In this study, we observed that RA patients undergoing shoulder arthroplasty were significantly younger than non-RA patients undergoing shoulder arthroplasty. At first, this observation seems to counter recent literature suggesting that the age of patients with inflammatory arthropathy undergoing TJA is increasing over time;1 however, looking more closely at the data, it becomes clearer that the mean age we report is actually a relative increase as compared with past clinical studies pertaining to RA patients undergoing shoulder arthroplasty (mean ages of 47 years,23 55 years,24 60 years,10 and 62 years25). On the other hand, the continued existence of an age gap between RA and non-RA patients undergoing shoulder arthroplasty may be the result of several possible phenomena. First, this may reflect issues with patient access to and coverage of expensive biologic antirheumatic medication that would otherwise mitigate disease progression. For instance, the out-of-pocket expense for biologic medication through Medicaid and Medicare is substantial,26 which has direct implications on over two-thirds of our RA cohort. Second, it may be skewed by the proportion of RA patients who have previously been or continue to be poorly managed, enabling disease progression to end-stage arthropathy at a younger age. Ultimately, further investigation is needed to determine the reasons for this continued age disparity.
In comparing RA and non-RA patients undergoing shoulder arthroplasty, we did not find a significant difference in the overall nor the individual rates of early adverse events. This finding appears to be unique, as similar studies pertaining to total knee arthroplasty (TKA) demonstrated a significantly higher incidence of postoperative pneumonia and bleeding requiring transfusion among RA patients as compared with non-RA patients.27 In patients with RA being treated with biologic medication and undergoing shoulder arthroplasty, the frequent concern in the postoperative period is the integrity of the wound and the potential for infection.28 In this study, we did not find a significant difference in the rate of early infection, and although the difference in the rate of early wound dehiscence approached significance, it did not meet the threshold of 0.05 (P = .09). This finding is in keeping with the aforementioned NIS study pertaining to TKA, and we believe that it likely reflects the short duration of follow-up for patients in both studies. Given the nature of the database we utilized, we were only privy to complications that arose during the inpatient hospital stay, and it is likely that the clear majority of patients who develop a postoperative infection or wound dehiscence do so in the postoperative setting following discharge. A second concern regarding postoperative wound complications is the management of biologic medication in the perioperative period, which we cannot determine using this database. Despite all these limitations specific to this database, a past systematic review of reverse TSA in RA patients found a low rate of deep infection after reverse TSA in RA patients (3.3%),17 which was not higher than that after shoulder arthroplasty performed in non-RA patients.
A final demonstration from this study is that the hospital length of stay was significantly longer for RA patients than non-RA patients undergoing shoulder arthroplasty; however, given that the difference was only 0.1 days, and there was no significant difference in hospitalization cost, we are inclined to believe that statistical significance may not translate into clinical significance in this scenario. Ultimately, we do believe that length of stay is an important consideration in the current healthcare system, and given our finding that shoulder arthroplasty in the RA patient is safe in the early postoperative period, that a prolonged postoperative hospitalization is not warranted on the sole basis of a patient’s history of RA.
As with all studies using data from a search of an administrative database, such as the NIS database, this study has limitations. First, this type of research is limited by the reliability of both diagnosis and procedural coding. Although the NIS database has demonstrated high reliability,3 it is still possible that events may have been miscoded. Second, the tracking period for adverse events is limited to the inpatient hospital stay, which may be too short to detect certain postoperative complications. As such, the rates we report are likely underestimates of the true incidence of these complications, but this is true for both the RA and non-RA populations. Third, the comparisons we draw between RA and non-RA patients are limited to the scope of the NIS database and the available data; as such, we could not draw comparisons between preoperative disease stage, intraoperative findings, and postoperative course following hospital discharge. Lastly, our data are limited to a distinct period between 2002 and 2011 and may not reflect current practice. Ultimately, our findings may underestimate current trends in shoulder arthroplasty utilization among RA patients, particularly for the reverse TSA.
CONCLUSION
In this study, we found that the utilization of shoulder arthroplasty in patients with RA increased significantly from 2002 to 2011, largely related to a rise in the utilization of TSA. Similarly, we observed a rise in the proportion of RA patients undergoing shoulder arthroplasty with a corresponding diagnosis of rotator cuff disease, and we believe the increased utilization of shoulder arthroplasty among RA patients resulted from management of both end-stage inflammatory arthropathy and rotator cuff disease. Although we did not find a significant difference between RA and non-RA patients in the rates of early adverse events and overall hospitalization costs following shoulder arthroplasty, length of stay was significantly longer among RA patients; however, the absolute difference does not appear to be clinically significant.