Monday, October 29, 2012

Shoulder arthroplasty lessons from Twelve-Year Risk of Revision After Primary Total Hip Replacement in the U.S. Medicare Population JBJS

Twelve-Year Risk of Revision After Primary Total Hip Replacement in the U.S. Medicare Population was just published by JBJS.
As we've seen from previous posts, rate of revision is revision is a distinct outcome measure that is often applied in population based studies, such as registries and, as here, in data bases such as that from Medicare. This article may provide some suggestions regarding reducing the rate of revision in total shoulder arthroplasty. 

Their methods are of interest in that in this retrospective Medicare cohort study of total hip replacements for osteoarthritis performed between 1995 and1996 they determined the per year risk of revision and death. This is important because many studies report the 'revision rate' (revisions/procedures) without normalizing the result to how long after the index procedure the revision was performed. Thus one study with an average followup of 5 years may have a revision rate of 2.5% while another with an average folow-up of 10 years may have a revision rate of 5%. The per year risk of revision is the same for each of these studies.

The authors found that the risk of revision total hip replacement for patients remaining alive was approximately 2% per year for the first eighteen months and then 1% per year afterwards. As we've pointed out in two recent posts here and here, the per year revision rate for total shoulders in studies of national registries is much higher for total shoulders than what is reported here for total hips.

Using multivariate Cox proportional hazard models, the relative risk of revision was 1.2 times higher in men than in women and 1.5 times higher in patients sixty-five to seventy-five years of age at the time of primary total hip replacement than in those over seventy-five years. 

Patients of surgeons who performed fewer than six total hip replacements annually in the Medicare population had a higher risk of revision than those whose surgeons performed more than twelve per year (HR, 1.21; 95% CI, 1.12, 1.32). The effect of surgeon volume on the quality of the result of shoulder arthroplasty has been posted before in this blog.  It is of more than philosophical interest to determine the number of cases per year needed to keep a surgeon on top of the factors contributing to the outcome of joint arthroplasty.


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