Robotic Arm-Assisted Total Hip Arthroplasty Is More Cost-Effective Than Manual Total Hip Arthroplasty

A Markov Model Analysis

David R. Maldonado, MD; Cammille C. Go, BS; Cynthia Kyin, BA; Philip J. Rosinsky, MD; Jacob Shapira, MD; Ajay C. Lall, MD, MS; Benjamin G. Domb, MD

Disclosures

J Am Acad Orthop Surg. 2021;29(4):e168-e177. 

In This Article

Results

Reference Case

For the reference case, RAA THA was both less costly and more effective than mTHA. At the 5-year time point, mean cumulative Medicare costs were $14,410 ± 40 and $15,355 ± 115 for RAA THA and mTHA, respectively, whereas the mean cumulative private payer costs were $15,212 ± 82 and $17,022 ± 204, respectively. The mean cumulative utilities were 2.96 ± 0.58 and 2.92 ± 0.57 QALY for RAA THA and mTHA, respectively. Thus, RAA THA cost saving had an average differential of $945 for Medicare and $1,810 for private insurance relative to mTHA. The calculated ICER for Medicare was −$23,625 per QALY. The ICER was negative because RAA THA was dominant over mTHA, being both less costly and more effective.

Sensitivity Analyses

Model parameters were varied individually by 10% as part of the 1-way sensitivity analyses to determine which parameters had the greatest impact on cost effectiveness.[24] A tornado diagram was created to show the impact of each parameter on ICER (Figure 2). Only two parameters were sensitive and affected preferred treatment strategy: utility of RAA THA and utility of mTHA. Although not sensitive, costs of infection and dislocation had the next-most impact on the treatment of choice.

Figure 2.

Tornado diagram of the Medicare cost differential ranges for mTHA versus RAA THA. Tornado diagram of the Medicare cost differential ranges for mTHA versus RAA THA, resulting from 1-way sensitivity analyses in which the different costs were individually varied by 10%. Only the top eight most impactful parameters are shown. The black line represents the ICER of −$23,625 per QALY for the reference case. ICER = incremental cost-effectiveness ratio, mTHA = manual total hip arthroplasty, QALY = quality-adjusted life year, RAA = robotic arm-assisted, THA = total hip arthroplasty

One hundred thousand microsimulations were run to assess the potential variability of outcomes among patients. At the selected WTP threshold of $50,000/QALY, RAA THA was determined to be more cost effective than mTHA in 99.4% of the cases (Figure 3). Probabilistic sensitivity analysis indicated that cumulative Medicare costs at 5 years ranged from $14,274 to $14,456 for RAA THA and from $14,646 to $15,084 for mTHA (Figure 4). Cumulative private payer costs ranged from $15,012 to $15.411 for RAA THA and $16,526 to $17,516 for mTHA.

Figure 3.

Incremental cost-effectiveness ratio (ICER) Scatter plot. Scatterplot of resulting ICER from 100,000 microsimulations showing individual patient variability. mTHA = manual total hip arthroplasty, RAA = robotic arm-assisted, THA = total hip arthroplasty

Figure 4.

Graph showing the cumulative costs for Medicare. The values are derived from 100,000 simulations using a probabilistic sensitivity analysis. $ = 2019 US dollars, mTHA = manual total hip arthroplasty, RAA = robotic arm-assisted, THA = total hip arthroplasty

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