Background/Purpose:

Individuals with systemic lupus erythematosus (SLE) frequently have arthralgia, but joint damage leading to surgery is thought to be less common. In addition to inflammatory damage, other reasons like avascular necrosis (AVN), often associated with steroid use and antiphospholipid syndrome (APS), may increase the likelihood of large joint failure.  Demonstrating the risk of joint replacement in lupus patients and factors contributing to this may allow preventative action.

Methods:

We performed a retrospective matched case control study of all total hip replacements (THR) and total knee replacements (TKR) between 1991 and 2011 recorded in the General Practice Research Database (GPRD), a primary care database containing data on approximately 3.6 million patients from over 480 primary care practices. There were two controls for each case of primary THR or TKR, matched for age, sex and GP practice location (a proxy for socio-economic status). The odds of having THR or TKR for individuals with SLE were compared with those without lupus through Chi-squared analysis followed by conditional logistic regression taking account of the matching. Individuals with inflammatory arthritis due to any other cause were excluded and results adjusted for steroid use and APS.

Results:

During the 20-year study period 63162 patients had a primary THR (123624 matched controls). Within this total sample size of 186786, 122 individuals with a previous diagnosis of SLE had a THR performed (see table). After excluding those who had an inflammatory arthritis other than lupus, there remained 181464 individuals without lupus and 60167 of them underwent primary THR (see table). During the same period 54276 individuals had a primary TKR (106302 matched controls). Again out of this new total sample size of 160578, 124 individuals with a diagnosis of SLE had a TKR performed (see table). After exclusions for other inflammatory arthritis, there were 154850 individuals without lupus, 50658 of whom underwent primary TKR (see table). Overall, for individuals with a previous diagnosis of SLE, the unadjusted odds ratio (OR) of having a THR was 1.43 (95% confidence interval (CI): 1.13 to 1.81, p=0.0030) over those without lupus and that for having a TKR was 2.54 (95% CI: 1.94 to 3.33, p<0.0001). However, after adjustment the OR were 1.20 (95% CI: 0.94 to 1.52, p=0.1441) and 1.91 (95% CI: 1.44 to 2.53, p<0.0001) respectively.

Conclusion:

Patients with lupus who have a THR or TKR tend to be younger than their peers without lupus. In addition, they appear to have a significantly increased risk of TKR but the increased risk of THR does not remain after adjustment for anti-phospholipid syndrome and steroid use.

	THR	THR	TKR	TKR
	Without Lupus	With Lupus	Without Lupus	With Lupus
Number of individuals	60167	122	50658	124
Mean Age (years)	69.5	65.7	70.4	66.3
Male:Female	1:1.6	1:10	1:1.3	1:8
OR unadjusted		1.43              (p = 0.0030)		2.54 (p = <0.0001)
OR adjusted		1.20 (p = 0.1441)		1.91 (p = <0.0001)

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/what-is-the-risk-of-having-a-total-hip-or-knee-replacement-for-patients-with-lupus/