Economic evaluation of access to musculoskeletal care: the case of waiting for total knee arthroplasty

Abstract

Background: The projected demand for total knee arthroplasty is staggering. At its root, the solution involves increasing supply or decreasing demand. Other developed nations have used rationing and wait times to distribute this service. However, economic impact and cost-effectiveness of waiting for TKA is unknown.

Methods: A Markov decision model was constructed for a cost-utility analysis of three treatment strategies for end-stage knee osteoarthritis: 1) TKA without delay, 2) a waiting period with no non-operative treatment and 3) a non-operative treatment bridge during that waiting period in a cohort of 60 year-old patients. Outcome probabilities and effectiveness were derived from the literature. Costs were estimated from the societal perspective with national average Medicare reimbursement. Effectiveness was expressed in quality-adjusted life years (QALYs) gained. Principal outcome measures were average incremental costs, effectiveness, and quality-adjusted life years; and net health benefits.

Results: In the base case, a 2-year wait-time both with and without a non-operative treatment bridge resulted in a lower number of average QALYs gained (11.57 (no bridge) and 11.95 (bridge) vs. 12.14 (no delay). The average cost was $1,660 higher for TKA without delay than wait-time with no bridge, but $1,810 less than wait-time with non-operative bridge. The incremental cost-effectiveness ratio comparing wait-time with no bridge to TKA without delay was $2,901/QALY. When comparing TKA without delay to waiting with non-operative bridge, TKA without delay produced greater utility at a lower cost to society.

Conclusions: TKA without delay is the preferred cost-effective treatment strategy when compared to a waiting for TKA without non-operative bridge. TKA without delay is cost saving when a non-operative bridge is used during the waiting period. As it is unlikely that patients waiting for TKA would not receive non-operative treatment, TKA without delay may be an overall cost-saving health care delivery strategy. Policies aimed at increasing the supply of TKA should be considered as savings exist that could indirectly fund those strategies.

Figure 1

Health state diagram. The figure shows the health state diagram used to model patients undergoing either TKA without delay, delayed TKA with non-operative bridge treatment, or delayed TKA with no bridge treatment. The diagram reflects the distinct health states in the model.

Figure 2

Sensitivity analysis on potential wait times with net benefits as outcome. The graph shows the results of a one-way sensitivity analysis on wait times up to 60 months for primary TKA with net benefits as the outcome.

Figure 3

Societal economic impact of potential wait times. The figure shows the estimated future societal costs of delayed TKA. Values are costs only and do not include monetary value of utility. These values represent the incremental cost of each wait time with non-operative treatment bridge compared to TKA without delay baseline. They are extrapolated from data from out model combined with volume projections from Kurtz et al. [3].