Hip Surgery Safe, Effective in Psoriatic Arthritis

Pam Harrison

October 12, 2015

Patients with psoriatic arthritis (PsA) or cutaneous psoriasis (PsC) are not at risk for worse outcomes after total hip arthroplasty (THA) than patients with osteoarthritis (OA), and they need to be counseled accordingly, according to a nested case-control study.

The study was published online September 11 in Arthritis & Rheumatology.

In a comparison of outcomes after hip replacement surgery between patients with PsA and PsC and control patients with OA, neither PsA nor psoriatic skin disease nor extent of skin disease at the time of surgery were independent risk factors for worse pain or function after THA. Nor were there any differences in overall satisfaction with the surgery between the three treatment groups, with approximately 80% to 90% of the patients in each group indicating they were very satisfied with results, and only 1% to 3% of each group indicating that they were very dissatisfied.

"The older literature suggested that patients with PsA were prone to extremely high rates of complications, specifically infection, but they also didn't tend to do as well functionally after THA — they developed contractures and had poorer functional outcomes," senior author Susan Goodman, MD, associate professor of clinical medicine, Weill Cornell Medical School, New York City, told Medscape Medical News.

"But the treatment of both PSA and surgical techniques have changed markedly in the past several decades, and this topic just warranted a re-evaluation," she said. "And our hypothesis was that these patients would do as well as patients with OA, so we weren't surprised by the results, but we were delighted that we were dead-on."

Lead author Lisa Mandl, MD, MPH, from the Hospital for Special Surgery, New York City, and colleagues identified 63 patients with PsA and 153 patients with PsC who had undergone THA at the Hospital for Special Surgery. Pre- and postoperative features of both groups were compared with those of 915 control patients with OA treated at the same facility.

"There were no statistically significant differences in age, race, or education between THA patients with psoriatic arthritis, cutaneous psoriasis, or osteoarthritis," Dr Mandl and colleagues observe. Patients with OA did have a lower body mass index, at 27.8 kg/m2, than those with PsA, at 30.1 kg/m2, and those with PsC, at 29.0 kg/m2 (P = .002). In addition, patients with OA had a lower American Society of Anesthesiologists class: only 15% were class III or above vs 32% of patients with PsA and 23% of those with PsC (P < .001).

Comparisons between patients with PsA and those with psoriatic skin disease also showed that patients with PsA were more likely to be receiving biologic therapy compared with those with psoriatic skin disease (P < .001), but there were no differences in self-reported severity of skin disease at the time of THA between patients with PsA and those with PsC. There were also no statistically significant or clinically meaningful differences in either preoperative or postoperative measures of pain or function between the three treatment groups.

However, as the authors note, worse preoperative Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain was associated with worse postoperative WOMAC pain among all patients, whereas a better mental component score significantly decreased the risk for worse pain and being a current smoker significantly increased the risk for worse pain. In addition, worse preoperative function and physical and mental component scores, being a current smoker at the time of the procedure, and age were all associated with worse postoperative function in multivariable adjusted regression analysis.

Table. Pain and Function 2 Years After THA

Pain and Function PsA Skin Psoriasis OA
Preoperative WOMAC function 51.4 49.4 49.3
Postoperative WOMAC function 16.3 19.6 18.8
Poor postoperative function 12% 18% 20%
Preoperative WOMAC pain 49.1 44.7 45.9
Postoperative WOMAC pain 14.9 16.1 22.1
Poor postoperative pain 12% 13% 16%

The only outcome measure that appeared to be worse in patients with PsA and PsC compared with in patients with OA was the postoperative Euroqol ED-5Q score, at 0.6 for patients with PsA patients, 0.7 for those with skin psoriasis, and 0.8 for control patients with OA (P < .0001).

"This is interesting," the investigators note, "as it suggests that psoriasis patients may not perceive the same benefit from their surgery for similar levels of pain and function." The authors also felt it was interesting that patients in all three treatment groups had similar levels of pain and disability at the time they chose hip replacement surgery.

"I think what we did show is that outcomes are as good for these two groups of patients as they are for patients with OA, and that importantly, we didn't see an increase in complications in these patient groups," Dr Goodman said. "So I think the usual criteria for suitability and referral for arthroplasty should apply to PsA patients as well."

Risk for Infection

Asked by Medscape Medical News to comment on the study, Elaine Husni, MD, director, arthritis and musculoskeletal treatment center, Cleveland Clinic, Ohio, felt that reluctance to offer joint replacement surgery to patients with certain comorbidities, such as PsA, probably included any patient with any form of inflammatory arthritis, among whom the risk for infection after surgery was potentially higher because of their need for immunomodulatory drug therapy. And as a rheumatologist who cares for patients with joint disease, Dr Husni herself recommends hip arthroplasty when a patient needs one.

"I think the literature is now showing us that people should do joint replacement surgery if it's medically indicated, and they might want to do it at a time when the patient's preoperative function is still relatively better preserved, rather than waiting until the patient is really immobile," Dr Husni said. "So I think this study gives surgeons more confidence that they should be able to operate safely and effectively on patients with inflammatory arthritis, and I'm glad the authors did it."

The study was funded by a discovery grant from the National Psoriasis Foundation and the Agency for Healthcare Research and Quality Centers for Education & Research on Therapeutics. The authors and Dr Husni have disclosed no relevant financial relationships.

Arthritis Rheumatol. Published online September 11, 2015. Abstract

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