eligibility increases OA-related costs substantially for the population, underscoring the need for more effective nonoperative therapies.

Figure 1. Utilization and duration of Knee OA treatments under guideline-concordant care, assuming TKA eligibility criteria is defined by persistent pain, unrelieved by non-surgical regimens and evidence of advanced knee OA (K-L grades 3 or 4)

Treatments under Treatment Strategy 2 (guideline-concordant care) are organized chronologically in order of increasing intensity along the x-axis. Intervening periods of occasional analgesic use are depicted with the hatched portions, with the longest duration of analgesic use occurring after Non-Surgical Regimen 2 and prior to primary TKA. The vertical height of each segment represents the proportion of those with symptomatic knee OA who ever received the treatment. The horizontal width of each segment represents the average duration (in years) of non-surgical regimens or prosthesis survival for those who ever received the treatment. The average time spent within each time period is written under each segment with the standard deviation, reported in years, in parenthesis. The average time spent living with symptomatic knee OA was 28.4 years. Primary and revision TKA were offered to patients with K-L grades 3 or 4.

Figure 2. Varying eligibility criteria for TKA: Effects on distribution of OA-related, lifetime direct medical costs in patients with knee OA under guideline-concordant care

The series of stacked columns compares the percent and dollar distribution of lifetime direct medical costs (discounted) attributable to the four treatments for knee OA as well as occasional analgesic use under Treatment Strategy 2 (guideline-concordant care). Columns are presented across expanding eligibility criteria for TKA (left to right). The total direct medical costs attributable to knee OA under guideline-concordant care are listed above the columns. The cost of occasional analgesic use is shown in black and positioned between regimens 2 and 3 because use of analgesics is greatest during this treatment phase. Non-surgical Regimen 1 consists of office visits, physical therapy, assistive devices, and typical pain relief medications such as NSAIDs, acetaminophen, etc. Non-surgical Regimen 2 consists of intra-articular steroid injections. Surgical Regimen 3 is total knee arthroplasty and follow-up appointments, and Regimen 4 is revision total knee arthroplasty and follow-up appointments. Analgesics are used as needed between treatment regimens, with the majority of usage occurring after Non-surgical Regimen 2 and prior to TKA.

Figure 3. Varying eligibility criteria for TKA: Effects on lifetime direct and indirect medical costs for patients with knee OA

The series of stacked columns compares the distribution of lifetime total medical costs in knee OA patients receiving guideline-concordant care across expanding eligibility criteria for TKA (left to right). The total costs for each TKA eligibility criterion are listed above the columns. OA-related direct medical costs are shown in between total indirect medical costs attributable to knee OA (above) and non-OA related direct medical costs (below). For comparison, the horizontal line represents the total cost under TKA eligibility K-L grade 2 or greater.