Method: We performed a retrospective analysis of patient hospital discharges data between 1993 and 2008 in the United States from the Nationwide Inpatient Sample (NIS) of the Healthcare Cost and Utilization Project (HCUP). We used a coding algorithm to identify all 1,742,935 patients having THR or TKR procedures, 58,036 of which had a diagnosis of RA. Difference-in-differences methodology was utilized to examine the potential effect of the introduction of biologic agents on the likelihood that RA is the primary reason for receiving THR or TKR by comparing RA patients after the time these drugs were introduced with RA patients before their introduction, and to patients' without a diagnosis of RA in order to capture general trends for THR and TKR. All models controlled for patient demographics and co-morbidities
Result: The number of annual THR procedures more than doubled between 1993 and 2008 (25,987 to 56,478), and the number of annual TKR procedures more than tripled over this period (38,136 to 125,881). However, patients with RA (as a primary or secondary diagnosis), had a statistically significant (p<.01) 28% decrease in the likelihood of RA being the primary reason for receiving THR or TKR after the time that biologic agents (In particular the TNF inhibitors etanercept, infliximab and then adalimumab) were introduced.
Conclusion: Since the time of the introduction of biologics for the treatment of RA, there has been a reduction in THR and TKR surgeries among patients with a primary diagnosis of RA. This consistent and significant finding suggests that the availability of biologic agents, as well as other changes in the therapeutic approach to RA, may confer long term benefits to both RA patients and health care systems.
Disclosure: N. Tandon, Janssen Services, LLC, 3 ; G. David, Janssen Services, LLC, 5 ; A. Kavanaugh, Centocor R and D, a division of J and J Pharmaceutical R and D, LLC, 2 ; C. Gunnarsson, Janssen Services, LLC, 5 .