Sunday, January 15, 2017

Pseudoparalysis - what is it and how should it be treated?

Cost-Effectiveness of Arthroscopic Rotator Cuff Repair Versus Reverse Total Shoulder Arthroplastyfor the Treatment of Massive Rotator Cuff Tears in Patients With Pseudoparalysis and Nonarthritic Shoulders

These authors define pseudoparalysis as a condition of the shoulder with active elevation of less than 90 in association with full passive elevation. They performed a Markov decision model analysis for the cost effectiveness of treatment of shoulders with pseudoparalysis without osteoarthritis, in other words the patients in question did not have cuff tear arthropathy. They compared  arthroscopic rotator cuff repair (ARCR) to reverse total shoulder arthroplasty (RTSA).

They found that for the base-case scenario(60-year-old patient), ARCR with conversion to RTSA on potential failure was the most cost-effective strategy when they assumed equal utility for the ARCR and RTSA health states. Primary RTSA became cost-effective when the utility of RTSAexceeded that of ARCR by 0.04 quality-adjusted life-years per year. Age at decision did not substantially change this result. These results are shown in the table below.

Comment: This article is important because it challenges the common paradigm that reverse total shoulder is the indicated treatment for most cases of pseudo paralysis.

Instead, this article is based on the assertions that (1) pseudo paralysis can be reversed without a reverse total shoulder, (2) reverse total shoulders are more expensive than non-prothesthetic approaches to pseudoparalysis, and (3) reverse total shoulders can have more serious and more expensive complications than non-prosthetic approaches to pseudoparalysis.

With these assumptions, their model suggests that an arthroscopic attempt to improve the integrity of the rotator cuff followed by a period of rest and rehabilitation is a more cost-effective alternative than a primary reverse total shoulder.

In trying to understand Markov model formulations, it is important to consider the utilities of the two treatments. Here the health related quality of life (HRQoL) for each treatment experienced over time was accumulated into quality-adjusted life-years (QALYs).

In this case these utilities were gathered from a small number of studies. 

The 2 studies included for RTSA utility reported on largely female (approximately 75%) and elderly (mean age 75 years) samples and found a mean HRQoL of 0.68 after RTSA.

The 4 studies included for arthroscopic cuff repair reported on relatively younger (mean age 55 years) and predominantly male (approximately 43% female) undergoing ARCR to find an average HRQoL of 0.78. None of these studies evaluated the integrity of the cuff after repair, so although the authors state that they were 'clearly able to repair' massive cuff tears, the durability of these attempted reattachments of the tendons to their insertion site has not been determined. In one of these studies  (see this link), the pseudoparalysis was acute, having been present for a mean of 3.9 months before surgery and was traumatic in origin in 45 (80.4%) patients. 

Lacking a clear best estimate for utility after RTSA and ARCR in an equivalent patient set, the authors arbitrarily assumed an equal base case HRQoL of 0.788 for both RTSA and ARCR. It is left to the reader to determine whether this assignment is reasonable.

Here are some other elements of the model

These authors have created a model based on available data. We suspect that they will continue to refine the model as more data become apparent so that it can develop into useful practice guidelines.

Such studies need to be interpreted with care as shown in this link, which points out that the sophisticated mechanics of the Markov model cannot compensate for uncertain assumptions.


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