PT VS TKA: WEIGHING THE PROS AND CONS

Purpose: The purpose of this project is analyze the decision of a patient with knee osteoarthritis (OA) who must choose to either immediately undergo total knee arthroplasty (TKA) or to use physical therapy (PT) in the hope of delaying or avoiding the need for surgery. A cost effectiveness analysis was conducted to determine whether the potential of PT to delay or avoid an eventual TKA outweighs the disadvantages both in terms of cost and diminished quality of life (QOL) of undergoing PT. The findings of this analysis should be relevant to third party payers in addition to patients.

Method:    A Markov model was used because it simulates the ongoing possibilities of TKA failure and of ceasing PT treatment in order to undergo surgery. The six possible states in the Markov model are: PT treatment, post successful surgery, post unsuccessful surgery, failed TKA, post salvage procedure, and death. The analysis was conducted for a patient who is 65 years old when they initially make the decision between TKA and PT and analyzes outcomes and costs over a 25 year time horizon. Data for the transition probabilities between states and the QOL values of the six states were obtained from published studies where possible. Where this was not possible, baseline assumptions were made about the model parameters and preliminary sensitivity analyses were conducted. Sensitivity analyses were performed with the values for annual probability of requiring a revision, QOL in the PT state, cost of PT, and probability that a person undergoing PT can avoid surgery in a given year. All analyses were conducted with TreeAge Pro 2012 (Williamstown, Massachusetts).

Result:    The results based on the baseline assumptions were that the expected costs for an initial choice of TKA are $29,273.71 and the expected costs for an initial choice of PT are $25,356.22. The expected utility for TKA is 14.19 QALYs and for PT is 13.89 QALYs. Thus TKA has an incremental cost effectiveness ratio (ICER) of $13,058.30 / QALY.

Conclusion: The conclusion of this project is that depending on the assumptions made, it may or may not be cost effective for patients to use PT in the hope of delaying the use of TKA. More precise parameter estimates and further sensitivity analyses will enable more definitive conclusions.