Volume-Outcome Relationships in Reverse TSA

In an OrthoBuzz post from early 2016, JBJS Editor-in-Chief Marc Swiontkowski, MD observed the following about volume-outcome relationships in total hip and total knee arthroplasty: “the higher the surgeon volume, the better the patient outcomes.”

Now, in a national database analysis of >38,200 patients who underwent a reverse total shoulder arthroplasty (RSA), Farley et al. find a similar inverse relationship between hospital volumes of this increasingly popular surgery and clinical outcomes. Reporting in the March 4, 2020 issue of JBJS, they found a similarly inverse relationship between hospital volume and resource utilization.

This study distinguishes itself with its large dataset and by crunching the data into specific hospital-volume strata for each category of clinical outcome (90-day complications, 90-day revisions, and 90-day readmissions) and resource-utilization outcome (cost of care, length of stay, and discharge disposition).

Specifically, on the clinical side, Farley et al. found the following:

• A 1.42 times increased odds of any medical complication in the lowest-volume category (1 to 9 RSAs/yr) compared with the highest-volume category (≥69 RSAs/yr)
• A 1.38 times increased odds of any readmission in the lowest-volume category (1 to 16 RSAs/yr) compared with the highest-volume category (≥70 RSAs/yr)
• A 1.88 times increased odds of any 90-day revision in the lowest-volume category (1 to 16 RSAs/yr) compared with the highest-volume category (≥54 RSAs/yr)

Here are the findings from the resource-utilization side:

• A 4.03 times increased odds of increased cost of care in the lowest-volume category (1 to 5 RSAs/yr) compared with the highest-volume category (≥106 RSAs/yr)
• A 2.26 times increased odds of >2-day length of stay in the lowest-volume category (1 to 10 RSAs/yr) compared with the highest-volume category (≥106 RSAs/yr)
• A 1.68 times increased odds of non-home discharge in the lowest-volume category (1 to 31 RSAs/yr) compared with the highest-volume category (≥106 RSAs/yr)

Farley et al. say hospital volume should be interpreted as a “composite marker” that is probably related to surgical experience, ancillary staff familiarity, and protocolized pathways. They “recommend a target volume of >9 RSAs/yr to avoid the highest risk of detrimental 90-day outcomes,” and they suggest that the outcome disparities could be addressed by “consolidation of care for RSA patients at high-performing institutions.”