Background/Purpose: Outcomes of total hip replacements (THR) in psoriatic arthritis (PsA) are poorly studied.  Previous studies are conflicting, often not separating inflammatory PsA from osteoarthritis (OA) with cutaneous psoriasis (PsC). This study evaluates THR outcomes in PsA compared to both PsC+OA and OA alone.

Methods: This study utilized cases from a high volume single institution THR registry enrolled between 5/2007 and 12/2011. Potential PsA cases were identified by ICD-9 code (696.0-.1) and matched 4:1 (on age, primary vs. revision and date of surgery) with OA THR.  THR with other rheumatic disease or fractures were excluded. Patient reported outcomes were collected at baseline and 2 years; non-responders received an additional questionnaire at 3-5 years.  Differences between groups were compared using ANOVA, and multivariate logistic regressions were performed to identify independent predictors of poor post-op pain and function, (WOMAC < 60). This study was IRB approved.

Results: 289 potential PsA were identified; 69 PsA and 167 PsC+OA were validated by chart review.  Post-op self-report data were available in 64% PsA, 63% PsC+OA and 83% OA.  4% of self-reported outcomes were elicited 3-5 years post-op.  There was no difference in race, age or education between groups.  PsA and PsC+OA had more co-morbidities (0 Deyo co-morbidities: PsA 61% vs. PsC+OA 68% vs. OA 80%; p-value=0.004) and worse ASA class.  More PsA and PsC+OA were current or previous smokers. 87% of PsA were on biologics or non-biologic DMARDs compared to 7% of PsC+OA. There was no statistically significant difference in pre-or post-op WOMAC pain or function or SF-12 PCS scores between groups. SF-12 MCS scores were higher in OA both pre-and post-operatively (p-values=0.003 and <0.001 respectively). EQ-5D scores were worse both pre- and post-operatively in PsA and PsC+OA (p-value=0.006 and p-value<0.001). Overall satisfaction with THA was equally high for all groups, with > 80% being very satisfied (p-value=0.82).  In multivariate logistic regressions, (Table 2), a diagnosis of PsA or PsC+OA did not statistically significantly increase the odds of either poor post-op pain or function.  Revision THR had much higher odds of poor post-op pain, and worse pre-op pain and function were statistically associated with poor post-op pain and function, respectively. Current smoking has >3x increased odds of poor post-op pain and function.

Conclusion: Despite worse pre-operative health status, PsA or PsC+OA were not independent risk factors for poor THR outcomes.  These results should be communicated to PsA and PsC+OA patients contemplating THR.

 

Table 1: Demographic Data	PsA (N=69)	PsC+OA (N=167)	OA (N=771*)	P-Value
Male, n (%)	36 (52%)	92 (55%)	343 (45%)	0.035
Age, years (SD)	60.6 (11.2)	63.6 (11.9)	63.2 (11.0)	0.14
BMI (SD)	29.6 (5.1)	29.3 (6.5)	27.6 (5.2)	<0.001
Caucasian, n (%)	43 (93%)	93 (98%)	715 (94%)	0.26
Pre-operative SF-12 MCS (SD)	47.9 (13.8)	46.9 (12.9)	51.2 (12.3)	0.003
Post-op  SF-12 MCS (SD)	50.8 (10.9)	49.4 (11.6)	53.5 (9.5)	<0.001
Pre-operative EQ-5D (SD)	0.6 (0.2)	0.6 (0.2)	0.7 (0.2)	0.006
Post-op  EQ-5D (SD)	0.6 (0.3)	0.7 (0.2)	0.8 (0.2)	<0.001
ASA Class, n (%)				<0.001
Class 1	0 (0%)	12 (7%)	70 (9%)
Class 2	47 (68%)	116 (69%)	590 (77%)
Class 3	22 (32%)	36 (22%)	110 (14%)
Class 4	0 (0%)	3 (2%)	1 (0%)
≥College Education, n (%)	27 (75%)	48 (72%)	559 (74%)	0.91
Pre-op WOMAC Pain (SD)	52.9 (17.0)	55.6 (17.4)	54.6 (18.6)	0.74
Post-op WOMAC Pain (SD)	84.5 (20.2)	84.6 (20.3)	83.7 (22.6)	0.92
Pre-op WOMAC Function (SD)	49.3 (17.2)	50.7 (18.8)	51.1 (19.1)	0.85
Post-op WOMAC Function (SD)	83.0 (19.9)	81.0 (21.8)	80.5 (23.7)	0.82
Do you currently smoke?				0.005
Yes	4 (9%)	2 (2%)	29 (4%)
No, but I smoked previously	26 (60%)	58 (61%)	345 (46%)
Never	13 (30%)	35 (37%)	371 (50%)
*771/931 OA control data were available for analysis

 

Table 2: Predictors of Having Poor Post-Operative Pain or Function (WOMAC <60) After THR*
	Poor Post-Operative Pain WOMAC (<60) Odds Ratio (95% CI)	Poor Post-Operative Function WOMAC (<60) Odds Ratio (95% CI)
PsC+OA vs. OA	1.00 (0.46, 2.19)	1.01 (0.49, 2.08)
PsA vs OA	0.83 (0.28, 2.43)	0.83 (0.29, 2.38)
Primary vs. Revision	0.40 (0.19, 0.84)	0.73 (0.35, 1.56)
Current Smoker vs Never Smoked	3.44 (1.40, 8.49)	3.60 (1.47, 8.82)
Past Smoker vs Never Smoked	1.02 (0.67, 1.55)	1.32 (0.89, 1.98)
Pre-operative WOMAC Pain	0.95 (0.93, 0.97)	1.01 (0.99, 1.03)
Pre-operative WOMAC Function	1.00 (0.98, 1.02)	0.95 (0.93, 0.97)
*Multivariate regression controlling for gender, diagnosis, BMI, ASA class, number of comorbidities, primary vs revision surgery, smoker status, pre-operative WOMAC pain and function, pre-operative MCS, Pre-operative EQ Score.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/total-hip-arthroplasty-outcomes-in-patients-with-psoriatic-arthritis-osteoarthritis-with-cutaneous-psoriasis-and-osteoarthritis/